The figure is intended to illustrate the arrangement of the vasa efferentia.
C, Reduction of vasa efferentia to a single one posteriorly (Protopterus).
These tubes to the number of 40-50 constitute, we believe, the vasa efferentia.
A, Distributed condition of vasa efferentia (Acipenser, Lepidosteus).
In Protopterus the vasa efferentia are reduced to a single one on each side at the extreme hind end of the testis.
The Teleostei must, moreover, have sprung from Ganoidei in which the vasa efferentia had become aborted.
Very early the vasa efferentia are fully formed, and their arrangement in an embryo eight centimetres long is shewn in Pl.
vas efferens vas ef·fer·ens (vās' ěf'ər-ənz, -ə-rěnz')
n. pl. vasa ef·fer·en·ti·a (ěf'ə-rěn'shē-ə)
Any of a number of small ducts that carry semen from the testis to the epididymis.