Distribution of Primary Afferent Neurons Innervating the Porcine Oviduct and Their Immunohistochemical Characterization

Abstract

Previous studies have revealed that some nerve fibres supplying the porcine oviduct may be of sensory origin. Therefore, the present study was aimed at disclosing the distribution of porcine ‘oviductal’ primary afferent neurons and the pattern(s) of putative coincidence of substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and nitric oxide synthase (NOS) within these nerve cell bodies using combined retrograde tracing and double-labelling immunohistochemistry. We also investigated the existence and coexistence of immunoreactivities to tyrosine hydroxylase (TH) and dopamine β-hydroxylase within the neurons because in some mammals, dorsal root ganglia (DRG) were previously found to contain perikarya immunoreactive (IR) to TH. Retrograde labelling revealed a population of large sensory neurons located in the Th₁₀–L₃ DRG. There were no significant differences in the number or distribution between the ampulla- and isthmus-projecting neurons. Double-labelling immunoflourescence allowed several subpopulations of the studied perikarya to be distinguished. The largest one consisted of SP/CGRP-IR nerve cells, while the smallest subpopulation comprised NOS/VIP-IR neurons. Either SP/NOS, solely SP- or solely NOS-IR neurons were also found. Because identically coded nerve fibres have been observed within the wall of the porcine oviduct, based on their association with particular organ structures, it can be assumed that SP/CGRP-, SP/NOS- or solely NOS-IR neurons are involved in the antidromic relaxation of the oviductal vessels, SP-, NOS- or SP/CGRP-IR nerve cells control the oviductal tonus and that some neurons project beneath the epithelium and are involved in the transmission of sensory modalities from the oviduct to the spinal cord.

Immunohistochemical Properties of the Peripheral Neurons Projecting to the Pig Bulbospongiosus Muscle

“…In sacral SGs we tested a small number of pig BSM‐projecting neurons. They were immunoreactive only for CGRP, LENK, NPY, nNOS, SP, and VChAT and could be involved in visceral sensation, according to Russo et al (), or in the relaxation of the BSM blood vessels throughout an antidromic mechanism, as it has already been hypothesized for the sow oviduct by Czaja ().…”

Sensory and Autonomic Neurons Project Both to the Smooth Retractor Penis and to the Striated Bulbospongiosus Muscles. Neurochemical Features of the Sympathetic Subset

“…This peptide is commonly considered a marker of afferent pathways (Majewski et al, 1995;Kaleczyc et al, 1997;Czaja, 2000), therefore, its presence within sympathetic neurons is an unforeseen finding. However, CGRP has been also shown in the STG neurons of the boar (Hill and Elde, 1989;H€ app€ ol€ a et al, 1993;Lakomy et al, 1994), sow (Panu et al, 2001;Ragionieri et al, 2008) cat (Kummer and Heym, 1988;Lindh et al, 1989) and horse (Nasu et al, 2003).…”

Double Labelling Immunohistochemistry on the Nerve Fibres of Retractor Clitoridis Muscle of the Sow

“…The study of the innervation of the female genital organs, carried out by combining retrograde neuronal tracing and immunofluorescence methods, allowed identification of the site and the neurochemical content of the neurons connected to them in the rat (Papka et al, 1991(Papka et al, , 1995a(Papka et al, ,b, 1996(Papka et al, , 1997(Papka et al, , 1999aSerghini et al, 1997;Houdeau et al, 1995Houdeau et al, , 1997Houdeau et al, , 1998, the guinea-pig (Alm and Lundberg, 1988), the cat (Kawatani and de Groat, 1991), the dog (Li and Masuko, 2001) and the sow (Majewski and Heym, 1991;Majewski et al, 1996;Czaja, 2000;Czaja et al, 2001). In swine, our research (Panu et al, 2001;Bo Minelli et al, 2002) contributed to the study of the innervation of the sole smooth genital musculature, taking the retractor clitoridis muscle (RCM) as an experimental model.…”