Intrauterine position in pigs: effects on conceptus development and fetal fluids steroid content

Abstract

The purpose of this study was to investigate the effect of intrauterine position and its possibly resultant steroid differential on conceptus growth and steroid content in allantoic and amniotic fluid of pigs. six conceptus variables (placental weight, placental length, fetal weight, fetal length, allantoic fluid volume and amniotic fluid volume) and seven steroids (progesterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, estrone and estrone sulfate) were evaluated. Four fetal positions were studied: females between females (f2F), females between males (fOF) , males between females (m2F) and males between males (mOF).

Fetuses examined from ovariectomized (OVX) pregnenolone (PS)-treated gilts showed differences in placental weight, allantoic fluid estrone and androstenedione content and amniotic fluid androstenedione content as a result of intrauterine position. Fetuses from OVX gilts treated with either medroxyprogesterone acetate (MPA) I or progesterone (P4) showed differences in placental length due to intrauterine position. Allantoic and amniotic fluid content of any of the steroids studied from OVX MPA- and P4-treated gilts was not altered as a result of intrauterine position. Intrauterine position appears to have a definite influence on conceptus development and possibly on steroid content. However, discrepancies' of results among trials possibly as a result of differences in type and amount of exogenous precursor enable us to draw stronger conclusions on the intrauterine position effect.