The genesis of exstrophy of the bladder and epispadias.

The niainier of origin of exstrophy of thc bladder, and more particularly the cpispadias commonly associated with it, has long i ~ m n i n e d a subject of conjec4ure and controversy. This is duc primarily to the lack of availability of stages in their genesis. No one, as fa r as we could ascertain from the literature, has ever seen epispadias o r exstrophy i i i young em1)ryos. Tlint, after all, is not snuprisiiig because of tlic i ~ l a t i v c infrequency of these anomalies. Campbell, in his 4'Clinical Pediatric Urology" ( '51), states that this combination of abnoi*~iialities occurs once in 40,000 to 50,000 hirths. Winsbury-TVliite ('48) gives the same range of iiicitlence. It is quite understandable, therefore, that as j-et no embryos have been described which show exstropliy and epispndias in their @.xelopmental phases. In the absence of material showing the crucial developmental steps involved, the condition as seen a t birtli has remained a constant invitation to theorizing. Since it is well known that tlic human embryo does not normally pass through any derelopmental stage comparable to either exstrophy or epispadias, the much overworked developmental arrest concept is obviously futile in intciyreting these assoriated anomalies. It would needlessly expand the present communication to attempt to discuss all the alternative theories that have been advanced. The papers of Connell ('01)9 von Geldern ('24), and Wybiirii ( '37) give excellent acconiits of the work