What are the four phases of oocyte maturation?
Table of Contents
Once meiosis gets started, the oocytes undergo the leptotene, zygotene, and pachytene stages, and then arrest at the dictyate stage. During each estrus cycle in mammals, or menstrual cycle in humans, a small portion of oocytes within preovulatory follicles may resume meiosis.
What is the process of oocyte maturation?
Abstract. Normal female fertility relies on proper development of the oocyte. This growth culminates just prior to ovulation, when oocyte maturation occurs. Oocyte maturation refers to a release of meiotic arrest that allows oocytes to advance from prophase I to metaphase II of meiosis.
What role does the Cumulus play in fertilization?
During fertilization, the cumulus cells attract (Eisenbach, 1999), trap (Bedford & Kim, 1993), and select spermatozoa (Carrell et al., 1993), and prevent the premature hardening of the zona pellucida (ZP) (Tanghe et al., 2002), all of which are necessary for successful fertilization.
What are cumulus oocyte complexes?
The cumulus-oocyte complex is ovulated during the ovulatory phase of the menstrual cycle and is just what it seems: an oocyte surrounded by specialized granulosa cells, called cumulus cells. The cumulus cells surrounding the oocyte ensure healthy oocyte and embryo development. Also Known As: COC.
What causes oocyte maturation?
Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) stimulate expansion of cumulus granulosa cells, loss of gap junctions, and oocyte maturation (depicted by loss of gray nucleus).
What stimulates oocyte maturation?
Gonadotropin hormones, follicle-stimulating hormone (FSH) and luteinizing hormone are well recognized as the physiologic stimulants of oocyte maturation during the final stages of preovulatory development in mammals.
Where does oocyte maturation occur?
Oocyte Meiotic Maturation Oocyte maturation stands uniquely at the center and culmination of female reproductive biology. This process is driven by both the oocyte intrinsic developmental programs and the gonadotropins secreted by pituitary.
What do cumulus cells secrete?
Cumulus cells surrounding pre-ovulatory human oocytes were found to secrete a variety of proteins which became firmly associated with the cumulus intercellular material. Antibodies raised against human cumuli oophori completely blocked fertilization in vitro by impairing the sperm-zona pellucida interaction.
Are cumulus cells differentiated?
Origin of Cumulus Cells The cumulus are clearly a distinct cell type since they have different functions, hormone responsiveness and fate to the granulosa cells. In fact granulosa cells can be divided into three sub-lineages based on distinctions in hormone responsiveness and gene expression: 1.
Where are cumulus cells found?
ovarian follicle
The cumulus oophorus, (discus proligerus), is a cluster of cells that surround the oocyte both in the ovarian follicle and after ovulation. In the antral follicle, it may be regarded as an extension of the membrana granulosa.
Is corona radiata granulosa cells?
Corona radiata. The first layer of follicular (granulosa) cells outside the zona pellucida.
What is maturation ovulation and fertilization?
Ovulation is the appropriately timed release of a mature, developmentally competent oocyte from the ovary into the oviduct, where fertilization occurs. Importantly, ovulation is tightly linked with oocyte maturation, demonstrating the interdependency of these two parallel processes, both essential for female fertility.
What is the difference between do + cumulus cells and oocytes?
Cumulus cells were removed by gentle pipetting. Oocytes were divided into four groups for maturation: in vivoOCC, in vitroOCC, in vitrodenuded oocyte (DO) + cumulus cells, and in vitroDO. For OCCs matured in vivoor in vitro, oocytes were divided into three groups for insemination: OCC, DO + cumulus, and DO.
What is the role of cumulus cells in mouse oocyte maturation?
Coculture with cumulus cells improves maturation of mouse oocytes denuded of the cumulus oophorus: observations of nuclear and cytoplasmic events. Fertility and Sterility. 2008;90:2376–2388. doi: 10.1016/j.fertnstert.2007.10.054. [PubMed] [CrossRef] [Google Scholar]
How are cumulus cells collected for oocyte co-culture?
For cumulus cell and oocyte co-culture, cumulus cells were collected from GV-stage OCCs by pipetting. The cumulus cells collected from each OCC were supplemented back to the corresponding oocyte.
What is the function of cumulus cells?
Abstract Cumulus cells are a group of closely associated granulosa cells that surround and nourish oocytes. Previous studies have shown that cumulus cells contribute to oocyte maturation and fertilization through gap junction communication.