Ultrastructural examination and cell count determinations of avian glomeruli from grossly normal and grossly swollen kidneys of broilers at slaughter.

Kidneys from broiler chickens at slaughter (6 to 7 weeks of age and mixed sex) were collected by U.S. Department of Agriculture personnel. Forty kidneys were collected from grossly normal birds with grossly normal kidneys (Group D). Grossly swollen kidneys were collected from birds that were otherwise grossly normal (Group A), that had gross lesions of Marek's disease (Group B), or that had gross lesions of squamous cell carcinoma (Group C). These kidneys were fixed in Carson's 10% buffered formalin, embedded in plastic, sectioned at 2 microns, and then stained with periodic acid-Schiff-hematoxylin for glomerular cell counting. Tissue was also processed for electron microscopy from six Group D birds and from six birds total from Groups A, B, and C that had the most severe histologic glomerular lesions. Glomerular tuft cell counts and visceral epithelial cell counts were performed by light microscopy at a magnification of 100x (oil immersion). Total tuft cell counts of all abnormal groups (A, B, and C) were significantly higher (P < 0.05) than those of Group D. Reptilian glomerular tuft cell counts for all abnormal groups were significantly higher (P < 0.05) than the reptilian glomerular tuft counts for Group D. Mammalian glomerular tuft cell counts for Groups A and B were significantly higher than those of the control group (Group D). Electron microscopic examination of the glomeruli from selected birds revealed no dense deposits in the basement membrane and no effacement of epithelial podocyte foot processes. No essential ultrastructural differences were noted between the control group and the abnormal groups.