It is curious that research in endocrinology has largely ignored the testis until quite recently. There were two impor- tant reasons for this neglect; first, methods of study were difficult, and second, sperinatogenesis was considered to be the concern of the urologist or cell biologist but not the endocrinologist. Since it is now almost an ethical imperative that we develop a male contraceptive, and since a host of new techniques can be brought to bear on problems of testis function, research in male reproductive biology has effloresced. In fact, it has become possible to project aseries of...