Pituitary stores of fsh and lh were determined in female rats of ages ranging from 12 to 14 days (24 g body weight) to an estimated 280 days (>375 g body weight). The aim was to study the endocrine basis for lack of ovarian compensatory hypertrophy in the aged rat. Both the concentration (μg/mg) and total content (μg/gland) of fsh in the pituitary glands of aged rats were two to three times higher than those in the glands from the adult rats (60 to 180 days old and weighing 200 to 300 g). A similar but less marked tendency was present for lh.
These results support the view that lack of ovarian compensatory hypertrophy in the aged rat is due to a decline in the output of fsh and lh from, but not due to deficiency of gonadotrophins in, the pituitary gland of the aged rat.