Testis Mapping

MC170HD 118 FNA nl

This procedure is provided by the Men’s Health Center at UW Medicine. The Male Fertility Lab analyzes slides and produces the maps. In some men with low sperm counts, or with no sperm, the testis is not making normal numbers of sperm. Sometimes sperm production is present in a few areas of the testis, and not in others. The advantage of Testis Mapping (also called FNA, for fine needle aspiration) is that the physician can later go to the right area of the testis to recover sperm during TESA (testicular sperm aspiration), TESE (testicular sperm extraction) or micro-TESE (sperm extraction using a surgical microscope). 

Sperm mapped and then retrieved by any of these methods must be used for IVF-ICSI. 


In some cases, no spermatogenesis may be found during testis mapping. This condition is called Sertoli Cell-Only (SCO). It is unlikely, although not impossible, that any sperm are present in the testis. In other cases, sperm production stops at meiosis, and no mature sperm are formed.

Above, normal spermatogenesis, with testicular sperm, primary spermatocytes (immature germ cells), and Sertoli cells.
Right, only Sertoli cells are found in SCO.