Effects of cumulus cells and follicle‐stimulating hormone during in vitro maturation on parthenogenetic activation of bovine oocytes

Abstract

The response to parthenogenetic activation (calcium ionophore A23187) of bovine oocytes after 30 hr of culture in different maturation conditions was evaluated. The activation rates of oocytes in response to 10 mu M A23187 were similar (86% +/- 4 vs. 89% +/- 8) when the oocytes matured with or without cumulus cells were cultured in TCM-199 + 10% fetal calf serum (maturation medium [MM]) alone. However, the activation rates were significantly lower in oocytes matured with than without cumulus cells (48 +/- 10 vs. 79% +/- 16; P < 0.05) when MM was supplemented with 0.5 microgram/ml follicle-stimulating hormone (FSH), 50 micrograms/ml luteinizing hormone (LH), and 1.0 microgram/ml estradiol-1 beta (E2). When oocytes with cumulus cells were cultured in different media, MM along, MM + 0.5 microgram/ml FSH, MM + 50 micrograms/ml LH, MM + 1.0 microgram/ml E2, and MM + all three hormones, the percentages of activated oocytes were 91% +/- 3.52% +/- 14.83% +/- 7, 83% +/- 13, and 54% +/- 7, respectively. Oocytes with or without cumulus cells during culture began to form a pronucleus 5 hr after activation (5% +/- 1 and 7% +/- 1, respectively). Finally, the proteins synthesized by oocytes matured with or without cumulus cells before (3 hr) and after (10 hr) activation was labelled with [35S]methionine for analysis. Before activation, a 47 kD protein complex was produced by cumulus cell-intact oocytes. An active protein synthesis of 60 kD was characteristic for the oocytes with cumulus cells cultured in MM containing 0.5 micrograms/ml FSH. After activation, there was an appearance of proteins at 75 kD and 47 kD in the oocytes with cumulus cells but not in the oocytes without cumulus cells during the maturation period. These results indicate that bovine oocytes matured in vitro have different capacities for parthenogenetic activation depending on the presence or absence of cumulus cells and the presence of FSH in MM during culture.

UV irradiation of pig metaphase chromosomes: maturation-promoting factor degradation, nuclear cytology and cell cycle progression

“…Furthermore, pig eggs are entirely dependent upon stored maternal mRNA for support during this period (Jarrell et ah, 1991). In the present study, cleavage of parthenotes did not proceed beyond the four-cell stage in both groups, probably due to both the activation procedure and the culture conditions, which can affect parthenogenetic activation rates (Hagen et ah, 1991;Funahashi et ah, 1994;Chian and Sirard, 1995). Until normal young are produced, the possibility that irradiation and the presence of damaged DNA has some adverse effects on cleavage at later stages of development cannot be ruled out.…”

Apoptosis in bovine cumulus–oocyte complexes after exposure to polychlorinated biphenyl mixtures during in vitro maturation

“…Further, we have shown that PCB toxicity in bovine oocytes is related to a reduced competence of the oocytes to undergo normal cytoplasmic maturation, as indicated by an abnormal migration of cortical granules during maturation and subsequent fertilization and by changes in the polyadenylation pattern of several maternal mRNAs (Pocar et al 2001a). Because cumulus cells play an important role in the nuclear and cytoplasmic changes associated with oocyte maturation (Larsen & Wert 1988, Mattioli et al 1988, Fukui 1990, Chian & Sirard 1995, Tanghe et al 2003, in the present study we decided to investigate whether cumulus cells can modulate the adverse reproductive effects of environmental toxicants.…”

Recombinant Human Bone Morphogenetic Protein 6 Enhances Oocyte Reprogramming Potential and Subsequent Development of the Cloned Yak Embryos

“…The CCs provide the nutrients and the regulatory signals upon which the oocytes are dependent, and these elements play very crucial roles in the maturation of oocytes cytoplasm and nucleus; in this way, developmental competence is acquired. (Chian and Sirard, 1995;Gilchrist et al, 2008). It has been shown that when CCs are removed at early stage of IVM from oocytes or before the IVF, the rates of maturation, cleavage, and blastocyst formation are reduced.…”