Age-related changes in adenohypophyses of mice with the hereditary obese hyperglycemic syndrome (ob/ob) in relation to the diabetic state of the animals.

Mice with hereditary, monogenic obese-hyperglycemic syndrome (ob/ob) were shown to have smaller adenohypophyses in comparison to their normal littermates from an age of 4 weeks onward. The size of the pars intermedia of obese mice was not, however, significantly different from that of normal littermates. Morphometric criteria strongly suggest hyperactivity of the cells of the pars intermedia of obese hyperglycemic mice. The enhanced secretion of bioactive peptides of the pars intermedia may contribute to the diabetic aspects of the obese-hyperglycemic syndrome. The hyperactivity of the pars intermedia is likely to be allophenic.