Quantitative Analysis of Neurosecretory Granules in the Median Eminence of the Rat during the Estrous Cycle and in the Senium

Abstract

Neurosecretory granules in the female rat median eminence were quantitatively analyzed. The alterations of tbe granules during the whole estrous cycle and those relating to aging were examined. On the basis of the size, four types of grannies were classified. They were about 95, 120, 140 and 170 nm in each mean diameter. The former two types were present in all zones of the median eminence, although the smallest granule was few in the internal zone. The third type was found in the external zone alone and the last in the internal. The changes in the numerical and volume density accompanied with estrous cycle and with aging were most obvious of the smallest type especially in the pericapillary zone. The numerical density of the largest type granules of the internal zone decreased In the senium group as compared with the estrus and metestrus group.