Abstract
A comparative gross anatomical study was carried out on six apparently healthy adult male albino rats (Rattus norvegicus) and albino mice (Mus musculus) (Three rats and three mice) The aim of the current work is to demonstrate the gross anatomical topography, morphology and fixation of (liver, kidney, spleen, stomach and pancreas) in order to highlight similarities and differences between both species. The animals were brought from local animal markets and delivered to the anatomy laboratory of the Faculty of Veterinary Medicine Cairo University, Egypt. After euthanasia, animals were anatomically dissected via mid laparotomy to study the concerned abdominal viscera in both species. The organs were removed separately and preserved by both freezing and immersion in a container filled with 10% neutral buffered formalin solution for further examination. Photographs of the organs insitu and isolated were taken, discussed and compared with that of the other lab mammals in previous literatures. The study confirmed the absence of the gall bladder and the round ligament of liver in albino rat, while the hepatorenal ligament was absent in albino mouse. Also, the site of renal impression was found to be located on the right lateral hepatic lobe in albino rat while on the caudate process of liver in the albino mouse. Albino rats and mice had a bean shaped smooth unipapillated kidneys, however the position of kidneys greatly varied between both species. The characteristic crescentic-shaped stomach in rats with a tightly closed esophageal opening compared to the thumb-shaped stomach of mice with slightly loose esophageal opening were anatomical remarks. The proper knowledge of the normal morphology and topography of these abdominal viscera would assist veterinarians in designing of therapeutic surgical approaches in abdominal cavity and experimental transplantations.

Key words: Anatomy, Abdominal organs, Albino Rat (Rattus norvegicus) and Albino Mouse (Mus musculus)