Structural study of the involution of the seminal vesicles of the guinea pig following orchiectomy.

The involution of the seminal vesicles of the guinea pig after castration has been studied by electron microscopy. The epithelial cells decreased in size and the basal lamina became more tortuous after castration. The most obvious changes occurred in the amount and configuration of the granular endoplasmic reticulum (GER). Besides a general decrease in GER, there was also a change from predominantly parallel arrays to a spiral or concentric arrangement, followed by dilation and vesiculation of the GER. There was an increase in glycogen and lipid contents of the epithelial cells. Large aggregates of glycogen particles were found associating with dilated GER and lipid droplets and these glycogen particles increased with the progression of involution. The Golgi complex became smaller and a slight increase in the number of autophagic and lysosomal granules was observed. Secretory granules decreased in size and quantity but persisted even at 4 months after the operation. The postcastration response of the seminal vesicles of the guinea pig was slow and incomplete and was different from that of the rat and mouse, where involution was virtually completed within 3 weeks. The slow and incomplete regression is not clear, but is believed to be related to the function of the adrenal glands which may provide the extratesticular source of hormone to partially maintain the gland after castration.