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

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.

Sentan: A Novel Specific Component of the Apical Structure of Vertebrate Motile Cilia

Human respiratory and oviductal cilia have specific apical structures characterized by a narrowed distal portion and a ciliary crown. These structures are conserved among vertebrates that have air respiration systems; however, the molecular components of these structures have not been defined, and their functions are unknown. To identify the molecular component(s) of the cilia apical structure, we screened EST libraries to identify gene(s) that are exclusively expressed in ciliated tissues, are transcriptionally up-regulated during in vitro ciliogenesis, and are not expressed in testis (because sperm flagella have no such apical structures). One of the identified gene products, named sentan, was localized to the distal tip region of motile cilia. Using anti-sentan polyclonal antibodies and electron microscopy, sentan was shown to localize exclusively to the bridging structure between the cell membrane and peripheral singlet microtubules, which specifically exists in the narrowed distal portion of cilia. Exogenously expressed sentan showed affinity for the membrane protrusions, and a protein–lipid binding assay revealed that sentan bound to phosphatidylserine. These findings suggest that sentan is the first molecular component of the ciliary tip to bridge the cell membrane and peripheral singlet microtubules, making the distal portion of the cilia narrow and stiff to allow for better airway clearance or ovum transport.

Effect of nitric oxide synthase inhibitors on ovum transport and oviductal smooth muscle activity in the rat oviduct

The effect of the inhibition of nitric oxide synthase (NOS) on ovum transport and oviductal motility in rats was investigated. Three different NOS inhibitors were injected into the ovarian bursa at oestrus or day 3 of pregnancy. Oviducts and uteri were flushed 24 h later and the presence of ova was recorded. In oestrous and pregnant rats, treatment resulted in accelerated egg transport, as shown by a decrease in the number of ova present in the oviducts. In cyclic rats, intrabursal injection of 1 mg kg-1 of either N-monomethyl-L-arginine (L-NMMA) or N omega nitro-L-arginine methyl ester (L-NAME) elicited a 30% reduction in the number of ova present in the oviducts, whereas in pregnant animals, the same dose of L-NMMA produced a reduction of 40%. Simultaneous administration of the NO donor spermine NONOate (5 mg kg-1) completely reversed the effect of L-NMMA. Tubal motility was assessed by microsphere displacement analysis within the oviduct. Surrogate ova were transferred to the oviductal lumen at oestrus and 24 h later the effect of intraoviductal injection of 1 microgram L-NMMA or vehicle was assessed. The microspheres in the isthmus showed an oscillating motion, and periods in which movement was not detectable. However, L-NMMA treatment produced a 3.6-fold increase in the maximum instant velocities and a significant reduction in the resting periods of the microspheres compared with the control group (P < 0.001). These results provide evidence that NO inhibition increases tubal motility that results in accelerated ovum transport, and indicate that NO could act as a paracrine signal between different layers of the oviductal wall, providing a role for endogenous NO in regulation of tubal function.