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The Journey of the Porcine Spermatozoa from Its Origin to the Fertilization Site: The Road In Vivo vs. In Vitro
Published in Juan Carlos Gardón, Katy Satué, Biotechnologies Applied to Animal Reproduction, 2020
Cristina Soriano-Úbeda, Francisco Alberto García-Vázquez, Carmen Matás
After spermatozoa penetration of the egg vestments, the acrosome-reacted sperm goes through the perivitelline space and adheres its equatorial region and fuses with the egg plasma membrane, the oolemma (sperm-egg fusion). The cortical reaction then takes place, which results in changes to the structure of the ZP and its proteins (Wolf, 1981). This converts the ZP into a ‘hardened’ state, which helps to block polyspermy. This particular phenomenon is of special interest in porcine because this species has a high incidence of polyspermy under in vitro conditions (Funahashi et al., 2000). The spermatozoon next penetrates the oocyte and introduces its nucleus into the ooplasm (Yanagimachi, 1994b). Despite the continuous advance in the knowledge of the physiology of gametes as well as their interaction, there are still many aspects to be clarified to efficiently extrapolate the in vivo environment in the oviduct to the in vitro conditions in the laboratory. Many strategies and protocols have been carried out so far; however, the efficiency obtaining quality embryos in vitro remains lower than that of them in vivo counterparts.
Regulation of Reproduction by Dopamine
Published in Nira Ben-Jonathan, Dopamine, 2020
After digesting a hole in the ZP, the sperm head enters the egg’s parenchyma and the membranes of the two cells fuse. The next critical step is prevention of polyspermy, given that polyploidy is not compatible with life. Within seconds of contact with a sperm, Na+ channels in the egg’s membrane are activated, and a rushed entry of sodium depolarizes the egg’s resting potential of –70 mV. The fast, although transient, electrical block to polyspermy is followed within 10–15 min by the cortical reaction. The lysosome-like cortical granules are released from the egg’s membrane, destroying the oocyte’s sperm receptors, and modifying the extracellular matrix around the egg, which becomes impenetrable to additional sperm entry. Although there are several publications on DAR expression and putative functions of DA in Drosophila, Xenopus, and Zebrafish oocytes, there are no comparable records on mammalian oocytes.
The Male Factor in Recurrent Pregnancy Loss
Published in Howard J.A. Carp, Recurrent Pregnancy Loss, 2020
Catherine F. Ingram, Nannan Thirumavalavan, Marc Goldstein, Dolores J. Lamb
Fertilization begins when the male gamete contacts the zona pellucida of the mature oocyte. Thereafter, the acrosomal reaction occurs in which hydrolytic proteases released from the sperm head break down the zona for the male gamete to approach the oocyte plasma membrane, or oolemma. Fusion of sperm with the egg first triggers rapid depolarization of the oolemma to prevent polyspermy. Soon after, increased intracellular calcium activates the cortical reaction, during which the oocyte releases granules to react with the zona and make it impenetrable.
A tree of life? Multivariate logistic outcome-prediction in disorders of consciousness
Published in Brain Injury, 2020
Inga Steppacher, Peter Fuchs, Michael Kaps, Fridtjof W. Nussbeck, Johanna Kissler
Various cerebral measures of information processing have also been found to correlate with outcome (see, for example (8,9)). These include several, mostly auditory, electroencephalographic event-related potentials (ERPs). For example, the absence of the N100, an index of cortical sensory stimulus registration, is considered to be predictive of a negative outcome (10). The presence of the so-called mismatch negativity (MMN), indicating an automatic detection of deviant stimuli in continuous auditory stimulation streams, on the other hand, has been shown to be a positive sign (11,12). The presence of a P300, reflecting higher-order stimulus discrimination, also often correlates with a positive outcome (12,13). Another recently discussed and possibly very promising ERP is the N400, the cortical reaction to semantic violations in spoken speech. Although rarely found in patients, its presence correlates highly with a positive outcome (14).
A retrospective analysis of artificial oocyte activation in patients with low or no fertilisation in intracytoplasmic sperm injection cycles
Published in Journal of Obstetrics and Gynaecology, 2022
Kevin K. W. Lam, Jacki Y. Y. Wong, Tak-Ming Cheung, Raymond H. W. Li, Ernest H. Y. Ng, William S. B. Yeung
Successful oocyte activation is triggered by a sperm borne soluble factor, the phospholipase C (PLC) zeta (Kashir et al. 2010). It is generally agreed that PLC-zeta hydrolises inositol 4, 5-bisphosphate (PIP2), producing inositol triphosphate (IP3) which induces calcium ion (Ca2+) oscillation through interaction with receptors on the endoplasmic reticulum of oocytes (Swain and Pool 2008). Upon oocyte activation, a series of biological events, such as cortical reaction, resumption of meiosis and formation of pronuclei, leading to successful fertilisation (Ducibella et al. 2006).