Effect of Epidermal Growth Factor on in-vitro culture of feline preantral follicles

In vitro culture of preantral follicles would result in follicular development and production of a high number of competent oocytes that can be destined to assisted reproduction programs. However, in vitro systems supporting complete follicular growth from early primordial stages have only been achieved in mice (I). The improvement of culture system is aimed at defining cultural conditions similar to the in vivo environment. Growth factors may act as autocrine or paracrine regulators to locally modulate follicular development. It has been shown that Epidermal Growth Factor (EGF) is a vigorous mitogen of follicular cells and induces follicular development (2). The aim of this study was to investigate the effect of EGF on the in vitro development of preantral follicles recovered from domestic cat ovaries. Secondary follicles surrounded by complete basal membrane and containing more than one layer of granulosa cells were selected as previously described (3) and cultured for 6 days at 37°C and 5% C02 in air in Minirnum Essential Medium (Sigma Chemical Co., USA) with EGF 100 ng/ml or without (Control). In vitro development was assessed by measuring the diameter of follicles and oocytes before and after culture. A significant increase in the size of follicles was observed when EGF was supplemented to the culture medium (increase of 15.8%±2.53% vs 7.6%±5.2%; P<0.05), whether oocyte diameter was not affected by cultural conditions. Viability of follicles was assessed at D6 by trypan blue staining and the results showed that follicle viability was also enhanced by EGF (75% vs 50%; P<O.05). In conclusion, feline preantral follicles respond to culture conditions and these results prompt to extend the culture time in order to achieve the antrum formation. References 1) Demeestere et al., Hum Reprod. 2002; 17:2152-9. 2) Morbeck et al., J Reprod Fertil. 1993;99:577-84.3) Lima et al., Rev Bras Reprod Anim 2003;27:396-7.