Interaction between keratinocyte growth factor-1 and kit ligand on the goat preantral follicles cultured in vitro

Studying the interactions among growth factors that act in the ovary is a fundamental step to clarify the mechanisms controlling follicle development. Thus, the aim of this study was to evaluate the effect of the interaction between keratinocyte growth factor-1 (KGF-1) and kit ligand (KL) on early folliculogenesis in the goat. Goat ovarian fragments were cultured in vitro for 7 days in media supplemented with KGF-1 (1 ng/mL) or KL (50 ng/mL) alone or in combination (KGF + KL). Non-cultured control and cultured ovarian fragments were processed for histological and viability analyses, transmission electron microscopy (TEM) and qPCR evaluation. After in vitro culture, all treatments reduced the percentage of normal and viable follicles compared to the non-cultured control (P < 0.05). However, no difference was observed among the cultured treatments (P > 0.05). TEM confirmed the follicular integrity after 7 days of culture with KGF-1 and KL. In addition, a larger percentage of growing follicles and large-diameter follicles were observed when KL was added alone to the culture medium compared to the cultured control (P < 0.05). Ovarian tissues cultured in KGF-1 alone or KGF-1 in combination with KL showed lower levels of mRNA for KGF-1 receptor (FGFR2IIIb) than the non-cultured control (P < 0.05). In contrast, the mRNA expression for KL and its receptor (c-kit) decreased in all cultured treatments (P < 0.05). In conclusion, under our culture conditions, we could not confirm that the oft-quoted KGF-1/KL system is playing an essential role in goat initial folliculogenesis.