Certain anomalous conditions associated with the reproductive organs have arisen in a line of King-Holtzmann hybrid rats maintained in our laboratory. These are sterile pseudohermaphroditic males in which the entire reproductive tract except the testes is missing; apparent males demonstrating a n ectopic inguinal ring and testis on one or both sides; and sterile males with descended scrotal testes. The procedure developed by Moore ('55) for staining sex chromatin was applied to cells from liver, spinal cord, testis, and parotid gland of rats. A sex difference is clearly shown, however, only with the liver cells. Ford and Woollam's ('64) sequence for demonstrating mammalian chromosomes renders positive results on bone marrow cells. This method applied to liver and testis yields unsatisfactory results.
Examination of idiograms and sex chromatin bodies from animals exhibiting the conditions outlined above leads to the following conclusions: (1) all abnormal animals studied are genetic males; and (2) the pseudohermaphrodites, though genetically male, exhibit a pattern of differentiation of chromosomes during the metaphase plate stage resembling that in the female.
Similarities between certain anatomic and physiologic factors exhibited in pseudohermaphroditic rats and those present in "testicular feminization" in man are discussed. Male rats exhibiting a n ectopic inguinal ring and testis and sterile males with descended scrotal testes also may have their counterpart in man.