Oocyte activation, phospholipase C zeta and human infertility

Abstract

Although ICSI results in average fertilization rates of 70%, complete or virtually complete fertilization failure still occurs in 1-5% of ICSI cycles. While oocyte activation failure can, in some cases, be overcome by artificial oocyte activators such as calcium ionophores, a more physiological oocyte activation agent might release Ca(2+) within the oocyte in a more efficient and controlled manner. As PLCζ is now widely considered to be the physiological agent responsible for activating mammalian oocytes, it represents both a novel diagnostic biomarker of oocyte activation capability and a possible mode of treatment for certain types of male infertility.

Trends, Fads and ART!

“…This variability is compounded by its partner gamete, the spermatozoon which, as we have mentioned, has the non-genomic roles of activating the oocyte and delivering the centrosome. Oocyte activation appears to be triggered by a soluble sperm-borne factor [13], which may be a phospholipase [14] and since gametes are heterogeneous populations of cells it is not surprising that the activating capability will vary from one spermatozoon to another [15,16]. In fact, it is well known that time of entry of fertilized oocytes into S-phase in the bovine is dependent on the fertilizing capacity of the bull used [17,18].…”

Magnifying human fertility: microscopy and assisted reproductive technology

“…The localisation patterns of PLCζ are thought to be highly dynamic within both mouse and human sperm (Grasa et al, 2008;Young et al, 2009), depending upon the stage of sperm maturity. Morever, reduced levels or absence of PLCζ has been implicated as a causative factor for infertility in sperm from men who routinely fail ICSI (Yoon et al, 2008;Heytens et al, 2009;Kashir et al, 2010). Indeed, PLCζ is thought to represent a future prognostic and diagnostic marker of a sperm's oocyte activation capability ( Fig.…”

“…Indeed, PLCζ is thought to represent a future prognostic and diagnostic marker of a sperm's oocyte activation capability ( Fig. 8; Kashir et al, 2010;2011a;2011b). and are thus theoretically incapable of activating an egg (Kashir et al, 2011a;2011b).…”

Assessment of the relationship between follicular fluid calcium ion concentration and reproductive outcomes

“…The initiation of calcium oscillations is considered to be triggered by the sperm factor phospholipase C zeta (PLCz), which is released into the oocyte following oocyte fertilization. 8,9 PLCz triggers a cascade of reactions which finally activates the receptors located on the membrane of the endoplasmic reticulum leading to the cytoplasmic release of calcium. 10,11 It is presumable that the absence or aberrant of calcium oscillations at the time of fertilization could lead to failed or low fertilization following ICSI.…”