vascular and leptomeningeal projections of the subcommissural organ in reptiles. lectin-histochemical, immunocytochemical, and ultrastructural the snake, natrix maura, and the turtle, mauremys caspica, the basal processes of the ependymal cells of the subcommissural organ project toward the local blood vessels and the leptomeninges. these processes and their endings were studied using aldehyde-fuchsin (af), periodic-acid schiff (pas), periodic-acid silver-methenamine (pa-sm), concanavalin a (cona), wheat germ agglutinin (wga), immunoperoxidase staining (employing an antiserum against bovine reissner's fiber; afru), and conventional ...19873692928
an application of numerical taxonomy to the study of the cerebral cortex of natrix maura (l).the separate cellular regions of the reptilian cerebral cortex were studied using numerical taxonomy. three parameters were employed: a) the area occupied by each region at the several levels studied. b) the total area of the cell nuclei present in each level. c) the average are of these nuclei. numerical taxonomy resolves the problem by means of a dendrogram which represents the normalised distances, which indicate levels of similarity on absciassas. the elements studies are on the ordinate axi ...19806997689
histological study of the ependyma of the hypothalamic third ventricle in the water snake natrix maura (l).the ependyma of the hypothalamic third ventricle of natrix maura (l) has been investigated by light microscopy employing nissl and golgi stains. electron microscopy was also used. brains were fixed by intraventricular perfusion and embedded in paraffin, celloidin and spurr resin. light-microscopically the ependyma appears as a simple layer epithelium with round or enlarged nuclei. it sometimes shows basal processes extending into the subependymal tissue. these processes can be clearly seen in ri ...19817234071
ultrastructure of the paraphysis cerebri of the water snake natrix maura l.paraphyseal epithelial cells of natrix maura have been studied with light and electron microscopy. they showed a clear polarity apically related to the third ventricle and, basally, to a connective tissue layer which surrounded the whole organ. the apical surface of the cells, attached by junctional complexes, showed many microvilli, scarce cilia, and some pinocytotic coated vesicles. in their apical cytoplasm many mitochondria and a well-developed golgi apparatus and endoplasmic reticulum were ...19827119164
mitochondria with atypical cristae in the hypothalamic neuropil of the water snake natrix maura. 19827151187
morphological evidence for the presence of two cell types in the ependyma of the subcommissural organ of the snake, natrix maura.two different types of ependymal cells were found in the subcommissural organ (sco) of natrix maura. most secretory cells showed morphological features resembling the general structure and ultrastructure of cells in the sco of other vertebrates. this report describes a second population of cells lining a portion of the dorsal groove of the sco. these cells were not selectively stained by chromalum-hematoxylin and, under the electron microscope, they were characterized by scarce surface different ...19846509515
immunohistochemical localization of gut peptides in the small intestine of snakes.the small intestine of vipera aspis, natrix natrix and natrix maura has been investigated for the presence of six gastrointestinal peptides reported to occur in mammals. gastrin/cck and somatostatin were present in endocrine cells of the gut of all the species investigated. the neuropeptide vasoactive intestinal polypeptide was located within nerve terminals and in body cells only in the small intestine of vipers and was absent in the natricinae investigated. no immunoreactivity was found with t ...19863790035
immunocytochemical localization of peptides in the endocrine pancreas of the snakes vipera aspis and natrix maura.the endocrine pancreas of vipera aspis and natrix maura has been investigated by immunocytochemistry for the presence of six peptides reported to occur in mammals or in reptiles. gastrin/cck and pp were absent in the endocrine cells, vip was located within nerve terminals only. insulin, glucagon, and somatostatin were localized both in vipera and natrix, generally with a ring of d (somatostatin) cells surrounding a core of glucagon (a) and insulin (b) producing cells; however frequent clusters o ...19882907396
[increase in the number of colloidal droplets in the hypothalamus of natrix maura caused by dehydration].the influence of osmotic stress on the number of colloid droplets in the magnocellular neurosecretory nuclei of the water snake natrix maura, has been studied. five experimental groups of five specimens each, were submitted to dehydration by immersion in sea water for several periods of time (3 to 60 h). the number of colloid droplets, identified by histochemical procedures, was counted in serial sections of the retrochiasmatic nuclei. the study of the mean of each group revealed that the amount ...19892631162
a morphological study of the tracheal epithelium of the snake natrix maura.the epithelium of the trachea of the natrix maura snake was studied by conventional light microscopy and transmission and scanning electron microscopy. the epithelium is formed of basal, ciliated, endocrine and secretory cells. it shows different thickness and distribution of the cells, depending on the area (covering the cartilaginous or the membranous zone). secretory cells show a morphology similar to that found in lizards but it is different from the mucous cells reported in the extrapulmona ...19902272908
[effect of dehydration on crh and vasotocin in the median eminence of the snake natrix maura]. 19911798859
exploring the origin of egg protein in an oviparous water snake (natrix maura).reptiles are typical capital breeders that fuel reproduction by the use of lipids stored in fat bodies. however, little is known about the origin (exogenous or endogenous) of egg protein. we have examined the origin of egg protein by means of the analysis of protein content of liver and carcass (skeletal muscle) of the oviparous snake natrix maura throughout an annual cycle. we have also measured monthly variation of the digestive-content mass and the ovarian mass. results showed that protein in ...200717293142
myth busting? effects of embryo positioning and egg turning on hatching success in the water snake natrix is a common belief that reptile eggs should not be turned after oviposition once the embryo has attached itself to the inner membrane of the shell as it might kill developing embryos. here, we used 338 eggs from 32 clutches of the water snake natrix maura to (1) thoroughly describe natural clutch arrangement, (2) experimentally assess the effects of natural embryo positioning and (3) egg turning on embryo metabolism, hatching success, and hatchling phenotype. clutches contained, on average, 5 ...201526294250
heartbeat, embryo communication and hatching synchrony in snake eggs.communication is central to life at all levels of complexity, from cells to organs, through to organisms and communities. turtle eggs were recently shown to communicate with each other in order to synchronise their development and generate beneficial hatching synchrony. yet the mechanism underlying embryo to embryo communication remains unknown. here we show that within a clutch, developing snake embryos use heart beats emanating from neighbouring eggs as a clue for their metabolic level, in ord ...201626988725
only child syndrome in snakes: eggs incubated alone produce asocial individuals.egg-clustering and communal nesting behaviours provide advantages to offspring. advantages range from anti-predatory benefits, maintenance of moisture and temperature levels within the nest, preventing the eggs from rolling, to enabling hatching synchrony through embryo communication. it was recently suggested that embryo communication may extend beyond development fine-tuning, and potentially convey information about the quality of the natal environment as well as provide an indication of forth ...201627761007
gastrointestinal responses to feeding in a frequently feeding colubrid snake (natrix maura).ectotherm vertebrates show physiological mechanisms that reduce metabolic costs during prolonged fasting. once feeding, these animals adopt a wide variety of metabolic responses such as changes in gastrointestinal organ masses. up-regulatory responses after feeding have been widely explored in infrequently feeding snakes like pythons, whereas few studies have been devoted to frequently feeding snakes. in this study, we have considered the gastrointestinal responses after feeding in a frequent fe ...200818440261
immunocytochemical study of the hypothalamic magnocellular neurosecretory nuclei of the snake natrix maura and the turtle mauremys immunocytochemical study of the magnocellular neurosecretory nuclei was performed in the snake natrix maura and the turtle mauremys caspica by use of antisera against: (1) a mixture of both bovine neurophysins, (2) bovine oxytocin-neurophysin, (3) arginine vasotocin, and (4) mesotocin. arginine vasotocin- and mesotocin-immunoreactivities were localized in individual neurons of the supraoptic and paraventricular nuclei, with a distinct pattern of distribution in both species. the same cells ap ...19883409295
ultrastructural immunocytochemistry and lectin histochemistry of the subcommissural organ in the snake natrix maura with particular emphasis on its vascular and leptomeningeal projections.the ependymal cells of the subcommissural organ (sco) of the snake natrix maura display long basal processes which terminate either on blood vessels or on the leptomeninges. the cell body and the basal processes contain a secretory material detectable immunocytochemically at the light-microscopic level using an antibody raised against bovine reissner's fiber. the present investigation deals with the ultrastructural location in these cells of the (i) immunoreactive material; (ii) concanavalin a ( ...19902312353
[notes on reptiles of tunesia. vii. observations on a double-headed snake natrix (reptilia: colubridae)].a case of a double-headed viperine snake natrix maura (linné, 1758) hatching is reported. its two heads are side by side, about equally and perfectly developed and the neck is dual for the 8 first vertebras. two post-pharyngeal fistulas and dissymetries in the cephalic markings and scales are noted. the origin of such an anterior dichtomy is discussed.2006546368
[cytoarchitectonic study of the cerebral cortex of natrix maura]. 1977757441
immunocytochemical and ultrastructural evidence for a neurophysinergic innervation of the subcommissural organ of the snake natrix maura.the subcommissural organ (sco) of the snake natrix maura was studied by use of the immunoperoxidase procedure. primary antisera against bovine neurophysins (nps i + ii, oxy-np), oxytocin (oxy), mesotocin (mst), arginine-vasotocin (avt), somatostatin (som), beta-endorphin (end) and bovine reissner's fiber were used. a conventional ultrastructural study, with special emphasis on the nerve fibers present in the sco, was also performed. nerve fibers containing immunoreactive oxy-np and mst were seen ...19872884036
[immunocytochemical study of the hypophyseal neural lobe of natrix maura in dehydration].the influence of the dehydration treatment on the hypophysial neural lobe of the water snake natrix maura, has been investigated. whereas control animals stayed in fresh water, experimental snakes were immersed in a hypertonic solution of sodium chloride (35%) for 48 h. all specimens were fixed by vascular perfusion with bouin fluid and the pituitaries embedded in paraffin. the sections were stained through histochemical procedures and immunocytochemistry by means of antisera against bovine neur ...19902274703
combined use of immunocytochemistry and lectin histochemistry for the study of the hypothalamic neurosecretory system of the snake natrix maura (l.).natrix maura snakes were processed for immunocytochemistry and lectin histochemistry at both light- and electron-microscopic levels. antisera against bovine neurophysins, vasotocin and mesotocin were used as well as concanavalin a, wheat germ and limax flavus agglutinin lectins. the hypothalamic supraoptic and paraventricular nuclei were studied. vasotocin neurons should contain a glycopeptide and displayed large colloid droplets consisting of large cisternae filled with packed secretory materia ...19948059970
invasive predator snake induces oxidative stress responses in insular amphibian species.the presence of predators induces physiological stress responses in preys to avoid being captured. a stressful situation enhances reactive oxygen species production with potential damage to macromolecules and alterations in oxidant defences levels. the antioxidant enzyme response of the endemic majorcan midwife toad (alytes muletensis) and the balearic green toad (bufotes balearicus) tadpoles against an invasive predator, the viperine snake (natrix maura) was investigated. tadpoles were introduc ...201627213671
the distribution of corticotropin-releasing factor--immunoreactive neurons and nerve fibers in the brain of the snake, natrix maura. coexistence with arginine vasotocin and mesotocin.the anatomical distribution of neurons and nerve fibers containing corticotropin-releasing factor (crf) has been studied in the brain of the snake, natrix maura, by means of immunocytochemistry using an antiserum against rat crf. to test the possible coexistence of crf with the neurohypophysial peptides arginine vasotocin (avt) and mesotocin (mst) adjacent sections were stained with antisera against the two latter peptides. crf-immunoreactive (crf-ir) neurons exist in the paraventricular nucleus ...19911868522
induced defences in an endangered amphibian in response to an introduced snake predator.introduced species have contributed significantly to the extinction of endemic species on islands. they also create new selection pressures on their prey that may result in modified life history strategies. introduced viperine snakes ( natrix maura) have been implicated in the decline of the endemic midwife toad of mallorca ( alytes muletensis). a comparison of a. muletensis tadpoles in natural pools with and without snakes showed that those populations subject to snake predation possessed longe ...200415338267
behavioural responses of mallorcan midwife toad tadpoles to natural and unnatural snake predatorsthe activity levels of mallorcan midwife toad tadpoles, alytes muletensis, were compared in two natural torrent pools which differed in their use by predatory viperine snakes, natrix maura. activity levels were lower in a pool regularly used by snakes than they were in a snake-free pool, but were reduced in both pools when snakes were experimentally introduced in nylon bags. in the presence of snakes, however, activity was more suppressed in the pool that was usually snake-free. corresponding re ...19989480687
from tameness to wariness: chemical recognition of snake predators by lizards in a mediterranean island.antipredatory defenses are maintained when benefit exceeds cost. a weak predation pressure may lead insular lizards to tameness.podarcis lilfordiexhibits a high degree of insular tameness, which may explain its extinction from the main island of menorca when humans introduced predators. there are three species of lizards in menorca: the nativep. lilfordi, only on the surrounding islets, and two introduced lizards in the main island,scelarcis perspicillataandpodarcis siculus. in addition, there a ...201728123905
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