THE UTERUS. 255 



The wall proper of the oviduct consists of the mucous and muscular 

 coats and is embedded within the loose connective tissue of the broad liga- 

 ment (tunica adventitia}, and surrounded by the serous coat, which com- 

 pletely invests the duct with the exception of the narrow interval through 

 which the tubal vessels and nerves pass. The wall is thickest and firmest 

 in the isthmus, less so in the ampulla, and thinnest and most relaxed in the 

 infundibulum and fimbriae. The mucous coat is thrown into longitudinal 

 folds, which in the ampulla attain much complexity and in transverse sec- 

 tions appear as branching villus-like projections. 



The mucous membrane is covered by a single layer of columnar 

 epithelium provided with cilia, whose current is directed towards the uterus, 

 thus favoring the progress of the ova along the tube but retarding the ascent 

 of the spermatozoa. The tunica propria consists of bundles of fibrous tissue, 

 is rich in cells and directly continuous with the intermusculor connective 

 tissue. Its deepest layer often contains irregular strands of muscle-bundles, 

 which suggest a muscularis mucosae. The muscular coat, upon which 

 the mucosa rests without the intervention of a submucous layer, is most 

 robust towards the uterus and thinnest at the infundibulum. It includes an 

 inner circular and an outer longitudinal layer of unstriped muscle. At the 

 isthmus, where the firmness of the tubal wall depends chiefly on the muscular 

 coat, the circular layer is the thicker (.5-1 mm.) and the longitudinal one 

 is incomplete; towards the infundibulum the reverse is true, the longitudinal 

 layer being better developed and the circular muscle reduced to . 2 mm. or 

 less. The surrounding fibrous tissue, sometimes described as a distinct coat, 

 the tunica adventitia, blends with the fibro-elastic stroma of the investing 

 peritoneum, which may be regarded as the serous coat. Since these 

 structures consist of the usual connective tissue and mesothelial elements of 

 peritoneum (page 175), a special description is unnecessary. 



The blood-vessels supplying the oviduct, derived from the tubal 

 branches of the uterine and ovarian arteries, gain the wall of the tube along 

 the nonperitoneal tract and break up into numerous branches between the 

 outer and inner muscular layers, from which capillaries pass to the muscular 

 tissue and to the mucous membrane. The veins begin within the mucosa 

 and join the many intermuscular channels, from which tributaries pass to the 

 subserous meshwork. The lymphatics, after emerging from the wall of 

 the tube within which they begin as irregular spaces between the fibrous 

 bundles of the muscular coat, form three or four stems that accompany the 

 blood-vessels. The nerves are numerous and chiefly sympathetic fibres 

 from the ovarian and the uterine plexus. Within the subserous tissue they 

 form a peritubal plexus, from which twigs penetrate the wall of the canal to 

 supply chiefly the involuntary muscle, some fibres entering the mucosa. 



THE UTERUS. 



The uterus or womb is a hollow pear-shaped muscular organ, receiving 

 the oviducts above and opening into the upper part of the vagina below, in 

 which the fertilized ovum is retained and develops, and from which the 

 resulting foetus is expelled at the completion of gestation. It measures 

 about 7 cm. in length, of which the lower 2.5 cm. constitutes the neck, or 

 cervix, and the remainder the body; its greatest breadth is about 4 cm. and 

 its thickness 2.5 cm. The convex upper extremity of the organ is known 

 as ihefundus. Of the two surfaces, the anterior is only partially and the 

 posterior almost completely covered with peritoneum. 



