Association Between Leptin, LH and its Receptor and Luteinization and Progesterone Accumulation (P4) in Bovine Granulosa Cell In Vitro

A full understanding of the cellular events that occur during in vitro luteinization of bovine granulosa cells, stimulated by LH and by leptin, is a complex goal that has not been completely achieved. The aim of this work was to study the effects of leptin, LH and leptin + LH on progesterone accumulation (P4) and on the expression of LH receptors (LHR) in bovine granulosa cells in culture. The results confirm that this in vitro model is representative of functional and morphological luteinization/differentiation. The pattern of expression of LHR with time of incubation was an important marker of in vitro luteinization, with 50–90% of cells expressing LHR by 96 h in culture. Cytoplasmic lipidic droplets were highly abundant in granulosa cells, suggesting a sufficient source of precursors for steroid hormone synthesis: P4 accumulation ranged between 40 and 550 ng/ml. In addition, a positive correlation ( r  = 0.58, p < 0.05) between the expression of LHR and accumulation of P4 throughout the time of incubation was observed. The expression of LHR was inhibited by LH and leptin + LH treatment. In conclusion, we found an inverse modulation between the expression of LHR and the concentration of LH, and the expression of LHR could be regulated by P4 produced by the luteinized granulosa cells. These findings are contributing to elucidate further the panoply of interactions during the differentiation of granulosa cells into luteal cells in vitro .     

The Influencing Factor of In Vitro Fertilization and Embryonic Transfer in the Domestic Fowl (Gallus domesticus)

This study was conducted to explore the influencing factors of ova in vitro fertilization (IVF) and transfer of the fertilized ova into the oviduct of recipient hens. The efficiency of fertilization was compared using three aspects: (i) the different time of ova collection and transfer, (ii) egg‐laying period of recipient hen; and (iii) semen volume. The following results are observed: 72%, 40% and 0% of ova were found in ovarian sac in 30～40 min, 50～60 min and more than 90 min post‐oviposition, respectively; 20%, 18%, 14% and 5.8% of ova were fertilized with 0.1, 0.2, 0.5 and 1.0 ml semen, respectively; and 33% and 100% of healthy chickens were hatched from fertile ova with 0.1 and 0.5 ml of semen, respectively. All oocytes obtained from ovary and mid‐oviduct were unfertilized. Embryos were transferred into recipient hens 30 min ± 10 min post‐oviposition, and 70% of shelled eggs were produced. There were no eggs produced in the other transfer times. This demonstrated that live chicken can be obtained by IVF of ova collected shortly after oviposition. It was important that the ovum was transferred into the oviduct infundibulum of recipient hens immediately or shortly after oviposition.