In search of suitable in vitro models to study germ cell movement across the blood-testis barrier

The movement of preleptotene/leptotene spermatocytes across the blood-testis barrier, also known as the Sertoli cell barrier, during stages VIII to XI of the seminiferous epithelial cycle is one of the most important cellular events taking place in the mammalian testis. Without the passage of spermatocytes, spermatogenesis would be halted, resulting in transient or permanent sterility. Unfortunately, we have very little knowledge on how preleptotene/leptotene spermatocytes cross the blood-testis barrier. While we know cytokines, proteases and androgens to mediate Sertoli cell junction restructuring, most data continue to be derived from experiments using Sertoli cells cultured alone in two dimensions. Thus, additional in vitro models which include germ cells must come into use. In this Commentary, we hope to shed new light on how we may better study spermatocyte movement across the BTB.