Ethnically pure Mayos tend to segregate themselves from mestizos and other ethnicities. To make sure their members remain celibate they segregate the sexes during rituals. This verdict supported railroad companies that chose to racially segregate their passengers. There are severe repercussions when chromosomes do not segregate properly. The "regulationist policy" was to isolate, segregate, and control prostitution. This causes chromosomes to fail to properly segregate in a process called nondisjunction. Epithelia actively pump and differentially segregate ions. South African Muslims generally do not segregate themselves from people of other faiths. Some streetcar companies did not segregate voluntarily. They segregate (separate) during meiosis such that each gamete contains only one of the alleles. Females segregate themselves from males after mating. In 1204 the papacy required Jews to segregate themselves from Christians and wear distinctive clothing. Within the pods, the hippos tend to segregate by gender. For Friday prayers, by custom, Muslim congregations segregate men, women, and children in separate groups. They then made the decision to segregate the Jews to end the conflict.