Abstract
Considerable information is now available concerning the histologic structure of the anterior pituitary of the female rat during the normal estrous cycle, 1 and after various experimental procedures. 2 , 3 However, as far as the writers are aware, there are available in the literature no reports of definite histologic studies on the anterior pituitaries of old female rats. Below are presented certain observations on a histologic condition found in the anterior pituitaries of old female rats which we have not observed in the anterior lobes of younger animals.
We have examined the pituitaries of 26 old breeding female rats of the experimental colony strain of the Wistar Institute. A majority had given birth to from 4 to 6 litters; all had delivered at least one litter. At autopsy the animals ranged in age from 543 to 848 days, the average age being 632 days. Three animals were found to have small subcutaneous tumors in the mammary region; subsequent histologic examination revealed that these were fibroadenomata of the mammary gland. The pituitaries were variable in weight, ranging from 10 to 45 mg., the majority weighing less than 17 mg. In 2 animals the right lateral halves of the anterior lobes were markedly and irregularly enlarged, causing a definite anterior and dorsal bulging of the anterior lobe tissue. The enlarged areas were extremely congested and very soft. In both, the posterior lobe appeared to be compressed and reduced in size.
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