Interactive effects of granulosa cell apoptosis, follicle size, cumulus–oocyte complex morphology, and cumulus expansion on the developmental competence of goat oocytes: a study using the well-in-drop culture system

Abstract

Interactive effects of granulosa cell apoptosis, follicle size, cumulus-oocyte complex morphology, and cumulus expansion on the developmental competence of goat oocytes: a study using the well-in-drop culture system Zheng-Bin Han, Guo-Cheng Lan, Yan-Guang Wu, Dong Han, Wei-Guo Feng, Jun-Zuo Wang and Jing-He Tan AbstractUsing a well-in-drop (WID) oocyte/embryo culture system that allows identification of follicular origin, we have investigated the effects of granulosa cells (GCs) apoptosis, follicle size, cumulus-oocyte complexes (COCs) morphology, and cumulus expansion on the developmental competence of goat oocytes matured and cultured individually following parthenogenetic activation. The WID system supported oocyte maturation and embryo development to a level similar to the conventional group system. The majority of goat oocytes acquired competence for development up to the 8-16 cell stage in follicles larger than 2 mm, but did not gain the ability to form morula/blastocyst (M/Bs) until follicles larger than 3 mm in diameter. The extent of atresia affected M/Bs formation. This effect varied according to the follicle size. Cumulus expansion increased with follicle size and decreased with increasing incidence of GCs apoptosis. Oocyte developmental potential was also correlated with cumulus expansion. Regardless of the degree of follicle atresia, 73-84% of the floating cells in the follicular fluid (FF) underwent apoptosis. Correlation between floating cell density in FF and oocyte developmental potency suggests the possibility to use the floating cell density as a simple and non-invasive marker for oocyte quality. It is concluded that the developmental potential of an oocyte is determined by multifactor interactions, and multiple factors must be considered together to accurately predict the quality of an oocyte. Reproduction (2006) 132 749-758Introduction A number of studies have shown that in vitro development of pre-implantation stage mammalian embryos is better when cultured in groups (group culture) than cultured singly in microdrops (microdrop individual culture, MIC) (Gardner et al. 1994, Kato & Tsunoda 1994, Keefer et al. 1994, Moessner & Dodson 1995. However, apart from the large-scale production of embryos for experimental purposes, most commercial and human embryo culture systems require culturing individually or in small groups. The reason for this need is the small number of oocytes available (ovum pick-up (OPU) technology, single slaughtered valuable oocyte donors and human IVF) or the required identification after culture. Besides, sometimes zona-free eggs must be cultured in isolation from each other to prevent conglomeration. Therefore, the establishment of an individual culture system that is as efficient as group culture has become of prime importance. Furthermore, although there are quite a few reports on individual culture of embryos, studies on individual culture of oocytes during maturation are few and with conflicting results (Carolan et al. 1996, Hagemann et al. 1998, Jewgenow et al. 19...

Effect of follicular diameter, time of first cleavage and H3K4 methylation on embryo production rates of Bos indicus cattle

“…These data are also in agreement with the results reported by other groups, confirming the positive influence of larger follicular diameter on development at the blastocyst stage that has been championed by many authors (HAN et al, 2006;LEQUARRE et al, 2005;LONERGAN et al, 1999). Despite the several important reproductive differences between taurus and indicus, it seems that this current point is quite similar.…”

Selection of oocytes for in vitro maturation by brilliant cresyl blue staining: a study using the mouse model

“…Many studies have suggested that a low level of atresia tends to improve the in vitro competence of oocytes [23,[64][65][66]. Our recent work showed that early atresia was beneficial to both competent and incompetent goat oocytes [67].…”

Effects of oocyte quality and semen donor on the efficiency of <i>in vitro</i> embryo production in cattle

“…In addition, oocytes matured in vivo are more competent than those matured in vitro (Blondin et al, 2002;Rizos et al, 2002). Moreover, it has been shown that developmental competence may differ signifi cantly among oocytes with the same COC morphology and follicle size and the same extent of cumulus expansion (Han et al, 2006). These observations suggest that the developmental potential of an oocyte is determined by multifactorial interactions (Han et al, 2006).…”