Female sperm: Difference between revisions

== FemaleArtificial female sperm production ==

Creating female sperm was first raised as a possibility in a patent filed in 1991<ref>{{cite web|url=http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5858354.PN.&OS=PN/5858354&RS=PN/5858354|publisher=U.S. Patent Office|title=Repopulation of testicular Seminiferous tubules with foreign cells, corresponding resultant germ cells, and corresponding resultant animals and progeny|access-date=2013-11-09}}</ref> by injecting
a womanfemale's cells into a manmale's testicles, though the patent focused mostly on injecting altered male cells into a manmale's testes (to correct genetic diseases). In 1997, [[Japanese people|Japanese]] scientists partially confirmed such techniques by creating chicken female sperm in a similar manner. "However, the ratio of produced [[ZW sex-determination system|W chromosome]]-bearing (W-bearing) [[spermatozoa]] fell substantially below expectations. It is therefore concluded that most of the W-bearing [[Germ cell#Migration|PGC]] could not differentiate into spermatozoa because of restricted [[spermatogenesis]]."<ref name="chicken sperm">{{cite journal|last1=Tagami|first1=Takahiro|last2=Matsubara|first2=Yuko|last3=Hanada|first3=Hirofumi|last4=Naito|first4=Mitsuru|date=June 1997|title=Differentiation of female chicken primordial germ cells into spermatozoa in male gonads|journal=Development, Growth and Differentiation|volume=39|issue=3|pages=267–71|doi=10.1046/j.1440-169X.1997.t01-2-00002.x|pmid=9227893|doi-access=free}}</ref> These simple transplantation methods follow from earlier observations by developmental biologists that germ [[stem cell]]s are autonomous in the sense that they can begin the processes to become both sperm and eggs.

One potential roadblock to injecting a womanfemale's cells into a manmale's testicles is that the manmale's immune system might attack and destroy the womanfemale's cells. In usual circumstances, when foreign cells (such as cells or organs from other people, or infectious bacteria) are put into a human body, itsthe immune system will reject such cells or organs. However, a special property of a man's testicles is that they are [[Immune privilege|immune-privileged]], that is, a manmale's immune system will not attack foreign cells (such as a womanfemale's cells) injected into the sperm-producing part of the testicles. Thus, a womanfemale's cells will remain in the manmale's testicles long enough to be converted into sperm.

However, there are more serious challenges. Biologists have well established that male sperm production relies on certain genes on the [[Y chromosome]], which, when missing or defective, lead to such menmales producing little to no sperm in their testicles. An analogy, then, is that aXX cellcells from a woman hashave complete Y chromosome deficiency. While many genes on the Y chromosome have backups (homologues) on other chromosomes, a few genes such as RBMY on the Y chromosome do not have such backups, and their effects must be compensated for to convert cellsa fromfemale's acells womanfrom into sperm. In 2007, a patent application was filed<ref>{{cite web|url=http://www.samesexprocreation.com/document/femsperm.pdf|title=Methods for Female Mammalian Spermatogenesis and Male Mammalian Oogenesis Using Synthetic Nanobiology|publisher=Gregory Aharonian|access-date=2013-11-09}}</ref> on methods for creating human female sperm using artificial or natural Y chromosomes and testicular transplantation.<ref>{{cite web|urlname=http"://www.samesexprocreation.com/archive/sprmpict.pdf|title=Color0" illustration of female sperm making procress|publisher=Human Samesex Reproduction Project|access-date=2013-11-09}}{{dead link|date=November 2013}}</ref> Key to successful creation of female sperm (and [[male egg]]s) will be inducing male [[epigenetic]] markings for female cells that initially have female markings, with techniques for doing so disclosed in the patent application.<ref>{{cite web|url=http://www.samesexprocreation.com/epigenet.htm|title=EPIGENETICS: the key to healthy female sperm|publisher=Human Samesex Reproduction Project|access-date=2013-11-09}}</ref>

In 2018, Chinese research scientists produced 29 viable mice offspring from two female mother mice by creating sperm-like structures from haploid [[embryonic stem cell]]s using [[Genome editing|gene editing]] to alter imprinted regions of DNA. Experts noted that there was little chance of these techniques being applied to humans in the near future.<ref>{{Cite news|url=https://www.thetimes.co.uk/article/no-father-necessary-as-mice-are-created-with-two-mothers-2vskf8w58|title=No father necessary as mice are created with two mothers|last=Blakely|first=Rhys|date=2018-10-12|work=The Times|access-date=2018-10-12|language=en|issn=0140-0460|url-access=subscription }}</ref><ref>{{Cite journal|last=Li|first=Zhi-Kun|last2=Wang|first2=Le-Yun|last3=Wang|first3=Li-Bin|last4=Feng|first4=Gui-Hai|last5=Yuan|first5=Xue-Wei|last6=Liu|first6=Chao|last7=Xu|first7=Kai|last8=Li|first8=Yu-Huan|last9=Wan|first9=Hai-Feng|date=2018-10-01|title=Generation of Bimaternal and Bipaternal Mice from Hypomethylated Haploid ESCs with Imprinting Region Deletions|journal=Cell Stem Cell|volume=23|issue=5|pages=665–676.e4|doi=10.1016/j.stem.2018.09.004|pmid=30318303|issn=1934-5909|doi-access=free}}</ref>

[[Category:SexualitySex]]