An ultrastructural study of the rat's suprachiasmatic nucleus

SUBURO, AM; PELLEGRINO DE IRALDI, A

JOURNAL OF ANATOMY

WILEY-BLACKWELL PUBLISHING, INC

Año: 1969 vol. 105 p. 439 - 445

0021-8782

The small neurons that lie along the walls of the third ventricle have received the general name of substantia grisea. Within this area Spiegel & Zweig (1917)-in rodents, carnivores and primates-recognized a nuclear mass dorsal to the optic chiasma which they called the suprachiasmatic nucleus. This was described in the hypothalamus of the rat by Griinthal (1930) and Krieg (1932). It corresponds also to the nucleus T gamma (Friedman, 1912), nucleus ovoideus (Gurdjian, 1927; Rioch,1929; Ingram, Hannet & Ranson, 1932), and noyaux accessoire supraoptique (Foix & Nicolesco, 1925). With Nissl and silver impregnation methods these authors describedthe main histological features of the nucleus and tried to establish its connexions.Using fluorescence microscopy, Fuxe (1965) has shown that this nucleus isthe only place in the rat hypothalamus where numerous serotonin-containing terminals can be found. According to Dahlstrom & Fuxe (1964) these terminalsoriginate from mesencephalic neurons. Here we will describe the ultrastructure of the suprachiasmatic nucleus of the rat.Two types of neurons, both of them containing granulated vesicles, and several types of nerve endings characterized by their vesicle content were recognized.