S. Goubau et al., INSULIN-LIKE GROWTH-FACTOR-I (IGF-I) COLOCALIZES WITH IGF-BINDING PROTEINS (ICFBPS) IN MOUSE AND RAT OVARY, Endocrine, 4(3), 1996, pp. 213-221
The cellular localization of insulin-like growth factor (ICF)-I mRNA,
IGF-I peptide, and IGF-binding proteins (IGFBPs) was examined in mouse
and rat ovaries through use of in situ hybridization and immunohistoc
hemical methods. IGF-I mRNA was found to be most abundant in granulosa
cells, although lower levels were also detected in cells of the theca
interna, stroma, and corpus luteum. In contrast, IGF-I immunoreactivi
ty was undetectable or low in granulosa cells, weak and variable in oo
cytes, high in theca interna and the corpus luteum, and highest in the
stroma. Antibodies directed against IGFBP-2, 3, and 5 yielded similar
patterns of immunoreactivity to that observed for IGF-I peptide. The
results indicate that IGF-I is synthesized in ovarian follicles, and t
hat IGF-I of ovarian or systemic origin becomes localized to sites con
taining IGFBPs in the ovary.