[Gradient of serotonergic innervation of internal organs]

The unidirectional synergistic effect of the vegetative nervous system departments was studied at the regulation of the activity of internal organs. It was shown that the sympathetic nerve intensification of the vagal stimulation of EMA of stomach, urinary bladder, ureters, uteruss, fallopian tubes and deferent duct is realized by means of activation of serotonergic fibrae preganglionares that transmit the activation to 5-NTS,4 serotonin receptors of intramural ganglia that, in their turn, activate 5-NT1,2 serotonin receptors of effector cells.

The effects of testicular denervation on spermatogenesis in the Sprague-Dawley rat

In the rat, regression of spermatogenesis during the chronic stages of spinal cord injury (SCI) occurs in the presence of normal function of the pituitary-testis hormone axis, thus suggesting that nonendocrine mechanisms might be involved. The current study examined whether disruption of neural input to the testis contributes to the cascade that leads to the regression of spermatogenesis. Four weeks after denervation of the superior spermatic nerve (SSN), testis weight was 25% lower (p < 0.01) than that of the contralateral sham-operated testis. Defects in spermatogenesis including phagocytosis of mature spermatids, vacuolization of spermatid nuclei, delayed spermiation and incomplete cellular associations were observed in >60% of the tubules. In the remaining 30-40% of tubules, the seminiferous epithelium was severely regressed. While cutting the inferior spermatic nerve (ISN) alone did not affect spermatogenesis significantly, it enhanced the effect of SSN denervation on both spermatogenesis and testis weight (p < 0.01). Spermatogenesis was totally regressed in the SSN/ISN-denervated testes. At this time, quantitatively normal spermatogonial proliferation was maintained in SSN- or ISN-denervated testes. Twelve weeks after surgery, regression of the seminiferous epithelium characterized by absence of proliferating spermatogonia, while undifferentiating spermatogonia were present, was observed in all SSN-denervated testes. At this time, regression of the seminiferous epithelia also occurred in >30% of the tubules in ISN-denervated testes. At both times, serum follicle-stimulating hormone, luteinizing hormone and testosterone levels were normal and >60% of normal testicular testosterone concentrations were maintained in the denervated testes. These results indicate that disruption of neural input to the testis is not a cause for the decrease in spermatogonial proliferation during the acute phase of SCI, but may contribute to the chronic effects of SCI on spermatogenesis.

Presence of neuropeptide--Y and its C-terminal flanking peptide immuno-reactivity in the seminiferous tubules of human testis

The presence of neuropeptide Y (NPY) and its C-terminal flanking peptide (C-PON) was described by immunohistochemistry in human testes. The immunopositive material was visualized in the spermatogenic elements of the seminiferous tubules. More NPY occurred in the younger testis and more C-PON in the older ones. NPY positive material was present mainly in the spermatogonia, and in the primary spermatocytes, where C-PON also occurred. The megalospermatocytes, present in aged testis, showed C-PON immunoreactivity. Both NPY and C-PON were present in granular form in the perinuclear zone of the cells. No positive material was detected in the Sertoli cells or in the Leydig cells. It is possible that NPY and its precursor are synthetized within the testis and might play a role in the paracrine and/or autocrine regulation of spermatogenesis.

[Microscopic innervation of the spermatic ducts and testicle. IV. Testis]

The presence of nerve fibers in the testicle of the rat has been investigated both in light (silver and osmium-iodide impregnations, and histochemistry for acetylcholinesterase) and electron microscope. Nerve fibers were found in the albuginea and close to the intertubular blood vessels. However, these were not observed at ultrastructural level. On the other hand, the Leydig cells do not have a direct innervation but nerve fibers containing large and small granular synaptic vesicles were observed in the vicinity (3,000 A). The authors discuss the possible control of the testicular function by the peripheral nervous system.

[Microscopic innervation of the spermatic ducts and the testis. III: Tubuli seminiferi recti, rete testis and ductuli efferentes testis]

The cholinesterase activity and ultrastructural characteristics of the nerves in tubuli seminiferi recti, rete testis and ductuli efferentes testis have been studied in Wistar rats. The tubuli seminiferi recti and rete testis are innervated by a dense network which has varicosities containing different types of synaptic vesicles. The nerve fibres are located between the smooth muscle cells and the fibroblasts, and under the epithelial basement membrane. Inside the ductuli efferentes testis, the nerves form perivascular, subepithelial and muscle plexuses. According to the positive reaction for cholinesterase as well as the characteristics of the synaptic vesicles, these structure have at least a double adrenergic-cholinergic innervation. Our results demonstrate that the nervous fibres in ductuli efferentes testis are more abundant than in tubuli seminiferi recti and rete testis. The role of the vegetative nervous system in the initial segments of the spermatic pathways is discussed.

Evidence for innervation of the myoid cell in the human seminiferous tubule

Although the existence of the seminiferous tubule contractions attributed to myoid cells is established, the control of the contractions is poorly understood. Recently, we have suggested the possible neural control mechanism for contractility of the human seminiferous tubule. In an effort to identify the nerve supply to the myoid cells in the human seminiferous tubules, we studied the paraffin sections of biopsied testicular specimens using a protein silver impregnation technique (Bodian's method). Here we demonstrate evidence for the presence of nerve fibers close to the myoid cells. It is highly suggested that contraction of the human seminiferous tubule may play an important role in the transport of spermatozoa, and neurohumoral regulatory mechanism may partly exist in this connection.

Pharmacological and histological evidence for adrenergic innervation of the myoid cells in the rat seminiferous tubule

Although the existence of seminiferous tubule contractions attributed to peritubular myoid cells is established, the control of the contractions is poorly understood. In this communication, it is shown that the rat seminiferous tubule responds to autonomic drugs and to stimulation of the perivascular nerve running along the spermatic vessels, by means of recording the intratubular pressure with a servo-null micropressure measuring device. Furthermore, the presence of nerve fibers close to the myoid cells is shown using a silver impregnation technique. Furthermore, the nature of the neurotransmitter contained in synaptic vesicles using 5-hydroxydopamine and L-DOPA as markers of adrenergic nerve elements with electron microscopy is shown in this report. It is concluded that there are adrenergic alpha- and beta-receptors and muscarinic receptors in myoid cells of the rat seminiferous tubule and that the contractions of seminiferous tubules are regulated by adrenergic nerve fibers.

Varicose axons bearing "synaptic" vesicles on the basal lamina of the human seminiferous tubules

Normal (infant and adult) and pathological testes were examined by electron microscopy in order to study testicular innervation. Nerves composed of non-myelinated fibres were abundant in the tunica vasculosa of the tunica albuginea. These nerves penetrated into the testicular septa reaching the interstitial tissue. This showed numerous non-myelinated nerve fibres running among the Leydig cells and blood vessels. Single axons or small groups of them, partially surrounded by Schwann cells, approached: 1) the Leydig cells, 2) the interstitial blood vessels, and 3) the seminiferous tubules. Single naked axons were also observed primarily in the proximity of the seminiferous tubules. These axons showed varicosities containing both small and large "synaptic" vesicles. The latter were less numerous and contained a central dense core. Small vesicles were agranular. Some varicose axons ran across the myofibroblast layer of the tunica propria reaching the basal lamina of the seminiferous tubules at the level of the Sertoli cells but not at the level of the spermatogonia. The intercellular space between Sertoli cell and axon membrane was about 150-200 nm.