Gomori-positive elementary granules in inner and outer layer of the infundibulum

Effect of salt loading and salt deprivation on the vasopressin and oxytocin content of the median eminence and the neural lobe in adrenalectomized rats

In adrenalectomized rats the influence of salt loading or salt deprivation on the vasopressin and oxytocin content of the median eminence (ME) and the neural lobe (NL) was studied by means of various methods: morphometric and microphotometric analysis of aldehyde fuchsin-stained sections of ME and NL; immunohistochemical demonstration of neurophysin, oxytocin, and vasopressin in the ME and in the NL; radioimmunological measurement of oxytocin and vasopressin in the ME and in the NL. Adrenalectomy in salt-substituted rats raised the vasopressin content of the outer layer of the ME (OLME) but had no influence on the amount of vasopressin in the inner layer of the ME and in the NL. Osmotic stimulation of adrenalectomized rats by hypertonic saline markedly diminished vasopressin and oxytocin in the inner layer of the ME and in the NL but did not, or only slightly reduced vasopressin in the OLME. Withdrawal of salt supplementation in adrenalectomized rats resulted in a decrease of plasma sodium and plasma volume. It did not change the vasopressin or oxytocin content of the inner layer of the ME and of the NL, but it was correlated with a decrease of vasopressin in the OLME. The present findings may suggest that vasopressin in the OLME is involved in salt and/or volume regulation by influencing the hypophysial-adrenal axis.

Detection of aldehydefuchsin-positive neurosecretory granules in the cells of the suprachiasmatic nucleus of the rat

Application of dark field microscopy to sections fixed with picric acid--formalin and stained with crotonaldehydefuchsin allows the demonstration of neurosecretory granules in the neurones of the suprachiasmatic nuclei of normal rats.

Immuno-cytochemical demonstration, in the external region of the amphibian median eminence, of separate vasotocinergic and mesotocinergic nerve fibres

By means of single and double immuno-enzyme cytochemical staining techniques, it was shown that the external region of the amphibian median eminence contains separate vasotocinergic and mesotocinergic nerve fibres. Moreover, it was demonstrated that the vasotocinergic fibres also contain neurophysin. In animals in which the hypothalamic magnocellular neurosecretory preoptic nuclei had been completely removed, the immuno-reactive vasotocinergic and mesotocinergic fibres of the median eminence had disappeared. From this result, it is concluded that, at least the great majority of the vasotocinergic and mesotocinergic fibres of the external region of the amphibian median eminence are processes of neurosecretory perikarya located in the hypothalamic magnocellular preoptic nuclei. On the other hand, our results do not exclude the possibility that a minority of these neurosecretory fibres originate from small immuno-reactive perikarya which were found in the tuber cinereum. The observation that both kinds of processes accumulate around blood capillaries of the hypophysial portal system strongly suggests that they play a role in the control of the activity of the pars distalis of the hypophysis.

Electron microscopic immunohistochemical localization of vasopressin and neurophysin in the median eminence of normal and adrenalectomized rats

Using an immunoperoxidase technique at the ultrastructural level, vasopressin (VP) and neurophysin (NP) were localized in the axons of the median eminence of normal and adrenalectomized rats. Whereas VP and NP were generally found in 150-nm granules in the internal zone of the normal rat median eminence, in the adrenalectomized rat, many granules of about 80 to 100 nm in diameter were found to contain NP and VP in the external zone of the median eminence.