the fusion of sperm and egg occurs at ampulla of the fallopian tube.
the fusion of sperm and egg occurs at ampulla of the fallopian tube.
where does the fusion of sperm and egg occur?
ampulla of the fallopian tube
when sperm cells are deposited into the anterior vagina, they are not capable of fertilization (i.e., non-capacitated) and are characterized by slow linear motility patters. this motility pattern, combined with muscular contractions enables sperm transport towards the uterus and fallopian tubes. there is a ph gradient within the microenvironment of the female reproductive tract such that the ph near the vaginal opening is lower (approximately 5.0) than the fallopian tubes (approximately 8.0). the sperm-specific ph-sensitive calcium transport protein called catsper increases the sperm cell permeability to calcium as it moves further into the reproductive tract. intracellular calcium influx contributes to sperm capacitation and hyperactivation, causing a more violent and rapid non-linear motility pattern as the sperm approach the oocyte. the capacitated spermatozoon and the oocyte meet and interact in the "ampulla" of the fallopian tube. rheotaxis, thermotaixs and chemotaxis are known mechanisms in guiding sperm towards the egg during the final stage of sperm migration. spermatozoa respond (see sperm thermotaxis) to the temperature gradient of ~2 °c between the oviduct and the ampulla, and chemotactic gradients of progesterone have been confirmed as the signal emanating from the cumulus oophorus cells surrounding rabbit and human oocytes. capacitated and hyperactivated sperm respond to these gradients by changing their behaviour and moving towards the cumulus-oocyte complex. other chemotactic signals such as formyl met-leu-phe (fmlf) may also guide spermatozoa.
fertilisation
fertilization consists of a sequence of specific cell-cell interactions culminating in the fusion of the sperm and egg plasma membranes. recognition, binding, and fusion occur through the interaction of complementary molecules that are localized to specific domains of the sperm and egg plasma membranes. in the sperm, the postacrosomal region or equatorial segment is involved in sperm-egg plasma membrane fusion. the protein encoded by this gene is a member of the cysteine-rich secretory protein (crisp) family. this protein is expressed in the epididymis, is secreted into the epididymal lumen, and binds to the postacrosomal region of the sperm head where it plays a role at fertilization in sperm-egg fusion through complementary sites localized on the egg surface. two isoforms are encoded by transcript variants of this gene.
crisp1