Shoulder

Brachium

Antebrachium

Facial and Masticatory Muscles

Thorax and Heart

Brain

Body Wall

Hip and Thigh

Shank and Foot

Digestive System

Urinary and Reproductive Systems

Hip and Tail

Urinary and Reproductive Systems of the Cat (Felis catus)

Photo and text by Adam Hartstone-Rose

Introduction:

The dissection of the urogenital system of a pregnant female cat is fairly amazing.  The urogenital system is made up of several organs: the kidneys, bladder, ovaries, uterus, genitals and all of the vasculature, ducts and tubes that connect them.  This rather histologically complicated system is actually fairly easy to understand on a gross anatomical scale during dissection.

Dissection:

Before the urogenital system can be examined, the gut tube, and all of its associated organs (liver, spleen, gall bladder, pancreas, etc.) must be removed.  To do this, sever the esophagus close to its entrance to the stomach, and the rectum close to its origin at the colon.  Enough rectum should be left in situ to keep evident the anatomical orientation of the pelvic viscera.  Much of the gut will have to be carefully separated from its mesentery.  Sever the postcaval vein close to the liver.  Remove all of the now free viscera together being careful not to damage the urogenital organs and all of their associated vasculature and ducts.  The region dorsal to the guts should be cleaned.

Kidneys:

The kidneys are “retroperitoneal” or embedded in the abdominal wall dorsal to the peritoneal coelomic sac.  They are also surrounded by a relatively thick pad of fat.  Remove the tissue ventral to the kidneys and the fat surrounding them.  Be careful not to damage any of the vessels running to and from the kidneys, the ureters running from the kidneys to the bladder, or the suprarenal (adrenal) glands, which sit on the cranial end of each kidney.  This last objective is particularly difficult in that the glandular tissue that makes up the suprarenal gland has a very similar texture and appearance to the fat in which it and the kidney are embedded.  A good way to find this important but difficult to identify gland is to follow its vasculature.

Kidney abnormalities are common, but the usual state is two roughly equal sized kidneys, one on either side of the aorta and postcaval vein, the right kidney is usually slightly craniad of the left.

Bladder:

Follow the ureters caudally to the bladder.  The bladder is ventral to the uterus and rectum in the pelvis.  The two ureters carry urine produced in their respective kidneys, where it is stored in the bladder.  Upon urination, the bladder contracts and the urine leaves the body through the single urethra.

Ovaries and uterus:

Female cats, like all female mammals, have two small ovaries.  They are located caudal to the kidneys and craniolaterally to the uterus.  Each has its own vascular supply and is attached to the body wall via the ovarian ligament (see figure).  The ovaries are closely associated with the uterus (and indeed appear attached to it) and lie at the apex of each of the two uterine cornua (or horns).

The uterus of the cat is very different than that of the human (in fact, the cat’s uterus is closer to the typical mammalian condition) in that it has two distinct horns [1].  In the pregnant cat, each of these horns can contain multiple developing fetuses with zonary placentas.  Each fetus has its own placenta, chorion and amnion and its own pouch-like region of the uterus.  The cat I dissected had four developing fetuses.

Reference:

1. Walker, W. F. 1970. Vertebrate Dissection.  Philadelphia: W. B. Saunders Co.