WEIGHT AND HISTOLOGY OF THE PITUITARY GLAND IN CASTRATED MALE RATS WITH HYPOTHALAMIC LESIONS

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Abstract
SUMMARY: The effect of bilateral electrolytic lesions in the ventral hypothalamus at the coronal level of the posterior ventromedial nucleus and anterior premammillary nucleus on the weight and cytology of the pituitary gland of castrated male Lewis rats was investigated. All castrated rats were carrying successful intrasplenic isologous grafts of neonatal testes. The hypothalamic lesions resulted in a significant inhibition of pituitary hypertrophy in the castrated animals, but did not alter appreciably the cytology of the gland as compared with that of castrated rats without hypothalamic damage. The development of castration cells was not impaired by these lesions. It is concluded that hypertrophy of the pituitary gland after castration and the development of castration cells are two manifestations of the pituitary response to a low concentration of circulating testicular hormone. The former requires the integrity of the posteroventral hypothalamus while the latter is independent of this hypothalamic region.