NPY-LIKE AND CGRP-LIKE IMMUNOREACTIVE NERVE-FIBERS IN THE TESTIS AND MESORCHIUM OF THE TOAD (BUFO-ARENARUM)

The presence and distribution of peptidergic nerve fibers were studied in the testis and mesorchium of the toad by means of immunohistochemi stry. Cryostat sections of the testis and whole-mount preparations of mesorchia were immunostained with antisera to calcitonin gene-related peptide (CGRP) and neuropeptide tyrosine (NPY). After leaving the meso rchium CGRP-immunoreactive (IR) fibers were seen predominantly running in between the seminiferous tubules. In addition, a small population of CGRP-IR nerve fibers formed thin plexuses around blood vessels. Con versely, NPY-like immunoreactivity predominated in nerve fibers that f ormed dense plexuses around vessels both in the mesorchium and testis. Additionally, some single NPY-IR nerve fibers could be seen in both s tructures studied. The functional significance of these peptidergic sy stems in the testis of the toad remains to be analyzed.