Abstract
The histological structure of the glomerulus in the dog, cat, rabbit, and guinea pig, used in various studies of renal function, is, in general, similar. The glomeruli vary in size and number in such animals, and the degree of lobulation of the capillary tufts shows some difference in the various species, yet the finer structure of these bodies remains constant. The epithelium which lines Bowman's capsule consists of a single layer of flattened, non-specialized cells and the reflection of these cells over and between the capillary loops of the glomeruli is made up of an even flatter type of cell.
In 1924 a study was commenced of the histology of the kidney in certain older animals to ascertain if there was any difference in structure in the vascular and tubular units in such ancestral species which might be indicative of a difference in the function of these structures as compared with similar units in more recent species, now used for experimental purposes. The first animal studied was the marsupial, Didelphys virginiana.
Twenty-seven opossum have been used in this study. The animals were placed in large types of rabbit cages and the urine collected. The urine from all of the animals was normal. It was free from albumin, glucose and diacetic acid. The microscopic studies showed an absence of casts. Various types of epithelial cells with occasional red and white blood cells were present. After such initial observations the animals were killed by a stroke behind the head, and the kidneys immediately removed for fixation. The kidneys were sectioned through their long axes, and tissue for fixation removed from each lateral half. The fixatives employed were 95% alcohol, Zenker's fluid, 10% formalin, and a solution of corrosiveacetic. Both paraffin and celloidin sections were made and stained with eosin and haematoxylin and with eosin and methylene blue.
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