The fertilization process is the net result of a complex sequence of events that collectively result in the fusion of theopposite gametes. The male gamete undergoes continuous morphological and biochemical modificatio...The fertilization process is the net result of a complex sequence of events that collectively result in the fusion of theopposite gametes. The male gamete undergoes continuous morphological and biochemical modifications during spermdevelopment in the testis (spermatogenesis), maturation in the epididymis, and capacitation in the female reproductivetract. Only the capacitated spermatozoa are able to recognize and bind to the bioactive glycan residue(s) on the ovum'sextracellular coat, the zona pellucida (ZP). Sperm-zona binding in the mouse and several other species is believed totake place in two stages. First, capacitated (acrosome-intact) spermatozoa loosely and reversibly adhere to the zona-in-tact ovum. In the second stage tight irreversible binding occurs. Both types of bindings are attributed to the presence ofglycan- binding proteins (receptors) on the sperm plasma membrane and their complementary bioactive glycan units(ligands) on the surface of the ZP. The carbohydrate-mediated adhesion event initiates a signal transduction cascade re-sulting in the exocytosis of acrosomal contents. This step is believed to be prerequisite which allows the hyperactivatedacrosome-reacted spermatozoa to penetrate the ZP and fertilize the ovum. This review focuses on the role of carbohy-drate residues in sperm-ovum interaction, and triggering of the acrosome reaction. I have attempted to discuss extensiveprogress that has been made to enhance our understanding of the well programmed multiple molecular events necessaryfor successful fertilization. This review will identify these events, and discuss the functional significance of carbohy-drates in these events.展开更多
We developed tests of sperm-oocyte interaction: sperm-zona binding, zona-induced acrosome reaction, sperm-zona penetration and sperm-oolemma binding, using oocytes which failed to fertilise in clinical in vitro fertil...We developed tests of sperm-oocyte interaction: sperm-zona binding, zona-induced acrosome reaction, sperm-zona penetration and sperm-oolemma binding, using oocytes which failed to fertilise in clinical in vitro fertilization(IVF). Although oocyte defects contribute to failure of sperm oocyte interaction, rarely are all oocytes from one wom-an affected. Low or zero fertilization in standard IVFwas usually caused by sperm abnormalities. Poor sperm-zona pel-lucida binding was frequently associated with failure of standard IVF and obvious defects of sperm motility or morpholo-gy. The size and shape of the acrosome is particularly important for sperm binding to the oocyte. The proportion ofacrosome intact sperm in the insemination medium was related to the IVF rote. Inducing the acrosome reaction with acalcium ionophore reduced sperm-zona binding. Blocking acrosome dispersal with an acrosin inhibitor prevented sperm-zona penetration. Sperm-zona penetration was even more highly related to IVF rates than was sperm-zona binding.Some patients had low or zero fertilization rates with standard IVF but normal sperm by conventional tests and normalsperm-zona binding. Few of their sperm underwent the acrosome reaction on the surface of the zona and none penetrat-ed the zona. In contrast, fertilization and pregnancy rates were high with intmcytoplasmic sperm injection. We call thiscondition defective zona pellucida induced acrosome reaction. Discovery of the nature of the abnormalities in the signaltmnsduction and effector pathways of the human zona pellucida induced acrosome reaction should result in simpler testsand treatments for the patients and also provide new leads for contraceptive development.展开更多
Mammalian fertilization is a highly regulated process, much of which are not clearly understood. Here we presentsome information in order to elaborate a working hypothesis for this process, beginning with the sperm mo...Mammalian fertilization is a highly regulated process, much of which are not clearly understood. Here we presentsome information in order to elaborate a working hypothesis for this process, beginning with the sperm modifications inthe epidydimis up to sperm and egg plasmalemma interaction and fusion. We also discuss the still poorly understood ca-pacitation process, the phenomenon of sperm chemo-attraction that brings the capacitated sperm to interact with theoocyte vestments and certain aspects of the acrosome reaction. (Asian J Androl 2001 Dec; 3 : 243 - 249)展开更多
基金The work was supported in part by grants HD25869 and HD34041 from the National Institute of Child & Human Development
文摘The fertilization process is the net result of a complex sequence of events that collectively result in the fusion of theopposite gametes. The male gamete undergoes continuous morphological and biochemical modifications during spermdevelopment in the testis (spermatogenesis), maturation in the epididymis, and capacitation in the female reproductivetract. Only the capacitated spermatozoa are able to recognize and bind to the bioactive glycan residue(s) on the ovum'sextracellular coat, the zona pellucida (ZP). Sperm-zona binding in the mouse and several other species is believed totake place in two stages. First, capacitated (acrosome-intact) spermatozoa loosely and reversibly adhere to the zona-in-tact ovum. In the second stage tight irreversible binding occurs. Both types of bindings are attributed to the presence ofglycan- binding proteins (receptors) on the sperm plasma membrane and their complementary bioactive glycan units(ligands) on the surface of the ZP. The carbohydrate-mediated adhesion event initiates a signal transduction cascade re-sulting in the exocytosis of acrosomal contents. This step is believed to be prerequisite which allows the hyperactivatedacrosome-reacted spermatozoa to penetrate the ZP and fertilize the ovum. This review focuses on the role of carbohy-drate residues in sperm-ovum interaction, and triggering of the acrosome reaction. I have attempted to discuss extensiveprogress that has been made to enhance our understanding of the well programmed multiple molecular events necessaryfor successful fertilization. This review will identify these events, and discuss the functional significance of carbohy-drates in these events.
文摘We developed tests of sperm-oocyte interaction: sperm-zona binding, zona-induced acrosome reaction, sperm-zona penetration and sperm-oolemma binding, using oocytes which failed to fertilise in clinical in vitro fertilization(IVF). Although oocyte defects contribute to failure of sperm oocyte interaction, rarely are all oocytes from one wom-an affected. Low or zero fertilization in standard IVFwas usually caused by sperm abnormalities. Poor sperm-zona pel-lucida binding was frequently associated with failure of standard IVF and obvious defects of sperm motility or morpholo-gy. The size and shape of the acrosome is particularly important for sperm binding to the oocyte. The proportion ofacrosome intact sperm in the insemination medium was related to the IVF rote. Inducing the acrosome reaction with acalcium ionophore reduced sperm-zona binding. Blocking acrosome dispersal with an acrosin inhibitor prevented sperm-zona penetration. Sperm-zona penetration was even more highly related to IVF rates than was sperm-zona binding.Some patients had low or zero fertilization rates with standard IVF but normal sperm by conventional tests and normalsperm-zona binding. Few of their sperm underwent the acrosome reaction on the surface of the zona and none penetrat-ed the zona. In contrast, fertilization and pregnancy rates were high with intmcytoplasmic sperm injection. We call thiscondition defective zona pellucida induced acrosome reaction. Discovery of the nature of the abnormalities in the signaltmnsduction and effector pathways of the human zona pellucida induced acrosome reaction should result in simpler testsand treatments for the patients and also provide new leads for contraceptive development.
文摘Mammalian fertilization is a highly regulated process, much of which are not clearly understood. Here we presentsome information in order to elaborate a working hypothesis for this process, beginning with the sperm modifications inthe epidydimis up to sperm and egg plasmalemma interaction and fusion. We also discuss the still poorly understood ca-pacitation process, the phenomenon of sperm chemo-attraction that brings the capacitated sperm to interact with theoocyte vestments and certain aspects of the acrosome reaction. (Asian J Androl 2001 Dec; 3 : 243 - 249)