418 TEXT-BOOK OF EMBRYOLOGY. 



and mesonephric ducts are different in different parts of their courses. At the 

 cephalic end the Mlillerian lies dorsal to the mesonephric, but farther back it 

 runs more laterally, then ventrally, and finally opens into the urogenital sinus 

 on the medial side of the mesonephric duct. 



THE OVIDUCT. The single part of each Miillerian duct gives rise to the 

 oviduct. The opening at the cephalic end remains as the ostium abdominale 

 tubcz, which from the beginning communicates directly with the abdominal 

 cavity (ccelom) and never becomes connected with the ovary (Fig. 366). The 

 rim of the opening sends from three to five projections into the abdominal 

 cavity to form the primary fimbrice. Secondary branches grow out from these 

 and form the numerous fimbriae of the adult oviduct. The part of each 



Bladder 



Uterus Rectum 



vS^' 



|r Cervix uteri 



Symphysis pubis 



Labium majus | Hymen 



Labium minus 



Vagina 



FIG. 372. Right half of the pelvic region of a female human foetus of 7 months. Nagel. 



Miillerian duct between the fimbriated end and the fused caudal end, grows in 

 length as the embryo develops, but not proportionately, so that in the adult the 

 oviduct is relatively shorter than in the embryo. At first it is lined with simple 

 cylindrical epithelium, but later the cells become cuboidal, and during the 

 second half of foetal life acquire distinct cilia. The connective tissue and muscle 

 of the oviduct are derived from the mesenchyme that primarily surrounds the 

 Miillerian duct. 



In connection with one of the fimbriae of the oviduct there is sometimes found 

 a small vesicle lined with ciliated epithelium, forming the non-stalked hydatid 

 (of Morgagni), which possibly represents the extreme cephalic end of the 

 Miillerian duct (Fig. 380). In this case the permanent ostium of the tube 

 would be of secondary origin. 



