The cellular localization of the inhibin subunits (α, β A, and β B), steroidogenic
enzymes (3β-hydroxysteroid dehydrogenase (3βHSD) and cytochrome P450 aromatase
(P450arom) were evaluated in the ovaries of cyclic (n=6) and pregnant (n=2) Shiba goats
(Capra Hircus). The immunointensity of inhibin α and βA subunits showed an increase in the
granulosa cells (GC) of developing follicles. Inhibin βB subunit and P450arom showed high
expression in GC of antral follicles. 3βHSD immunoreactivity was uniform in preantral and
antral follicles. In follicular phase and late pregnancy, there was a strong expression of inhibin
α subunit in GC of antral follicles. Although in mid pregnancy, antral follicles GC showed
moderate immunostaining of inhibin β subunits, the immunoreactivity of inhibin βA and βB
subunits was high during the follicular and luteal stages, respectively. While, immunoreactivity
of GC to P450arom was moderate during all studied stages, and 3βHSD immunoreactivity
was plentiful in antral follicles during the luteal phase. The immunoreactivity to inhibin α
subunit and P450arom was abundant during mid pregnancy in the luteal tissues.
Immunoreaction to inhibin β subunits was faint-to-moderate in cyclic and pregnancy corpora
lutea. Immunoexpression of 3βHSD was maximal in late pregnancy corpora lutea. The
present results suggest that, in goats, the GC of antral follicles are the main source of dimeric
inhibins and that corpora lutea may partially participate in the secretion of inhibin. Changes
in ovarian hormonal levels might depend on the synthesizing capacity of hormones in the
follicles and corpora lutea to regulate the goat’s reproductive stages.
Key words: goat, immunohistochemistry, inhibin, ovary, pregnancy