Recent evidence suggests that Leukemia Inhibitory Factor (LIF), a member of interleukin-6 family, has biological actions on preimplantation embryo development. Also it is established that Epidermal Growth Factor (EGF), a strong mitosis-promoting agent, improves the preimplantation embryo development by increasing the cell metabolism and proliferation. The purpose of the present study is to investigate the effects of these factors, alone and in combination together, on preimplantation and development of the embryo.
Six to eight weeks old NMRI mice were super ovulated by injection of 10IU PMSG and 10IU hCG, then the mated mice were killed 46 hours later. Their oviducts were flushed, two-cell embryos collected and divided randomly to the four groups as following: Control, treatment 1 (LIF), treatment 2 (EGF), treatment 3 (LIF+EGF). In each group, the embryos were cultured in an incubator at 37°C with 5% CO2 and 90% humidity for 72hrs. The state of embryo development was evaluated in 24,36,48,60 and 72hrs following the embryos cultures. By the end of the cultures, cell apoptosis was studied by the terminal deoxynucleotidyl transferas-mediated dUTP nick end-labeling (TUNEL) technique.
Significant difference was detected in the rate of hatching in the LIF and LIF+EGF groups. This difference was also seen in the rate of blastocyst formation after 36hrs (p<0.05) and in the average of the total cell number (p<0.05) after 72hrs. In comparison to the apoptotic index, there was no significant difference between the control and treatment groups.
The findings in this study show a beneficial effect of LIF and EGF on the blastocyst formation, hatching and its total cell numbers in vitro.