The nuclei of the hypothalamus in cow

Abstract

As a research material we have used the hypothalamo-hypophyseal complexes of 21 cows in the phases of their sexual cycle. From the 21 samples, we have obtained only ten hypothalamico-hypophyseal complexes; in 11 females, the hypothalamus has been obtained separately from the hypophysis, because of the difficulty in getting the complex of the whole. The samples have been fixed in Orth, Carnoy and Helly, led up to paraffin and serially sectioned at 5 μm. We have finally obtained 550 serial sections, stained through the methods Novelli, PAS, Fontana, Steedman-Mowry, Mikami, Bielschowsky, Bodian, Holmes and Nissl. In the cow hypothalamus, we have found the following groups of neurons: anterior (nucleus supraopticus – NSO; nucleus paraventricularis – NPV), middle (nucleus infundibularis), lateral (nucleus hypothalamicus dorsomedialis; nucleus hypotalamicus ventromedialis) and posterior (nucleus periventricularis caudalis; nucleus premamilaris; nucleus corporis mamilaris). The name of the groups was given according to their site, compared to the hypothalamo-neurohypophyseal tract. In the walls of the third hypothalamus ventricle in cow the neurons were localized, which elaborated the releasing hormones (RH) for the gonadotrophic hormones. These neurons have structured the nucleus infundibularis of the cow hypothalamus. The neurons were multipolar, with an average size of 10-12 μm, a 5 μm large vesiculous nucleus and nucleolated. In the neuroplasm of the axon hillock, we have found the numerous PAS-positive granules. These granules were positive in Mikami staining, got stained in blue, which demonstrated that they were of polypeptidic nature. FSH-RH and LH-RH are polypeptids and stimulated the secretions of the gonadotrophic hormones in the β-FSH and the γ-LH cells from the cow adenohypophysis.