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X0 sex-determination system - Wikipedia
Bonnevie-ullrich-turner syndrome ; 45 X 0. XO syndrome is a disorder of the sex chromosomes, occurring in females, in which one of the two X chromosomes is completely or partially absent. XO syndrome causes a number of symptoms that vary greatly among individuals, but generally include small stature, amennorhea and infertility. Estimates of the prevalence of XO syndrome vary from study to study, with the most common estimate being 1 in 2, live female births. However, lower prevalence rates, as low as 1 in 5,—8, female live births, have been reported in some studies.
XX/"XO" sex determination system in a population of Peruvian owl monkey, Aotus
In scarab beetle species of the genus Pentodon, the lack of analysis of sex chromosomes in females along with the poor characterization of sex chromosomes in the males, prevented all previous investigations from conclusively stating sex determination system. In this study, somatic chromosomes from females and spermatogonial chromosomes from males of Pentodon bidens punctatum Coleoptera: Scarabaeoidea: Scarabaeidae from Sicily have been analyzed using non-differential Giemsa staining. Spermatocyte chromosomes have also been examined after a number of banding techniques and fluorescent in situ hybridization with ribosomal sequences as a probe rDNA FISH. The results obtained showed that silver and CMA 3 staining were inadequate to localize the chromosome sites of nucleolus organizer regions NORs due to the over-all stainability of both constitutive heterochromatin and heterochromatin associated to the NORs. This suggests that heterochromatic DNA of P.
In this system, there is only one sex chromosome, referred to as X. Males only have one X chromosome X0 , while females have two XX. The zero sometimes, the letter O signifies the lack of a second X.