The Experts below are selected from a list of 993 Experts worldwide ranked by ideXlab platform
Takayuki Mori - One of the best experts on this subject based on the ideXlab platform.
-
mating induced Cumulus oocyte maturation in the shrew suncus murinus
Reproduction, 2003Co-Authors: Takane Kaneko, J M Bedford, Hiroshi Iida, Takayuki MoriAbstract:The mus ks hrew,Suncus murinus ,i s an induced ovulator, the Cumulus Oophorus of which is unusual in several respects: it has no matrix, it always induces the acrosome reaction and it appears to be essential for fertilization. The present study documents distinctive features of the Cumulus Oophorus before and after ovulation, and of copulationinduced maturation of the ovulatory follicle, which has no antrum. In unmated females, potentially responsive ovarian follicles are distinguishable from large secondary follicles by differentiation of the granulosa into outer and inner cell layers, the latter being characterized particularly by intracellular glycogen deposits. The average number of responsiv ef ollicles equates with the number that ovulate. By about 10 h after mating, meiosis has reached metaphase II, with extrusion of the first polar body. Coincidentally, a cavity has developed between the inner and outer follicular layers, demarcating the smaller cells of the granulosa from the glycogen-rich cells of the Cumulus Oophorus. Subsequently, the glycogen becomes restricted primarily to the inner Cumulus, and the corona cells began to retreat from the zona pellucida surface to form an unusual very distinct perizonal space that is clearly evident at the time of ovulation. The Cumulus is stabilized by gap and tight junctions, and presents a smooth external surface that appears to initiate the acrosome reaction. After fertilization, at which time the zona pellucida becomes more resistant to both trypsin and dithiothreitol, the Cumulus develops intercellular lacunae, and is eventually discarded about 15 h after ovulation.
-
the unusual state of the Cumulus Oophorus and of sperm behaviour within it in the musk shrew suncus murinus
Reproduction, 1997Co-Authors: John Michael Bedford, Takayuki MoriAbstract:in the musk shrew, Suncus murinus, the behaviour of the Cumulus-egg complex and its interaction with spermatozoa were unusual in several respects. The Cumulus Oophorus was ovulated about 15.5 h after mating or treatment with hCG as a hyaluronidase-insensitive matrix-free ball of cells which remained for relatively long periods of about 14 h around fertilized, and for about 24 h around unfertilized eggs. As a probable function of the small number of up to about 10 or 20 spermatozoa that generally reached the oviduct ampulla from isthmic crypts, there was often a delay of up to 10 h after ovulation before most eggs were penetrated. Soon after ovulation, however, the corona radiata retreated progressively from the zona pellucida, creating a closed perizonal space within the Cumulus Oophorus. Usually, most spermatozoa that did reach the ampulla were found within a Cumulus and generally within that perizonal space. However, whereas the acrosome was intact among the few free ampullary spermatozoa, and in those adhering to the zona of Cumulus-free eggs after delayed mating, all spermatozoa seen moving within the Cumulus or adhering to the zona of unfertilized eggs had shed the giant acrosome. In accord with current observations in other shrews, the Cumulus in Suncus may therefore function not only to sequester spermatozoa, but also as an essential mediator of fertilization - probably by inducing the acrosome reaction. In the absence of the acrosomal carapace that expresses the zona receptors in most mammals, fertilizing Suncus spermatozoa could use an unusual array of barbs on the exposed perforatorium to attach to the zona pellucida.
John Michael Bedford - One of the best experts on this subject based on the ideXlab platform.
-
spermatozoa of the shrew suncus murinus undergo the acrosome reaction and then selectively kill cells in penetrating the Cumulus Oophorus
Biology of Reproduction, 2001Co-Authors: Takane Kaneko, Hiroshi Iida, John Michael BedfordAbstract:In the musk shrew, Suncus murinus (and other shrews), the Cumulus Oophorus is ovulated as a discrete, compact, matrix-free ball of cells linked by specialized junctions. In examining how they penetrate the Cumulus, Suncus spermatozoa were observed to first bind consistently by the ventral face over the acrosomal region to the exposed smooth surface of a peripheral Cumulus cell. This was apparently followed by point fusions between the plasma and outer acrosomal membranes. Thereafter, spermatozoa without acrosomes were observed within Cumulus cells that displayed signs of necrosis, as did some radially neighboring Cumulus cells linked by zona adherens and gap junctions. Eventually, penetration of spermatozoa as far as the perizonal space around the zona pellucida left linear tracks of locally necrotic cells flanked by normal Cumulus cells. Based on these and previous observations, we conclude that the acrosome reaction in Suncus is always induced by Cumulus cells, and that reacted spermatozoa penetrate the Cumulus by selective invasion and killing of Cumulus cells along a linear track. Loss of the acrosome also exposes an apical body/perforatorium that is covered with barbs that appear to assist reacted fertilizing spermatozoa in binding to the zona pellucida. Because fertilized eggs displayed no other spermatozoa within or bound to the zona, an efficient block to polyspermy must prevent such binding of additional spermatozoa.
-
the unusual state of the Cumulus Oophorus and of sperm behaviour within it in the musk shrew suncus murinus
Reproduction, 1997Co-Authors: John Michael Bedford, Takayuki MoriAbstract:in the musk shrew, Suncus murinus, the behaviour of the Cumulus-egg complex and its interaction with spermatozoa were unusual in several respects. The Cumulus Oophorus was ovulated about 15.5 h after mating or treatment with hCG as a hyaluronidase-insensitive matrix-free ball of cells which remained for relatively long periods of about 14 h around fertilized, and for about 24 h around unfertilized eggs. As a probable function of the small number of up to about 10 or 20 spermatozoa that generally reached the oviduct ampulla from isthmic crypts, there was often a delay of up to 10 h after ovulation before most eggs were penetrated. Soon after ovulation, however, the corona radiata retreated progressively from the zona pellucida, creating a closed perizonal space within the Cumulus Oophorus. Usually, most spermatozoa that did reach the ampulla were found within a Cumulus and generally within that perizonal space. However, whereas the acrosome was intact among the few free ampullary spermatozoa, and in those adhering to the zona of Cumulus-free eggs after delayed mating, all spermatozoa seen moving within the Cumulus or adhering to the zona of unfertilized eggs had shed the giant acrosome. In accord with current observations in other shrews, the Cumulus in Suncus may therefore function not only to sequester spermatozoa, but also as an essential mediator of fertilization - probably by inducing the acrosome reaction. In the absence of the acrosomal carapace that expresses the zona receptors in most mammals, fertilizing Suncus spermatozoa could use an unusual array of barbs on the exposed perforatorium to attach to the zona pellucida.
Koji Kimata - One of the best experts on this subject based on the ideXlab platform.
-
defect in shap hyaluronan complex causes severe female infertility a study by inactivation of the bikunin gene in mice
Journal of Biological Chemistry, 2001Co-Authors: Lisheng Zhuo, Masahiko Yoneda, Ming Zhao, Wannarat Yingsung, Naoko Yoshida, Yasuo Kitagawa, Kumiko Kawamura, Toshiro Suzuki, Koji KimataAbstract:Abstract Hyaluronan (HA) associates with proteins and proteoglycans to form the extracellular HA-rich matrices that significantly affect cellular behaviors. So far, only the heavy chains of the plasma inter-α-trypsin inhibitor (ITI) family, designated as SHAPs (serum-derivedhyaluronan-associated proteins), have been shown to bind covalently to HA. The physiological significance of such a unique covalent complex has been unknown but is of great interest, because HA and the ITI family are abundant in tissues and in plasma, respectively, and the SHAP-HA complex is formed wherever HA meets plasma. We abolished the formation of the SHAP-HA complex in mice by targeting the gene of bikunin, the light chain of the ITI family members, which is essential for their biosynthesis. As a consequence, the Cumulus Oophorus, an investing structure unique to the oocyte of higher mammals, had a defect in forming the extracellular HA-rich matrix during expansion. The ovulated oocytes were completely devoid of matrix and were unfertilized, leading to severe female infertility. Intraperitoneal administration of ITI, accompanied by the formation of the SHAP-HA complex, fully rescued the defects. We conclude that the SHAP-HA complex is a major component of the HA-rich matrix of the Cumulus Oophorus and is essential for fertilizationin vivo.
-
Cumulus Oophorus Extracellular Matrix: Its Construction and Regulation
Cell Structure and Function, 2001Co-Authors: Lisheng Zhuo, Koji KimataAbstract:Cumulus Oophorus, an investing structure unique to oocytes of higher mammals, is induced to synthesize an extensive extracellular matrix by ovulatory stimulus, leading to the characteristic preovulatory expansion of the Cumulus-oocyte complex. The extracellular matrix consists of Cumulus cell-secreted hyaluronan, proteoglycans and proteins, as well as extrafollicularly originated SHAPs (serum-derived hyaluronan-associated proteins) that are bound covalently to hyaluronan. The secretion and assembly of matrix molecules by Cumulus cells are temporally regulated by factors derived from both mural granulosa cells and oocyte, which synchronize the deposition of the Cumulus Oophorus matrix with other intrafollicular ovulatory events. The Cumulus Oophorus matrix is essential for ovulation and subsequent fertilization. Recently, taking advantage of animal models with defined genetic modifications, it has become possible to investigate in vivo the structure of the Cumulus Oophorus matrix, the regulatory mechanism for matrix deposition and its biological functions. This review focuses on the recent findings on the construction of the Cumulus Oophorus matrix and the regulation.
Henrique Almeida - One of the best experts on this subject based on the ideXlab platform.
-
age related expression of tgf beta family receptors in human Cumulus Oophorus cells
Journal of Assisted Reproduction and Genetics, 2017Co-Authors: A Ribeiro, Liliana Matos, F Gomes, Claudio Froes De Freitas, Alexandra Gouveia, Silva J Carvalho, Henrique AlmeidaAbstract:During ovarian follicle growth, local cellular interactions are essential for oocyte quality acquisition and successful fertilization. While Cumulus cells (CCs) nurture oocytes, they also deliver oocyte-secreted factors (OSFs) that activate receptors on CCs. We hypothesized that disturbance of those interactions contributes to age-related lower reproductive success in women submitted to assisted reproductive technology treatments. Women aged 27–48, without recognized personal reproductive disorder, were enrolled in the study and divided in <35- and ≥35-year-old groups. CCs collected upon follicle aspiration were processed for immunocytochemistry and RNA extraction. The expression patterns of OSF receptors BMPR2, ALK 4, ALK5, and activin receptor-like kinase (ALK6) were studied. Independently of age, receptors were found mostly in the cell periphery. The quantitative assay revealed that in older women, BMPR2, ALK 4, and ALK6 were all significantly decreased, whereas ALK5 was slightly increased. Female age imparts an effect on the expression of OSF receptors in CCs. The findings indicate that reproductive aging affects the local regulation of signaling pathways mediated by BMPR2, ALK6, and ALK4 receptor activation, suggesting their joint involvement.
-
superoxide dismutase expression in human Cumulus Oophorus cells
Molecular Human Reproduction, 2008Co-Authors: Liliana Matos, D Stevenson, F Gomes, J L Silvacarvalho, Henrique AlmeidaAbstract:Success in assisted reproductive techniques (ART) is influenced by gamete and embryo quality but the assessment of these parameters has been thwarted by the lack of reliable biomarkers. Follicular fluid and Cumulus Oophorus cells may provide biomarkers due to their close relationship to the oocyte. These cells produce antioxidants and thus protect the oocyte from oxidative damage exerted by reactive oxygen species (ROS). ROS and antioxidants are known to intervene in reproductive physiology and pathology, but their roles are unclear. It is hypothesized that superoxide dismutase (SOD), a first line antioxidant enzyme, is associated with oocyte quality. Cells obtained in the course of ART for the treatment of infertility due to male factor or female pathology were processed for SOD intracellular isoforms (CuZnSOD and MnSOD) immunodetection, total SOD activity and isoforms content. Cells presented strong positive staining for CuZnSOD and MnSOD. SOD activity decreased with increasing female age but was increased in endometriosis and in ovulatory dysfunction. When male factor was the cause for infertility, successful ART was associated with higher SOD activity. Variations in SOD emphasize the relevance of oxidative stress in the oocyte maturation process. These variations also suggest that SOD is a potential biomarker for ART success.
David M. Phillips - One of the best experts on this subject based on the ideXlab platform.
-
9 Maturation of the Rat Cumulus Oophorus A Scanning Electron Microscopic Study
2016Co-Authors: Nava Dekel, David M. PhillipsAbstract:The process of mucification of the preovulatory Cumulus Oophorus in the rat was examined by the scanning electron microscope (SEM). Induction of mucification in vitro by either LH or FSH was also studied. Mucification in vivo was studied in follicular cumuli isolated at different times during proestrus. The morphology of these cumuli was compared with that of postovulatory cumuli isolated from the oviductal ampullae. For the in vitro studies, follicular cumuli were isolated at early proestrus and incubated for various time periods in presence of ovine or rat preparations of either LH or FSH. The beginning of mucus deposition in follicular cumuli was observed at about 5 h before the expected ovulation. Cumuli isolated 2 h before ovulation were totally embedded in the extracellular matrix. In vitro, first stages of mucification were observed in cumuli incubated for 3 h in medium containing LH. Extracellular hyaluronidase-sensitive material completely covered the cumuli by 20 h of culture in presence of either LH or FSH. In the absence of the gonadotropins, mucification was not observed. Parietal granulosa tissue showed inability to mucify in the presence of LH in vitro. No accumulation of extracellular material could be observed in cumuli cultured for 24 h in hormone free medium and then exposed to LH. It was concluded that the hyaluronidase sensitive matrix is accumulated between the Cumulus cells in the follicle before ovulation. This intercellular mucus is secreted specifically by the Cumulus cells as a direct response to gonadotropic stimulation. The cultured Cumulus cells lose their ability to respond to LH
-
unusual ampullary sperm crypts and behavior and role of the Cumulus Oophorus in the oviduct of the least shrew cryptotis parva
Biology of Reproduction, 1997Co-Authors: J M Bedford, Orin B Mock, David M. PhillipsAbstract:The gametes of the least shrew, Cryptotis parva, were studied in regard to their maturation and structure, and with particular emphasis on their behavior in the fallopian tube, from the time of ovulation until the appearance of two-cell embryos beginning some 9 h after ovulation. Cryptotis spermatozoa are organized according to the conventional eutherian mold, with the exception of a barbed perforatorium and an unusual plasma membrane density lent by a bristly coat where it overlies the acrosome rim. In the epididymis they undergo a maturation of the capacity for motility and an -S-S-related stabilization of the nucleus and tail organelles, with the cauda housing only approximately 4-5 million spermatozoa. Mating involves penile locking and also the deposition of a modest vaginal plug that covers the cervix. The short (4-5 mm) fallopian tube has three regions-a simple isthmus, a relatively narrow ampulla populated throughout by ciliated crypts, and a crypt-free terminal infundibulum-the fertilization site. Unlike the situation in most mammals, the tubal isthmus was devoid of spermatozoa in mated females before and after ovulation, which occurred approximately 13 h post-hCG and produced a mean of 5.7 ova. However, the ampulla then housed approximately 1500 active cells in groups within the ciliated crypts, sometimes together with leukocytes but with few spermatozoa above in the infundibulum. Within about 1 h after their ovulation from approximately 400-microm follicles, eggs were penetrated while in the infundibulum despite the nonexpanded hyaluronidase-resistant state of the Cumulus Oophorus. However, on moving down to the ampulla by 2-4 h after ovulation, the dense Cumulus around fertilized eggs appeared to proliferate and began to disperse coincidentally with secretion of a hyaluronidase-sensitive matrix in which hundreds of motile spermatozoa often became enmeshed. This Cumulus change also occurred around unfertilized eggs, though more slowly, but not around fertilized or unfertilized eggs cultured in vitro. Thus, Cumulus matrix production appeared to be stimulated to an important degree by factors in the oviduct, not by preovulatory gonadotropins as in many mammals. Although Cumulus-invested eggs were fertilized readily in vitro, Cumulus-free eggs of the same age were never fertilized, and spermatozoa bound to the zona pellucida had intact acrosomes. This and related evidence from other shrews makes it seem likely that the soricid Cumulus has an essential role in fertilization and may induce the acrosome reaction.
-
novel sperm storage and behavior of gametes in the fallopian tube of the white toothed shrew crocidura russula monacha
Journal of Experimental Zoology, 1997Co-Authors: Michael J Bedford, David M. Phillips, Haya MoverlevAbstract:The gametes of an insectivore, the white-toothed shrew, Crocidura russula monacha, present certain idiosyncratic features not seen in most other eutherian mammals. The spermatozoa display an acrosome of giant proportions, and are produced in relatively small numbers. In trans-illuminated oviducts examined with DIC optics, spermatozoa were first sequestered in languid clutches within the isthmus in deep narrow crypts, with some eventually ingested by the crypt epithelium. Then, at ovulation (ca. 15 hr after hCG), many ascended to occupy “bubble-like” ciliated crypts distributed randomly within the ampulla, as active groups of acrosome-intact spermatozoa. However, eggs (3.95; range 2–6) were first retained for several hours and were fertilized in an upper crypt-free infundibulum before moving down to the ampulla. At fertilization, individual spermatozoa penetrate an unusually compact matrix-free Cumulus Oophorus which is stabilized by intercellular junctions, is insensitive to hyaluronidase, and persists for ∼13 hr around fertilized and for ∼24 hr around unfertilized eggs. In contrast to the free ampullary spermatozoa, active spermatozoa accumulating within the Cumulus all had shed the acrosome, an observation consistent with evidence from other shrews suggesting that the Cumulus may necessarily induce the acrosome reaction in this ancient line. Hypertrophy of the acrosome, isthmic sperm storage crypts, and stable Cumulus Oophorus that develops a peri-zona space, all may prove to be typically crocidurine characteristics of use where the classification of a shrew is in doubt. J. Exp. Zool. 277:262–273, 1997. © 1997 Wiley-Liss, Inc.
