The corpus cavernosum urethræ is the spongy portion of the urethra which lies in the groove on the ventral surface of the penis, between the corpora cavernosa penis. It becomes greatly enlarged at the distal end of the penis, forming the glans (m). A small bone (os penis) is imbedded in the distal end of the penis.
B. Female Genital Organs
([Fig. 112]).—The urinal organs of the female are like those of the male. The neck (k) of the bladder is, however, much longer, extending almost to the border of the ischiatic ramus. The urethra is consequently short.
The genital organs consist of the ovaries (c) (the organs which produce the eggs), the oviducts or uterine tubes (e) (Fallopian tubes), which receive the eggs from the ovaries; a bifid uterus (f and i) in which the ova undergo their development, and a vagina (m) which leads from the uterus to its junction with the neck of the bladder.
The neck of the bladder (k) unites with the vagina to form the urogenital sinus (n) which is very short, leads to the external opening, and is comparable to the male urethra. Ventrad of the external orifice of the urogenital sinus is the clitoris, a rudimentary structure homologous with the penis of the male.
The Ovaries (c).—The ovaries lie in the abdominal cavity in the same longitudinal line with the kidneys and a short distance caudad of them. Each is an ovoid body about one centimeter long and one-third to one-half as broad. On its surface are numerous whitish projecting vesicles, the larger of which show clear centres. They are the Graafian follicles (best seen in section), which contain the eggs. There may be present one or more elevations of the size of the largest Graafian follicles, but of a bright red or brown color. They are the corpora lutea (sing. corpus luteum),—Graafian follicles from which the eggs have been discharged.
The ovary is held in position by the broad ligament of the uterus, a fold of the peritoneum, which passes here from the uterine tube to the adjacent body wall. The ovary lies in a sort of a pocket formed by the broad ligament. In the natural position the pocket opens ventrolaterad. The ovary is further held in position by the ligament of the ovary (ligamentum ovarii), a short thick cord which passes from the ventral face of the ovary at its uterine end to the adjacent ventral surface of the uterus.
The Uterine Tubes (e).—The uterine (or Fallopian) tubes or oviducts are the tubes which convey the ova from the ovary (c) to the uterus (f). Each begins with an expanded trumpet-shaped opening, the ostium tubæ abdominale (d). Its walls are thin, and the mucosa of its inner surface is thrown up into undulating, radiating ridges.
The ostium (d) lies on the lateral side of the ovary (c) at its cranial end, and the trumpet partly clasps the ovary. From the ostium the tube (e) turns craniad, then mediad, and then caudad, so as to describe a curve about the cranial end of the ovary. It then extends caudad on the mediodorsal aspect of the ovary to its junction with the uterine cornu (f). It is sinuous throughout its course, and the first two-thirds (the vestibulum) is of considerably greater diameter than the last third. Throughout the last two-thirds of its course it lies in the free border of the broad ligament. Its mucosa is thrown into irregular folds, mostly longitudinal, and is lined by ciliated epithelium. From the foregoing description it is seen that the ova must pass through the body cavity in order to reach the ostium tubæ.
