Search results for "LIZARD"
showing 10 items of 106 documents
Delayed postnatal neurogenesis in the cerebral cortex of lizards
1988
Labelled cells were consistently observed in the medial cortex of the lizard brain after i.p. injections of tritiated thymidine (5 microCi/g b. wt.), 1, 7, 18 or 28 days of survival and posterior autoradiographic evaluation. In 3 groups of specimens (postnatal, young and adult) of the species Podarcis hispanica, after one day of survival, labelled cells were located in the ependymal cell layer underlying the medial cortex. After intermediate survival times (7, 18 days), labelled cells were found in 3 zones: the ependymal layer, the inner plexiform layer and the granular layer. After one month of survival, most labelled cells were observed in the granular layer. In the granular layer, these …
The GABAergic system of the dorsal cortex of lizards: a combined HRP-GABA immunohistochemistry study.
1990
Abstract γ-Aminobutyric acid (GABA)-like immunoreactive (GABA-LI) neurons were found throughout the mediolateral and rostrocaudal axis of the dorsal cortex. They were horizontal, vertical and multipolar cells, mainly distributed in layers 1 and 3. GABA-LI boutons were diffusely distributed in layers 1 and 3, as well as forming basket-like images around layer 2 pyramidal perikarya. Double labelling experiments indicate that GABA-LI cells are an origin of and a target for rostrocaudal intrinsic projections within the dorsal cortex.
Ultrastructure of putative migrating cells in the cerebral cortex of Lacerta galloti.
1986
Cells considered to be migratory in the cerebral cortex of adult lizards are ultrastructurally of two types. Nuclei in the first type have highly dispersed chromatin, creating a spongy appearance, whereas in the second type the chromatin is irregularly clumped. Both types of cells are closely associated with processes of radial ependymal glia cells, which perhaps orient their migratory pathways. Cells with spongy chromatin show an increase in cytoplasmic organelles and progressive chromatin condensation as they travel from the ependymal layer to the granular layer. Possibly these cells account for the neuronal increase that takes place in the granular layer during postnatal life. Cells with…
Neurons of the medial cortex outer plexiform layer of the lizard Podarcis hispanica: Golgi and immunocytochemical studies.
1994
The study of Golgi-impregnated lizard brains has revealed a scarce but heterogeneous neuronal population in the outer plexiform layer of the medial cortex. Some of the neuronal types detected here resemble the neurons of the dentate molecular layer of the mammalian hippocampus. According to their morphology, five intrinsic neuronal types have been clearly identified: short axon aspinous bipolar neuron (type 1, or sarmentous neuron), short axon aspinous juxtasomatic neuron (type 2, or coral neuron), short axon sparsely spinous multipolar neuron (type 3, or stellate neuron), short axon sparsely spinous juxtasomatic multipolar neuron (type 4, or deep stellate neuron, and sparsely spinous juxta…
Postnatal neurogenesis in the medial cortex of the tropical lizard Tropidurus hispidus.
2004
Young, adult and presumed old specimens of the tropical lizard Tropidurus hispidus, living in an almost steady warm habitat, have been the subjects of a 5-bromodeoxiuridine immunocytochemical study to label proliferating brain cells. All animals showed abundant 5-bromodeoxiuridine-labeled nuclei in the ependyma of their telencephalic lateral ventricles, with these being especially abundant in the medial cortex ependyma. Surprisingly, adult animals displayed higher numbers of labeled nuclei when compared with those of young specimens. In a second experiment, in order to check the evolution of ependymal-labeled nuclei, adult specimens were allowed 4 h or 2, 4, 7, 15 or 30 days of survival aft…
Long-spined polymorphic neurons of the medial cortex of lizards: a Golgi, Timm, and electron-microscopic study.
1988
The morphology, ultrastructure, and principal synaptic input of longspined neurons located in the inner plexiform layer of the medial cortex in three related species of lizards is described. Golgi impregnations have been used to define the external morphology of these neurons and their axonal trajectories. Their most striking characteristic is the presence of very long spines or “microdendrites” especially abundant on the distal dendritic segments. Axons have ascendent trajectories, pass through the cell layer, and ramify in the outer plexiform layer. Combined Golgi-electron microscopy as well as standard electron microscopy permitted the definition of the ultrastructure of these neurons. T…
Photoperiod-temperature and neuroblast proliferation-migration in the adult lizard cortex.
1997
The lizard medial cortex (a zone homologous to the mammalian fascia dentata) shows delayed postnatal neurogenesis throughout the lifetime of these animals. Experimental lesioning of this area is followed by neuronal regeneration, a unique phenomenon in the adult amniote telencephalon. The differential effects of temperature and photoperiod on postnatal neurogenetic activity were studied using tritiated thymidine pulses and posterior autoradiography as well as proliferating cell nuclear antigen (PCNA) immunostaining. Long (summer) photoperiods increased the number of proliferating neuroblasts in the ependymal neuroepithelium. Cold (winter) temperature prevented migration of the newly generat…
Laminar distribution and morphology of gamma-aminobutyric acid (GABA)-immunoreactive neurons in the medial and dorsomedial areas of the cerebral cort…
1988
The morphology and laminar distribution of immunolabeled neurons in the medial and dorsomedial telencephalic cortices of the lizard Podarcis hispanica were examined in vibratome sections after preembedding γ-aminobutyric acid (GABA)-immunocytochemistry. In both cortical areas and at all rostrocaudal levels, GABA-immunoreactive neurons were found in all cortical layers, with the largest number (74%) of GABA-positive cells in layer 3. GABA-positive neurons were classified into pyramidlike, vertical-fusiform, multipolar, and horizontal neurons. Cells that could be so classified were counted in each cortical lamina. In the medial cortex, multipolar and horizontal-bipolar cells dominated layer 1…
Size variation and cell proliferation in chemosensory brain areas of a lizard (Podarcis hispanica): effects of sex and season
2008
Many lizards rely on chemoreception for crucial aspects of their biology, including exploration, prey and predator detection, and intraspecific communication. Here we investigate sex and seasonal variation in size and proliferative activity in chemosensory areas of the lizard brain. We captured adult Iberian wall lizards (Podarcis hispanica) of either sex in the breeding (April) and non-breeding (November) season, injected them with 5-bromo-2'-deoxyuridine (BrdU) and killed them 3 weeks later. We removed the brains, measured the length of the olfactory bulbs, and counted BrdU-labelled cells in the main and accessory olfactory bulbs (MOB, AOB), lateral cortex (LC) and nucleus sphericus (NS).…
Chemosensory Recognition of Familiar and Unfamiliar Conspecifics by Juveniles of the Iberian Wall Lizard Podarcis hispanica
2002
Chemosensory recognition of familiar conspecifics has been reported in studies with members of several lizard families and may be advantageous to distinguish between intruders and neighbors or group members. However,few species have been studied and information on the ability to discriminate between familiar and unfamiliar conspecifics by chemosensory means is lacking for most lizard families. In this paper we ask whether juveniles of the Iberian wall lizard Podarcis hispanica (Lacertidae),can discriminate between chemical signals from familiar conspecifics with whom they have shared a terrarium for several months and those from unfamiliar conspecifics housed in a different terrarium. Exper…