Adrenal changes in genetically hypothyroid mice

The adrenocortical X-zone was very poorly developed in young female mice homozygous for the hypothyroid, hyt, mutation, Feeding the mice thyroid powder resulted in the development of an X-zone. This subsequently degenerated in the same way as the X-zone found in the normal litter-mates of the mutants. We suggest that the adrenocortical effects may be due to changes in prolactin stimulation consequent upon the lack of response to thyrotrophin of the mutants.