Reproduction Abstracts

Introduction: Bi-directional communication between the oocyte and cumulus cells (CCs) is essential for the production of competent oocytes. Previous studies analyzed the relative transcript abundance in oocytes from small follicles (SF) and medium follicles (MF) to determinate the likely use of oocytes from SF in artificial reproductive techniques. The aim of this study was to examine the relative transcript abundance of CCs from cumulus–oocyte complexes (COCs) from SF and MF.

Materials and methods: CCs were obtained from COCs derived from SF (<3 mm) and MF (3–6 mm). We studied genes involved in oocyte developmental competence: hormonal receptors (GHR, BMPR2, LHR, and FSHR), genes related with oocyte maturation (INHBA and FST), genes related with CCs expansion and oocyte meiotic resumption (AREG and CD44), one gene related with gap-junction communication (ARID1B) and another related with hormonal response (NR2F6). RNA was extracted from CCs (30 COCs) and cDNA was synthesized and used in quantitative PCR.

Results and discussion: Significant effect of follicular size was detected in INHBA and GHR transcripts (P<0.05). INHBA was more expressed in CCs from MF whereas GHR was more abundant in the CCs from SF. Rest of the genes didn’t show significant differences. The higher expression of INHBA might reflect the oocyte’s degree of maturation since COCs from MF are closer to resumption meiosis and complete maturation than SF-derived COCs. The abundance of GHR transcripts in CCs from SF follicles might be related to the preparation of these follicles for a better response of the somatotropic axis.