In vitro Survival of Follicles Collected from Domestic Cats' Ovaries at Different Stages of Oestrous Cycle and Cultured with IGF‐1

Abstract

ContentsOptimal conditions for in vitro culture of feline ovarian follicles have not yet been defined. Follicular development is regulated by intraovarian growth factors, as insulin-like growth factor (IGF-1), and during the different stages of the oestrous cycle, follicles are exposed to specific hormonal environments. The aim of this study was to investigate the effect of IGF-1 on in vitro growth and granulosa cell (GC) viability of preantral follicles collected from domestic cats at follicular and luteal phases of the oestrous cycle. Oestrus and ovulation were induced in 12 cats. A total of 39 and 32 follicles collected at the follicular and luteal phases, respectively, were individually cultured in vitro for 6 days in minimum essential medium media supplemented with or without IGF-1 (100 ng/ ml). Follicles collected during the follicular phase and cultured without IGF-1 displayed a significant increase in size and higher GC viability (46.5 ± 22.1 lm, 66.7%, respectively) than that of follicles collected at the luteal phase and cultured without IGF-1 (26.7 ± 14.4 lm, 50%, respectively; p < 0.05). In contrast, when IGF-1 was added to the culture medium, no differences were observed in size or GC viability between follicles collected at the two phases of the cycle. Nonetheless, follicles collected at the luteal phase and cultured with IGF-1 had a significant increase in their diameter and GC viability (31.9 ± 15.9 lm, 63.6%, respectively) than that cultured without IGF-1 (26.7 ± 14.4 lm, 50%, respectively; p < 0.05). These data suggest that in vitro growth and GC survival of feline preantral follicles are affected by the oestrous cycle phase, and the IGF-1 exerts a positive effect on follicles collected at the luteal phase.

Viability and growth of feline preantral follicles in vitro cultured with insulin growth factor and epidermal growth factor supplemented medium

“…After 6 days of culture, an increase in diameter and granulosa cell viability was observed when follicles collected at the luteal phase were cultured with IGF‐1, compared to those cultured in control medium. The degeneration rates were also lower when IGF‐1 was present (Alves et al., ).…”

“…Fifteen microlitres of MEM was exchanged for fresh medium every other day. At the end of culture (T6), preantral follicles characterized by the integrity of basal membrane and of GC layers were considered as intact, whereas degenerated follicles showing breakdown or rupture of the basement membrane, opacity of GC or extrusion of the oocyte from within the follicle were recorded and discarded (Alves et al., ).…”

“…The diameter of the intact follicles and of the contained oocytes was measured as previously described, and the GC viability was assessed by fluorescein diacetate (FDA) staining. Follicles containing 75% of live GC were considered viable (Alves et al., ).…”

“…In vitro culture systems for the growth of preantral follicles have been developed in different farm animals (for review, see Silva, Van den Hurk, & Figueiredo, ), in dogs (Songsasen, Comizzoli, Nagashima, Fujihara, & Wildt, ) and in cats (Alves et al., ; Fujihara, Comizzoli, Keefer, Wildt, & Songsasen, ; Jewgenow, , ), with variable results. Several studies have shown that follicular growth and survival depend on the presence of gonadotropins and of a variety of factors that are locally produced in the ovary (Fortune, ), but relatively little is known about the precise mechanisms that activate and stimulate primordial follicles to grow and develop (Silva et al., ).…”

“…The addition of growth factors such as IGF (insulin‐like growth factor) and EGF (epidermal growth factor) in culture medium has provided superior results of follicular development, antrum formation and proliferation of granulosa cells of preantral follicles from different species (cattle: Gutierrez, Ralph, Telfer, Wilmut, & Webb, ; pigs: Mao et al., ; goat: Zhou & Zhang, ; horses: Silva et al., ). In addition, we previously demonstrated the benefit of the presence of IGF‐I on in vitro culture of preantral follicles from queens at different stage of oestrous cycle (Alves et al., ).…”