Abstract
It is well known that spermatozoa in mammals attain what appears to be their full structural development while contained in the seminiferous tubules, but that they are not in a position to be discharged until they have passed through the long coiled ductus epididymidis and have reached the posterior end of the vas deferens.
There is no agreement as to the significance of this long passage through the epididymis. In earlier papers (Young 1 , 2 ), the suggestions were made: First, that the epididymis provides an environment in which spermatozoon development, not complete when these cells leave the testis, can continue until functional maturity has been attained, and (2) that once spermatozoa become mature, there is no influence which preserves them indefinitely in a condition for effecting fertilization.
Because this general idea has not been expressed previously, except possibly as isolated statements by different writers might be pieced together, supplementary experiments seemed desirable. In addition, the suggestion that spermatozoa age and become incapable of functioning interested us in the nature of the mechanism by which a constant supply of viable spermatozoa is maintained at the posterior end of the vasa deferentia in males which are not allowed to mate.
The suggestion that the epididymis is an organ in which spermatozoa may at one time be maturing and may at another time be aging was tested by 2 experiments.
In the first, 68 females selected during the oestrum were inseminated with spermatozoa removed from the proximal ends of the epididymides from normal males, and 69 were inseminated with spermatozoa removed from the distal ends of the same epididymides. The percentage of fertile inseminations was 32.4 in the former group and 71.0 in the latter group.
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