Immunohistochemical techniques have been employed to observe the arrangement and distribution of the autonomic nervous systems in the normal rat vas deferens and to observe periodic alterations of the innervation patterns following surgical
division of
the vas. 18 male Sprague-Dawley rats were divided into 6 groups-normal control group, 1 week after vasectomy group, 3 weeks after vasectomy group, 5 weeks after vasectomy group, 8 weeks after vasectomy group and 16 weeks after vasectomy group.
Samples
from sites on the testicular and urethral sides of the original vasectomy have been compared with the other group specimens as to the arrangement and distribution of autonomic nerves containing vasoactive intestinal polypeptide (VIP) and
catecholamine.
The VIPergic and adrenergic innervation patterns of the normal control group is almost identical with that of a normal human vas. In contrast with tissues from the testicular portions and from the controls, the testicular specimens were devoid of
autonomic nerve fibers, which were neither reinnervated nor redistributed in every vasectomy group. In the urethral portion of the vas, it was observed that the adrenergic nerve fibers had few changes after vasectomy and that VIPergic nerve
fibers
became thicker from 3 weeks after vasectomy, showing axonal growth into the smooth muscle coat from 8 weeks after it, and showing axonal growth into the deep muscle cost from 16 weeks after it. These findings indicate firstly that the autonomic
nerve
fibers run from the urethral portion towards the testis; secondly that VIPergic nerve fibers have high a possibility to be reinnervated by axonal growth from the urethral portion to the testicular portion after vasovasostomy; thirdly that
injuring
autonomic nerves to the vas deferens during vasectomy could result in poor function of the vas after vasovasostomy in relation to the contractile and secretory activities of the vas that may be of importance to the maturation and fertility of
spermatozoa.
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