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Avi Baranes – One of the best experts on this subject based on the ideXlab platform.

  • Morphological and cytological ontogenesis of the Ampullae of Lorenzini and lateral line canals in the Oman shark, Iago omanensis Norman 1939 (Triakidae), from the Gulf of Aqaba, Red Sea.
    The Anatomical record, 1998
    Co-Authors: Lev Fishelson, Avi Baranes
    Abstract:

    The Oman shark, Iago omanensis, is a small, placental viviparous species encountered in great numbers in the deeper waters of the Gulf of Aqaba, Red Sea. It reproduces year-round, providing an opportunity to study ontogenesis of organ systems at various stages of development. This study examines the morphological and cytological development of the mechanoreceptive lateral line (LL) system and the electrosensory Ampullae of Lorenzini. Female I. omanensis were collected bimonthly from the Gulf of Aqaba at depths of 300–800 m and sacrificed with an overdose of MS222. Their uteri were dissected and the embryos separated and fixed for light and electron microscopy. A total of 260 embryos of varying dimensions were studied. The first primordia of neuroectodermal LL neuromasts are seen in embryos of 18 mm TL. These then sink into the dermis, ripen, and develop tubuli that join to form the LL canal systems, especially developed on the head. In contrast, the primordia of Ampullae of Lorenzini start out as groups of embryonic cells situated subdermally. In embryos of 24–26 mm TL initially they develop into tubuli. With growth, the ampullar alveoli gradually widen at their ends to form the sensory epithelium. The ampullar tubuli elongate, bringing the alveoli to sites over the rostrum and head, where the ampullar capsules are formed. The presynaptic electrosensory cells are attached to afferent neural extensions forming sensory rami which extend, as in adult sharks, to the dorsal nucleus in the medulla. In preterm juveniles of 150–160 mm TL, the LL system and the Ampullae of Lorenzini are fully developed cytologically. The results of this study support the hypothesis that the LL system and electrosensory Ampullae of Lorenzini develop as separate modalities and that their structural similarity is due to the origin from the embryonic neuroectoderm. The dichotomy of their evolution occurred in very early ancestry as an ecomorphological adaptation to different sensory functions. Anat. Rec. 252:532–545, 1998. © 1998 Wiley-Liss, Inc.

  • Distribution, morphology, and cytology of Ampullae of Lorenzini in the Oman shark, Iago omanensis (Triakidae), from the Gulf of Aqaba, Red Sea
    The Anatomical record, 1998
    Co-Authors: Lev Fishelson, Avi Baranes
    Abstract:

    Ampullae of Lorenzini are electrosensitive organs that, together with the olfactory organs, form the main sensory systems for foraging and navigation in skates, rays, and sharks. In sharks, these organs are mainly found on the rostral part of the head. This study describes the morphology and cytology of the ampullar system in the Oman shark, Iago omanensis, which is common in the Red Sea. The sharks were collected in the Gulf of Aqaba, Red Sea, at depths of 300–750 m, by a specially designed net. They were brought to the surface and sacrificed by an overdose of MS222, and their heads were fixed and prepared for LM, TEM, and SEM studies. The Ampullae are of the polyvesicular type, and their sensory alveoli are situated on the head only and form groups enclosed in capsules of collagenous connective tissue. The dorsal side of the head features pairs of mediorostral (MRC), laterorostral (LRC), and preorbital (POC) capsules and one frontal capsule (FC), situated at the base of the rostrum in front of the eyes. The ventral side possesses only two, small mandibular (MC) capsules. The number of sensory alveoli differs in each of the capsules, and the largest group of 500 is found in the two mediorostral capsules. Each alveolus is formed by seven to nine sensory vesicles, from which a common tubule, piercing the capsule envelope, extends to a cutaneous pore. Groups of such pores form a pattern typical for Iago. A detailed description is given of the sensory epithelium, kinociliar, and microvillar cells as well as of the supporting cytological elements. The Ampullae of Lorenzini in adult I. omanensis are generally similar to those of a number of other studied sharks. However, as the study shows, their number and configuration differ and form a morphological and topographic pattern typical for this species. Anat. Rec. 251:417–430, 1998. © 1998 Wiley-Liss, Inc.

Barbara E. Wueringer – One of the best experts on this subject based on the ideXlab platform.

  • Anatomy of the mechanosensory lateral line canal system and electrosensory Ampullae of Lorenzini in two species of sawshark (fam. Pristiophoridae)
    Journal of fish biology, 2020
    Co-Authors: Barbara E. Wueringer, Marit Winther-janson, Vincent Raoult, Tristan L. Guttridge
    Abstract:

    It has long been assumed that the elongated rostra (the saws) of sawsharks (family: Pristiophoridae) and sawfish (family: Pristidae) serve a similar function. Recent behavioural and anatomical studies have shed light on the dual function of the pristid rostrum in mechanosensory and electrosensory prey detection and prey manipulation. Here, the authors examine the distributions of the mechanosensory lateral line canals and electrosensory Ampullae of Lorenzini in the southern sawshark, Pristiophorus nudipinnis and the longnose sawshark, Pristiophorus cirratus. In both species, the receptive fields of the mechano- and electrosensory systems extend the full length of the rostrum indicating that the sawshark rostrum serves a sensory function. Interestingly, despite recent findings suggesting they feed at different trophic levels, minimal interspecific variation between the two species was recorded. Nonetheless, compared to pristids, the pristiophorid rostrum possesses a reduced mechanosensory sampling field but higher electrosensory resolution, which suggests that pristiophorids may not use their rostrums to disable large prey like pristids do.

  • Sensory systems in sawfishes. 1. The Ampullae of Lorenzini
    Brain behavior and evolution, 2011
    Co-Authors: Barbara E. Wueringer, Stirling C. Peverell, Jamie Seymour, Lyle Squire, Stephen M. Kajiura, Shaun P. Collin
    Abstract:

    The distribution and density of the ampullary electroreceptors in the skin of elasmobranchs are influenced by the phylogeny and ecology of a species. Sensory maps were created for 4 species of pristid sawfish. Their ampullary pores were separated into pore fields based on their innervation and cluster formation. Ventrally, ampullary pores are located in 6 areas (5 in Pristis microdon), covering the rostrum and head to the gills. Dorsally, pores are located in 4 areas (3 in P. microdon), which cover the rostrum, head and may extend slightly onto the pectoral fins. In all species, the highest number of pores is found on the dorsal and ventral sides of the rostrum. The high densities of pores along the rostrum combined with the low densities around the mouth could indicate that sawfish use their rostrum to stun their prey before ingesting it, but this hypothesis remains to be tested. The directions of ampullary canals on the ventral side of the rostrum are species specific. P. microdon possesses the highest number of ampullary pores, which indicates that amongst the study species this species is an electroreception specialist. As such, juvenile P. microdon inhabit low-visibility freshwater habitats.

  • Ultrastructure of the Ampullae of Lorenzini of Aptychotrema rostrata (Rhinobatidae)
    Zoomorphology, 2009
    Co-Authors: Barbara E. Wueringer, Ian R. Tibbetts, Darryl L. Whitehead
    Abstract:

    Small epidermal pores of the electrosensory Ampullae of Lorenzini located both ventrally and dorsally on the disk of Aptychotrema rostrata (Shaw and Nodder, 1794) open to jelly-filled canals, the distal end of which widens forming an ampulla that contains 6 ± 0.7 alveolar bulbs ( n  = 13). The sensory epithelium is restricted to the alveolar bulbs and consists of receptor cells and supportive cells. The receptor cells are ellipsoid and their apical surfaces are exposed to the alveolar lumen with each bearing a single central kinocilium. Presynaptic bodies occur in the basal region of the receptor cell immediately proximal to the synaptic terminals. The supportive cells that surround receptor cells vary in shape. Microvilli originate from their apical surface and extend into the alveolar lumen. Tight junctions and desmosomes connect the supportive cells with adjacent supportive and receptor cells in the apical region. The canal wall consists of two cell layers, of which the luminal cells are squamous and interconnect via desmosomes and tight junctions, whereas the cells of the deeper layer are heavily interdigitated, presumably mechanically strengthening the canal wall. Columnar epithelial cells form folds that separate adjacent alveoli. The same cells separate the ampulla and canal wall. An afferent sensory nerve composed of up to nine myelinated nerve axons is surrounded by several layers of collagen fibers and extends from the ampulla. Each single afferent neurneuron can make contacts with multiple receptor cells. The ultrastructural characteristics of the Ampullae of Lorenzini in Aptychotrema rostrata are very similar to those of other elasmobranch species that use electroreception for foraging.

Ian R. Tibbetts – One of the best experts on this subject based on the ideXlab platform.

  • Morphological comparison of the Ampullae of Lorenzini of three sympatric benthic rays
    Journal of fish biology, 2018
    Co-Authors: Arnault R.g. Gauthier, Darryl L. Whitehead, Ian R. Tibbetts, Bronwen W. Cribb, Michael B. Bennett
    Abstract:

    This study investigated and compared the morphology of the electrosensory system of three species of benthic rays. Neotrygon trigonoides, Hemitrygon fluviorum and Maculabatis toshi inhabit similar habitats within Moreton Bay, Queensland, Australia. Like all elasmobranchs, they possess the ability to detect weak electrical fields using their Ampullae of Lorenzini. Macroscopically, the ampullary organs of all three species are aggregated in three bilaterally paired clusters: the mandibular, hyoid and superficial ophthalmic clusters. The hyoid and superficial ophthalmic clusters of Ampullae arise from both dorsal and ventral ampullary pores. The dorsal pores are typically larger than the ventral pores in all three species, except for the posterior ventral pores of the hyoid grouping. Ampullary canals arising from the hyoid cluster possessed a quasi-sinusoidal shape, but otherwise appeared similar to the canals described for other elasmobranchs. Ultrastructure of the Ampullae of Lorenzini of the three species was studied using a combination of light, confocal and electron microscopy. All possess Ampullae of the alveolar type. In N. trigonoides and M. toshi, each ampullary canal terminates in three to five sensory chambers, each comprising several alveoli lined with receptor and supportive cells and eight to 11 sensory chambers in H. fluviorum. Receptor cells of all three species possess a similar organization to those of other elasmobranchs and were enveloped by large, apically nucleated supportive cells protruding well into the alveolar sacs. The luminally extended chassis of supportive cells protruding dramatically into the ampullary lumen had not previously been documented for any elasmobranch species.

  • Morphology of the Ampullae of Lorenzini in juvenile freshwater Carcharhinus leucas.
    Journal of morphology, 2014
    Co-Authors: Darryl L. Whitehead, Arnault R.g. Gauthier, Michael B. Bennett, Ian R. Tibbetts
    Abstract:

    Ampullae of Lorenzini were examined from juvenile Carcharhinus leucas (831-1,045 mm total length) captured from freshwater regions of the Brisbane River. The ampullary organ structure differs from all other previously described Ampullae in the canal wall structure, the general shape of the ampullary canal, and the apically nucleated supportive cells. Ampullary pores of 140-205 µm in diameter are distributed over the surface of the head region with 2,681 and 2,913 pores present in two sharks that were studied in detail. The primary variation of the ampullary organs appears in the canal epithelial cells which occur as either flattened squamous epithelial cells or a second form of pseudostratified contour-ridged epithelial cells; both cell types appear to release material into the ampullary lumen. Secondarily, this ampullary canal varies due to involuted walls that form a clover-like canal wall structure. At the proximal end of the canal, contour-ridged cells abut a narrow region of cuboidal epithelial cells that verge on the constant, six alveolar sacs of the ampulla. The alveolar sacs contain numerous receptor and supportive cells bound by tight junctions and desmosomes. Pear-shaped receptor cells that possess a single apical kinocilium are connected basally by unmyelinated neural boutons. Opposed to previously described Ampullae of Lorenzini, the supportive cells have an apical nucleus, possess a low number of microvilli, and form a unique, jagged alveolar wall. A centrally positioned centrum cap of cuboidal epithelial cells overlies a primary afferent lateral line nerve.

  • Ultrastructure of the Ampullae of Lorenzini of Aptychotrema rostrata (Rhinobatidae)
    Zoomorphology, 2009
    Co-Authors: Barbara E. Wueringer, Ian R. Tibbetts, Darryl L. Whitehead
    Abstract:

    Small epidermal pores of the electrosensory Ampullae of Lorenzini located both ventrally and dorsally on the disk of Aptychotrema rostrata (Shaw and Nodder, 1794) open to jelly-filled canals, the distal end of which widens forming an ampulla that contains 6 ± 0.7 alveolar bulbs ( n  = 13). The sensory epithelium is restricted to the alveolar bulbs and consists of receptor cells and supportive cells. The receptor cells are ellipsoid and their apical surfaces are exposed to the alveolar lumen with each bearing a single central kinocilium. Presynaptic bodies occur in the basal region of the receptor cell immediately proximal to the synaptic terminals. The supportive cells that surround receptor cells vary in shape. Microvilli originate from their apical surface and extend into the alveolar lumen. Tight junctions and desmosomes connect the supportive cells with adjacent supportive and receptor cells in the apical region. The canal wall consists of two cell layers, of which the luminal cells are squamous and interconnect via desmosomes and tight junctions, whereas the cells of the deeper layer are heavily interdigitated, presumably mechanically strengthening the canal wall. Columnar epithelial cells form folds that separate adjacent alveoli. The same cells separate the ampulla and canal wall. An afferent sensory nerve composed of up to nine myelinated nerve axons is surrounded by several layers of collagen fibers and extends from the ampulla. Each single afferent neuron can make contacts with multiple receptor cells. The ultrastructural characteristics of the Ampullae of Lorenzini in Aptychotrema rostrata are very similar to those of other elasmobranch species that use electroreception for foraging.

Lev Fishelson – One of the best experts on this subject based on the ideXlab platform.

  • Morphological and cytological ontogenesis of the Ampullae of Lorenzini and lateral line canals in the Oman shark, Iago omanensis Norman 1939 (Triakidae), from the Gulf of Aqaba, Red Sea.
    The Anatomical record, 1998
    Co-Authors: Lev Fishelson, Avi Baranes
    Abstract:

    The Oman shark, Iago omanensis, is a small, placental viviparous species encountered in great numbers in the deeper waters of the Gulf of Aqaba, Red Sea. It reproduces year-round, providing an opportunity to study ontogenesis of organ systems at various stages of development. This study examines the morphological and cytological development of the mechanoreceptive lateral line (LL) system and the electrosensory Ampullae of Lorenzini. Female I. omanensis were collected bimonthly from the Gulf of Aqaba at depths of 300–800 m and sacrificed with an overdose of MS222. Their uteri were dissected and the embryos separated and fixed for light and electron microscopy. A total of 260 embryos of varying dimensions were studied. The first primordia of neuroectodermal LL neuromasts are seen in embryos of 18 mm TL. These then sink into the dermis, ripen, and develop tubuli that join to form the LL canal systems, especially developed on the head. In contrast, the primordia of Ampullae of Lorenzini start out as groups of embryonic cells situated subdermally. In embryos of 24–26 mm TL initially they develop into tubuli. With growth, the ampullar alveoli gradually widen at their ends to form the sensory epithelium. The ampullar tubuli elongate, bringing the alveoli to sites over the rostrum and head, where the ampullar capsules are formed. The presynaptic electrosensory cells are attached to afferent neural extensions forming sensory rami which extend, as in adult sharks, to the dorsal nucleus in the medulla. In preterm juveniles of 150–160 mm TL, the LL system and the Ampullae of Lorenzini are fully developed cytologically. The results of this study support the hypothesis that the LL system and electrosensory Ampullae of Lorenzini develop as separate modalities and that their structural similarity is due to the origin from the embryonic neuroectoderm. The dichotomy of their evolution occurred in very early ancestry as an ecomorphological adaptation to different sensory functions. Anat. Rec. 252:532–545, 1998. © 1998 Wiley-Liss, Inc.

  • Distribution, morphology, and cytology of Ampullae of Lorenzini in the Oman shark, Iago omanensis (Triakidae), from the Gulf of Aqaba, Red Sea
    The Anatomical record, 1998
    Co-Authors: Lev Fishelson, Avi Baranes
    Abstract:

    Ampullae of Lorenzini are electrosensitive organs that, together with the olfactory organs, form the main sensory systems for foraging and navigation in skates, rays, and sharks. In sharks, these organs are mainly found on the rostral part of the head. This study describes the morphology and cytology of the ampullar system in the Oman shark, Iago omanensis, which is common in the Red Sea. The sharks were collected in the Gulf of Aqaba, Red Sea, at depths of 300–750 m, by a specially designed net. They were brought to the surface and sacrificed by an overdose of MS222, and their heads were fixed and prepared for LM, TEM, and SEM studies. The Ampullae are of the polyvesicular type, and their sensory alveoli are situated on the head only and form groups enclosed in capsules of collagenous connective tissue. The dorsal side of the head features pairs of mediorostral (MRC), laterorostral (LRC), and preorbital (POC) capsules and one frontal capsule (FC), situated at the base of the rostrum in front of the eyes. The ventral side possesses only two, small mandibular (MC) capsules. The number of sensory alveoli differs in each of the capsules, and the largest group of 500 is found in the two mediorostral capsules. Each alveolus is formed by seven to nine sensory vesicles, from which a common tubule, piercing the capsule envelope, extends to a cutaneous pore. Groups of such pores form a pattern typical for Iago. A detailed description is given of the sensory epithelium, kinociliar, and microvillar cells as well as of the supporting cytological elements. The Ampullae of Lorenzini in adult I. omanensis are generally similar to those of a number of other studied sharks. However, as the study shows, their number and configuration differ and form a morphological and topographic pattern typical for this species. Anat. Rec. 251:417–430, 1998. © 1998 Wiley-Liss, Inc.

N. O. Sherman – One of the best experts on this subject based on the ideXlab platform.

  • Actions of dalargin upon single unit activity in the Ampullae of Lorenzini of the skate Raja clavata.
    Neuroreport, 1993
    Co-Authors: G.n. Andrianov, G. N. Akoev, H. A. Braun, I. V. Ryzhova, K. H. Voigt, N. O. Sherman
    Abstract:

    In the present study we have shown by single afferent unit recording in electroreceptors of skates (the Ampullae of Lorenzini) that the synthetic analogue of leu-enkephalin, dalargin (DAL) at concentrations between 10(-6)-10(-10) M cause a concentration-dependent decrease in the resting discharge frequency as well as a decrease in stimulus evoked responses. The specific opiate antagonist naloxone (NAL, 10(-6) M) antagonizes responses induced by DAL. DAL depresses the excitatory action of L-glutamate (L-GLU). The data obtained speak in favour of the presence of opiate receptors at the synaptic membrane of the Ampullae of Lorenzini.

  • AFFERENT SYNAPSES of THE Ampullae of Lorenzini of SKATES
    , 1992
    Co-Authors: G. N. Akoev, N. Andrianov, V. Ryzhova, N. O. Sherman
    Abstract:

    In this work we analyzed the influence of L-serine-O-phesphate (SOP) on synaptic transmission in the Ampullae of Lorenzini of skates. Data that have appeared in the literature on the specific action of this agonist on the kainate-type of receptors in the retinal neurons of the mudpuppy [7] served as the basis for conducting such an investigation. EXPERIMENTAL The experiments were conducted on isolated mandibular groups of Ampullae of Lorenzini of Black Sea skates. The mandibular accumulations of electroreceptors were placed in a thermostatically controlled bath (10-12°C) under conditions of constant superfusion of the preparation with normal test solutions. Under a binocular microscope we removed the capsule and part of the gel preventing access of the investigated solutions to the synaptic region of the receptor cells. The rate of delivery of the solution to the perfusion chamber was 0.2 ml/min. Normal physiological saline solution of the following composition was used (in millimoles per liter): NaC1 – 260, KC1 – 3, MgC12 – i, CaC12 – 2, urea – 350, glucose – 5, Tris-buffer 2 (pH 7.4). The agonists and antagonists were added to the normal solution. The change in frequency of background and evoked pulse activity was analyzed 2-3 min after the beginning of application of the investigated substances. This time was determined by the rate of diffusion of the substances to the synaptic region (the values of the rate were varied from specimen to specimen on account of the different gel concentration) and was constant throughout one experiment. Substances from Sigma (USA) were used. The experimental procedure was described in more detail earlier [3].

  • L-serine-O-phosphate blocks NMDA-evoked responses in the Ampullae of Lorenzini of skates.
    Neuroreport, 1992
    Co-Authors: G. N. Akoev, G.n. Andrianov, I. V. Ryzhova, N. O. Sherman
    Abstract:

    In the present study, we have shown by single afferent unit recording in the organs of Lorenzini that L-serine-O-phosphate (L-SOP) decreases the resting discharge frequency as well as electrically evoked responses. L-SOP in a concentration of 0.1-100 microM antagonizes responses induced by L-glutamate (L-GLU) and N-methyl-D-aspartate (NMDA) and has no effect on the responses to application of kainate (KA) and quisqualate (Q). The results obtained confirm previous observations about the existence of NMDA receptors in the afferent synapse of the Ampullae of Lorenzini.