Effect of Pregnancy and Lactation on Granuloma Tissue Formation and Joint Permeability in Rats.

Summary 1. Pregnancy and lactation in the rat markedly influenced the formation of granuloma tissue induced by subcutaneously implanted cotton pellets. During pregnancy there was a progressive reduction in the amount of granuloma tissue formed, the least amount being formed at about the time of parturition. After parturition there is a pronounced increase, followed by a reduction to values approximately like those obtained during late pregnancy. 2. The injurious effect of formaldehyde on the synovialis of the knee joint as measured by the clearance of sodium para-amino hippurate (PAH) is like-; wise progressively decreased as pregnancy proceeds, injury being almost completely absent at about the time of parturition. After parturition the PAH clearance quickly returned to the non-pregnant or early pregnancy levels. Lactation did not provide the synovialis with i any measurable protection against formaldehyde. 3. The inhibition of granuloma formation and the protection of the synovialis against the injurious effects of formaldehyde are believed to be due primarily to an increase in the gluco-corticoid moiety of the unique complex of interacting steroids existing during t pregnancy especially, and to a lesser extent during lactation.