[Morphologic study of several hypothalamic centers in rats following deafferentation of the mediobasal hypothalamus]

Nuclear and nucleolar volumes of the cells of some hypothalamic centers (SON, PVN, SCN, VMN, AN) were estimated in control rats and in those with deafferented medial basal hypothalamus. There is sex difference in measured values among parvocellular formations of control animals: nuclei and nucleoli of the neurons in AN and in VMN and nucleoli of the neurons in SCN are larger in females than in males. Deafferentation led to an increase in the nuclear volume, especially in the formations outside the isolated area. It was more pronounced in rats with persistent estrus. The difference between estrous and diestrous rats is statistically significant for volumes of nuclei and nucleoli of the neurons in SCN and not for those in AN, inspite of the impressive diversity of the pituitary LH content. The suggestion is made that gonadoliberins are not secreted by the cells of AN, and that SCN might control the stage of the estrous cycle.