Comparative anatomy of the cardiac foramen ovale in cats (Felidae), dogs (Canidae), bears (Ursidae) and hyaenas (Hyaenidae)

Publication Type:Journal Article
Year of Publication:1995
Authors:Macdonald, AA, Johnstone, M
Journal:Journal of Anatomy
Volume:186
Pagination:235-243
Date Published:1995
Keywords:Canidae, Canis aureus, Canis lupus, Cuon alpinus, Felidae, Hyaena hyaena, Hyaenidae, Panthera leo, Panthera pardus, Uncia uncia, Ursidae, Ursus arctos, Vulpes vulpes
Abstract:

The structure of the foramen ovale from 16 species representing 4 carnivore families, the Felidae, Canidae, Ursidae and Hyaenidae, was studied using the scanning electron microscope. The Felidae were represented by 9 domestic cat fetuses (Felis catus), 2 snow leopard neonates (Uncia uncia), an ocelot neonate (Leopardus pardalis), 2 lion neonates (Panthera leo), a panther neonate (Panthera pardus) and 3 tigers (Neofelis tigris), comprising 2 fetuses and a neonate. The Canidae were represented by a golden jackal neonate (Canis aureus), a newborn wolf (Canis lupus), 8 domestic dog fetuses (Canis familiaris), 3 red fox neonates (Vulpes vulpes) and a dhole neonate (Cuon alpinus). The Ursidae were represented by a brown bear neonate (Ursus arctos), a day-old grizzly bear cub (Ursus arctos horribilis), a polar bear neonate (Ursus maritimus), and 2 additional bear fetuses (species unknown). The Hyaenidae were represented by a striped hyaena neonate (Hyaena hyaena). In each species, the foramen ovale, when viewed from the terminal part of the caudal vena cava, had the appearance of a short tunnel. A thin fold of tissue, the developed remains of the embryonic septum primum, extended from the distal end of the caudal vena cava for a variable distance into the lumen of the left atrium and contributed towards the 'tunnel' appearance in all specimens. It constituted a large proportion of the tube, and its distal end was straight-edged. There was fibrous material underlying the endothelium of the flap, the apparent morphology of which suggested that it comprised cardiac muscle. In each species, the pulmonary veins drained from close beside the interatrial septum and this venous drainage seemed to be directed along the length of the flap of tissue on its dorsal surface. Collapse of the 'tunnel' of the septum primum effected closure of the foramen ovale in most of the neonates studied. When closed, the tissue flap appeared to be anchored to the interatrial septum along the surface of the crista dividens which lay in the left atrium. The straight edge at the end of the 'tunnel' remnant was not usually attached and, when gently lifted, formed a small blind-ended pouch ending at the attachment of the flap to the crista dividens.

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