Effects of growth hormone on the adult canine thymus.

The ability of bovine growth hormone therapy to stimulate regeneration of age involuted thymus glands in adult dogs was evaluated. The thymuses of growth hormone treated dogs regenerated, resembling thymic tissue of young dogs. Some of the thymuses of bovine serum albumin treated control dogs also regenerated, but only 2 of 5 control dogs had marked regeneration. White blood cell counts in peripheral blood were not different between groups. Serum thymosin alpha 1 concentrations were not different between groups, but decreased in each group during the treatment period.