[The neurocytes of the caudal part of the tuberomamillary nucleus in Ovis aries L. (light microscopy and electron microscopy studies)].

The neurons of the pars caudalis nuclei tuberomammillaris (pc-NTM) were studed light-microscopically and electron-microscopically in sheep and rams of Merino breed. In our study we observed: In the regarded neural nucleus, there is the majority of the great neurons (up to 60 microns in diameter) rich in the NISSL's bodies. When stained with the cresyl violet, the NISSL's substance is apparently stored mainly in peripheral area of the cell body and in the distant parts of numerous protoplasmic processes, what evokes an impression of the "jagged" surface of these cells. After staining with paraldehyde fuchsin, we found purple coloured lumps of irregular shape stored outside the cell bodies, in the neuropil. The less extended cells, usually with lower content of NISSL bodies, are in pc-NTM less frequent. In the electron-microscopic study we identified 3 types of neurons: Cells rich in rough endoplasmic reticulum; "light" cells, "dark" cells. The cells of the 1st type were the most frequent ones. Cisterns of rough endoplasmic reticulum in the 1st type of cells are often dilated. The protoplasmic processes of these cells are frequently stepped over by flat tubuli of endoplasmic reticulum. The 2nd type of cells is characterized by the light cytoplasmic matrix, low quantity of endoplasmic reticulum and frequent occurrence of lipofuscin bodies. The 3rd type of cells are characterized by the high density of cytoplasmic matrix, well developed GOLGI complex, and very broad cisterns of endoplasmic reticulum, forming a labyrinth, and it is bound to a broad perinuclear space.