Male germ cell transplantation in rats: apparent synchronization of spermatogenesis between host and donor seminiferous epithelia.

Primordial germ cells (PGC) and gonocytes from male Sprague-Dawley rat fetuses and neonates were transplanted via the rete testis into the lumen of the seminiferous tubules of recipient adult Long Evans rats. The donor germ cells apparently differentiated into mini-tubules or irregular segments of seminiferous epithelium within the lumen of the host seminiferous tubules, and exhibited qualitatively normal spermatogenesis in 10 out of 16 recipients. The stage of spermatogenesis of the intraluminal epithelium was synchronized closely with that of the adjacent seminiferous tubule epithelium, suggesting that the spermatogenic cycle is regulated locally by the intraluminal microenvironment. Male germ cell transplantation provides an interesting new tool for investigating the control of spermatogenesis.