The granulosa cells of the ovarian follicle surround the oocyte and support it during follicle development. Once exposed to the LH surge, the granulosa cells are characterised by the induction of genes necessary for cellular differentiation. The extensive morphological and functional changes which characterise luteinisation involve the regulation of gene and protein expression responsible for the cessation of proliferation and the induction of differentiation in the individual granulosa cells.

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... he differentiating granulosa cell also functions in both an endocrine and paracrine manner mediating follicle and oocyte maturation and subsequent corpus luteum remodelling. The formation of the functional corpus luteum and secretion of progesterone is essential for the establishment of pregnancy following ovulation. Although much is known about the molecular mechanisms responsible for follicular development comparatively little study has been carried out to analyse the control of, and events which occur during, luteinisation. It is therefore pertinent to study gene expression changes to try to clarify and understand mechanisms which regulate and underpin ovarian granulosa cell luteinisation. In order to investigate the mechanisms underlying these processes we embarked on a time- and cell-specific analysis of gene expression in the granulosa cell during late follicle development and early luteinisation. Changes in gene expression during granulosa cell luteinisation were measured using serial analysis of gene expression (SAGE). Immature normal mice were treated with gonadotrophin to induce formation and luteinisation of ovarian follicles. SAGE libraries were generated from mRNA isolated from granulosa cells collected before and after induction of luteinisation. The combined libraries contained 105,224 tags representing 40,248 unique transcripts. Overall, 715 transcripts showed a significant difference in abundance between the two libraries of which 216 were significantly down-regulated by luteinisation and 499 were signific [...]