Effect of the Medium Replacement Interval on the Viability, Growth and In Vitro Maturation of Isolated Caprine and Ovine Pre‐Antral Follicles

Abstract

The aim of the present study was to evaluate the effects of different medium replacement intervals on the viability, antral cavity formation, growth and in vitro maturation (IVM) of oocytes from caprine and ovine pre-antral follicles. Pre-antral ovarian follicles (≥ 150 μm) were isolated from the ovarian cortex of goats and sheep and were individually cultured for 24 days using two different medium replacement intervals [2 days (T(1) ) or 6 days (T(2) )]. Follicle development was evaluated on the basis of antral cavity formation, increases in follicular diameter and the presence of healthy cumulus oocyte complexes and fully grown oocytes. For caprine species, results showed a higher percentage (p<0.05) of viable follicles in T(1) than T(2) from day 6 until the end of the culture. In addition, when comparing both treatments after the same culture duration, the rate of antrum formation was significantly higher in T(1) than in T(2) from day 12 onwards. Yet, in ovines, when both treatments were compared on day 24 of the culture, there were more viable follicles in T(2) than in T(1) (p<0.05). In the caprine species, percentages of fully grown oocytes (≥ 110 μm) acceptable for IVM after 24 days of culture were significantly higher in normal follicles cultured in T(1) (30.0%) than in T(2) (6.7%; p<0.05). On the other hand, in ovines, at the end of the culture, the percentage of oocytes destined for IVM was higher in T(2) than in T(1) (23.5% vs 2.9%; p<0.05). In conclusion, under the same conditions, the frequency of medium replacement significantly affected the in vitro development of caprine and ovine pre-antral follicles. To improve the efficiency of the culture system, the medium must be replaced every 2 and 6 days for goat and sheep pre-antral follicles, respectively.

Steady-state level of epidermal growth factor (EGF) mRNA and effect of EGF on in vitro culture of caprine preantral follicles

“…In goats, the isolated follicles contain some stromal tissue around them and several studies Saraiva et al 2010a, b;Magalhães et al 2011;Duarte et al 2010) have shown that these follicles can successfully be cultured directly on plastic. In this system, the vast majority of follicles form an antral cavity after 6 days of culture and the follicular diameter increases.…”

In vitro culture of secondary follicles and prematuration of cumulus–oocyte complexes from antral follicles increase the levels of maturation‐related transcripts in bovine oocytes

“…The success in culture of preantral follicles resulting in live births was only achieved in mice (Dela Peña, Takahashi, Katagiri, Atabay & Nagano, ; O'brien, Pendola & Eppig, ) to date. In larger species, the results reached only at variable production of a number of embryos in goats (Magalhães et al, ; Saraiva et al, ), sheep (Arunakumari, Shanmugasundaram, & Rao, ), and buffalo (Agarwal, Durairajanayagam, & Du Plessis, ). In cattle, secondary follicular grow in vitro up to antrum formation (Mbemya et al, ), but competent oocytes were still not reported after culturing these follicles.…”

Protein Localization of Epidermal Growth Factor in Sheep Ovaries and Improvement of Follicle Survival and Antrum Formation In Vitro

“…Moreover, some authors have shown higher follicular viability after culture in medium containing FSH (Magalhães et al. ; Silva et al. ).…”

“…Moreover, in the current study, the change of the medium and evaluation of the parameters were performed at each 6 days (Magalhães et al. ), while in caprine studies, the change and analysis were performed at each 2 days. Previous study suggested that EGF can efficiently activate the cascade of mitogen‐activated protein kinase (MAPK) in granulosa cells (Maizels et al.…”