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PubMed1992

Cholinergic, monoaminergic and peptidergic innervation of the primary visual centers in the brain of the lizards Gekko gecko and Gallotia galloti.

In order to study the relationship between retinal projections and immunohistochemically identified neurotransmitter systems in the primary visual centers of the brain in lizards, intraocular injections of horseradish peroxidase were combined with immunohistochemistry. Antibodies raised against six substances were applied: choline acetyltransferase (ChAT), serotonin (5-HT), tyrosine hydroxylase (TH), dopamine (DA), substance P (SP), and leu-enkephalin (LENK). In the primary visual centers of the lizards Gekko gecko and Gallotia galloti, notable overlap was observed between retinofugal fibers with: 1) ChAT-immunoreactive fibers in almost all primary visual centers; 2) 5-HT-immunoreactive fibers in the ventral lateral geniculate body and the basal optic nucleus; 3) TH-immunoreactive fibers in the nucleus ovalis and the dorsal lateral geniculate body; 4) SP- and LENK-immunoreactive fibers in the perirotundal belt; and 5) TH- and SP-immunoreactive fibers in the pretectal posterodorsal nucleus. The latter nucleus also contains dopaminergic cell bodies that lie outside the retinal target area but have dendrites extending into it. Several differences were noted in the distribution of 5-HT, TH-, DA-, and LENK-immunoreactive fibers in the tectum of the midbrain in the two species studied. Distinct laminae of 5-HT-immunoreactive fibers (layer 9) and TH- and DA-immunoreactive fibers (layers 9 and 11) are present in G. gecko but absent or, at least, less distinct in G. galloti. On the contrary, the optic layers in the tectum of G. galloti show a rather dense plexus of LENK immunoreactive fibers, whereas the corresponding layers in G. gecko are devoid of LENK-immunoreactivity. Since only a very few ChAT immunoreactive fibers were observed in the optic nerve of G. galloti, most of the observed immunoreactive fibers in the primary visual centers are considered to have an extraretinal origin. Putative sources of the cholinergic, the monoaminergic, and the peptidergic innervation of the primary visual centers in reptiles include the isthmic nucleus, the raphe nuclei, the substantia nigra and the nucleus of the posterior commissure, as reported in other amniotes.

Animals↗

PubMed1978

Hormonal control of male reproductive behavior in the lizard, Anolis carolinensis: role of testosterone, dihydrotestosterone, and estradiol.

The androgen aromatization hypothesis was examined in the male lizard, Anolis carolinensis. After castration, sc silastic implants of testosterone (T) restored both challenge and courtship behavior, while dihydrotestosterone (DHT) or 17beta-estradiol (E) had no effect on male behaviors. Both T and DHT, but not E, stimulated hypertrophy and colloid production by the renal sex segment, a secondary sexual characteristic of male lizards. In two separate studies, castrates received DHT in combination with E. In each replicate, half of the castrates responded with increases in courtship behavior after hormone treatment. Epithelial cell height of the sex segment of all DHT and E-treated castrates was comparable to T- or DHT-treated castrates, but colloid production was not stimulated. These experiments indicate that in this species, treatment with T stimulates both sexual behavior and secondary sex character development, whereas treatment with E alone is without effect centrally or peripherally.

Animals↗

PubMedDate not supplied

Effect of cortisone on aspartate and alanine aminotransferases in a desert lizard.

1. Liver and serum aspartate aminotransferase (GOT) and alanine aminotransferase (GPT) activities were measured in a hibernating desert lizard, Uromastix hardwickii. The levels of both enzymes were found to be lower in hibernation than during the active period, particularly in the liver. 2. After intramuscular injection of 2 mg of cortisone acetate there was a rapid rise in the levels of these enzymes with a peak of 18 hours (GOT) and 12 hours (GPT). 3. The response of both enzymes to cortisone was much greater during the active period than during hibernation. 4. GOT showed a much more rapid and greater response to cortisone than GPT. This is in contrast to the response of rat liver where GPT is more responsive to this hormone. 5. These studies indicate that the transferase enzymes of this lizard differ from those of the rat in their sensitivity and time of response to cortisone.

Alanine Transaminase↗

PubMedDate not supplied

Toxic effects of gentamicin on the basilar papilla in the lizard Calotes versicolor. A surface study.

Gentamicin in a dose of 100 mg and in some cases 150 mg per kg bodyweight and day was given intraperitoneally to healthy lizards, belonging to the species Calotes Versicolor. The animals were injected for 7, 14 and 21 days. After completed injections the animals were sacrificed and their hearing organ, the basilar papilla, was processed for scanning electron microscopy. Animals treated for 7 days did not show any significant surface damage in the basilar papilla. When gentamicin was administered for 14 days the normal appearance of the surface structure was lost. The ventral (apical) type A cells were relatively intact while the type B cell-population in the dorsal (basal) part of the organ showed sensory hair fusions and cytoplasmic herniations. Lizards treated for 21 days showed a severely damaged basilar papilla. The ventral (apical) type A cells still only were moderately damaged with some hair fusions and cytoplasmic herniations while the dorsal (basal) type B cells were more or less destroyed. Only occasional cells were left and some of these were severely damaged. The surface of the dorsal (basal) part of the organ instead was covered by supporting cells thus forming a sort of scar tissue.

Animals↗

PubMedDate not supplied

Gentamicin-induced changes in RNA content in sensory and ganglionic cells in the hearing organ of the lizard Calotes versicolor. A cytochemical and morphological investigation.

The effect of short-term administration of gentamicin on RNA content in isolated sensory and ganglionic cells in the hearing organ of the lizard Calotes versicolor was investigated. The effects of the drug on this biochemical parameter are compared with ultrastructural changes in sensory cells from the same material. In the first test group, daily intraperitoneal injections for 3 to 6 days resulted in a 30-50% decrease of the amount of RNA in sensory and ganglionic cells. No constant ultrastructural changes were recorded in the sensory cells at this point in time. A second test group received 3 or 5 injections of gentamicin and the animals were then left untreated for 21 days. The reduced RNA content persisted in both sensory cells and in ganglionic cells from animals that received 5 injections, whereas the content of RNA in ganglionic cells from lizards that received 3 injections was restored almost to control values at the end of this 21-day period. In the second test group, definite morphological derangements were observed in the sensory cells. The correlation between cytochemical and morphological findings as well as possible modes of action of gentamicin on inner ear ganglionic and sensory cell RNA content are discussed.

Animals↗

PubMed1976

Experimental alimentary infection of anole lizards (Anolis carolinensis) with Mycobacterium ulcerans.

Pathogenic Mycobacterium ulcerans were recovered from the stool of anole lizards up to 11 days after inoculation by stomach tube. M. ulcerans was isolated from the liver of 3 of 20 lizards and acid fast bacteria were seen in the mucosa of intrahepatic bile ducts in 2 of these 10 weeks post-inoculation. These results provide equivocal support for our hypothesis that herpetofauna are a reservoir of infection with M. ulcerans.

Administration, Oral↗

PubMed1976

Morphology of ovarian changes during the reproductive cycle of the house lizard, Hemidactylus flaviviridis.

Ovarian changes during the reproductive cycle of the oviparous wall lizard (Hemidactylus flaviviridis Rüppel) are described and discussed. It ovulates from mid-March to mid-May with a peak in April. Two eggs, one from each ovary, are ovulated at a time. After the breeding season is over, the ovaries are reduced in size. From June to third week of February they contain small pre-vitellogenic fillicles which start increasing in size with the approach of March when yolk deposition occurs rapidly. The histological details of developing the pre-ovulatory follicles are described. Follicle cell nuclei are taken into the ooplasm of pre-vitellogenic follicles; they are finally absorbed before yolk deposition starts. Pre-ovulatory follicles show highly vascularized thecae and invaginations of the follicular epithelium. Follicular atresia generally occurs in follicles with polymorphic granulosae, in post-ovulatory ovaries. Their granulosa cells give rist to phagocytes which, after removing the ooplasmic contents, degenerate, while the theca interna cells are hypertrophied to form the interstitial gland cells in the walls of degenerated follicles. After ovulation, the granulosa cells hypertrophy to form luteal cell mass filling the follicular cavity. Fibroblasts which appear to arise from the thecal layer, invade the luteal cell mass and form septa. Blood vessels occur in the luteal cell mass. The possible physiological significance of corpora lutea in the wall lizard is discussed.

Animals↗

PubMed1975

Dermatophilosis in Australian bearded lizards.

Dermatophilosis (Dermatophilus congolensis) was diagnosed in 3 Australian bearded lizards. Each lizard died of causes associated with stress and poor adaptability, although the lesions appeared to be regressing at the time of death.

Actinomycetales↗

PubMed1979

[Interaction between Karyolysus sp. and rock lizard liver cells during hibernation].

During the rock lizard hibernation, no nuclear division occurs in the exoerythrocytar trophozoites of Karyolysus sp., found in hepatocytes or Kupffer's cells. In addition, organelles of the apical complex are seen persisting in these trophozoites, unlike the situation routinely observed in the majority of other intracellular sporozoans. Thus, the parasites under study can be compared with hypnozoites of other coccidia. The material being examined from natural rather than experimental conditions, during lizards' hibernation, the dynamics of host-parasite interrelations can be followed that involves the appearance in the infected cell of autophagous vacuoles, changes in mitochondrial structure and pattern of endoplasmic reticulum, the connection of the system of lamellar channels with the space of the parasitophorous vacuole. The results of the present observations may suggest, first, that during the host hibernation, exoerythrocytar trophozoites of Karyolysus being intracellular in their spatial distribution, are able to obtain nutrients from the outer, extracellular space, through the system of lamellar channels; second, that these channels can represent intercellular connections, which makes one consider the exoerythrocytar trophozoites as intercellular rather than intracellular parasites.

Animals↗

PubMed1977

Effects of hormones on the aggressive behaviour and social organization of the scincid lizard, Sphenomorphus kosciuskoi.

In order to ascertain whether hormones influence social organization of lizards, caged Sphenomorphus kosciuskoi were studied both before and after treatment with testosterone, estradiol, adrenaline and thyroxine. Testosterone and estradiol increased aggressiveness in male lizards and caused shifts in dominance. Adrenaline caused a temporary increase in activity and agressiveness but no change in social structure. Thyroxine did not affect social behaviour.

Aggression↗

PubMed1976

Dermatophilosis in the marble lizard (Calotes mystaceus).

Dermatophilus congolensis was isolated from cutaneous hyperkeratotic nodules of two marble lizards. The organism was similar to strains of D congolensis previously characterized as mammalian pathogens. The isolate was experimentally transmitted to other marble lizards and to Spb:(SW)BR mice by subcutaneous inoculation and by topical application after skin scarification.

Actinomycetales↗

PubMed1976

Glucagon levels in pancreatic extracts and plasma of the lizard (1).

Levels of glucagon in the splenic pancreas and in plasma of the lizard Anolis carolinensis were estimated by radioimmunoassay. The splenic pancreas of Anolis has a glucagon concentration nearly a 1000 times greater, on a weight basis, than that of the mammalian pancreas. Glucagon-like immunoreactivity (GLI) of anolian plasma varied over a wide range, but relative to mammals the GLI levels were inappropriately elevated for the concentration of plasma glucagon secretion, particularly as related to alpha cell function in the diabetic state.

Animals↗

PubMed1978

Action of the pterygoideus muscle during feeding in the lizard Uromastix aegyptius (Agamidae).

The actions of the deep and superficial portions of the pterygoideus muscle and the depressor mandibulae were studied in the agamid lizard, Uromastix aegyptius, using fine wire electrodes. The EMG signals were recorded, while simultaneously recording the jaw positions during feeding on movie film at 32 fps. Muscle activity varies with different types of food. The deep and superficial portions of the pterygoideus performed different functions. The deep pterygoideus functioned during opening of the jaws, presumably to protract the jaw. The superficial pterygoideus was strictly a jaw elevator. The depressor mandibulae is not the initiator of jaw opening. When biting on tough food items, the deep pterygoideus and depressor mandibular were active.

Animals↗

PubMed1978

A study of the structure of the papilla neglecta in the lizard, Anolis carolinensis.

Scanning and transmission electron microscopy have been used to investigate the structure of the papilla neglecta in the lizard, Anolis carolinensis. Situated in the posterior part of the utricle, the receptor is innervated by a branch of the posterior ampullary nerve and is covered by an extracellular membrane that exhibits a tapering extension into the orifice of the utriculo-saccular duct. The neuroepithelium contains two populations of sensory cells within a matrix of sustentacular cells; one population (non-calyceal hair cells) is supplied primarily by boutons and clublike terminals, while the other (calyceal hair cells) is served by calycine terminals that invest from one to five sensory cells. The apices of calyceal hair cells bulge into the utricular lumen and have larger diameters and ciliary counts than non-calyceal cells, but other differences are not marked. Although the bases of calyceal hair cells are deeply indented by calyceal processes, both types show similar afferent synaptic structures confined to the nuclear and infranuclear regions. Efferent terminals synapse on afferent endings and hair cells in both cases; synapses directly on calyceal hair cells lie above the calyx, just beneath the apicolateral junctional complexes. Those complexes are basically similar throughout the receptor, except that a hemispheroidal gap junction between a supporting cell and adjacent hair cell was noted in several instances. Arrays of endoplasmic reticulum and specialized mitochondria occur adjacent to aggregations of afferent synaptic vesicles in both types of sensory cell; it is suggested that such arrays may participate in the production of the vesicles in a process involving membrane recycling similar to that at the neuromuscular junction. Differences between calycine units and the type I hair cell of mammals are discussed, and evidence that suggests an equilibratory function for the lacertilian papilla neglecta is presented.

Animals↗

PubMed1977

The cytoarchitecture of the torus semicircularis in the Tegu lizard, Tupinambis nigropunctatus.

The torus semicircularis (TS) of the Tegu lizard extends from the superficial caudal mesencephalon, dorsal to the exiting trochlear nerve, to a position ventral to the middle part of the optic tectum and its ventricle. It has an oblique orientation with the caudal pole abutting the midline while the rostal end is lateral and slightly ventral. The TS consists of a central nucleus and several adjacent cell groups. The central nucleus and the laminar nucleus, situated medially, extend the entire length of the TS while the cortical nucleus, situated dorsally and laterally, is present only in the caudal superficial portion. The central nucleus is composed of ovoid neurons with branched, radiating dendrites. The dendrites are directed medially and laterally with spines on the distal portion of the dendritic tree. The laminar nucleus consists of three to five neuronal layers. It is mainly composed of fusiform neurons with one dendritic trunk from each extremity of the soma. There is little branching and few dendritic spines. The cortical nucleus is a laminated region consisting of alternating layers of neurons and lateral lemniscal fibers. The neurons of the superficial layers are fusiform with their long axis perpendicular to the long axis of the brainstem. They possess two main dendritic trunks which parallel the laminae and are covered with dendritic spines. The deeper layers consist of pyramidal neurons with three dendritic trunks, secondary branches, and few spines. The long axis of these neurons extends from the center of the TS to the periphery. Two dendritic trunks extend dorsally or laterally towards the surface, while the third extends towards the central nucleus. The dendrites, thus, extend across the laminae. In addition, a cell-free lateral zone is described.

Animals↗

PubMed1978

The organization of the hippocampus of the fence lizard: a light microscopic study.

The hippocampus of the fence lizard (Sceloporus undulatus) is composed of two laminated regions that are readily distinguishable on the basis of position and perikaryal size in Nissl preparations: the small-celled (Hsc) and the large-celled (Hlc) hippocampal divisions. Based upon cellular and fibrillar characteristics, the layers of the Hsc are: (1) the superficial plexiform layer; (2) the cellular layer; (3) the deep plexiform layer; (4) the layer of deep fibers, or alveus; and, (5) the ventricular ependyma. The layers of the Hlc are: (1) the tangential layer; (2) the molecular layer; (3) the pyramidal layer; (4) the deep plexiform layer; (5) the alveus; and, (6) the ventricular ependyma. The neurons of each hippocampal layer were grouped into classes based upon somal position and appearance, and dentritic and axonal arborization patterns in Golgi sections. Neurons of the Hsc are more numerous and pleomorphic than those of the Hlc. Data do not suggest an intrinsic organization that closely parallels that found in the mammalian hippocampus.

Animals↗

PubMed1978

Ascending connections to the forebrain in the Tegu lizard.

The ascending connections to the striatum and the cortex of the Tegu lizard, Tupinambis nigropunctatus, were studied by means of anterograde fiber degeneration and retrograde axonal transport. The striatum receives projections by way of the dorsal peduncle of the lateral forebrain bundle from four dorsal thalamic nuclei: nucleus rotundus, nucleus reuniens, the posterior part of the dorsal lateral geniculate nucleus and nucleus dorsomedialis. The former three nuclei project to circumscribed areas of the dorsal striatum, whereas nucleus dorsomedialis has a distribution to the whole dorsal striatum. Other sources of origin to the striatum are the mesencephalic reticular formation, substantia nigra and nucleus cerebelli lateralis. With the exception of the latter afferentation all these projections are ipsilateral. The ascending connections to the pallium originate for the major part from nucleus dorsolateralis anterior of the dorsal thalamus. The fibers course in both the medial forebrain bundle and the dorsal peduncle of the lateral forebrain bundle and terminate ipsilaterally in the middle of the molecular layer of the small-celled part of the mediodorsal cortex and bilaterally above the intermediate region of the dorsal cortex. The latter area is reached also by fibers from the septal area. The large-celled part of the mediodorsal cortex receives projections from nucleus raphes superior and the corpus mammillare.

Animals↗

PubMed1979

Efferent projections of the dorsal ventricular ridge and the striatum in the Tegu lizard. Tupinambis nigropunctatus.

A H3 proline-leucine mixture was injected into the dorsal ventricular ridge (DVR) and striatum of the Tegu lizard in order to determine their efferent projections. The brains were processed according to standard radioautographic technique, and counterstained with cresyl violet. DVR projections were generally restricted to the telencephalon, while striatal projections were limited to diencephalic and mesencephalic structures. Thus the anterior DVR projects ipsilaterally to nuclei sphericus and lateralis amygdalae, striatum (ipsilateral and contralateral) ventromedial nucleus of the hypothalamus, nucleus accumbens, anterior olfactory nucleus, nucleus of the lateral olfactory tract and lateral pallium. Posterior DVR projections enter ipsilateral anterior olfactory nucleus, lateral and interstitial amygdalar nuclei, olfactory tubercle and bulb, nucleus of the lateral olfactory tract and a zone surrounding the ventromedial hypothalamic nucleus. Labeled axons from striatal injections pass caudally in the lateral forebrain bundle to enter (via dorsal peduncle) nuclei dorsomedialis, medialis posterior, entopeduncularis anterior, and a zone surrounding nucleus rotundus. Others join the ventral peduncle of LFB and enter ventromedial nucleus (thalami), while the remaining fibers continue caudally in the ventral peduncle to the mesencephalic prerubral field, central gray, substantia nigra, nucleus intercollicularis, reticular formation and pretectal nucleus posterodorsalis. These results are discussed in relation to the changing notions regarding terminology, classification and functions of dorsl ventricular ridge and striatum.

Amygdala↗