André Bisaillon

The anatomy of the male genital system of the beluga whale, Delphinapterus leucas, with special reference to the penis.

The genital organs of four male adult beluga whales and one newborn animal were dissected and the main characteristics are described. As in other species of cetaceans, the testes and the greatest part of the penis are located inside the abdominal cavity. The penis has a sigmoid flexure and belongs to the fibroelastic type with a thick tunica albuginea and a small amount of vascular spaces in the erectile tissue. The prostate gland, found in other cetaceans, was not seen macroscopically, but only small prostate rudiments could be identified histologically. The os penis and the other accessory glands are absent as in other whales.

Notes on the anatomy of the heart in the Harp seal (Pagophilus groenlandicus Erxleben, 1777).

The heart of the Harp seal (Pagophilus groenlandicus) is described based on the dissection of six specimens of both sexes ranging in body weight from 23.2 to 46.4 kg. The heart is characterized, as in other seals, by a transverse broadness and a flatness of the ventricles along with an apex formed by both ventricles. Heart parameters are used for comparisons with those of other seals and land mammals. The heart width index (heart height/heart circumference) averages 33.4 compared to 28.7 for the Weddell seal and 39.0 for the felids. The right ventricle of the Harp seal heart is relatively long and very broad with a mean length index (TS/heart height) of 68.8 and a mean width index (TP/heart height) of 54.8. These functional heart parameters are discussed and physiological adaptations are suggested.

Gross anatomy of the arterial supply of the stomach of the North American beaver (Castor canadensis)

The arterial pattern of the stomach of the North American beaver is studied by dissection of height specimens. The arrangement of the arteries resembles the typical mammalian pattern, although some variations are described. For example, the celiac artery gives off two large vessels, the cardiac and fundic arteries, which supply the corresponding regions of the stomach. Also, the right gastric artery originates from the gastroduodenal vessel instead of the hepatic artery.