sentences:  Biologists have well established that male sperm production relies on certain genes on the Y chromosome, which, when missing or defective, lead to such men producing little to no sperm in their testicles.An analogy, then, is that a cell from a woman has complete Y chromosome deficiency.While many genes on the Y chromosome have backups (homologues) on other chromosomes, a few genes such as RBMY on the Y chromosome do not have such backups, and their effects must be compensated for to convert cells from a woman into sperm.