DEVELOPMENT OF PEPTIDE-CONTAINING NERVES IN THE HUMAN FETAL VAS-DEFERENS AND SEMINAL-VESICLE

Objective To use immunohistochemical methods to study the developing a utonomic innervation of the human fetal vas deferens and seminal vesic le. Material and methods Thirteen pre-natal specimens ranging in gesta tional age from 13 to 30 weeks were acquired following abortion or mis carriage. The overall innervation of each specimen was visualized usin g protein gene product 9.5 (PGP), a general nerve marker, while the on set and development of specific neuropeptide-containing sub-population s were investigated using antisera to neuropeptide Y (NPY). vasoactive intestinal peptide (VIP), substance P (SP), calcitonin gene related p eptide (CGRP), bombesin (BOM), somatostatin (SOM), and met-enkephalin (ENK). In addition the occurrence and distribution of presumptive nora drenergic nerves was studied using antisera to dopamine-P-hydroxylase (DPH) and tyrosine hydroxylase (TH). Results At 13 weeks numerous PGP, DPH, TH, NPY and ENK immunoreactive (-IR) nerve trunks were present i n the adventitia of the vas deferens and seminal vesicle but at this s tage nerve fibres were not present in the smooth muscle coat of either organ. By 17 weeks, fine PGP-, D beta H- and TH-IR nerve fibres had p enetrated the outer aspect of the muscle coat of the seminal vesicle b ut not the vas deferens. At 20 weeks a branching network of PGP-, D be ta H- and TH-IR nerve fibres occurred throughout the full thickness of the muscle coat of the seminal vesicle while similar nerves were pres ent only in the outer half of the muscle coat of the vas deferens. At 23 weeks the full thickness of the muscle coat of the vas deferens was richly innervated by a branching plexus of PGP-IR nerves. Many of the se adventitial and intramuscular nerves were immunoreactive for DPH or TH while some were immunoreactive for either NYP or ENK. Occasional a dventitial nerves were immunoreactive for SP or CGRP, these being firs t observed at 10 weeks. VIP-IR nerves were extremely rare in the muscl e coat of either organ, being first observed at 17 weeks in the semina l vesicle and at 20 weeks in the vas deferens where they mainly formed perivascular plexuses. PGP-IR nerves were first observed in the submu cosa of the seminal vesicle at 20 weeks and in the vas deferens at 21 weeks, Some of these nerves were perivascular in location while others formed a subepithelial plexus which increased in density with increas ing gestational age, At 22 weeks of gestation some of the submucosal n erves were immunoreactive for SP or NPY, while at 30 weeks NPY-IR nerv es formed the majority of subepithelial nerves, Occasional VIP-IR sube pithelial nerves were first observed at 26 weeks but were extremely ra re even at 30 weeks. Submucosal nerves immunoreactive for CGRP, D beta W, TH or ENK did not occur in any of the specimens examined. Conclusi on (i) From 13 weeks gestation autonomic nerves develop in the muscle coat of the fetal seminal vesicle and vas deferens, being denser in th e seminal vesicle than the vas deferens up to 23 weeks gestation, (ii) The majority of the intramuscular nerves in either organ contain D be ta H, TH, NPY and ENK and are presumably noradrenergic in type, (iii) A subepithelial nerve plexus develops around 20 weeks gestation and co ntains NPY but not VIP, unlike the adult organs. (iv) Scattered neuroe ndocrine cells immunoreactive for SOM are present in the mucosa of the seminal vesicle from 23 weeks of gestation.