the egg is located in the ampulla of the fallopian tube when it is fertilized by a sperm.
the egg is located in the ampulla of the fallopian tube when it is fertilized by a sperm.
where is the egg located when it is fertilized by a sperm?
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
in pronuclear transfer, an oocyte is removed from the recipient, and fertilized with sperm. the donor oocyte is fertilized with sperm from the same person. the male and female pronuclei are removed from each fertilized egg prior to their fusing, and the pronuclei from the recipient's fertilized egg are inserted into the fertilized egg from the donor. as with mst, a small amount of cytoplasm from the donor egg may be transferred, and as with mst, the fertilized egg is allowed to form a blastocyst, which can then be investigated with preimplantation genetic diagnosis to check for mitochondrial mutations, prior to being implanted in the recipient's uterus.
mitochondrial replacement therapy