Fertilization- Lecture 9 Flashcards
Capacitation of spermatozoa
Occurs in female reproductive tract. Loss of membrane proteins and glycoproteins (membrane receptors exposed). Causes changes in the tail- hyperactivation. No change in sperm morphology. Loss of membrane cholesterol. Changes in intracellular Ca.
Immediate transport
Retrograde loss, phagocytosis, entrance into, entrance into cervix/uterus
ARPR
Acrosome reaction promotong region
Pronuclei
Male and female gamete DNA close together.
MPF
Maturation promoting factor.
OAM
Outer acrosomal membrane
Oocyte cumulus complex
Cumulus layer. ZP1 ZP2 ZP3 Perivitelline space with first polar body. Viteline membrane
Capacitation part 2
Transfer of cholesterol to albumin. PKA activation. Tyrosine phosphorylation of proteins (necessary for hyperactive sperm motility). Polymerization of globular actin to filamentous actin (necessary for sperm penetration into the oocyte).
Block to polyspermy
Zona block- hardening of ZP (modifiction of ZP3 and 2). Membrane block/vitelline block- changes in vitelline membrane polarization.
IAM
Inner acrosomal membrane
Epididymal vs ejaculated sperm
Epididymal- surface proteins and carbohydrates. Ejaculated- seminal plasma proteins.
Oviduct transport
Capacitation completed, hyperactive motility.
Cervix transport
“Privileged” pathways, removal of non-motile sperm, removal of some abnormalities.
Syngamy
Male and female gamete DNA fused.
Sequence of events of sperm/oocyte interaction
Oocyte- Maturation to 2nd meiotic division, ovulation. Sperm- capacitation, acrosome reaction. Penetration of cumulus and zona pellucida. Ionic changes, cortical granules release. Meiotic resumption, 2nd polar body extruded. Pronuclear formation. DNA synthesis. Metabolic exchange. Syngamy- merging haploid sets of chromosomes on mitotic spindle. Cleavage.
