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c.1600, "fleshy mass at the back of the testicles," Modern Latin, literally "that which is on the testicles," from Greek epididymis, a word probably coined by Greek anatomist Herophilus (c.300 B.C.E.) from epi "on" (see epi-) + didymos "testicle," literally "double, twofold" (adj.). "To save his Epididamies" [Richard Brome, "The Court Beggar," 1652].
epididymis ep·i·did·y·mis (ěp'ĭ-dĭd'ə-mĭs)
n. pl. ep·i·di·dy·mi·des (-mĭ-dēz')
A long, narrow, convoluted tube in the spermatic duct system that lies on the posterior aspect of each testicle and connects with the vas deferens.
either of a pair of elongated crescent-shaped structures attached to each of the two male reproductive organs, the testes (see testis). Sperm cells produced in the testes are transported to the epididymes, where they mature and are stored. Each epididymis has three regions, called, respectively, the head, body, and tail. The head is the uppermost and largest part of the epididymis; it lies on the top surface of the testis. The body is attached to the anal side of the testis and extends the length of the gland. The smallest region is the tail, which begins at the point of separation of the epididymis from the testis. Sperm cells mature primarily in the head and body of the epididymis and are stored in the tail