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#capacitation

2 public questions tagged with this topic.

Capacitation results in sperm gaining ability to:

Capacitation confers functional competence allowing sperm that are morphologically mature but physiologically dormant after leaving epididymis to fertilize egg. Molecular remodeling includes increased membrane fluidity, sodium bicarbonate influx activating cAMP-PKA pathway, enhanced calcium influx via CatSper, and development of hyperactivated motility pattern and ability to undergo acrosome reaction upon zona encounter. Result is acquisition of sperm-egg recognition and fusion capacity. Without capacitation sperm cannot bind zona or trigger activation. Hence process represents physiological unlocking of fertilization potential within female environment, signaling cascade, membrane preparation essential for conception and embryonic development initiation.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 7: Molecular aspects of capacitation and acquisition of fertilization competence.

Capacitation involves removal of:

Freshly ejaculated sperm are coated with cholesterol, glycoproteins and seminal plasma decapacitation factors stabilizing membrane preventing premature acrosome reaction. During capacitation within female tract, albumin and high-density lipoproteins act as sinks extracting cholesterol from plasma membrane, increasing fluidity and permeability, displacing SPINK proteins. Cholesterol removal alters lipid rafts, triggers adenylate cyclase activation, calcium permeability increase and tyrosine phosphorylation cascades. Membrane becomes fusogenic, receptors unmasked for zona binding. Cholesterol efflux therefore represents initiating step unlocking fertilizing potential, capacitation-associated signaling competence, acrosome responsiveness and fertilization readiness for conception.

Ref: Visconti et al., Development 1995: Cholesterol efflux and cAMP/PKA in sperm capacitation and membrane remodeling.