The pars distalis, pars intermedia and infundibular process make up, respectively, 61, 5 and 34% of the volume of the pituitary gland of normal mature female rhesus monkeys. The pars distalis is relatively smaller in immature animals, and larger during pregnancy.Section of the pituitary stalk is followed by a significant increase in the volume of the pars intermedia; the infundibular process always decreases in volume, while the pars distalis shrinks to a lesser and more variable extent.Histological changes in the pars intermedia suggest that cellular hypertrophy, infiltration of atypical cells, and cyst formation all contribute to the increase in volume, and that the changes are at any rate partly degenerative in nature.
SUMMARY
An attempt was made to separate the pituitary gland from the hypothalamus in eight mature female rhesus monkeys by placing a piece of polythene film between the cut ends of the pituitary stalk. One animal died shortly after operation. In two it was established that the stalk had not been divided, and normal menstrual cycles continued. In a fourth, normal cycles also continued in spite of extensive damage to the stalk.
Amenorrhoea set in in three of the monkeys despite variable degrees of regeneration of hypothalamo-hypophysial vascular connexions. One animal underwent two phases of uterine bleeding in spite of complete structural and vascular separation of the pituitary gland from the hypothalamus.
The neural process was found to be atrophic in each of the seven surviving animals, and all developed diabetes insipidus. The severity of the polyuria could be correlated with the amount of damage to the median eminence rather than to the stalk.
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