Morphological study on the central subdivision of the rat hypothalamic ventromedial nucleus

Central subdivision of the rat hypothalamic ventromedial nucleus (VMN) was examined with the transmission electron microscope. This portion of VMN consists of densely packed neuronal somata which are characterized by a large pale nucleus with a prominent nucleolus, with clear cytoplasm containing many free ribosomes and randomly distributed fragments of rough endoplasmic reticulum, with small mitochondria and homogeneous lysosomes, with well developed Golgi complex surrounded by a few clear and largely 2-3 dense-core vesicles of 90-110 nm in size and with nucleotid bodies. Besides neuronal somata and their processes also astrocytes, oligodendrocytes and microglial cells and their processes are often seen in this portion of VMN. In the neuropil axo-somatic and axo-dendritici synapses, capillaries, myelinated nerve fibers, nerve profiles filled with dense-core vesicles and distal parts of ependymal tanycytic processes are usually found in the central subdivision of VMN.