Normal conception
David M. Luesley, Mark D. Kilby in Obstetrics & Gynaecology, 2016
The oocyte released at the time of ovulation is surrounded by granulosa cells known as the cumulus oophorus, which is separated from the actual oocyte by a layer of glycoprotein known as the zona pellucida. Within 2–3 minutes of ovulation, the oocyte (surrounded by the cumulus) is within the ampullary part of the Fallopian tube. The fertilisable life span of the human ovum is estimated to be 24–36 hours. Although several million sperm are deposited in the vagina, only about 200 will come in contact with the oocyte. For the sperm to bind with the zona pellucida, a receptor is required, which is species specific. The sperm has to undergo a process known as 'capacitation' in order to be able to bind with the receptor and penetrate the egg. The zona pellucida not only contains the receptors for the sperm, but also has a mechanism by which it prevents more than one sperm from entering the oocyte (polyspermy). This mechanism is known as the zona reaction.
Assisted conception
David J Cahill in Practical Patient Management in Reproductive Medicine, 2019
When an oocyte is released at ovulation, it is surrounded by a dense group of cells which are derived from the cumulus oophorus and which must be penetrated by sperm to achieve fertilisation – these cells and the oocyte itself secrete a dense protective layer made up of glycoproteins, known as the zona pellucida. Once the oocyte is fertilised, this layer surrounds the embryo and effectively contains it. The zona pellucida must be disrupted and the growing embryo (now a blastocyst) allowed to ‘hatch’ at 5–6 days of age to be free to grow further and then to implant, maybe 1 day later. Spontaneous hatching appears dependent on a number of genes whose expression is correlated with hatching. These genes produce cathepsin V, GATA-binding protein 3 and human chorionic gonadotropin beta subunit 3, 5, 7 and 8. Hatching does not appear to be dependent on zona pellucida or gamete quality (46). Artificial hatching of the oocyte was first described in 1991 by Cohen and his group (47). It relies on breaching of the zona pellucida by chemical (acidified Tyrode's solution), by laser or by mechanical methods (using a glass microneedle) (48). The ASRM paper comprehensively covers the risks and complications as well as the value of assisted hatching – in essence, to date, there is a small (though significant) increase in pregnancy rates (and multiple pregnancy rates) associated with the use of assisted hatching (49).
Ultrasonic Monitoring of Follicular Growth and Ovulation in Spontaneous and Stimulated Cycles
Asim Kurjak in Ultrasound and Infertility, 2020
Bomsel-Helmreich et al.23 obtained clear evidence that the ultrasonic appearance of the triangular intrafollicular echogenic structure, regularly seen adjacent to the inner wall of the follicle, represents the dissociated cumulus oophorus. According to their results, echo of the cumulus oophorus can be demonstrated in the preovulatory follicle only after its dissociation, and therefore can be used as a reliable sign that LH surge has already occurred. Although this finding indicates forthcoming ovulation, its use in the assessment of the ovarian function is limited by the relatively low visualization rate of 15 to 20% of cases.24 There are a few reports that claim a much higher visualization rate of the cumulus oophorus, but to obtain such results, exceptionally good equipment, meticulous examination of the entire follicular surface, and extensive experience are required (Figure 8).25
Application of ultrasound markers measured at different time points of COH cycle in the prediction of ovarian response for individualised ovulation induction
Published in Journal of Obstetrics and Gynaecology, 2022
Yue-Wei Li, Xiao-Wen Liang, Jing-Hui Fang, Zhi-Yi Chen
The growth of cumulus cells is closely related to the development of the oocyte, and cumulus cell apoptosis affects the maturation, fertilisation, and cleavage of the oocyte and may thus be used to predict IVF outcomes. With the advancement of high-resolution TV-CDS, ultrasound features can be regarded as markers in the evaluation of ovarian response. Moreover, TV-CDS is more likely to detect the cumulus on the day of hCG injection, thus indirectly indicating a good ovarian response, which is correlated with the number of retrieved oocytes, fertilised eggs, and excellent-grade embryos (Jadaon et al. 2012). In this study, we found that the number of cumulus oophorus observed on the day of hCG injection was positively correlated with the number of oocytes and fertilised oocytes. The number of cumulus oophorus gradually increased from the low response group to the normal response group and the high response group, and the number of oocytes retrieved, the number of fertilised oocytes, and the number of high-quality embryos also gradually increased. These results indirectly prove that the cumulus oophorus is a syncytium with complete structure and function, which is closely related to the growth, development, maturation, and fertilisation of oocytes (Tola et al. 2019). According to Bertolin's study, successful fertilisation is related to the quantity and quality of cumulus expansion. The cumulus oophorus creates a beneficial microenvironment for the growth and development of oocytes (Bertolin et al. 2017). The cumulus oophorus is essential for normal oocyte development, ovulation, and fertilisation.
Telomeres as a molecular marker of male infertility
Published in Human Fertility, 2019
Ewa Boniewska-Bernacka, Anna Pańczyszyn, Natalia Cybulska
Infertility resulting from male factors is a growing social problem that requires understanding many cellular and molecular mechanisms. Therefore, evaluation of the sperm’s ability to properly fertilize an egg should be the main objective of semen analysis. To accomplish this multistage process, spermatozoa must undergo capacitation and the acrosome reaction, so that mutual recognition and fusion of gametes are possible. This process involves: (i) penetration through the cumulus oophorus cell layer; (ii) penetration of the zona pellucida; (iii) fusion of the spermatozoon plasma membrane with oolemma, activation of the dormant egg cell; (iv) spermatozoon chromatin decondensation; (v) male pronucleus formation; and (vi) fusion with the female pronucleus in the final stage. The male infertility factor for a given couple may be related to a disorder at each of the above stages, and the underlying cause cannot be identified in 30–40% of men (Jungwirth et al., 2015; Reig-Viader et al., 2014).
Thymoquinone ameliorates obesity-induced metabolic dysfunction, improves reproductive efficiency exhibiting a dose-organ relationship
Published in Systems Biology in Reproductive Medicine, 2019
Seba Harphoush, Guoqing Wu, Gao Qiuli, Margaret Zaitoun, Maissam Ghanem, Yonghui Shi, Guowei Le
The left ovary in three non-reproductive females each group and a part of left mammary gland in six lactating females each group was fixed in Paraformaldehyde 4% in PBS for 24 h and embedded in paraffin. Hematoxylin and Eosin (HE) staining was performed on 5 mm serial to analyze the histopathological changes of ovarian follicle cells and mammary alveolar lumens. HE sections were observed with a CX31 RTSF microscope (Olympus Corporation, Tokyo, Japan). In lactating mammary glands, alveolar Lumens area was measured using Image-J NIH software (McGinley and Thompson 2011). In non-reproductive females’ ovaries, follicular stages were classified to early stage follicles (primary follicles; secondary follicles; antral follicles) and later stage follicles (Graafian follicles; corpus luteum) according to the Erickson’s classification (Williams and Erickson 2012). Graafian follicle: the oocyte is surrounded by cumulus oophorus cells, and is adjacent to a single large antrum (an ovum develops prior to ovulation). Corpus luteum: It is the remains of the ovarian follicle that has released a mature ovum during a previous ovulation. Only later stage follicles were observed and counted per one ovary to estimate ovulation.
Related Knowledge Centers
- Amino Acid Transporter
- Antral Follicle
- Corona Radiata
- Ovarian Follicle
- Ovulation
- Spermatozoon
- Sterol
- Oocyte
- Membrana Granulosa
- Fertilisation