Effects of Estradiol and Dehydroepiandrosterone on the Reproductive Cycle of the Cow. II. Histology of Primary and Accessory Reproductive Organs, Pituitary, Thyroid, and Adrenal Glands

~Iistological examination of ovarian follicles from three heifers receiving daily injections of 250 to 350/~g of estradiol for varying lengths of time revealed an abnormal or absent granulosa layer and a thickening and partial luteinization of the thecal layers.In one heifer injected daily with 3.5 mg estradiol for 30 days prior to slaughter, all follicles larger than 1 mm in diameter exhibited follicular atresia; no follicle exceeded 10 mm in size.The percentage of granular small beta cells from the basophilic zone of the anterior pituitary was increased in the heifers receiving at least 350 >g of estradiol daily.Cystic corpora lutea were present on the ovaries of three out of four animals injected daily with 20 to 80 mg of dehydroepiandrosterone (DHA).The percentage of hyalinized small beta cells from the basophilie core of the anterior pituitary was increased with daily injections of at least 40 mg of DHA.Epithelial eelI heights of the thyroid, oviduct, cervix, uterine superficial and basal glands were greater in the animals treated with estradiol than in the animals treated with DHA.The differences in height were not significant (P < .05),however, except in the uterine superficial and basal glands.The effects of estradiol and DHA on length of estrous cycle, time of ovulation, tmnperature changes, and vaginal mucus flow were reported in a previous paper by Rahlmann and Cupps (17).The histological condition of pituitaries, thyroids, adrenal glands, ovaries, oviducts, uteri, cervices, and vaginas from two groups of four animals injected with estradiol-17-fl or DttA will be considered in the present paper. EXPERI~IENTAL PROCEDURE