Editing In vitro fertilisation (section)

===Co-incubation===
[[File:Ivf.png|thumb|317x317px|Demonstration of ICSI]]
The sperm and the egg are incubated together at a ratio of about 75,000:1 in a [[culture media]] in order for the actual [[Human fertilization|fertilisation]] to take place. A review in 2013 came to the result that a duration of this co-incubation of about 1 to 4 hours results in significantly higher [[pregnancy rate]]s than 16 to 24 hours.<ref>{{cite journal | vauthors = Zhang XD, Liu JX, Liu WW, Gao Y, Han W, Xiong S, Wu LH, Huang GN | display-authors = 6 | title = Time of insemination culture and outcomes of in vitro fertilization: a systematic review and meta-analysis | journal = Human Reproduction Update | volume = 19 | issue = 6 | pages = 685–695 | year = 2013 | pmid = 23912477 | doi = 10.1093/humupd/dmt036 | doi-access = free }}</ref> In most cases, the egg will be fertilised during co-incubation and will show two [[pronuclei]]. In certain situations, such as low sperm count or motility, a single sperm may be injected directly into the egg using [[intracytoplasmic sperm injection]] (ICSI). The fertilised egg is passed to a special growth medium and left for about 48 hours until the embryo consists of six to eight cells.

In [[gamete intrafallopian transfer]], eggs are removed from the woman and placed in one of the fallopian tubes, along with the man's sperm. This allows fertilisation to take place inside the woman's body. Therefore, this variation is actually an in vivo fertilisation, not in vitro.<ref>{{cite journal | vauthors = Abyholm T, Tanbo T, Dale PO, Magnus O | title = In vivo fertilization procedures in infertile women with patent fallopian tubes: a comparison of gamete intrafallopian transfer, combined intrauterine and intraperitoneal insemination, and controlled ovarian hyperstimulation alone | journal = Journal of Assisted Reproduction and Genetics | volume = 9 | issue = 1 | pages = 19–23 | date = February 1992 | pmid = 1617244 | doi = 10.1007/BF01204109 | s2cid = 25057205 }}</ref><ref>{{cite journal | vauthors = Wetscher F, Havlicek V, Huber T, Gilles M, Tesfaye D, Griese J, Wimmers K, Schellander K, Müller M, Brem G, Besenfelder U | display-authors = 6 | title = Intrafallopian transfer of gametes and early stage embryos for in vivo culture in cattle | journal = Theriogenology | volume = 64 | issue = 1 | pages = 30–40 | date = July 2005 | pmid = 15935840 | doi = 10.1016/j.theriogenology.2004.11.018 }}</ref>