[Changes in neurosecretory activity in the hypothalamus of sheep after administration of PMSG].

By means of histological methods of histochemical nature we examined the qualitative alterations in neurosecretory cells of anterior (nucl. paraventricularis - NPV. nucl. preopticus medialis - NPM), medial (nucl. arcuatus s. infundibularis - NARC), and posterior (nucl. tuberomamillaris - NTM) hypothalamus of sheep with a simultaneous caryometric analysis of neurons of the same nuclei after administration of various PMSG doses. The examination was performed on the brain samples of 23 two- to three-year-old sheep, of the Slovak Merino breed, at the live weight of 30 to 40 kg. in the period of physiological anoestrus (June-July). The animals were divided into three experimental groups and were instilled agellin sponges (20 mg). On the 13th day the sponges were removed and the first group was applied 1000 i. u. PMSG, the second group 750 i. u. PMSG. The sheep were killed within 30 to 36 hours after the oestrus determination with a teaser ram. After bleeding of animals the brains were perfused with 2% buffered paraformaldehyde and after taking out the brains from the crania their fixation was finished in buffered picroformol. Paraffin slices were stained with haematoxylin-eosine and crotonaldehyde-fuchsin to neurosecretions. Caryometric analysis was carried out with a 1000 fold magnifying and with a measuring of 200 cells from one sample. We recorded the neurosecretion increase in all hypothalamic nuclei under study. The caryometric analysis has shown a moderate shift to the right, it means the volume increase of nuclei of neurosecretory cells, which demonstrates a stimulation of the function of hypothalamic structures.