Localization and secretion of inhibins in the equine fetal ovaries.
To clarify the source of inhibins in equine female fetuses, concentrations of immunoreactive (ir-) inhibin, inhibin pro-alphaC, and inhibin A in both fetal and maternal circulation and in fetal ovaries were measured. In addition, the localization of inhibin alpha and inhibin/activin beta(A), and beta(B) subunits and the expression of inhibin alpha(A) and inhibin/activin beta(A) subunit mRNA in fetal ovaries were investigated using immunohistochemistry and in situ hybridization. Concentrations of circulating ir-inhibin, inhibin pro-alphaC, and inhibin A were remarkably more elevated in the fetal than in the maternal circulation between Days 100 and 250 of gestation. Fetal ovaries contained large amounts of ir-inhibin, inhibin pro-alphaC, and inhibin A. In contrast, these inhibin forms were undetectable in both the maternal ovaries and placenta. The inhibin alpha and inhibin/activin beta(A) and beta(B) subunit proteins were localized to enlarged interstitial cells of the equine fetal ovary. Expression of inhibin alpha and inhibin/activin beta(A) subunit mRNAs were also observed in the interstitial cells. We conclude that the main source of large amounts of inhibins in fetal circulation is interstitial cells of fetal ovary and is not of maternal origin. Furthermore, these inhibins may play some important physiological roles in the development of gonads in the equine fetus.
Tanaka
Yumiko
Y
Department of Basic Veterinary Science, The United Graduate School of Veterinary Science, Gifu University, Gifu 501-1193, Japan.
Taniyama
Hiroyuki
H
Tsunoda
Nobuo
N
Herath
Chandana B
CB
Nakai
Rie
R
Shinbo
Hiromi
H
Nagamine
Natsuko
N
Nambo
Yasuo
Y
Nagata
Shun-Ichi
S
Watanabe
Gen
G
Groome
Nigel P
NP
Taya
Kazuyoshi
K
D000818:Animals; D005260:Female; D005333:Fetus / Q000378:metabolism*; D006736:Horses / Q000033:anatomy & histology / Q000502:physiology*; D028322:Inhibin-beta Subunits / Q000235:genetics / Q000378:metabolism; D007265:Inhibins / Q000235:genetics / Q000378:metabolism*; D008431:Maternal-Fetal Exchange; D009929:Organ Size; D010053:Ovary / Q000033:anatomy & histology / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D012333:RNA, Messenger; C422362:inhibin A; C103008:inhibin beta A subunit; C094377:inhibin-alpha subunit; D007265:Inhibins; D028322:Inhibin-beta Subunits