Internal surface and fine structure of the rat seminal vesicle.

The seminal vesicle of the rat was studied with scanning and transmission electron microscopy. The internal surface of the organ is partitioned into small areas by a system of elevated ridges of connective tissue and covered by a columnar epithelium. This consists of small basal cells, presumably reserve elements, and larger ones containing the typical cell organelles involved in protein synthesis. The surface of the cell is covered with slender microvilli, varying in height and number from region to region. It is suggested that they are involved in the maintenance of hydration and/or regulation of low molecular weight substances in the secretion product. The latter develops from small granules which pass the apical cell border and then fuse together as larger drops.