Male Gonadal Differentiation and the Paedomorphic Evolution of the Testis in Teleostei

ABSTRACT
Testis differentiation from representatives of the Otophysi (Cyprinus carpio), Percomorpha (Amatitlania nigrofasciata), and Atherinomorpha (Poecilia reticulata) was comparatively described. In the undifferentiated gonad of C. carpio, the primordial germ cells (PGCs) are scattered throughout the gonads while in A. nigrofasciata and P. reticulata the PGCs are restricted to the ventral periphery. In the dorsal region of the developing gonads, with the exception of C. carpio, somatic cell rearrangements result in the differentiation of the sperm duct. Pre‐Sertoli cells wrap around single spermatogonia forming cysts that proliferate forming acinar‐clusters. In C. carpio and A. nigrofasciata, the cysts in each acinar‐cluster move away from each other, creating a central lumen. In C. carpio, the acinar‐clusters then fuse to each other forming tubules that become lined by the germinal epithelium. Subsequently, the tubules anastomose dorsally and create the sperm duct. In A. nigrofasciata, the acinar‐clusters elongate, forming lobules that individually connect to the sperm duct. These are lined by the germinal epithelium. In P. reticulata, the spermatogonial cysts remain in the acinar‐cluster organization. Subsequently, developing ducts connect each cluster to the sperm duct and lobules subsequently develop. In the differentiated testis of C. carpio and A. nigrofasciata, spermatogonia are distributed along the lengths of the anastomosing tubules or lobules, respec...

Source: The Anatomical Record Part B: The New Anatomist - April 1, 2014 Category: Anatomy Authors: Talita Sarah Mazzoni, Harry J. Grier, Irani Quagio‐Grassiotto Tags: Full Length Article Source Type: research