Cumulus cell function during bovine oocyte maturation, fertilization, and embryo development in vitro

Abstract

Several contemporary micromanipulation techniques, such as sperm microinjection, nuclear transfer, and gene transfer by pronuclear injection, require removal of cumulus cells from oocytes or zygotes at various stages. In humans, the cumulus cells are often removed after 15-18 hr of sperm-oocyte coincubation to assist the identification of the fertilization status. This study was designed to evaluate the function of cumulus cells during oocyte maturation, fertilization, and in vitro development in cattle. Cumulus cells were removed before and after maturation and after fertilization for 0, 7, 20, and 48 hr. The cumulus-free oocytes or embryos were cultured either alone or on cumulus cell monolayers prepared on the day of maturation culture. Percentages of oocyte maturation, fertilization, and development to cleavage, morula, and blastocyst stages and to expanding or hatched blastocysts were recorded for statistical analysis by categorical data modeling (CATMOD) procedures. Cumulus cells removed before maturation significantly reduced the rate of oocyte maturation (4-26% vs. 93-96%), fertilization (0-9% vs. 91-92%), and in vitro development at all stages evaluated. Cumulus cells removed immediately prior to in vitro fertilization (IVF) or 7 hr after IVF reduced the rates of fertilization (58-60% and 71%, respectively, vs. 91-92% for controls), cleavage development (40-47% and 53-54% vs. 74-78% for controls), and morula plus blastocyst development (15% and 24% vs. 45%, P < 0.05). Cumulus cell co-culture started at various stages had no effect on fertilization and cleavage development but significantly improved rates of embryo development to morula or blastocyst stages (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effects of the cumulus-corona radiata complex during vitrification of horse oocytes

“…MAP kinase, MPF: Bogliolo et al 2007). It has also been proposed that damage to the cumulus investment plays a role in compromised developmental competence since freezing and thawing damages cumulus cells surrounding mouse oocytes (Ruppert-Lingham et al 2003) and the gap junctions between equine oocytes and their surrounding cumulus-corona radiata cells (Hochi et al 1996), where the interaction between oocyte and cumulus has been shown to be critical to successful nuclear and cytoplasmic maturation for at least bovine oocytes (Zhang et al 1995, Hassan 2001, Tanghe et al 2003. While Bogliolo et al (2007) reported a counterintuitive improvement in survival and meiotic competence for immature sheep oocytes denuded of their cumulus prior to vitrification, they also noted the depletion of enzymes (MPF and MAPK) required to support embryo development.…”

Interação entre células do cumulus e atividade da proteína quinase C em diferentes fases da maturação nuclear de oócitos bovinos

“…1). Apesar da presença das células do cumulus ser importante para o processo de maturação e competência no desenvolvimento embrionário (Zhang et al, 1995) e sua ausência acelerar o RVG em oócitos bovinos (Fissore et al, 1996), elas não foram essenciais para a ação da PK-C, na mudança da cinética da meiose durante o início do processo de maturação do oócito. A percentagem média de oócitos que estavam em RVG, após sete horas de cultivo, ficou entre 1,7% e 28,6% nos vários tratamentos (Fig.…”

“…As células do complexo cumulus-oócito (CCO) exercem importante papel na regulação da maturação do oócito e a retirada dessas células reduz significativamente o desenvolvimento embrionário subseqüente (Zhang et al, 1995;Shioya et al, 1998). Há evidência suficiente da importância da PK-C no processo de maturação de oócitos.…”

Evaluation of laser-assisted lentiviral transgenesis in bovine

“…Several studies confirm that removal of cumulus cells strongly decreases developmental capacity (Cox et al, 1993;Zhang et al, 1995 …”