|Mccoard, Susan - FORMER ARS EMPLOYEE|
Submitted to: Journal of Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 10, 2002
Publication Date: November 1, 2002
Citation: MCCOARD, S.A., WISE, T.H., FORD, J.J. 2002. EXPRESSION LEVELS OF MULLERIAN-INHIBITING SUBSTANCE, GATA4 AND 17ALPHA-HYDROXYLASE/17,20-LYASE CYTOCHROME P450 DURING EMBRYONIC GONADAL DEVELOPMENT IN TWO DIVERSE BREEDS OF SWINE. JOURNAL OF ENDOCRINOLOGY. v. 175(2). p. 365-374. Interpretive Summary: Chinese Meishan (MS) and pigs common in U.S. pork production, of which White composite (WC) is representative, differ greatly in appearance and rate of sexual development. MS boars and gilts reach puberty at 60-100 days earlier than WC pigs. MS boars have smaller testes, and MS sows have greater ovulation rate than WC pigs. The objective of the current study was to determine if these two diverse breeds differed in their rate of embryonic sexual differentiation. Based on the appearance of key proteins associated with gonad differentiation and rate of morphological changes in embryonic gonads, we conclude that male and female embryos of the MS breed undergo sexual differentiation at a similar rate as embryos of the WC breed.
Technical Abstract: Substantial differences exist in reproductive characteristics of Chinese Meishan (MS) and traditional (WC) pigs. Embryos/fetuses were evaluated on d 26, 28, 30, 35, 40, and 50 of gestation. Gonadal differentiation was based on morphological criteria and on localization of Gata4, Mullerian-inhibiting substance (Mis) and 17a-hydroxylase/17,20-lyase cytochrome P450 (P450c17). Timing of testicular cord formation, Sertoli and Leydig cell differentiation, organization of ovarian medullary cords and formation of egg cell nests were observed at similar ages in both breeds. Levels of Gata4, Mis and P450c17 proteins increased with advancing gestation, with greater levels of Mis and P450c17 in testes of MS compared to WC embryos. Thus, rate of sexual differentiation does not differ between these diverse breeds, and gonadal development is not associated with subsequent reproductive performance.