THE GENITAL GLANDS AND DUCTS — LIGAMENTS 221 



The Hymen. — At the point where the utero-vaginal anlage breaks through 

 the wall of the urogenital sinus there is present the tubercle of Miiller, which 

 marks the lower Hmits of the vagina. The tubercle is compressed into a disk 

 lined internally by the vaginal epithelium, externally by the epithehum of the 

 urogenital sinus. These layers with the mesenchyma between them constitute 

 the hymen, which thus guards the opening into the vagina. A circular aperture 

 in the hymen is for a time closed by a knob of epithelial cells, but later when the 

 hymen becomes funnel-shaped the opening is compressed laterally to form a 

 sagittal slit, the ostium vagina. Miiller's tubercle persists in the male as the 

 colliculus seminalis, from the summit of which leads off the prostatic utricle. 



The Growth of the litems. — The uterus grows but slowly until near puberty, being about 

 the same length (27 mm.) at birth as in a girl of nine years. Just before and after puberty 

 growth is more rapid, a length of 72 mm. being attained at 18 years. This is nearly the 

 maximal length of the virginal uterus. 



Anomalies. — Owing to the complicated processes leading to their formation, many cases 

 of abnormal uterus and vagina occur. A complete classification is given by Felix (Keibel 

 and Mall, vol. 2.) The more common anomalies are (1) complete duplication of the uterus 

 and vagina due to the failure of the Miillerian ducts to fuse; (2) uterus bicornis, due to the in- 

 complete fusion of the ducts. Combined with these defects the lumen of the uterus and 

 vagina may fail, partly or completely, to develop and the vaginal canal may not open to the 

 exterior. (3) The body of the uterus may remain flat (uterus planifundis) or may fail to 

 grow to normal size (uterus fetaUs and infantahs). (4) Congenital absence of one or both 

 uterine tubes or of the uterus or vagina rarely occurs, but may be associated with hermaph- 

 roditism of the external genitaha. 



The Ligaments of the Internal Genitalia. — Female. — The loose mesenchyma 

 of the genital cord gives rise laterally to the broad ligaments of the uterus in 

 females. A portion of the primitive genital fold unites the caudal end of the 

 ovary to the genital cord. This acquires connective tissue and smooth muscle 

 fibers and forms the proper ligament of the ovary. Since the uterus develops in 

 the genital cord the ligament of the ovary extends to the posterior surface of the 

 uterine wall. In the male the homologue of the proper hgament of the ovary is 

 the ligament of the testis. 



In both sexes the inguinal fold extends from the urogenital fold to the crista 

 inguinalis, located on the inside of the ventral abdominal wall, a point which 

 marks the future entrance of the inguinal canal. The inguinal fold thus forms a 

 bridge in 14 mm. embryos between the urogenital fold (in the middle portion of 

 which the uterus develops in the female) and the abdominal wall at the entrance 

 of the inguinal canal (Fig. 232). In the inguinal crest is differentiated the 

 conical anlage of the chorda guhernaculi, which later becomes a fibrous cord. The 



