The stem cell factor (SCF), binding its tyrosine kinase receptor c-Kit, has been shown to play essential roles in the proliferation, differentiation, and survival of germline cells. However, few reports are available about the effect of SCF on the development of human gonocytes within the fetal testis. The objective of this study was to investigate whether SCF affects the biological behaviors of human gonocytes before or after they enter the mitotic arrest stage. Employing an organ culture system, we observed that addition of exogenous SCF could influence the morphology of human gonocytes in vitro. Moreover, SCF was able to trigger the colony formation of round gonocytes, which were characterized positive for alkaline phosphatase activity, Oct-4, SSEA-4, and c-Kit as well. We found that SCF exerted actions in a dose-and age-dependent manner, although the stimulatory effect lasted no more than 14 days. We also showed that SCF played a role in suppressing the apoptosis of human gonocytes. Blocking of SCF signaling with either phosphatidylinositol 3-kinase or mitogen-activated protein kinase inhibitor resulted in similar apoptotic features as well as the SCF-withdrawal cultures. Taken together, we report that SCF acts as a potent regulator in the fate determination of human gonocytes. Our studies should form the basis for in vitro studies and facilitate investigation of the molecular mechanisms underlying this unique stage. Reproduction (2007) 134 757-765

In an attempt to evaluate the effectiveness of a novel modified ultra-long agonist (ULA) protocol on polycystic ovary syndrome (PCOS) patients undergoing in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI), a retrospective study of 499 women employed with either ULA or conventional long agonist (LA) protocol was analyzed. In high BMI group (>25 kg/m²), the ULA protocol yielded significant higher clinic pregnancy rate (PR) (70.2% versus 50.8%, p < 0.05), implantation rate (52.7% versus 35.7%, p < 0.05) and live birth rate (63.8% versus 39.0%, p < 0.05) when compared with LA protocol. In low BMI group (≤25 kg/m²), the ULA protocol also demonstrated a higher clinic PR (70.8% versus 59.5%, p < 0.05) whereas implantation rate and live birth rate are comparable. Within ULA protocol, the clinic PR, implantation rate and live birth rate are similar between high and low BMI patients. Similarly, the clinic PR and live birth rate demonstrated no significant difference within LA group but there is a significant lower implantation rate (35.7% versus 63.9%, p < 0.05) observed in high BMI patients. No difference in miscarriage rate and severe OHSS rate was found among all groups. In conclusion, ULA protocol benefits the IVF outcomes of PCOS patients with high BMI status.

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