Immunohistochemical characterization of efferent neurons innervating the oviduct in the pig located in the sympathetic chain ganglia

Abstract

The present study was aimed at disclosing the pattern(s) of putative co-incidence of tyrosine hydroxylase (TH), dopamine -hydroxylase (DH), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP) and nitric oxide synthase (NOS) within the porcine “oviductal” efferent neurons using combined retrograde tracing and double-labelling immunohistochemistry. The fluorescent retrograde tracer Fast Blue (FB) was injected into the wall of the ampullar (n = 5) and isthmal (n = 5) part of the organ in ten sexually immature female pigs. After a survival period of three weeks sympathetic chain ganglia (SCG) were collected. 10 µm-thick cryostat sections of the ganglia were examined for the presence of FB-positive (FB⁺) nerve cells under the fluorescent microscope. Tracered neurons were processed for double-labelling immunofluorescence according to the method of Wessendorf and Elde. Retrograde labelling revealed a population of “oviductal” efferent neurons located in the thoracic (T) and lumbar (L) SCG at the level of T₁₄ to L₅. Double-labelling immunofluorescence allowed several subpopulations of the studied perikarya to be distinguished. The largest one consisted of TH⁺/DH⁺ (immunopositive) nerve cells. The moderate number of FB⁺ nerve cells expressed TH/NPY- immunoreactivity (IR). The tracered neurons did not show SP, CGRP and NOS immunoreactivity. Because identically coded nerve fibres have been observed within the wall of the porcine oviduct it can be assumed that TH⁺/DH⁺ or TH⁺/NPY⁺ neurons are involved in the control the oviductal tonus and ovum transport.