Composite nerve fibers in the hypogastric and pelvic splanchnic nerves: an immunohistochemical study using elderly cadavers / 대한해부학회지

To determine the proportion of nerve fibers in the hypogastric nerve (HGN) and pelvic splanchnic nerve (PSN), small tissue strips of the HGN and PSN from 12 donated elderly cadavers were examined histologically. Immunohistochemistry for neuronal nitric oxide synthase (NOS), vasoactive intestinal peptide (VIP), and tyrosine hydroxylase (TH) was performed. More than 70% of fibers per bundle in the HGN were positive for TH at the level of the sacral promontory. In addition, NOS- (negative) and/or VIP+ (positive) fibers were observed in small areas of each nerve bundle, although the proportion of each was usually less than 10%. In the PSN near the third sacral nerve root, the proportion of nerve fibers positive for NOS and/or VIP (or TH) was below 30%. In both the HGN and PSN, the number of VIP+ fibers was usually greater than that of NOS+ fibers, with frequent co-localization of NOS and VIP. More fibers in both nerves were positive for TH than for these other markers. In contrast to pelvic plexus branches, there were no differences in the proportions of NOS+ and VIP+ fibers between nerve bundles in each of the tissue strips. Thus, target-dependent sorting of nerve fibers was not apparent in the HGN at the level of the sacral promontory or in the PSN near the third sacral nerve root. The NOS+ and/or VIP+ fibers in the HGN were most likely ascending postganglionic fibers to the colon, while those in the PSN root may be preganglionic fibers from Onuf's nucleus.

Topohistology of sympathetic and parasympathetic nerve fibers in branches of the pelvic plexus: an immunohistochemical study using donated elderly cadavers / 대한해부학회지

Although the pelvic autonomic plexus may be considered a mixture of sympathetic and parasympathetic nerves, little information on its composite fibers is available. Using 10 donated elderly cadavers, we investigated in detail the topohistology of nerve fibers in the posterior part of the periprostatic region in males and the infero-anterior part of the paracolpium in females. Neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were used as parasympathetic nerve markers, and tyrosine hydroxylase (TH) was used as a marker of sympathetic nerves. In the region examined, nNOS-positive nerves (containing nNOS-positive fibers) were consistently predominant numerically. All fibers positive for these markers appeared to be thin, unmyelinated fibers. Accordingly, the pelvic plexus branches were classified into 5 types: triple-positive mixed nerves (nNOS+, VIP+, TH+, thick myelinated fibers + or -); double-positive mixed nerves (nNOS+, VIP-, TH+, thick myelinated fibers + or -); nerves in arterial walls (nNOS-, VIP+, TH+, thick myelinated fibers-); non-parasympathetic nerves (nNOS-, VIP-, TH+, thick myelinated fibers + or -); (although rare) pure sensory nerve candidates (nNOS-, VIP-, TH-, thick myelinated fibers+). Triple-positive nerves were 5-6 times more numerous in the paracolpium than in the periprostatic region. Usually, the parasympathetic nerve fibers did not occupy a specific site in a nerve, and were intermingled with sympathetic fibers. This morphology might be the result of an "incidentally" adopted nerve fiber route, rather than a target-specific pathway.

Spatial relationship between expression of cytokeratin-19 and that of connexin-43 in human fetal kidney / 대한해부학회지

Connexin-43, a major gap junction protein, and cytokeratin-19, one of the intermediate filament keratins, are known to be markers of well-differentiated epithelium. In this study, we investigated the expression of these markers in the head region, lungs, and abdominal organs of 10 human mid-term fetuses. The expression of connexin-43 was found to be restricted to the dura mater, kidney, and adrenal cortex. In the kidney, we found a clear site-dependent difference in the expression pattern of these markers: connexin-43 expression was observed in the tubules of the renal cortex whereas cytokeratin-19 was strongly expressed in the collecting ducts and renal pelvis. This difference remained unchanged throughout the fetal stages examined. Immunoreactivity was not observed for either of the markers in the intrarenal vessels, including the glomeruli, and mesangial cells. Connexin-43 expression seemed to be restricted to the metanephric vesicle-derived structures that differentiate in the urogenital ridge of the splanchnic mesoderm. The adrenal cortex also originates from the same para-aortic mesoderm. In contrast, in the urogenital organs, cytokeratin-19 seemed to be expressed in ducts derived from the urogenital sinus.

Reappraisal of intergender differences in the urethral striated sphincter explains why a completely circular arrangement is difficult in females: a histological study using human fetuses / 대한해부학회지

To investigate why the development of a completely circular striated sphincter is so rare, we examined histological sections of 11 female and 11 male mid-term human fetuses. In male fetuses, the striated muscle initially extended in the frontal, rather than in the horizontal plane. However, a knee-like portion was absent in the female fetal urethra because, on the inferior side of the vaginal end, a wide groove for the future vestibule opened inferiorly. Accordingly, it was difficult for the developing striated muscle to surround the groove, even though there was not a great difference in width or thickness between the female vestibule and the male urethra. The development of a completely circular striated sphincter seems to be impossible in females because of interruption of the frontal plane by the groove-like vestibule. However, we cannot rule out the possibility that before descent of the vagina, the urethral striated muscle extends posteriorly.

Reappraisal of intergender differences in the urethral striated sphincter explains why a completely circular arrangement is difficult in females: a histological study using human fetuses / 대한해부학회지

To investigate why the development of a completely circular striated sphincter is so rare, we examined histological sections of 11 female and 11 male mid-term human fetuses. In male fetuses, the striated muscle initially extended in the frontal, rather than in the horizontal plane. However, a knee-like portion was absent in the female fetal urethra because, on the inferior side of the vaginal end, a wide groove for the future vestibule opened inferiorly. Accordingly, it was difficult for the developing striated muscle to surround the groove, even though there was not a great difference in width or thickness between the female vestibule and the male urethra. The development of a completely circular striated sphincter seems to be impossible in females because of interruption of the frontal plane by the groove-like vestibule. However, we cannot rule out the possibility that before descent of the vagina, the urethral striated muscle extends posteriorly.