Submitted to: General and Comparative Endocrinology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/8/1999
Publication Date: N/A
Citation: Interpretive Summary: Prehatch and the early posthatch stages of sexual development in poultry is impacted by the levels and types of estrogen and androgen produced by gonads of the developing chick. Since little is known regarding the early sexual development of the bird, we identified and described the sequence of events which contribute to sexual development in female Japanese quail. Ovarian histology and plasma estrogen concentrations were measured during the embryonic and early posthatch periods examined. Plasma estrogen levels and ovarian histology were investigated in female Japanese quail from Day 10 of incubation through their first week after hatching. Plasma estrogen levels in the embryos remained relatively high until hatching. After hatching the plasma estrogens levels dropped to about 50% of the incubation. Interestingly, cells in the central part of the ovary had a morphological appearance which was characteristic of that of cells which secrete steroid hormones. Estrogen is a steroid hormone. We concluded that these observations support the hypothesis that estrogen plays a very early role in the prehatch and in the early posthatch development of the reproductive system. This fundamental information will be used by scientists investigating aspects of embryo development and the impact of endocrine disruptors on sexual maturation.
Technical Abstract: Plasma concentrations of 17B-estradiol (E2) and left ovarian histology, at the level of light and electron microscopy were investigated in female Japanese quail from Day 10 of embryonic development through Day 7, posthatch. Plasma E2 levels remained relatively constant (102 pg/ml to 140 pg/ml) in the embryo followed by a sharp decrease posthatch (47 to 70 pg/ml). Beginning on Day 10 of incubation, cells in the medullary portion (medullary cell; MC) of the left ovaries exhibited ultrastructural evidence of steroidogenic capability. The MC had numerous lipid droplets in close proximity to the smooth endoplasmic reticulum (SER). Mitochondria were also observed in the vicinity of the lipid droplets and SER. On Days 10 and 12, the cristae of the inner mitochondrial membranes were of a lamellar configuration; the cristae of some mitochondria in MC had a tubular appearance by Day 14. These data document relative ontogenic changes in ovarian morphology and plasma E2 levels during the early developmental period in female Japanese quail. These data further support the role of this steroid in sexual differentiation.