Male hybrid mice created through speciation show reproductive isolation due to defects in spermatogenesis at three stages: pre-meiotic, metaphase I and prophase I. Previously, it was believed a single gene was responsible for sterility at one stage, but research shows the gene acts across multiple stages. A strain was created containing the X chromosome from one mouse species, and results demonstrated reduced sperm quantity and quality, smaller testes, and some mice failed to complete meiosis, leading to sterile hybrids. This research provides insight into developing techniques to help hybrids complete healthy meiosis to produce fertile offspring.

1. Ivan J. Garcia<br />Oct. 2010<br />RISE program<br />UPR-Cayey<br />Reproductive Isolation in hybrid mice due to Spermatogenesis Defects at Three Meiotic Stages<br />A review<br />Male hybrids created through speciation and hybridization are almost always infertile. Research says it is a reproductive isolation which occurs in different stages of cell development in a process called spermatogenesis (Oka, 2010). The animals showed this spermatogenesis in a pre-meiotic stage, metaphase I and prophase I. In the past it was thought that the allele (gene) that affected this sterilization was responsible only in one stage, now it is known it acts on these three stages. They constructed a strain called B6-ChrXMSM (Oka et al. 2004), which contained the X chromosome of one of the mice. Results show that this spermatogenesis reduces sperm quantity and quality, smaller testis, and in rare occasions incompatible gametes; some also failed to even complete the meiotic process. In all the tests sterile hybrids where made, even in the ones with compatible gametes. With the knowledge gained in this research, scientist can now make up a technique or strain to help these hybrids complete their meiosis healthy and completely in order to create fertile hybrids (or at least in a F2 generation).<br />Bibliography<br /> Oka, Ayako, and Akihiko Mita, et. Al., quot;
Reproductive Isolation in Hybrid Mice Due to Spermatogenesis Defects at Three Meiotic Stages.quot;
ProQuest Biology Journals. ProQuest, Sept. 2010. Web. 23 Oct. 2010. <http://http://proquest.umi.com.uprcdb.cayey.upr.edu:2048/pqdweb?index=1&did=2157786971&SrchMode=1&sid=1&Fmt=3&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1287876789&clientId=45093>.<br />