The genes that control spermatogenesis are called AZF (azoos permia fact or, AZF) and are located on chromosome Yq11, these genes or gene clusters are called azoospermia factors. the region on the long arm of the Y chromosome that dominates spermatogenesis is divided into AZFa, AZFb and AZFc regions, the genes on these three chromosomes dominate the different stages of spermatogenesis, respectively. The AZFa gene dominates the proliferation of spermatocytes; AZFb gene (DAZsY134) deletion is pathologically diagnosed as germ cell maturation arrest; AZFc region (DAZsY254) gene defect can cause azoospermia and also extreme oligospermia. male offspring of patients with Y chromosome AZF gene microdeletion also face fertility problems due to the presence of Y chromosome microdeletion, so Whether from a fertility or eugenic point of view, third generation IVF is recommended to select female offspring.