In patients with azoospermia (i.e., complete absence of sperms in the semen), an attempt can be made to extract sperms directly from the testicles. Often sperms are still being formed in the testicles, but in limited numbers. However, in many patients spermiogenesis in the testicles has ceased completely. Technique: Under local or general anesthesia, the skin of a testicle is opened and a few tiny pieces of tissue taken directly from the testicle (testicular biopsy, "TESE"). One of the tissue pieces is examined under a microscope (histology); the others are either deep-frozen ("cryopreservation") or, if ICSI treatment is performed immediately, used directly for ICSI.