An IVF system for successfully utilizing spermatozoa separated into X-chromosome bearing and into Y-chromosome bearing population for insemination. The IVF system includes fertilization medium that can shorten the time from insemination to cleavage and a portable incubator for the transportation of maturing oocytes and inseminated oocytes comrprising a straw (19) and an incubation element (20) that can be sealed with a cap (22).