COMPARATIVE CYTOLOGY AND MORPHOLOGY OF SEMINAL-VESICLES IN MALE GOBIID FISHES

Anatomical, histological and EM studies are presented on the male seminal vesicles of 111 species of gobies (Gobiidae, Teleostei). These vesicles, attached to the sperm-ducts, are lined with an excretory epithelium composed of three types of cells: 1) columnar cells with giant Golgi cisterns in the form of large rings apical to the nucleus; 2) excretory cells with remarkably interdigitative basal lamina, that resemble sperm-duct cells; and 3) groups of interstitial, Leydig-type cells that possibly from a part of the mesorchial gland. Morphologically the vesicles appear to be taxa specific, the simplest one in the form of a few tubules on the sperm duct, and the most elaborate one forming large, wing-like structures, with an elaborate mass of passages. In many species the final form of the vesicles develops during the fish ontogenesis; in others, the form of this organ does not change during the lifetime of the fish. With the onset of reproduction, secretion and sperm accumulate in the tubule of the seminal vesicle and are expelled from there onto the eggs during fertilization. The comparative morphology, as well as possible ecological and physiological role of this secretion is discussed.