Expression of Growth and Differentiation Factor-9 in the Ovaries of Fetal Sheep Homozygous or Heterozygous for the Inverdale Prolificacy Gene (FecXI)

• Published in: Biology of reproduction 2000-06, Vol.62 (6), p.1479-1485
• Main Authors: BODENSTEINER, K. J, MCNATTY, K. P, CLAY, C. M, MOELLER, C. L, SAWYER, H. R
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Bone Morphogenetic Protein 15; Female; Follistatin; Fundamental and applied biological sciences. Psychology; Gene Expression; Glycoproteins - genetics; Growth Differentiation Factor 9; Growth Substances - genetics; Growth Substances - physiology; Heterozygote; Homozygote; In Situ Hybridization; Infertility, Female - genetics; Infertility, Female - veterinary; Intercellular Signaling Peptides and Proteins; Mammalian female genital system; Morphology. Physiology; Ovary - embryology; Ovary - metabolism; Ovulation - genetics; Proto-Oncogene Proteins c-kit - genetics; RNA, Messenger - analysis; Sheep - genetics; Vertebrates: reproduction; X Chromosome
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod62.6.1479

Abnormal follicular and oocyte growth in ovaries of sheep homozygous (II) for the Inverdale gene, FecX I , suggest that this gene may influence a fundamental event in initiation of folliculogenesis, with two copies of the gene inhibiting growth at the primordial/primary stage. In addition, striking similarities in ovarian morphology between mice deficient in growth and differentiation factor-9 (GDF-9) and II sheep suggest a relationship between the FecX I gene and GDF-9 function in the ovary. Therefore, it was hypothesized that GDF-9 mRNA expression would be inhibited in ovaries of II fetal sheep. To test this hypothesis, in situ hybridization was used to characterize GDF-9 mRNA expression in ovaries of homozygous (II), heterozygous (I+), and control (++) fetal sheep at Day 135 of gestation. GDF-9 mRNA expression was localized exclusively to oocytes from the type 1 follicle stage onward in all genotypes and is the first demonstration of GDF-9 mRNA expression in ovaries of fetal sheep. In addition, GDF-9 mRNA expression was detected in oocytes of abnormal type 2 follicles in the ovaries of II sheep. Thus, it does not appear that inhibition of GDF-9 gene expression is the mechanism of action whereby the FecX I gene exerts its influence. However, the possibility of translation at specific stages of follicular development cannot presently be ruled out. In addition, the FecX I gene may be involved, either directly or indirectly, in regulating expression of receptors for GDF-9. At present, however, neither the FecX I gene product nor the GDF-9 receptor has been isolated or characterized.