Uteroglobin in the rabbit. II. Intracellular localization in the uterus after hormone treatment

Rabbit uterine uteroglobin (UGL) was studied by electrophoretic and immunological methods following normal copulation, after ovariectomy and progesterone treatment, 17beta-oestradiol and combined progesterone treatment, 17 beta-oestradiol treatment alone and after HCG-induced pseudopregnancy. Electrophoretic studies show the amount of ULG in uterine secretions, the immunological investigations indicate the intracellular localization of ULG and the distribution of ULG-positive cells in the endometrium. No obvious differences were found between the uteri 7 days after injection with chorion-gonadotropin and those 7 days following normal copulation. No differences could be domonstrated between the uteri of animals 35 days following ovariectomy and subsequent progesterone treatment on Days 31-33 and those of normal 7 d. post coitum (p.c.) animals. Uteri from animals treated with progesterone on Days 2-5 p.c. contained more ULG-positive cells than controls. 17beta-oestradiol treatment with and without subsequent progesterone treatment resulted, in both gravid and ovariectomized animals, in the formation of a tall columnar endometrial epithelium. Treatment with 17 beta-oestradiol on Days 1 and 2 p.c. led to a decrease in the number of UGL-positive cells at 7 days p.c. Even after ovariectomy with 17 beta-oestradiol substitution, UGL-positive cells were still present in the endometrium. However a secretion of any magnitude could not be detected. The importance of differentiation between synthesis and secretion (= release) as distinct phases of the glandular response is especially emphasised by the latter findings.