Azoospermia is the medical condition of a man whose semen contains no sperm.
The centromere is the specialized DNA sequence of a chromosome that links a pair of sister chromatids (a dyad).
Euchromatin is a lightly packed form of chromatin (DNA, RNA, and protein) that is enriched in genes, and is often (but not always) under active transcription.
Male infertility refers to a male's inability to cause pregnancy in a fertile female.
Meiosis (from Greek μείωσις, meiosis, which means lessening) is a specialized type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them.
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis.
The testicle or testis is the male reproductive gland in all animals, including humans.
Ubiquitin specific peptidase 9, Y-linked (fat facets-like, Drosophila), also known as USP9Y, is an enzyme which in humans is encoded by the USP9Y gene.
The Y chromosome is one of two sex chromosomes (allosomes) in mammals, including humans, and many other animals.