Page:Laboratory Manual of the Anatomy of the Rat (Hunt 1924).djvu/107

Rh thra. Trace it forward to the urinary bladder, and back to its entrance on the dorsal side of the preputial cavity. At the latter end insert a bristle and push it forward to the urinary bladder.

The urinary bladder is connected with the ventral wall of the abdomen by the suspensory ligament. As in the male, it temporarily stores urine which it receives through a pair of ureters, one from each kidney.

Remove the prepuce, its glans, and the clitoris. Pull the cut end of the urethra forward. This exposes the vagina. Separate the vagina from the surrounding tissues and observe that it lies immediately below the rectum. With a pair of scissors slit the vagina throughout its length. The margin of the vaginal orifice is thrown into longitudinal folds, as is also the internal surface of the vagina. The mucous membrane of the vagina is said to be without glands. The two horns of the uterus converge and join the anterior end of the vagina. The latter receives the penis of the male during copulation, and is therefore a temporary receptacle for spermatozoa. Slit each horn of the uterus a short distance in front of the vagina. Insert here a blunt probe into the lumen of each horn until the probe emerges through the external orifice (os uterus) into the vagina. There are two external orifices, one for each horn, showing that the fusion of the posterior part of the horns is superficial and does not involve the lumen (uterus duplex). The orifices are very easy to locate in an animal well advanced in pregnancy. They are surrounded by five lobes, one large dorsal lobe, one large ventral, and three smaller ventral lobes.

Each horn of the uterus is suspended from the dorsal side of the abdominal cavity by the broad ligament, which may contain considerable fat. This ligament extends an-