The extent to which contributions from the adrenals may ultimately affect patterns of uterine growth between birth and puberty in the pig remains unclear. However, Evans et al. found no clear relationship between patterns of adrenal or thyroid gland growth and gross aspects of reproductive tract growth in gilts between weaning, at 3 wk of age, and puberty. Although the critical experiments remain to be conducted, it may be that the porcine uterus develops independently of a requirement for ovarian, adrenal, or thyroid support during early postnatal life, particularly between birth and approximately PND 60. buy flovent inhaler
Present data indicate that the porcine uterus is ER negative at birth. Thereafter, development of ER-positive phenotype by the endometrium is progressive. Data are generally consistent with previous observations indicating that neonatal porcine uterine responses to estrogen are exposure period-specific. EV, administered to crossbred gilts for 7 days prior to hysterectomy on PND 7, 14, or 49, increased uterine wet weights 2.5-, 3.2-, and 4.2-fold. Consistently, endometrial development, while advanced in all EV-treated gilts, was more pronounced in older animals. In addition, EV treatment affected in vitro production of 3, 8, and 14 uterine proteins on PND 7, 14, and 49, respectively. Present data are consistent with the suggestion that such period-specific physical and biochemical responses of neonatal uterine tissues to EV reflect developmentally related changes in the size, nature, and distribution of uterine cell populations that are competent to respond to estrogen, as well as estrogen-induced, ER-mediated changes in the ratio of epithelium to stroma in the developing uterine wall.