Effects of cortisone on the fetal and neonatal thymo lymphatic organs in rats

Pregnant albino rats were treated daily with 10, 12.5 or 15 mg of cortisone acetate during days 8-20 of gestation. Offspring of untreated rats were injected with 1 mg cortisone either on their first day of life only, or else on the first and second days of life. Control animals were treated with normal saline. The young rats were examined between the 1st and 30th days of life, weighed and killed. The body weights of the prenatally treated offspring, as well as the weights of spleen, thymus and liver, were reduced at first, but gradually reached the control weight by the end of the first month. The body weights of the postnatally treated offspring, as well as the weights of the organs examined, were also reduced, and had not reached those of the controls even at the end of the first month. Histologically, depletion of lymphocytes in the thymo lymphatic organs was evident in all experimental offspring. The change was dose related. Recovery usually occurred during the third postnatal week. Groups of swollen hepatocytes, containing vacuoles of varying size, were found in the livers of all the experimental offspring during the first and second weeks of life. These vacuoles appeared as optically clear spaces, and the nature of any contents could not be determined histochemically. It appears that cortisone can produce structural alterations in the thymus, spleen and liver via the placenta and can retard postnatal maturation of these organs when administered to neonates.