The hypothalamic-hypophysial neurosecretory system in the iguanid lizard, Dipsosaurus dorsalis: a qualitative and quantitative study

Distribution of arginine vasotocin in the brain of the lizard Anolis carolinensis

The distribution of immunoreactive arginine vasotocin (AVT-ir) was determined in the brain of the lizard Anolis carolinensis. Cells and fibers containing AVT-ir were found in the medial septal region, lamina terminalis, lateral forebrain bundle, preoptic area, supraoptic nucleus, anterior hypothalamus, paraventricular nucleus, periventricular nucleus, arcuate nucleus, and ventromedial nucleus of the thalamus. Occasional AVT-ir cells were found in the interpeduncular nucleus. Fibers containing AVT-ir were found in the cortex, around the olfactory ventricle, in the diagonal band of Broca, amygdala area, dorsal ventricular ridge, striatum, nucleus accumbens, septum, ventromedial hypothalamus, lateral hypothalamus, medial forebrain bundle, median eminence, pars nervosa, nucleus of the solitary tract, locus coeruleus, cerebellar cortex (granular layer), dorsal part of the nucleus of the lateral lemniscus, substantia nigra, and myelencephalon. The intensity of AVT-ir staining was, in general, greater in males than in females. Comparison of AVT-ir distribution in A. carolinensis with those previously published for other reptilian species revealed species-specific differences in distribution of AVT.

Immunocytochemical study of the hypothalamic magnocellular neurosecretory nuclei of the snake Natrix maura and the turtle Mauremys caspica

An 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 appeared to be stained by the anti-oxytocin-neurophysin and antimesotocin sera. The supraoptic nucleus can be subdivided into rostral medial and caudal portions. In N. maura, but not in M. caspica, neurophysin-immunoreactive neurons were found in the retrochiasmatic nucleus. No immunoreactive elements were seen in the suprachiasmatic nucleus of both species after the use of any of the antisera. A dorsolateral aggregation of neurophysin-containing cells, localized over the lateral forebrain bundle, was present in both species. Magnocellular and parvocellular neurophysin-immunoreactive neurons were present in the paraventricular nucleus of both species. In the turtle, the paraventricular neurons were arranged into four distinct layers parallel to the ependyma; these neurons were bipolar with the major axis perpendicular to the ventricle, and many of them projected processes toward the cerebrospinal-fluid compartment. In N. maura a group of large neurons of the paraventricular nucleus was found in a very lateral position. The posterior lobe of the hypophysis and the external zone of the median eminence contained arginine vasotocin- and mesotocin-immunoreactive nerve fibers. The lamina termialis of both species was supplied with a dense bundle of fibers containing immunoreactive neurophysin. Neurophysin-immunoreactive fibers were also present in the septum, some telencephalic regions, including the cortex and the olfactory tubercule, in the paraventricular organ, and the periventricular and periaqueductal gray of the brainstem.

The distribution of hypothalamic and extrahypothalamic vasotocinergic cells and fibers in the brain of a lizard, Gekko gecko: presence of a sex difference

The distribution of vasotocin in the brain of the lizard Gekko gecko was studied with immunocytochemical methods. Vasotocinergic cells were found in the nucleus supraopticus, the nucleus paraventricularis, the bed nucleus of the stria terminalis, and in the rhombencephalon. Vasotocinergic fibers were found in the preoptic area, the lateral and ventral hypothalamus, and in many extrahypothalamic brain areas. Furthermore, evidence was obtained of a conspicuous sex difference with regard to vasotocinergic innervation of the lateral septum, the ventrocaudal telencephalon (nucleus sphericus), and the periaqueductal gray; in these areas vastocinergic innervation is much denser in males than in females. The results are discussed in relation to the sexually dimorphic vasopressinergic innervation of the rat brain. It is suggested that the vasotocinergic fiber system in the sexually dimorphic brain areas in Gekko gecko is related to the bed nucleus of the stria terminalis.

A cytoarchitectonic study of the hypothalamus of the lizard, Calotes versicolor

The hypothalamic nuclei of the lizard, Calotes versicolor, can be broadly divided into "AF-positive" and "AF-negative". The AF-positive cell complexes include the nucleus supraopticus, nucleus paraventricularis, and a few interconnecting bridge cells. In addition, some AF-positive neurones are also observed in the median eminence. As many as 15 AF-negative nuclei-like accumulations of nerve cells can be identified in the hypothalamus. The nucleus periventricularis hypothalami of earlier authors is subdivided into eight circumscribed neuronal complexes. In addition, a few AF-negative nuclei, e.g. nucleus subfornicalis, nucleus ventralis tuberis, nucleus med. recessus infundibuli, nucleus lat. recessus infundibuli and nucleus praemamillaris, are regarded for the first time as anatomical entities. The distribution of the hypothalamic nuclei and their cytoarchitectonic features are described at the light microscopical level. An attempt has been made to interprete the nuclei identified in the present study on a comparative and phylogenetic basis.