THE URINOGENITAL SYSTEM 401 
condition is maintained permanently, as in some reptiles, or 
not. 
The atrophy of the Wolffian body is much more complete in 
the female than in the male; no part of it remains in a functional 
condition, but the part corresponding to the epididymis of the 
male remains as a rudiment, known as the epodphoron. It has 
almost the same structure in young females as in young males, 
but the sexual cords uniting it with the ovary do not become 
tubular, nor does the rete ovarii. A rudiment of the non-sexual 
part of the Wolffian body is also found in the hen between ovary 
and kidney in the lateral part of the mesovarium; it has been 
named the paroophoron. 
Development of the Genital Ducts. Vhe Wolffian Duct. The 
origin and connections of the Wolffian ducts have been already 
sufficiently described. In the male they are connected with the 
semeniferous tubules by way of the rete, vasa efferentia, and 
epididymis, and function as vasa deferentia exclusively, after 
degeneration of the mesonephros. Subsequently they become 
somewhat convoluted, acquire muscular walls and a slight ter- 
minal dilatation. The details of these changes are not described in 
the literature. In the female the Wolffian duct degenerates; at 
what time is not stated in the literature, but presumably along 
with the Wolffian body. 
The Miillerian Duct. The Miullerian duct, or oviduct, is laid 
down symmetrically on both sides in both male and female em- 
bryos; subsequently both right and left Millerian ducts degen- 
erate in the male; in the female the right duct degenerates, the 
left only remaining as the functional oviduct. We have now to 
consider, therefore, (1) the origin of the ducts during the in- 
different stage, and (2) their subsequent history in the male 
and in the female. 
The origin of the Millerian duct is preceded by the formation 
of a strip of thickened peritoneum on the lateral and superior 
face of the Wolffian body extending all the way to the cloaca 
(cf. Fig. 220). This strip, which may be called the tubal ridge, 
appears first at the anterior end of the Wolffian body on the 
fourth day, and rapidly differentiates backwards; it lies imme- 
diately external to the Wolffian duct. The anterior part of the 
Miillerian duct arises as a groove-like invagination of the tubal 
ridge at the cephalic end of the Wolffian body immediately 
