Ontogeny and cellular localization of 125I-labeled insulin-like growth factor-I, 125I-labeled follicle-stimulating hormone, and 125I-labeled human chorionic gonadotropin binding sites in ovaries from bovine fetuses and neonatal calves.
In a previous study we reported that ovaries from bovine fetuses, which consist mainly of preantral follicles with few antral follicles, are weakly responsive to gonadotropins (FSH and LH). Insulin-like growth factor-I (IGF-I) is known to enhance gonadotropin responsiveness in vitro, but there is a lack of consistent data on the involvement of IGF-I, FSH, and LH during early stages of folliculogenesis in cattle. In the study reported here, we assessed autoradiographically the ontogeny of 125I-gonadotropin and 125I-IGF-I binding activities during preantral and early antral stages in cattle. Follicular growth was initiated around Day 180 of gestation in fetuses. The density of 125I-FSH binding was high in granulosa cells from primary (mean +/- SEM 10.5 +/- 0.7 grains/cell, 0.05-mm diam.) and secondary follicles (10.8 +/- 0.8 to 13.6 +/- 1.2 grains/cell, 0.06-0.15 mm) but increased significantly (p < 0.05) in early antral follicles (18.2 +/- 1.1 grains/cell, 0.16-3.0 mm). Specific 125I-IGF-I binding levels were low in granulosa cells from preantral follicles, averaging 2.5 +/- 0.6-3.1 +/- 0.9 grains/cell. However, after antrum formation, the density of 125I-IGF-I binding increased significantly (p < 0.05) with follicular diameter in granulosa cells and was 5.7 +/- 0.7 and 9.1 +/- 0.6 grains/cell for antral I (0.16-0.5 mm) and antral II (0.6-3.0 mm) follicles, respectively. 125I-FSH and 125I-IGF-I binding densities were low in theca cells from preantral and early antral follicles as well as in the interstitial tissue and granulosa cells from atretic follicles.(ABSTRACT TRUNCATED AT 250 WORDS)
Wandji
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SA
Département de Zootechnie, FSAA, Centre de Recherche du CHUL, Université Laval, Québec, Canada.
Pelletier
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Sirard
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MA
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001345:Autoradiography; D002417:Cattle; D006063:Chorionic Gonadotropin / Q000378:metabolism; D005260:Female; D005333:Fetus / Q000378:metabolism*; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D006107:Granulosa Cells / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D006080:Ovarian Follicle / Q000196:embryology / Q000502:physiology; D010053:Ovary / Q000378:metabolism*; D017526:Receptor, IGF Type 1 / Q000096:biosynthesis*; D011962:Receptors, FSH / Q000096:biosynthesis*; D011967:Receptors, Gonadotropin / Q000096:biosynthesis*; D013799:Theca Cells / Q000378:metabolism
D006063:Chorionic Gonadotropin; D007328:Insulin; D011962:Receptors, FSH; D011967:Receptors, Gonadotropin; D007334:Insulin-Like Growth Factor I; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D017526:Receptor, IGF Type 1