Mesangiocapillary glomerulonephritis in lambs: the ultrastructure and immunopathology of diffuse glomerulonephritis in newly born Finnish Landrace lambs.

Renal biopsies were obtained by laparotomy from eight newborn C3 deficient Finnish Landrace lambs, and examined by light, electron and immunofluorescence microscopy. The capillaries of all glomeruli contained numerous neutrophils and peripheral capillary walls were thickened and refractile at high magnifications. Almost continuous subendothelial electron-dense deposits were seen in peripheral capillary walls. Large amounts of C'3, and small amounts of IgM and IgA were also seen in these sits. No IgG was seen in these glomeruli. Four lambs died within 96 hr of birth. The remaining four lambs all had severe clinical mesangiocapillary glomerulonephritis (MCGN) by 21 to 42 days after birth. Amounts of C'3, IgM and IgA in glomeruli had increased by comparison with amounts at birth, and IgG was present in the deposits. It was concluded that the processes ultimately expressed as MCGN in these lambs were initiated before birth.