Functional and morphologic studies of the adrenal cortex and kidney in ovine toxaemia of pregnancy.

Functional and morphologic studies of the adrenal cortex and kidney have been carried out in pregnant sheep with spontaneous or dietary restriction-induced ovine toxaemia. It was found that proteinuria was an inconstant feature and no animal showed glomerular lesions analogous to those found in human preeclampsia; thus ovine toxaemia cannot be regarded as a precise experimental model for human toxaemia of pregnancy. The elevation of blood cortisol levels and the morphologic appearance of the adrenal zona fasciculata found in such animals suggest an adrenal response comparable to that caused by adrenocorticotrophic hormone. In addition, animals with severe disease showed evidence of stimulation of the renin-angiotensin-aldosterone system as reflected by elevated blood renin and aldosterone concentrations and raised renal juxtaglomerular indices. Ultrastructural changes in the adrenal zona glomerulosa and renal juxtaglomerular myoepithelioid cells in toxaemic animals resembled those described in non-pregnant sodium-depleted sheep. The finding of juxtaglomerular peripolar cell mitoses and granule exocytosis, the latter only being previously observed in sodium depleted sheep, together with the ultrastructural changes in the adrenal zona glomerulosa and juxtaglomerular myoepithelioid cells, suggest that sodium depletion may play a role in this disease.