Microanatomical Study of Embryonic Gonadal Development in Japanese Quail (Coturnix japonica)

Abstract

Gonadal development of quail embryos was examined histologically using histological and histochemical methods. In the present study, quail embryos were studied at various stages of incubation period based on phases of gonadogenesis. Germ cell migration was observed on day 3-4 but gonadal differentiation and gonadal function were observed on day 6–8 and day 11–14, respectively. During germ cell migration, quail primordial germ cells (qPGCs) were successfully detected in both left and right genital ridges as well as the dorsal mesentery by lectin histochemistry. Unexpectedly, qPGCs-like cells were found next to the neural tube by Mallory-AZAN stain. During gonadal differentiation, embryonic sex can be distinguished histologically since day 8 of incubation. Embryonic testis exhibited a thin cortex, whereas embryonic ovary exhibited a thick cortex. Testicular cord formation was found in the medulla of embryonic testes while the lacunae and fat-laden cells were found in the medulla of embryonic ovary during gonadal function. This is the first report on a comparison of phases of gonadogenesis and histochemical study of quail embryonic gonads in both sexes.

Pre-Hatching Development of the Alexandria Chicken Ovaries

“…[9,18] The genital ridge located at the medioventral surface of the developing mesonephroi near the base of the dorsal mesentery. [16,18] The current study revealed the boundaries of the undifferentiating gonads were well defined and separated from the mesonephroi. While Chang, Chen found the undifferentiated gonads shared the same parenchyma with the kidney tube suggesting that, [19] some kidney cells shared in the gonadal formation.…”

“…[7,15,16] In contrary Fargeix, Didier noted the genital ridge appeared at HH13 (E.2), [17] Sekido and Lovell-Badge marked that it appeared at HH23 (E.4) and Al-Saffar and Ab.Abood claimed the genital ridge appeared at 7-8 days old duck embryo. [9,18] The genital ridge located at the medioventral surface of the developing mesonephroi near the base of the dorsal mesentery.…”

“…The same results approved by Fargeix, Didier in chicken, [17] Intarapat and Satayalai in quail. [16] While Guioli, Nandi observed that at HH24 (E.4.5), [8] Sekido and Lovell-Badge found that at HH26 (E.5). [9] At the initial stages of the gonadogenesis, the germinal epithelium was stratified squamous epithelium, while Carlon and Stahl explained that, [20] at the initial stages of the development, the epithelial ridge composed of columnar cells.…”

“…[29] While Intarapat and Satayalai noted the sexual differentiation stage in the quail embryo at days 5-7 of the development. [16] The differentiated left ovary composed of an outer cortex and inner medulla separated from each other by a thin layer of connective tissue that form the primary tunica albuginea. [18,29] The stroma of the left ovary showed lipid droplets and have a role of a steroid production.…”

“…The ovary undergone the light microscopic examination at HH38 (E.12) and HH42 (E.16), SEM at HH26 (E.5), HH29 (E.6), HH36 (E.10), HH38 (E.12), HH39 (E.13) and HH42 (E. 16), and TEM at HH38 (E.12), HH42 (E.16).…”