Ultrastructural postmortem changes in chicken kidneys at 27 C.

Ultrastructural postmortem changes of glomeruli, proximal tubules (PT), distal tubules (DT), and cortical collecting ducts (CD) were studied in adult chickens held at 27 C for 0, 1, 5, 10, 30, 60, or 360 minutes. There were marked ultrastructural alterations in tissues considered normal by light microscopy. The earliest changes, evident in immediately fixed samples, consisted of apical cell swelling of PT and DT epithelium and formation of smaller projections from glomerular capillary endothelium. Swelling increased with time, and gaps in cell membranes of tubular cytoplasmic blebs were evident by 10 minutes postmortem. The urinary space also contained cellular debris in immediately fixed samples and was filled by swollen epithelial cells by 10 minutes postmortem. Organelle changes were pronounced by 5 minutes in PT epithelium and by 10 minutes in DT epithelium. These initial changes consisted of dilation of mitochondrial and endoplasmic reticulum. Flocculent mitochondrial matrix densities were present by 5 minutes in PT epithelium and enlarged and appeared in other tubular segments as the time postmortem increased. Nuclear chromatin margination occurred first in 10-minute samples of PT and DT, and it was present by 30 minutes in glomerular epithelial cells. Chromatin clumping was present in PT and DT epithelium at 30 minutes and was followed by pyknosis and karyorrhexis at 360 minutes. These latter nuclear changes were not found in glomerular cells during the study. Nuclei of CD showed little change during the periods studied. The glomerular basement membrane appeared as a single hyaline membrane by 30 minutes postmortem, but this membrane and podocyte foot processes showed little further change by 360 minutes postmortem.