Prevention of wasting disease by pregnancy associated with hypertrophy of the fetal thymus.

Neonatally thymectomized female mice were studied and compared to appropriate controls. Neonatal thymectomy appears to decrease fertility significantly in the female C3H/HeJ mouse. However, if a thymectomized female mouse becomes pregnant, pregnancy offers significant protection against wasting disease and death. The maternal thymus appears to play no significant role in the development of the fetus as measured by gross examination and organ weights. Offspring of thymectomized females had comparable body and organ weights when compared to offspring from sham-operated females, except for the thymus gland and gastrointestinal tract. The absence of the maternal thymus gland did stimulate a significant increase in the gland weight of her offspring compared to sham-operated control female offspring. Parity, per se, in intact females also causes a significant increase in the weights of the thymus of newborn offspring.