The magnocellular neurosecretory system of the hamster hypothalamus: an ultrastructural and morphometric study during lifetime

Abstract

A quantitative study regarding the age-related changes occurring in the nucleus and the somatic organelles of neurosecretory magnocellular neurons of the hypothalamo neurohypophyseal system (HNS) was carried out in the hamster at six age-points during animal life. The magnocellular cells of both parts of the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) of male Syrian hamsters between 3 and 30 months of age were examined ultrastructurally. Cells of all age groups present the same morphological ultrastructure. Standard manual morphometric techniques are used to calculate the following parameters related directly or indirectly with cellular activity: nuclear area, nucleolar area, nuclear invagination index and volumetric fractions of some intracellular structures (Golgi apparatus, mitochondria, rough endoplasmic reticulum and lipofuscin). With respect to the cell nucleus, the parameters are not modified during aging. No significant differences in the volume density of subcellular components, except lipofuscin, were detected at the age groups studies. However, there is a positive linear trend among all parameters and age except for the rough endoplasmic reticulum. Our results suggest maintenance of the synthetic activity of the magnocellular neurons in the hamster during aging but in no case an increase in their metabolic activity.