Localization of 3 beta-hydroxysteroid dehydrogenase in the chicken ovarian follicle shifts from the theca layer to granulosa layer with follicular maturation.
3 beta-Hydroxysteroid dehydrogenase (3 beta-HSD) catalyzes the conversion of pregnenolone to progesterone in the delta 4-3-ketosteroid metabolic pathway and dehydroepiandrosterone to androstenedione in the delta 5-3 beta-hydroxysteroid pathway. It has been suggested that small follicles of the chicken ovary that have not entered the follicular hierarchy metabolize steroids via the delta 5-3 beta-hydroxysteroid pathway, whereas preovulatory follicles that have entered the hierarchy metabolize steroids via the delta 4-3-ketosteroid pathway. Our objective was to localize 3 beta-HSD in follicles of the chicken ovary by immunocytochemistry using an anti-human placental 3 beta-HSD polyclonal antiserum to identify steroidogenic cells that convert pregnenolone to progesterone and/or dehydroepiandrosterone to androstenedione. Three groups of follicles of different maturities were examined: small follicles (1-10 mm in diameter and that have not entered the hierarchy), preovulatory follicles (10-35 mm in diameter and that have entered the hierarchy), and the most recent postovulatory follicle. Chicken ovaries were obtained 2 h after oviposition and fixed with Bouin's solution. Tissues were dehydrated with a series of ethanol, embedded in Paraplast (Brunswick Company, St. Louis, MO), and sectioned. Sections (4 microns) were immunostained for 3 beta-HSD with a Rabbit ExtrAvidin Staining Kit (Sigma Chemical Co., St. Louis, MO). 3 beta-HSD was localized in the single theca layer of cortical follicles (approximately 1 mm in diameter), which are still embedded in the stromal tissue, and in the theca interna and externa of other small follicles (< 10 mm in diameter). No immunoreactivity was observed in the granulosa layer of the majority of small follicles.(ABSTRACT TRUNCATED AT 250 WORDS)[1]References
- Localization of 3 beta-hydroxysteroid dehydrogenase in the chicken ovarian follicle shifts from the theca layer to granulosa layer with follicular maturation. Nitta, H., Mason, J.I., Bahr, J.M. Biol. Reprod. (1993) [Pubmed]
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