Gonadotropin-Prolactin Interrelationships in the Hre/+ Rat:

produces infertility in males, but has no ap-parent effect on reproductive function in females (Gumbreck et a!., 1971, 1972; Russel and Gardner, 1974). In addition to its effect on fertility, the Hre gene also restricts the coat color on the head of pigmented rats, which allows for easy recognition of animals which transmit this gene. For this reason, the affected animals have been termed restricted (Gumbreck et a!., 1971, 1972). Several studies on testicularutero at approximately 20 days of embryonic life, whereas heterozygous (H’/+) animals ar