noun
epididymis
Anatomical term for the coiled tube at the back of the testicle that stores and carries sperm.
精巣上体は精子の成熟に関与している。
The epididymis is involved in sperm maturation.
精巣 means testicle, while 精巣上体 specifically refers to the epididymis attached to it.
Compound of 精巣 (testicle) and 上体 (upper body), referring to the structure sitting atop the testicle. The exact historical derivation is uncertain; the spelling is conventionally associated with the anatomical meaning.