[Fig. 112].—Female Urogenital Organs, Obliquely Ventral View.

a, kidney; b, ureter; c, ovary; d, ostium tubæ abdominale; e, uterine (Fallopian) tube; f, cornua of the uterus; g, cranial edge of broad ligament; h, round ligament of the uterus; i, body of the uterus; j, bladder; k, neck of the bladder; l, position of cervix uteri; m, vagina; n, urogenital sinus or vestibule, with M. urethralis; o, corpus cavernosum clitoridis, with M. ischiocavernosus (cut); p, fibres of M. constrictor vestibuli. 1, aorta; 2, internal spermatic arteries; 3, uterine arteries; 4, external iliac arteries; 5, hypogastric arteries; 6, umbilical artery; 7, inferior hemorrhoidal artery; 8, branches of N. pudendus.

The Uterus (f, i).—The uterus consists of a median portion or body (i) which is unpaired, and of two horns or cornua (f) which extend from the body to the uterine tubes. The body (i) of the uterus is a tube about four centimeters long which lies in the abdominal cavity, ventrad of the rectum and between it and the bladder. Its caudal end is at the level of the cranial border of the pubis. The cranial end of its cavity is divided by a median dorsoventral partition into lateral halves, while the cavity of its caudal portion is unpaired. The mucosa is thrown up into large longitudinal folds. At its caudal end the uterus projects into the vagina (m), so that when the vagina is opened the end of the uterus is seen projecting into it as a prominent papilla. The portion of the uterus thus enclosed by the vagina is the cervix uteri or neck of the uterus. Its free end is directed ventrocaudad, and a prominent ridge is continued from its caudodorsal side along the mid-dorsal wall of the vagina. The uterine cavity communicates with the vaginal cavity by a V-shaped opening, the os uteri, which looks ventrocaudad and has its apex directed cranioventrad. Each horn (f) of the uterus passes craniolaterad in a nearly straight course from the body (i) to the uterine tube (e). It narrows rapidly and becomes continuous with the tube. The mucosa is thrown into longitudinal folds.

Ligaments of the Uterus.—The Broad Ligament.—The uterus is held in place principally by the broad ligaments. These are two folds of the peritoneum, each of which is attached to the whole length of one of the cornua and the adjacent part of the uterine tube and to the corresponding lateral surface of the body of the uterus. Each ligament ends craniad in a concave free border. Its attached border forms a curved line which begins laterad of the kidney and extends thence to the lateral ligament of the bladder. From the lateral ligament of the bladder the broad ligament extends caudad into the rectovesical pouch of the peritoneum, which lies between the rectum and the bladder. It holds the body of the uterus to the lateral wall of this pouch, and together with the opposite ligament and the body of the uterus forms thus a transverse partition, which divides the rectovesical pouch into dorsal and ventral portions.

The round ligament (h) is a fibrous band which extends from a point of the body wall, which corresponds exactly to the internal inguinal ring of the male, to the cornu of the uterus about two centimeters from the cranial end. It is attached to the broad ligament by an intervening fold of peritoneum.

The Vagina (m).—The vagina extends from the os uteri (at l) dorsad of the symphysis of the pelvis to a point a short distance craniad of the caudal border of the ischiatic symphysis. At this point it joins the neck of the bladder (k) to form the vestibulum or urogenital sinus (n), which is homologous with the urethra of the male.

Urogenital Sinus (n).—The urogenital sinus extends from the caudal end of the vagina (m) to the external opening, which is situated ventrad of the anal opening. It is about a centimeter long and nearly as wide, and is marked off from the vagina by a circular fold of mucosa, while its inner surface presents longitudinal folds. On its ventral wall at its cranial end is the opening of the neck of the bladder, which is enclosed by a ring-like elevation of the mucosa, most prominent at the sides. The external entrance to the urogenital sinus forms the vulva.

The Clitoris.—The clitoris is a minute organ homologous with the penis and lying on the ventral floor of the urogenital sinus. Its distal end lies at the entrance of the urogenital sinus on its ventral border. In adult specimens the prepuce of the clitoris appears as a slight elevation of the integument surrounding a central vascular structure which appears red in the fresh organ. From the clitoris there are two small corpora cavernosa clitoridis (o) passing craniad and then diverging to be attached to the ischiatic rami. The ischiatic portion of each is covered by a muscle (ischiocavernosus). The clitoris is said to contain a bone.

Mammary Glands.—The mammary glands secrete the milk, and lie on the ventral surface of the body beneath the integument. The separate glands are closely gathered into two chief masses, one on each side the ventral middle line. Each of these extends from about the region of the fourth rib to the caudal end of the abdomen, ending over the pubic symphysis. On each side the glands are gathered into five groups, each of which is furnished with a nipple. The nipple is a projection of the integument, having near its distal end numerous fine openings for the ducts of the glands. The first two nipples are on the thorax, the other three on the abdomen, the most caudal ones being about two or three centimeters in front of the cranial edge of the pubis.

Rudimentary mammary glands and nipples are present in the male.