On possible involvement of adrenocorticoids in chicken spleen development.

The possible effects of glucocorticoids on spleen development were assessed by the determination of changes in mean organ weight and histology in chicken (Gallus gallus) embryos at stages 44 and 45 of Hamburger and Hamilton on days 19.5 and 20 of incubation (N = 10--13). After the administration of 1 to 6 mg of metopirone (an 11-beta-hydroxylase inhibitor) the numbers of white-pulp periarterial nests and red-pulp granulocytes decreased. The changes associated with metopirone treatment were less evident after the addition of corticosterone (20 and 200 microgram). After adding corticosterone alone (200 microgram), the white-pulp nests appeared larger than in control. Mean body and spleen weights or spleen-body weight ratios did not change much after treatment. Possibly glucocorticoids normally direct these aspects of spleen histogenesis in chicken embryos.