Editing Intracytoplasmic sperm injection (section)

==Round spermatid injection (ROSI)==

Round spermatid injection (ROSI) is a technique of assisted reproduction whereby a round spermatid is injected into oocyte cytoplasm in order to achieve fertilization. This technique can be used to enable genetic fatherhood to some men who have no spermatozoa in the ejaculate (azoospermia) and in whom spermatozoa cannot be obtained surgically from the testicles. This condition is called non-obstructive or secretory azoospermia, as opposed to obstructive azoospermia, in which complete sperm production does occur in the testicles, and potentially fertilizing spermatozoa can be obtained by [[testicular sperm extraction]] (TESE) and used for ICSI. In cases of nonobstructive (secretory) azoospermia, on the other hand, testicular sperm production is blocked at different stages of the process of sperm formation (spermatogenesis). In those men in whom spermatogenesis is blocked at the stage of round spermatids, in which meiosis has already been completed, these round cells can successfully fertilize oocytes after being injected into their cytoplasm.<ref name="Tesarik_1996b">{{cite journal | vauthors = Tesarik J, Rolet F, Brami C, Sedbon E, Thorel J, Tibi C, Thébault A | title = Spermatid injection into human oocytes. II. Clinical application in the treatment of infertility due to non-obstructive azoospermia | journal = Human Reproduction | location = Oxford, England | volume = 11 | issue = 4 | pages = 780–783 | date = April 1996 | pmid = 8671328 | doi = 10.1093/oxfordjournals.humrep.a019254 | doi-access = free }}</ref>

Even though many technical aspects of ROSI are similar to those of ICSI, there are also significant differences between both techniques.<ref name="Tesarik_1996a">{{cite journal | vauthors = Tesarik J, Mendoza C | title = Spermatid injection into human oocytes. I. Laboratory techniques and special features of zygote development | journal = Human Reproduction | volume = 11 | issue = 4 | pages = 772–779 | date = April 1996 | pmid = 8671327 | doi = 10.1093/oxfordjournals.humrep.a019253 | s2cid = 10309237 | doi-access = free }}</ref> In the first place, as compared to spermatozoa, round spermatids do not possess easily perceptible morphological characteristics and are immotile. Consequently, the distinction between round spermatids and other round cells of similar size, such as leukocytes, is not an easy task. Moreover, the distinction between living round spermatids, to be used in ROSI, and dead round spermatids, to be discarded, needs specific methods and skills, not required in the case of ICSI where sperm cell viability can be easily evaluated on the basis of sperm motility in most cases.<ref name="Tesarik_1996a"/> The microinjection procedure for ROSI also differs slightly from that of ICSI, since additional stimuli are needed to ensure proper oocyte activation after spermatid injection. If all requirements for round spermatid selection and injection are successfully met, the injected oocytes develop to early embryos and can be transferred to the mother's uterus to produce pregnancy.<ref name="Tesarik_1996a"/><ref name="Tesarik_1996b"/>

The first successful pregnancies and births with the use of ROSI were achieved in 1995 by Jan Tesarik and his team.<ref name="Tesarik_1995">{{cite journal | vauthors = Tesarik J, Mendoza C, Testart J | title = Viable embryos from injection of round spermatids into oocytes | journal = The New England Journal of Medicine | volume = 333 | issue = 8 | pages = 525 | date = August 1995 | pmid = 7623897 | doi = 10.1056/nejm199508243330819 | doi-access = free }}</ref> The clinical potential of ROSI in the treatment of male infertility due to the total absence of spermatozoa has been corroborated recently by a publication reporting on the postnatal development of 90 babies born in Japan and 17 in Spain.<ref name="fertstertdialog.com">{{cite journal | vauthors = Tanaka A, Suzuki K, Nagayoshi M, Tanaka A, Takemoto Y, Watanabe S, Takeda S, Irahara M, Kuji N, Yamagata Z, Yanagimachi R | display-authors = 6 | title = Ninety babies born after round spermatid injection into oocytes: survey of their development from fertilization to 2 years of age | journal = Fertility and Sterility | volume = 110 | issue = 3 | pages = 443–451 | date = August 2018 | pmid = 30098696 | doi = 10.1016/j.fertnstert.2018.04.033 | s2cid = 51968167 | doi-access = free }}  {{cite web | vauthors = Tesarik J, Mendoza C, Mendoza-Tesarik R | title = Comments | date = 24 April 2018 | url = https://www.fertstertdialog.com/users/16110-fertility-and-sterility/posts/32485-25452 | access-date = 16 October 2018 | archive-date = 20 September 2018 | archive-url = https://web.archive.org/web/20180920160839/https://www.fertstertdialog.com/users/16110-fertility-and-sterility/posts/32485-25452 | url-status = dead }}</ref> Based on the evaluation of the babies born, no abnormalities attributable to the ROSI technique have been identified.<ref name="Tesarik_1996a"/><ref name="Tesarik_1996b"/><ref name="Tesarik_1995"/><ref name="fertstertdialog.com"/>