In the ovariole of Cynips, cell groups that have arisen in the initial period of oogenesis, presumably from one gonial cell, differentiate into the oocyte and 12 nurse cells (which constitute the nutritive chamber). The oocyte remains connected with the nurse cells by a strand of cytoplasm; the whole group acts as a physiological unit till the completion of vitellogenesis. Ribonucleoproteins ar...

In sexually reproducing animals, the ability to coordinate oocyte maturation and sperm availability has profound effects on reproductive success. InCaenorhabditis elegans, cell–cell signaling is crucial for promoting germline development, oocyte maturation, and ovulation. In this issue of Genes & Development, Miller et al. (2003) provide new insights into the role that sperm play in oocyte matu...

this study investigated the effect of different harvesting techniques on the recovery rate and quality of bovine cumulus oocyte complexes (cocs) and their subsequent developmental competence including in vitro maturation, fertilization and blastocyst formation. the cocs were retrieved from slaughter ovaries using aspiration, slicing, or aspiration followed by slicing. the cocs were examined mic...

The molecular underpinnings of the oocyte-to-embryo transition are poorly understood. Here we show that two protein tyrosine phosphatase-like (PTPL) family proteins, EGG-4 and EGG-5, are required for key events of the oocyte-to-embryo transition in Caenorhabditis elegans. The predicted EGG-4 and EGG-5 amino acid sequences are 99% identical and their functions are redundant. In embryos lacking E...

MicroRNAs (miRNAs) have been improved to regulate oocyte development in a cell- or stage-specific manner. In this study, we aimed to clarify microRNA-224's (miR-224) role in cumulus cells (CCs), to find out whether a change level of miR-224 in CCs could influence the maturation of oocyte. We found that overexpression of miR-224 of CCs led to the impairment of cell expansion, along with a decrea...

Vertebrate female reproduction is limited by the oocyte stockpiles acquired during embryonic development. These are gradually depleted over the organism's lifetime through the process of apoptosis. The timer that triggers this cell death is yet to be identified. We used the Xenopus egg/oocyte system to examine the hypothesis that nutrient stores can regulate oocyte viability. We show that pento...

Genetic experiments suggest that polarization of the oocyte is linked directly to the initial cell fate determination that singles out the oocyte from its 15 sister cells. Specification of oocyte cell fate as well as establishment and maintenance of a polarized microtubule network within the Drosophila oocyte require the activity of the egalitarian (egl) and BicaudalD (BicD) genes. We have isol...

Germ cell fate decisions are poorly understood, despite their central role in reproduction. One fundamental question has been whether germ cells are regulated to enter the meiotic cell cycle (i.e., mitosis-meiosis decision) and to be sperm or oocyte (i.e., sperm-oocyte decision) through one or two cell fate choices. If a single decision is used, a male-specific or female-specific meiotic entry ...

Oocyte-specific genes play important roles in regulating ovarian development, principally through the proper and timely progression of oogenesis and folliculogenesis. Development of transgenic mouse models has been critical in revealing how oocyte-specific transcripts influence oocyte development and growth, integrity of the oocyte-granulosa cell complex, oocyte maturation, fertilization, and e...

MicroRNA-protein complexes (microRNPs) can activate translation of target reporters and specific mRNAs in quiescent (i.e., G0) mammalian cell lines. Induced quiescent cells, like folliculated immature oocytes, have high levels of cAMP that activate protein kinase AII (PKAII) to maintain G0 and immature states. We report microRNA-mediated up-regulated expression of reporters in immature Xenopus ...