Gray commissure

About: Gray commissure is a research topic. Over the lifetime, 40 publications have been published within this topic receiving 3224 citations.

Crossed and uncrossed projections to the cat sacrocaudal spinal cord: III. Axons expressing calcitonin gene-related peptide immunoreactivity.

Abstract: We have investigated the projection patterns of peptidergic small-diameter primary afferent fibers to the cat sacrocaudal spinal cord, a region associated with midline structures of the lower urogenital system and of the tail. Calcitonin gene-related peptide (CGRP)-immunoreactive (CGRP-IR) primary afferent fibers were observed within the superficial laminae, rostrally as the typical inverted U-shaped band that capped the separate dorsal horns (S1 to rostral S2) and caudally as a broad band that spanned the entire mediolateral extent of the fused dorsal horns (caudal S2 and caudal). Within the dorsal gray commissure, labeling was seen as a periodic vertical, midline band. CGRP-IR labeling was prevalent in an extensive mediolateral distribution at the base of the dorsal horn, originating from both lateral and medial collateral bundles that extend from the superficial dorsal horn. Some bundles, in part traveling within the dorsal commissure, conspicuously crossed the midline. In addition to the robust projection to the superficial dorsal horn, there was a more extensive distribution of CGRP-IR fibers within the deeper portions of the cat sacrocaudal dorsal horn than has been reported for other regions of the cat spinal cord. Presumably, these deep projections convey visceral information to projection or segmental neurons at the neck of the dorsal horn and in the region of the central canal. This deep distribution overlaps the reported projections of the pelvic and pudendal nerves. In addition, the contralateral projections of CGRP-IR fibers may form an anatomical substrate of the bilateral receptive fields for selective dorsal horn neurons. The density and variety of CGRP-IR projection patterns is a reflection of the functional attributes of the innervated structures. J. Comp Neurol. 438:388–398, 2001. © 2001 Wiley-Liss, Inc.

Cauda equina syndrome and nitric oxide synthase immunoreactivity in the spinal cord of the dog.

Abstract: Summary The development of the cauda equina syndrome in the dog and the involvement of spinal nitric oxide synthase immunoreactivity (NOS-IR) and catalytic nitric oxide synthase (cNOS) activity were studied in a pain model caused by multiple cauda equina constrictions. Increased NOS-IR was found two days post-constriction in neurons of the deep dorsal horn and in large, mostly bipolar neurons located in the internal basal nucleus of Cajal seen along the medial border of the dorsal horn. Concomitantly, NOS-IR was detected in small neurons close to the medioventral border of the ventral horn. High NOS-IR appeared in a dense sacral vascular body close to the Lissauer tract in S1-S3 segments. Somatic and fiber-like NOS-IR appeared at five days post-constriction in the Lissauer tract and in the lateral and medial collateral pathways arising from the Lissauer tract. Both pathways were accompanied by a dense punctate NOS immunopositive staining. Simultaneously, the internal basal nucleus of Cajal and neuropil of this nucleus exhibited high NOS-IR. A significant decrease in the number of small NOS immunoreactive somata was noted in laminae I-II of L6S2 segments at five days post-constriction while, at the same time, the number of NOS immunoreactive neurons located in laminae VIII and IX was significantly increased. Moreover, high immunopositivity in the sacral vascular body persisted along with a highly expressed NOS-IR staining of vessels supplying the dorsal sacral gray commissure and dorsal horn in S1-S3 segments. cNOS activity, based on a radioassay of compartmentalized gray and white matter regions of lower lumbar segments and non-compartmentalized gray and white matter of S1-S3 segments, proved to be highly variable for both post-constriction periods.

Dual forms of aging-related NADPH diaphorase neurodegeneration in the sacral spinal cord of aged non-human primates

Abstract: NADPH diaphorase (NADPH-d) was used to detected neurodegeneration in animal models. In our previous studies, aging-related NADPH-d positive spheroidal bodies (ANB) occurred in the lumbosacral spinal cord of aged rats. Recently, NADPH-d enlarged-diameter neurites named as megaloneurites were detected in the sacral spinal cord of aged dogs. To generalize the occurrence of megaloneurites and/or ANB in non-human primates, the advanced examination of the aging-related phenotypes was undertaken in the monkeys by using the same approach. We discovered two different anomalous NADPH-d positive alterations, which were expressed as ANB and megaloneurites specially distributed in the superficial dorsal horn, dorsal gray commissure, lateral collateral pathway (LCP) and sacral parasympathetic nucleus in the aged monkeys’ sacral spinal cord, compared with the cervical, thoracic and lumbar segments. In the gracile nucleus of aged monkeys, only aging-related spheroidal bodies were observed and no megaloneurites occurred. The dense, abnormal NADPH-d positive megaloneurites, extremely different from regular NADPH-d positive fibers, were prominent in the sacral segments and occurred in extending from Lissauer’s tract through lamina I along the lateral boundary of the dorsal horn to the region of the SPN. Meanwhile, large diameter punctate NADPH-d activity occurred and scattered in the lateral white matter of the LCP and dorsal root entry zone at the same level of NADPH-d abnormality in the gray matters. Those dot-like NADPH-d alterations were examined by horizontal sectioning and indicated ascending or descending oriental fibers. These NADPH-d megaloneurites had the same composition as the punctate NADPH-d alterations and were co-localized with the vasoactive intestinal peptide (VIP) immunoreaction, while the ANB did not coexist with the VIP immunoreaction. Both ANBs and megaloneurites provide consistent evidence that the anomalous neuritic alterations in the aged sacral spinal cord are referred to as a specialized aging marker in the pelvic visceral organs in non-human primates.

Electron microscopic study of the median structure of the posterior column of the spinal cord of the adult rat with a special reference to the posterior median septum.

Abstract: In neuroanatomy textbooks on humans, the posterior median septum is commonly depicted along the midline of the posterior column of the spinal cord. For intramedullary spinal cord tumors, the standard surgical treatment is posterior midline myelotomy. However, its anatomical basis is still unclear. Therefore, in this study we focused on the ultrastructural characterization of the median structure of the posterior column in an adult rat. In the median part of the fasciculi gracilis, a fine lineal tissue continued from the posterior median sulcus to the 3/4th depth of the fasciculi. At higher magnification, this fine lineal tissue consisted of bundles of astrocytes, which are often disrupted and eventually disappeared. At the junction of the ventral part of the fasciculi cuneatus and the gray commissure, short lineal figures of glial tissues extended dorsally. These lineal figures of glial tissues were morphologically similar to other lineal figures of glial tissues found in the posterior column; bundles of astrocytes extending along the axons that entered the gray commissure and the perivascular lineal figures of glial tissues. In conclusion, this study revealed that the posterior median septum is composed of very fine lineal figures of glial tissues that are often disrupted and eventually disappear. We consider these basic structures to be similar in humans. Therefore, during posterior midline myelotomy, accurately separating along the posterior median septum in the posterior column is extremely difficult.

A pathway of NADPH diaphorase positivity between central canal and pial surface at anterior fissure in spinal cord: Supra fissure area with hypothesis configuring from dog, rat, monkey and pigeon

Abstract: The spinal cord is a cylinder structure in the vertebra and thought a simplified with the gray matter and white matter. Rexed lamination for the gray matter and regional sub-division for whiter matter are completely termed to date. Anterior commissure locates between the central canal and the anterior median fissure. However, some experimental data may still confront with new confined anatomical interpretation. By using NADPH diaphorase [N-d] enzyme histology, we found a vertical oriented neuronal pathway between the central canal and the anterior median fissure in the sacral spinal cord of young adult and aged dog. We used a term supra fissure area [SFA] to illustrate the region which consisted of the gray commissure and anterior white commissure. The N-d pathway was notably observable in aged animals. The vertical neurites revealed the cerebrospinal fluid [CSF] contacting neurites between the anterior median fissure and the central canal. We further examined the monkey, rat and pigeon in the region for better understanding of the structure and potential function. The neurodegeneration of N-d dystrophy was detected in the [SFA] in the thoracic spinal cord of the aged monkey. N-d positive fibers were detected in anterior fissure of the rat spinal cord. N-d fibrous structures were also detected in the pigeon spinal cord. These results suggested a new pathway of CSF contacting neurons and the neuronal communications about the central canal.