THE MAGNOCELLULAR NEUROSECRETORY-SYSTEM OF THE HAMSTER HYPOTHALAMUS -AN ULTRASTRUCTURAL AND MORPHOMETRIC STUDY DURING LIFETIME

A quantitative study regarding the age-related changes occurring in th e nucleus and the somatic organelles of neurosecretory magnocellular n eurons of the hypothalamo neurohypophyseal system (HNS) was carried ou t in the hamster at six age-points during animal life. The magnocellul ar cells of both parts of the supraoptic nucleus (SON) and the paraven tricular nucleus (PVN) of male Syrian hamsters between 3 and 30 months of age were examined ultrastructurally. Cells of all age groups prese nt the same morphological ultrastructure. Standard manual morphometric techniques are used to calculate the following parameters related dir ectly or indirectly with cellular activity: nuclear area, nucleolar ar ea, nuclear invagination index and volumetric fractions of some intrac ellular structures (Golgi apparatus, mitochondria, rough endoplasmic r eticulum and lipofuscin). With respect to the cell nucleus, the parame ters are not modified during aging. No significant differences in the volume density of subcellular components, except lipofuscin, were dete cted at the age groups studies. However, there is a positive linear tr end among all parameters and age except for the rough endoplasmic reti culum. Our results suggest maintenance of the synthetic activity of th e magnocellular neurons in the hamster during aging but in no case an increase in their metabolic activity. (C) 1997 Elsevier Science Irelan d Ltd.