[Changes in the hypothalamus in continuously irradiated sheep].

Neurosecretion, PAS-positive mucopolysaccharides and the Nissl substance were studied in the neurons of the rostral, medial and caudal hypothalamus of continuously irradiated ewes. The study was performed on 21 ewes of the Slovak Merino breed at the live weight of 34 kg. The animals were in the period of physiological anoestrus and their age was two to three years. The first group of six ewes was the control. The second group included 15 sheep irradiated with a total dose of 6.7 Gy (700 R) for seven days. Co60 was used as the source of irradiation. The animals of this group were killed seven days from treatment. The ewes in the third group were left for the study of mortality. The brains were perfused with 2% buffered paraformaldehyde immediately after the bleeding of the sheep; then the brains were removed from skulls and fixed in buffered picroformol. Paraffin slices were stained with haematoxylin-eosine, aldehyde-fuchsine and alcian blue for neurosecretion, with PAS-reaction for mucopolysaccharides and with cresyl violet for the Nissl substance. As found, the irradiation of the whole body inhibits the activity of neurosecretory cells in rostral and medial hypothalamus, thus reducing neurosecretion. These regions also show a reduced activity of PAS reaction used for the demonstration of mucopolysaccharides. The observed changes also included damage of the endothelium of blood vessels with the occurrence of erythrocyte extravasates and with haemorrhages.(ABSTRACT TRUNCATED AT 250 WORDS)