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Fabian Mohamed - One of the best experts on this subject based on the ideXlab platform.
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variations in the adenohypophysis of the expression of proliferating cellular nuclear antigen oestrogen and androgen receptors in relation to gonadal steroids during pregnancy of Viscachas lagostomus maximus maximus
Reproduction Fertility and Development, 2019Co-Authors: Gabriela Judith Rosales, Edith Perez, Graciela Beatriz Rodriguez, Veronica Palmira Filippa, Fabian MohamedAbstract:Viscachas are native rodents of South America that present a long pregnancy of ~154 days. In this work, we analysed variations in the expression of proliferating cellular nuclear antigen, oestrogen and androgen receptors (ERα and AR) in pituitary pars distalis (PD) and pars tuberalis (PT) in relation to oestradiol and testosterone serum levels in non-pregnant and pregnant Viscachas. In PD, cell proliferation increased with pregnancy and lactotrophs proliferated during mid-pregnancy (MP). ERα nuclear-immunoreactive cells (ERαn-ir) were maximal in late pregnancy and AR expression did not vary during pregnancy. In PT, cell proliferation and AR expression increased during pregnancy, but ERα expression was very scarce. The immunostaining pattern of receptors was different in PD and PT. The peak of serum oestradiol and testosterone occurred during MP. Our results suggest that cell proliferation and gonadal receptors might be differentially regulated in the pituitary by oestradiol and testosterone during Viscacha pregnancy.
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Immunomorphometric variations of sustentacular cells of the male Viscacha adrenal medulla during the annual reproductive cycle. Effects of androgens and melatonin.
Acta Histochemica, 2018Co-Authors: Luis Ezequiel Gallol, Fabian MohamedAbstract:Abstract The adrenal medulla is crucial for the survival of species facing significant environmental changes. The parenchyma is composed mainly of chromaffin cells, ganglion cells and sustentacular cells (SC). The male Viscacha exhibits seasonal variations of gonadal activity and other metabolic functions. The aim of this work was to investigate the influence of the reproductive conditions on the morphology of SC of this rodent. In addition, the effects of testosterone and melatonin on these cells were studied. Immunoexpression of S100 protein, GFAP and vimentin were analyzed. Furthermore, the distribution of adrenergic and noradrenergic chromaffin cells subpopulations was studied for the first time in this species. SC present long cytoplasmic processes in contact with chromaffin cells, probably generating an intraglandular communication network. Significant differences (p
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pigmented cells in the pineal gland of female Viscacha lagostomus maximus maximus a histochemical and ultrastructural study
International Journal of Endocrinology, 2017Co-Authors: Fabricio Ivan Busolini, Veronica Palmira Filippa, Graciela Rodriguez, Fabian MohamedAbstract:The presence of pigment has been demonstrated in different nervous structures such as those of retina, substantia nigra, and locus coeruleus. These pigments have also been described in the pineal gland of different mammal species. Histochemical and ultrastructural studies of the pineal gland of female Viscacha (Lagostomus maximus maximus) were performed to analyze the presence of pigmented cells under natural conditions and to evaluate a probable relation between pigment content and glandular activity during pregnancy. The following techniques were applied: hematoxylin-eosin, phosphotungstic acid-hematoxylin, Masson-Fontana silver, DOPA histochemistry, Schmorl’s reaction and toluidine blue. Estradiol and progesterone serum levels were determined by RIA. The ultrastructural features of the pineal pigment granules were also analyzed. Pigment granules were observed in a random distribution, but the pigmented cells were frequently found near blood vessels. The pineal pigment was histochemically identified as melanin. Differences in the amount of pigmented cells were found between pregnant and nonpregnant Viscachas. The ultrastructural analysis revealed the presence of premelanosomes and melanosomes. Estradiol and progesterone levels vary during pregnancy. In conclusion, the changes in the amount of pigment content and hormone levels may indicate that the pineal gland of female Viscacha is susceptible to endocrine variations during pregnancy.
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a seasonal and age related study of interstitial cells in the pineal gland of male Viscacha lagostomus maximus maximus
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2017Co-Authors: Fabricio Ivan Busolini, Gabriela Judith Rosales, Veronica Palmira Filippa, Fabian MohamedAbstract:The pineal gland of Viscacha exhibits histophysiological variations throughout the year, with periods of maximal activity in winter and minimal activity in summer. The aim of this study was to analyze the interstitial cells (IC) in the pineal gland of male Viscachas in relation to season and age. The S-100 protein, glio-fibrillary acidic protein (GFAP), and vimentin were detected in adult and immature animals by immunohistochemistry (IHC). Double-IHC was also performed. The S-100 protein was localized within both, IC nucleus and cytoplasm. GFAP was present only in the cytoplasm. Vimentin was expressed in some IC, besides endothelial cells, and perivascular spaces. In the adult males, the morphometric parameters analyzed for the S-100 protein and GFAP exhibited seasonal variations with higher values of immunopositive area percentage in winter and lower values in summer, whereas the immature ones showed the lowest values for all the adult animals studied. Colocalization of S-100 protein and GFAP was observed. The IC exhibited differential expression for the proteins studied, supporting the hypothesis of the neuroectodermal origin. The IC generate an intraglandular communication network, suggesting its participation in the glandular activity regulation processes. The results of double-IHC might indicate the presence of IC in different functional stages, probably related to the needs of the cellular microenvironment. The morphometric variations in the proteins analyzed between immature and adult Viscachas probed to be more salient in the latter, suggesting a direct relationship between the expression of the S-100 protein and GFAP, and animal age. This article is protected by copyright. All rights reserved.
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epididymis of Viscacha lagostomus maximus maximus a morphological comparative study in relation to sexual maturity
Anatomia Histologia Embryologia, 2017Co-Authors: Albana Cruceno, Claudia Aguileramerlo, E M Chaves, Fabian MohamedAbstract:Summary The morphological variations and the androgen receptor (AR) expression were studied in Viscacha epididymis in relation to sexual maturity. The animals were divided into immature, pre-pubertal and adult, according to their corporal weight and testicular histology. The epididymides were studied by light microscopy, immunohistochemistry for AR and morphometric analysis. In pre-pubertal and adult animals, four well-differentiated segments (initial, caput, corpus and cauda) were observed, while in immature animals, three segments were identified (initial-caput segment, corpus and cauda). In each segment, the structural parameters and the relative cell distribution were different between the groups. The serum testosterone levels of pre-pubertal and adults showed a very significant increase related to sexual maturity. The AR expression in epithelial and fibromuscular stromal cells was different between the groups. In conclusion, the present work demonstrates that the morphological characteristics of the Viscacha epididymis vary while sexual maturity is reached, the development of initial and caput is subsequent to corpus and cauda development and the androgens might play an important role during this process.
Teresa Tarifa - One of the best experts on this subject based on the ideXlab platform.
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can a habitat specialist survive urbanization the case of the Viscacha lagidium viscacia chinchillidae
Urban Ecosystems, 2014Co-Authors: Francisco E Fonturbel, Teresa TarifaAbstract:Urban growth is a strong driver of habitat degradation and loss. In spite of that, a surprising diversity of native species may survive in urban areas. In the La Paz, Bolivia metropolitan area and surroundings, local populations of “Viscachas” (Lagidium viscacia) currently survive in small, isolated habitat patches. We assessed 13 study sites in 1999, 2003, and 2007 to document the effects of urban growth on L. viscacia habitats. Degree of disturbance at the study sites increased more between 1999 and 2003 than it did between 2003 and 2007 due to patterns of urban expansion. Using satellite imagery we determined that the urban area increased 566 ha (from 1987 to 2001) mostly due to southward urban area expansion down the valley where the best Viscacha habitats were located. Occupied patch area decreased 74 % between 1999 and 2007, accompanied by significant increases in patch edge-to-area ratios. Currently L. viscacia populations in La Paz are experiencing a habitat attrition process. If a current urban expansion plan for La Paz is approved, about 75 % of the remaining habitat may be lost to urban development in a short time, compromising the future viability of this species in the metropolitan area and surroundings. Environmental regulations to control urban growth of the La Paz metropolitan area are urgently required and constitute the only hope for the survival of L. viscacia in the city.
Campos, Valeria Evelin - One of the best experts on this subject based on the ideXlab platform.
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¿La disponibilidad del recurso trófico afecta la selección de grietas por Octomys mimax en el Desierto del Monte?
Conicet. Cricyt. Instituto Argentino de Investigación de las Zonas Áridas. Unidad de Zoología y Ecología Animal, 2015Co-Authors: Reus, Maria Laura, Giannoni, Stella Maris, Díaz Gabriela, Campos, Valeria EvelinAbstract:Rocky habitats have a particular microclimate and a highly complex structure, providing sites that mammals can use as dens or as nesting sites to raise their young. The complex topography of these habitats also favors water retention, thereby promoting growth of plants. The Viscacha rat (Octomys mimax; Rodentia, Octodontidae) is a rock-dwelling hystricognath rodent that lives in rocky crevices with high vegetation cover. We hypothesized that Viscacha rat selects crevices with high availability of plants included in the diet. To test this, we analyzed the diet of the Viscacha rat and compared the availability of consumed plant species between used and available crevices. The diet of this species is composed mainly of leaves of shrubs and trees, includes cacti throughout the year and seeds and fruits, principally Prosopis spp., in the wet season. The food items present in caches confirmed the results obtained from microhistological analysis, with the addition of Ramorinoa girolae and Halophytum ameghinoi. This rodent takes advantage of consuming and storing available items, behaving as an opportunistic species. Selected plant species were similar in abundance in used and available crevices; consequently, crevices are likely selected for other characteristics such as thermal benefits, an important constraint in desert environments.Los ambientes rocosos se caracterizan por un microclima particular y una compleja estructura que es usada por los mamíferos como sitios de anidación o como guaridas para sus crías. La topografía de estos hábitats favorece la retención de agua, promoviendo así el crecimiento de las plantas. La rata vizcacha (Octomys mimax; Rodentia, Octodontidae) es un roedor histricognato rupícola que vive en grietas rocosas con alta cobertura vegetal. Nosotros planteamos la hipótesis de que la rata vizcacha selecciona grietas con abundante disponibilidad de las plantas que consume. Para ello, analizamos la dieta de la rata vizcacha y comparamos la disponibilidad de las especies de plantas que consume este roedor, entre grietas usadas y disponibles. Nuestros resultados mostraron que la dieta está compuesta principalmente por hojas de arbustos y árboles, incluyendo cactus a lo largo del año y semillas y frutos, principalmente Prosopis spp., en la temporada de lluvias. Las especies registradas en los cúmulos de las grietas confirmaron los resultados obtenidos a partir del análisis microhistológico y agregan a Ramorinoa girolae y Halopthytum ameghinoi. Este roedor consume y almacena ítems disponibles, por lo que se comporta como una especie oportunista. La abundancia de las especies seleccionadas por la rata vizcacha fue similar en las grietas usadas y disponibles; probablemente la selección de las grietas responda a otros factores como el beneficio térmico, una limitación importante en el desierto.Fil: Campos, Valeria Evelin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Giannoni, Stella Maris. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Reus, Maria Laura. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Físicas y Naturales; ArgentinaFil: Díaz, Gabriela. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Campos, Valeria Evelin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentin
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Remote sensing variables as predictors of habitat suitability of the vizcacha rat (Octomys mimax), a rock-dwelling mammal living in a desert environment
'Springer Science and Business Media LLC', 2015Co-Authors: Campos, Valeria Evelin, Gatica, Mario Gabriel, Bellis, María LauraAbstract:Identifying high-quality habitats across large areas is a central goal in biodiversity conservation. Remotely sensed data provide the opportunity to study different habitat characteristics (e.g., landscape topography, soil, vegetation cover, climatic factors) that are difficult to identify at high spatial and temporal resolution on the basis of field studies. Our goal was to evaluate the applicability of remotely sensed information as a potential tool for modeling habitat suitability of the Viscacha rat (Octomys mimax), a rock-dwelling species that lives in a desert ecosystem.We fitted models considering raw indices (i.e., green indices, Brightness Index (BI) and temperature) and their derived texture measures on locations used by and available for the Viscacha rat. The habitat preferences identified in our models are consistent with results of field studies of landscape use by the Viscacha rat. Rocky habitats were well differentiated by the second-order contrast of BI, instead of BI only, making an important contribution to the global model by capturing the heterogeneity of the substratum. Furthermore, rocky habitats are able to maintain more vegetation than much of the surrounding desert; hence, their availability might be estimated using SATVI (Soil Adjusted Total Vegetation Index) and its derived texture measures: second-order contrast and entropy. This is the first study that evaluates the usefulness of remotely sensed data for predicting and mapping habitat suitability for a small-bodied rock dwelling species in a desert environment. Our results may contribute to conservation efforts focused on these habitat specialist species by using good predictors of habitat quality.Fil: Campos, Valeria Evelin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Juan. Centro de Investigaciones de la Geosfera y Biosfera; Argentina. Universidad Nacional de San Juan. Interacciones Biológicas del Desierto; ArgentinaFil: Gatica, Mario Gabriel. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico San Juan; ArgentinaFil: Bellis, María Laura. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Cordoba. Instituto de Diversidad y Ecologia Animal; Argentin
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La selección de microhábitat por Octomys mimax (Rodentia: Octodontidae) en el Desierto del Monte es afectada por los atributos y propiedades térmicas de las grietas
'SciELO Agencia Nacional de Investigacion y Desarrollo (ANID)', 2013Co-Authors: Campos, Valeria Evelin, Reus, Maria Laura, Andino, Natalia Del Pilar, Cappa, Flavio Martín, Giannoni, Stella MarisAbstract:The Viscacha rat (Octomys mimax; Rodentia, Octodontidae) belongs to a monotypic genus endemic to western Argentina and inhabits lowland deserts with abundant rocks and ravines. Our objectives were 1) to determine the attributes of crevices (depth, height, width, entrance orientation, and rock color) that influence selection by the Viscacha rat; 2) to compare the range and variance of temperature inside and outside crevices, at the soil surface, at the rock surface and in the air; and 3) to evaluate if there is a thermal gradient inside crevices, comparing range and variance of temperature at the soil surface at different depths (0, 30 and 50 cm). The Viscacha rat did not use microhabitats in proportion to availability; the species selected deep and narrow crevices with restricted access that might be used as refuge from predation and extreme climate conditions. The temperature at the soil surface and at the rock surface inside crevices was more stable (smaller ranges and variances) than the corresponding external temperatures in summer and winter. The range and variance of temperature in the air were different only in summer. Moreover, in summer the range and variance at the soil surface inside crevices were more stable with increasing depth. In winter, only temperature range showed a gradient. The insulating effect of rocks might benefit the Viscacha rat by providing a thermally stable environment, especially in summer. The present study provides quantitative evidence about the thermal behavior of rock crevices, which contributes with the traditional hypothesis proposed to explain the benefits of living in rock crevices.La rata vizcacha (Octomys mimax) pertenece a un género monotípico endémico del oeste de Argentina; habita en zonas desérticas con abundantes rocas y barrancos. Los objetivos de este trabajo fueron: 1) determinar los atributos de las grietas (profundidad, altura, ancho, orientación de la entrada y color de la roca) que influyen en la selección de grietas por parte de la rata vizcacha; 2) comparar el rango y la varianza de temperatura adentro y afuera de las grietas, en la superficie del suelo, en la superficie de la roca y en el aire y 3) evaluar si existe un gradiente térmico adentro de las grietas, comparando para ello el rango y varianza de temperatura en la superficie del suelo a diferentes profundidades (0, 30 y 50 cm). La rata vizcacha no usó los microhábitats en proporción a su disponibilidad; esta especie seleccionó grietas profundas y estrechas con accesos restringidos que pueden ser consideradas como refugio tanto del clima extremo como de los depredadores. Las temperaturas en la superficie del suelo y de la roca dentro de las grietas fueron más estables (menores rangos y varianzas) en comparación con las correspondientes temperaturas externas, tanto en verano como en invierno. El rango y la varianza de temperatura en el aire fueron diferentes sólo en el verano. Además, en verano, el rango y la varianza de temperatura en la superficie del suelo resultaron ser más estables a mayores profundidades dentro de las grietas. En invierno solo el rango de temperatura mostró un gradiente. El efecto aislante de las rocas beneficiaría a la rata vizcacha, ya que le provee un ambiente térmicamente estable, especialmente durante el verano. El presente estudio proporciona evidencia cuantitativa sobre el comportamiento térmico de las grietas, que contribuye con la hipótesis tradicional propuesta para explicar los beneficios de vivir en grietas.Fil: Campos, Valeria Evelin. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biologia; ArgentinaFil: Andino, Natalia del Pilar. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biologia; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cappa, Flavio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biologia; ArgentinaFil: Reus, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Giannoni, Stella Maris. Universidad Nacional de San Juan. Facultad de Ciencias Exactas, Fisicas y Naturales. Instituto y Museo de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biologia; Argentin
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Habitat selection by the Viscacha rat (Octomys mimax, Rodentia: Octodontidae) in a spatially heterogeneous landscape
'Walter de Gruyter GmbH', 2013Co-Authors: Campos, Valeria Evelin, Giannoni, Stella MarisAbstract:The Viscacha rat Octomys mimax is endemic to western Argentina; it inhabits lowland deserts and uses rocky crevices as resting sites. The aim of this study was to assess macrohabitat selection relative to the occurrence of rocky crevices and to evaluate seasonal variations in macrohabitats selected by this rodent in Ischigualasto Provincial Park, San Juan, Argentina. Random locations were classified as used or available based on signs recorded in rocky crevices. We confirmed the absence of the Viscacha rat in macrohabitats with sandy or silty substrates. We provide new records of Viscacha rat in creosote bush scrub, the most abundant macrohabitat of the Monte Desert. This result extends the known range of macrohabitat use for this species. The Viscacha rat increased the number of rocky crevices used in the dry season, probably because the species increased its foraging area due to the low food resource abundance. Another possible reason is an increase in density due to new births and dispersal of young in this season. The present study highlights the importance of considering signs of presence for species with low capturability as well as of collecting data throughout multiple seasons for a better understanding of habitat selection and species distribution.Fil: Campos, Valeria Evelin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; ArgentinaFil: Giannoni, Stella Maris. Universidad Nacional de San Juan. Facultad de Ciencias Exactas Físicas y Naturales. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Veronica Palmira Filippa - One of the best experts on this subject based on the ideXlab platform.
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variations in the adenohypophysis of the expression of proliferating cellular nuclear antigen oestrogen and androgen receptors in relation to gonadal steroids during pregnancy of Viscachas lagostomus maximus maximus
Reproduction Fertility and Development, 2019Co-Authors: Gabriela Judith Rosales, Edith Perez, Graciela Beatriz Rodriguez, Veronica Palmira Filippa, Fabian MohamedAbstract:Viscachas are native rodents of South America that present a long pregnancy of ~154 days. In this work, we analysed variations in the expression of proliferating cellular nuclear antigen, oestrogen and androgen receptors (ERα and AR) in pituitary pars distalis (PD) and pars tuberalis (PT) in relation to oestradiol and testosterone serum levels in non-pregnant and pregnant Viscachas. In PD, cell proliferation increased with pregnancy and lactotrophs proliferated during mid-pregnancy (MP). ERα nuclear-immunoreactive cells (ERαn-ir) were maximal in late pregnancy and AR expression did not vary during pregnancy. In PT, cell proliferation and AR expression increased during pregnancy, but ERα expression was very scarce. The immunostaining pattern of receptors was different in PD and PT. The peak of serum oestradiol and testosterone occurred during MP. Our results suggest that cell proliferation and gonadal receptors might be differentially regulated in the pituitary by oestradiol and testosterone during Viscacha pregnancy.
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pigmented cells in the pineal gland of female Viscacha lagostomus maximus maximus a histochemical and ultrastructural study
International Journal of Endocrinology, 2017Co-Authors: Fabricio Ivan Busolini, Veronica Palmira Filippa, Graciela Rodriguez, Fabian MohamedAbstract:The presence of pigment has been demonstrated in different nervous structures such as those of retina, substantia nigra, and locus coeruleus. These pigments have also been described in the pineal gland of different mammal species. Histochemical and ultrastructural studies of the pineal gland of female Viscacha (Lagostomus maximus maximus) were performed to analyze the presence of pigmented cells under natural conditions and to evaluate a probable relation between pigment content and glandular activity during pregnancy. The following techniques were applied: hematoxylin-eosin, phosphotungstic acid-hematoxylin, Masson-Fontana silver, DOPA histochemistry, Schmorl’s reaction and toluidine blue. Estradiol and progesterone serum levels were determined by RIA. The ultrastructural features of the pineal pigment granules were also analyzed. Pigment granules were observed in a random distribution, but the pigmented cells were frequently found near blood vessels. The pineal pigment was histochemically identified as melanin. Differences in the amount of pigmented cells were found between pregnant and nonpregnant Viscachas. The ultrastructural analysis revealed the presence of premelanosomes and melanosomes. Estradiol and progesterone levels vary during pregnancy. In conclusion, the changes in the amount of pigment content and hormone levels may indicate that the pineal gland of female Viscacha is susceptible to endocrine variations during pregnancy.
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a seasonal and age related study of interstitial cells in the pineal gland of male Viscacha lagostomus maximus maximus
Anatomical Record-advances in Integrative Anatomy and Evolutionary Biology, 2017Co-Authors: Fabricio Ivan Busolini, Gabriela Judith Rosales, Veronica Palmira Filippa, Fabian MohamedAbstract:The pineal gland of Viscacha exhibits histophysiological variations throughout the year, with periods of maximal activity in winter and minimal activity in summer. The aim of this study was to analyze the interstitial cells (IC) in the pineal gland of male Viscachas in relation to season and age. The S-100 protein, glio-fibrillary acidic protein (GFAP), and vimentin were detected in adult and immature animals by immunohistochemistry (IHC). Double-IHC was also performed. The S-100 protein was localized within both, IC nucleus and cytoplasm. GFAP was present only in the cytoplasm. Vimentin was expressed in some IC, besides endothelial cells, and perivascular spaces. In the adult males, the morphometric parameters analyzed for the S-100 protein and GFAP exhibited seasonal variations with higher values of immunopositive area percentage in winter and lower values in summer, whereas the immature ones showed the lowest values for all the adult animals studied. Colocalization of S-100 protein and GFAP was observed. The IC exhibited differential expression for the proteins studied, supporting the hypothesis of the neuroectodermal origin. The IC generate an intraglandular communication network, suggesting its participation in the glandular activity regulation processes. The results of double-IHC might indicate the presence of IC in different functional stages, probably related to the needs of the cellular microenvironment. The morphometric variations in the proteins analyzed between immature and adult Viscachas probed to be more salient in the latter, suggesting a direct relationship between the expression of the S-100 protein and GFAP, and animal age. This article is protected by copyright. All rights reserved.
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androgen receptors expression in pituitary of male Viscacha in relation to growth and reproductive cycle
International Journal of Endocrinology, 2015Co-Authors: Veronica Palmira Filippa, Gabriela Judith Rosales, Albana Cruceno, Fabian MohamedAbstract:The aim of this work was to study the androgen receptors (AR) expression in pituitary pars distalis (PD) of male Viscachas in relation to growth and reproductive cycle. AR were detected by immunocytochemistry and quantified by image analysis. Pituitary glands from fetus, immature, prepubertal, and adult Viscachas during their reproductive cycle were used. In the fetal PD, the immunoreactivity (ir) was mainly cytoplasmic. In immature and prepubertal animals, AR-ir was cytoplasmic (ARc-ir) and nuclear (ARn-ir) in medial region. In adult animals, ARn-ir cells were numerous at caudal end. AR regionalization varied between the PD zones in relation to growth. In immature animals, the ARn-ir increased whereas the cytoplasmic expression decreased in relation to the fetal glands. The percentage of ARc-ir cells increased in prepubertal animals whereas the nuclear AR expression was predominant in adult Viscachas. The AR expression changed in adults, showing minimum percentage in the gonadal regression period. The variation of nuclear AR expression was directly related with testosterone concentration. These results demonstrated variations in the immunostaining pattern, regionalization, and number of AR-ir cells throughout development, growth, and reproductive cycle, suggesting the involvement of AR in the regulation of the pituitary activity of male Viscacha.
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anatomical histological and immunohistochemical study of the reproductive system accessory glands in male Viscacha lagostomus maximus maximus
Anatomia Histologia Embryologia, 2011Co-Authors: E M Chaves, Veronica Palmira Filippa, Fabian Mohamed, Susana Dominguez, Claudia Aguileramerlo, Luis ScardapaneAbstract:The anatomy, histology and androgen receptor immunohistochemistry of the prostate (P), seminal vesicles (SV), bulbourethral and coagulant gland (CG) were studied in male Viscacha, a seasonally reproductive wild rodent. Two histologically well-defined zones, peripheral and central, were identified in the prostate, according to their relationship with the urethra. The epithelial cells were periodic acid-Schiff (PAS)-positive in the central zone and alcian blue negative in the two zones. The SV are a paired gland, tubular, of tortuous aspect and formed by radial layers. The bulbourethral glands were paired, formed by tubuloalveolar acini and surrounded by a thick layer of skeletal muscle. The CG was multilobulated. The large adenomers showed PAS-positive epithelium and were negative to alcian blue. Androgen receptors in the P, SV and coagulating gland showed variations in their distribution with immunohistochemistry heterogeneous pattern. Finally, the reproductive system accessory glands of male Viscacha may be considered as a novel and interesting model for the study of seasonal reproduction in photoperiod-dependent animals.
Mirta Alicia Flamini - One of the best experts on this subject based on the ideXlab platform.
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placentation and embryo death in the plains Viscacha lagostomus maximus
Placenta, 2021Co-Authors: Claudio Gustavo Barbeito, Enrique Leo Portiansky, Maria Angelica Miglino, Francisco Acuna, Mirta Alicia FlaminiAbstract:Caviomorpha are an exceptional group among rodents due to their extended gestational period and the delivery of precocial offspring. Among them, Lagostomus maximus is characterized by its polyovulation, polyembryony, and the highest embryonic death known in mammals. Its chorioallantoic placenta is hemomonochorial, an ancestral character among rodents. It resembles more the human placenta than the murine models. As in all caviomophs, the chorioallantoic placenta is divided in a main placenta and a subplacenta. The former is organized in labyrinth lobes surrounded by trophospongium, as in most caviomorphs. The giant cells (more numerous than in other caviomorphs) near the decidua could be related to invasiveness. During placentation of L. maximus, uterine natural killer cells are found. These cells have been related to invasiveness and remodeling of blood vessels in Mus musculus and Homo sapiens, although in other caviomorphs are not frequently found. In L. maximus, the placenta develops in all conceptuses (5-6 per uterine horn). Necrosis was observed in each implantation site at day 70 post-coitum, except in that closest to the vagina in each horn. This process of embryo death followed by resorption begins at day 26-30 post-coitum. Recently, we found variations in the percentage of blood vessel and uterine gland areas that could explain the regional differences in embryo survival. The characteristics of the placenta and implantation of L. maximus are important to stablish a unique model for studying placentation as well as early embryonic death, of interest for human and veterinary medicine.
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comparison of the structural and ultrastructural characteristics of the female prostate between pregnant and non pregnant plains Viscacha lagostomus maximus
Tissue & Cell, 2021Co-Authors: Mirta Alicia Flamini, Claudio Gustavo Barbeito, Alcira Ofelia Diaz, Enrique Leo PortianskyAbstract:Abstract Some years ago, our group reported the presence of the female prostate in all the studied females of the plains Viscacha (Lagostomus maximus). The goal of the present study was to characterize and compare the female prostate gland between adult pregnant and non-pregnant plains Viscacha using histochemical, lectin-histochemical and immunohistochemical techniques, as well as optic and electron microscopy. Structurally, alveoli are lined by a simple epithelium formed by different cell types: basal cells, secretory cells in different stages of the secretory cycle and cells of clear cytoplasm. Secretory cells are the most abundant cell type, differing between them depending on the quantity and electron-density of their granules. The basal cells are less abundant and are responsible for the renewal of the alveolar epithelium. Likewise, other cells with secretory morphology were found in all the studied females; these have a clear cytoplasm, few granules and mitochondria. It could be considered that they are degranulated secretory cells or that they have partially released their granules. The stroma of the organ is formed by connective tissue and smooth muscle fibers, which are immunohistochemically evidenced against desmin. Histochemical and lectin-histochemical analysis revealed the presence of different glucidic residues in the different cell types. No structural, histochemical, lectin-histochemical, and ultrastructural differences were observed between pregnant and non-pregnant females of plain Viscachas, except for the expression of some lectins. The paraurethral gland of Lagostomus maximus can be used as a model for studying the gland in other species since its structural and ultrastructural characteristics do not depend on the hormonal status of the female.
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115 role of the ovary and uterus for the plains Viscacha lagostomus maximus maximus chinchillidae reproduction
Reproduction Fertility and Development, 2017Co-Authors: Phelipe Oliveira Favaron, Mirta Alicia Flamini, Claudio Gustavo Barbeito, Andrea Mess, R N Barreto, Luciana S Simoes, Tais Harumi De Castro Sasahara, P Romagnoli, M A MiglinoAbstract:A dogma of mammalian reproduction states that primordial germ cells in females are restricted to the intrauterine phase and only small portions of oocytes are available for ovulation during the adult life. Among the rare exceptions to this rule is the plains Viscacha. It polyovulates up to 800 oocytes per cycle, from which 10 to 12 are implanted, but only 1 to 2 conceptuses survive. To better understand the main mechanisms involved in these patterns of super-ovulation, super-implantation, and embryonic loss in the Viscacha, we conducted an analysis of the ovary and uterus of pregnant females and their conceptuses. Pregnant females (n = 16) of ~50 and 90 days of gestation (early to mid-gestation) were selected for conceptus recovery. Hemi-ovariohysterectomy was performed following surgical and anaesthetic protocols used for laboratory animals and the conceptuses collected. Female fetuses of Day 50 (n = 2) and 90 (n = 1) of gestation were obtained from Estacion de Cria de Animales Silvestres, Buenos Aires, Argentina. The reproductive organs were investigated by means of gross morphology, histology (hematoxilin and eosin), stereology (quantification of the volume of the ovary and number of ovary follicles), immunohistochemistry (PCNA, Oct-4, VEGF, and Caspase-3), and transmission electron microscopy. In the Day 50 fetal samples, the ovaries had an ovoid shape with smooth surface without apparent folds. First steps of subdivision were observed in the ovary of fetus of 90 days. The total volume of all fetal ovaries was of 4.8 mm2 and a coefficient of variation (CV) of 0.32. The ovaries of adult individuals had remarkable invaginations with surface projections and were small, asymmetrical, and dorsoventrally flattened with a mean of 77.6 mm3 (CV = 0.47). Only adult females had differentiation of germ cells. Primordial follicles had a mean of 9.9 × 105 (CV = 0.19), representing 93% of the total number of ovarian follicles. The mean of primary follicles was 3.05 × 104 (CV = 0.36), whereas for secondary follicles it was 2.75 × 104 (CV = 0.50), each representing 3% of all ovarian follicles. The number of antral follicles in several stages of development was 8.64 × 103 (CV = 0.75), representing 1% of the follicles. Primordial follicles expressed pluripotency (Oct-4+) and proliferation (PCNA+) markers, as well as the primary follicles. The cells did not react for Caspase-3 as marker for apoptosis. Variations regarding to the vascularization of the different regions of the uterine horn were observed, which were more intense and efficient near to the cervix. Data showed that a specialised, highly convoluted structure of the ovarian cortex developed in the intrauterine phase as a prerequisite for massive super-ovulation, associated with the inhibition of apoptosis and continued proliferation of germ cells, as well as maintenance of several corpora lutea during the adult life. Thus, a highly complex pattern of polyovulation, polyimplantation, and controlling mechanisms has evolved in the female reproductive system of the Viscacha that mainly was associated with the maternal side. After an in-depth analysis of the arterial and venous vascularization of the uterine horns and uteri, we speculate that specializations regarding the vasculature and musculature evolved first and then contributed as a compensatory or controlling mechanism for polyovulation and polyimplantation. In conclusion, polyovulation in the Viscacha represents a unique enigma in reproductive biology.
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seasonal variations cause morphological changes and altered spermatogenesis in the testes of Viscacha lagostomus maximus
Animal Reproduction Science, 2014Co-Authors: Naira Caroline Godoy Pieri, Mirta Alicia Flamini, Claudio Gustavo Barbeito, Paulo Ramos Da Silva Santos, Kelly Cristine Santos Roballo, Carlos Eduardo Ambrosio, Maria Angelica Miglino, Daniele Dos Santos MartinsAbstract:This study complements the previous investigations of the reproductive biology of male Viscachas, a rodent of a seasonal Hystricognathi that exhibits photoperiod-induced morphological variations in the reproductive system. In the present study, a quantitative analysis of spermatogenesis was performed during the summer and the spring. Spermatogonial cells were analyzed to determine by immunolabelling for STRA8 and DAZL, which are essential for spermatogenesis. Six free-living male Viscachas were captured, three animals in the summer during the period of reproductive activity and three animals in the spring during the period of testicular regression. The testes of the Viscachas were collected and processed for light microscopy, macroscopic and immunochemical analyses. The germ and Sertoli cells present in the seminiferous tubules were quantitatively analyzed in each animal. The efficiency coefficient for spermatogonial mitosis, meiotic yield, overall spermatogenesis yield and Sertoli cell index, revealed that the Sertoli cells in male Viscachas captured during the summer had a reduced capacity to structurally and nutritionally support the developing round spermatids compared with the male Viscachas captured during the spring. The animals produced less sperm during the spring than the summer, suggesting a seasonal impact on spermatogenesis. Immunolabelling for STRA8 and DAZL was detected during summer and spring seasons. These results suggest that in seasonal rodents, such as the male Viscachas, the photoperiod promotes significant changes in the testis and in the germ cell yield.
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a morphological morphometric and histochemical study of the oviduct in pregnant and non pregnant females of the plains Viscacha lagostomus maximus
Acta Zoologica, 2014Co-Authors: Mirta Alicia Flamini, Claudio Gustavo Barbeito, Enrique Leo PortianskyAbstract:The oviduct is a very thin organ with a very tortuous appearance. It is divided into three segments: the infundibulum, the ampulla and the isthmus. Particularly, the oviduct of the Viscacha lacks the intramural portion described in other species. The mucosa shows longitudinal pleats. The free edge of the infundibulum ends as small fimbriae that are of variable length and do not completely cover the ovary. The proportion of ciliated and secretory epithelial cells varied both in relation to the segments of the oviduct analysed and to the physiological state (anoestrus, follicular phase, early pregnancy and late pregnancy). The glycocalix and the apical region of the superficial epithelial cells are PAS and alcian-blue positive. The muscular layers vary in thickness in different regions. Some lectins such as UEA-1 and DBA showed variations in the binding pattern during the different physiological stages analysed whereas RCA-1and WGA had a very stable pattern.
