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.
