Ovary-Independent Estrogen Receptor Expression: DISCUSSION(3)

24 Jan

While, in general, endometrial ER expression patterns changed positively in association with age, OVX of gilts at birth did not affect patterns of endometrial ER mRNA and protein expression. Therefore, mechanisms regulating acquisition of ER-positive phenotype by porcine endometrial cells between birth and PND 120 are developmentally regulated, but ovary independent. Because uterine tissues were collected at 15- to 30-day intervals from birth, the precise temporal sequence in which endometrial S, GE, and LE acquire ER after birth could not be determined. However, data are generally consistent with the idea that development of an ER-positive phenotype by porcine endometrial cells is regulated spatially as well as temporally. Such relationships are illustrated clearly when ER-negative tissues obtained at birth are compared with those obtained on PND 15. buy prednisone

During the period between birth and PND 15, the porcine endometrium is transformed from an aglandular, mor-phogenetically inactive, structurally infantile state to a mor-phogenetically active state characterized by the presence of new endometrial glands that are proliferating rapidly. New GE cells observed on PND 15 displayed strong ER-positive character, as reflected by both nuclear immuno-staining for ER protein and signal intensity indicative of ER mRNA. This was in substantial contrast to the weak to moderate ER signals observed for stromal cells, and in striking contrast to signals in LE, which were effectively absent on PND 15. Data can be interpreted to indicate that ER-positive character develops first in endometrial GE and S, while LE cells do not become consistently ER positive until after PND 30 in the pig. The clear temporal and spatial dichotomy in ER expression observed between uterine LE and GE in association with the appearance of uterine glands establishes the ER as a molecular marker of GE differentiation in the neonatal porcine uterus.