Objective To reveal the detailed histological characteristics of pyramidal neuron cell bodies and their axonal projections along the corticospinal tract in the primary motor cortex(M1)of the brain,by using the biotinylated dextran amine(BDA)neural tracing technique combined with panoramic and local microscopic imaging technologies.Methods A total of 100 nL of 10％BDA(10,000 molecular weight)was injected into M1 region using stereotaxic system.The distribution of BDA labeling along the corticospinal tract was continuously tracked with panoramic tissue scanning analysis system.Detailed observations of the histological characteristics of BDA labeling were carried out with laser confocal microscope.Results It is more convenient to observe the overall distribution of BDA neural labeling by using the panoramic tissue scanning analysis system.Around the injection site in M1,the BDA labeling was shown in the somas of pyramidal neurons in layer V.In the M1 region corresponding to the contralateral site of the injection site and ipsilateral primary sensory cortex,BDA showed predominantly the anterograde labeled nerve fibers accompanied by a few retrograde labeled neurons.Besides,BDA labeled nerve fibers-including bundles and terminals-projecting to regions such as the ipsilateral striatum,thalamus,internal capsule,cerebral peduncle,and pons,and further reaching the contralateral spinal cord via the brainstem pyramidal decussation.Confocal microscopy and its 3D reconstruction system facilitated detailed analysis of the local microscopic features of BDA labeling,revealing retrograde labeled neuron cell bodies,dendrites and their spines,as well as anterograde labeled nerve fibers and their terminals.Conclusions These findings demonstrated that the integration of traditional BDA neural tracing with panoramic tissue scanning analysis and confocal microscopy provided an effective approach to the observation and analysis of long-projection neural circuits from panoramic to local perspectives,with broad application prospects.

Objective To reveal the detailed histological characteristics of pyramidal neuron cell bodies and their axonal projections along the corticospinal tract in the primary motor cortex(M1)of the brain,by using the biotinylated dextran amine(BDA)neural tracing technique combined with panoramic and local microscopic imaging technologies.Methods A total of 100 nL of 10％BDA(10,000 molecular weight)was injected into M1 region using stereotaxic system.The distribution of BDA labeling along the corticospinal tract was continuously tracked with panoramic tissue scanning analysis system.Detailed observations of the histological characteristics of BDA labeling were carried out with laser confocal microscope.Results It is more convenient to observe the overall distribution of BDA neural labeling by using the panoramic tissue scanning analysis system.Around the injection site in M1,the BDA labeling was shown in the somas of pyramidal neurons in layer V.In the M1 region corresponding to the contralateral site of the injection site and ipsilateral primary sensory cortex,BDA showed predominantly the anterograde labeled nerve fibers accompanied by a few retrograde labeled neurons.Besides,BDA labeled nerve fibers-including bundles and terminals-projecting to regions such as the ipsilateral striatum,thalamus,internal capsule,cerebral peduncle,and pons,and further reaching the contralateral spinal cord via the brainstem pyramidal decussation.Confocal microscopy and its 3D reconstruction system facilitated detailed analysis of the local microscopic features of BDA labeling,revealing retrograde labeled neuron cell bodies,dendrites and their spines,as well as anterograde labeled nerve fibers and their terminals.Conclusions These findings demonstrated that the integration of traditional BDA neural tracing with panoramic tissue scanning analysis and confocal microscopy provided an effective approach to the observation and analysis of long-projection neural circuits from panoramic to local perspectives,with broad application prospects.

The present study aims to investigate the kinetic histocytochemical changes of acupoints in different condition. The expression of tryptase (+) mast cells, histamine (HA) , serotonin (5-HT) and nociceptive neuropeptides including calcitonin gene-related peptide (CGRP) and substance P (SP) were observed by immunohistochemistry combined with confocal technology. Mast cells were labeled with anti-mast cell tryptase antibody and simultaneously with HA or 5-HT primary antibodies to observe their co-expression. The results showed that: (1) SP and CGRP were expressed more highly on the cutaneous nerve fibers of "Hegu" (LI 4) after acupuncture stimulation than that of the control. Mast cells aggregated in close proximity to the blood vessels in intra-epidermis and dermis, and some of them with degranulation in the lower dermis and subcutaneous tissue of "Hegu" (LI 4). Both mast cells and their granules appeared with HA (+) and 5-HT (+) expression at stimulated LI 4 sites, while a few intact mast cells with a little expression of 5-HT and HA were distributed in areas of non-stimulated Ll 4. (2) The acupoints in different locations such as Baihui (GV 20), Weishu (BL 21), Zhongwan (CV 12) and LI 4 had the same constituent but the contents were different. (3) The histocytochemical responses of acupoints sensitized by the Gastric mucosa injury (GMI) were also investigated. GMI resulted in neurogenic plasma extravasation by Evans Blue (EB) in the skin of the acupoints over the back and abdomen, which mostly occurred in the T9-T11 dermatomere. The EB extravasation dots just like acupoints sensitization appeared after GMI and disappeared gradually during the natural self-recovery of the gastric mucosa. More SP and CGRP positive nerve fibers were distributed in EB dots than in regions beside EB dots and in the control, mostly distributed in the nerve fibers around both the vessels and root of hair follicle. Mast cells also aggregated and degranulated to release algogenic substances of 5-HT and HA around the vessels in areas of the EB dots. Collectively the acupoints displayed the same histocytochemical responses due to either acupuncture stimulation or GMI. This may potentially be the histocytochemical basis in the local acupoints and acupoints displayed kinetic changes in different condition.
Acupuncture Points ; Acupuncture Therapy ; Animals ; Calcitonin Gene-Related Peptide ; metabolism ; Gastric Mucosa ; chemistry ; metabolism ; Histocytochemistry ; Humans ; Mast Cells ; chemistry ; metabolism ; Mice ; Rats ; Serotonin ; metabolism ; Skin ; chemistry ; metabolism ; Substance P ; metabolism

L6.A longitudinal column of HRP-labeled motoneurons was found in the dorsolateral and mediolateral portions of the spinal cord,distributing in the lamina Ⅸ from the caudal L4 to the rostral L6.Additionally,the transganglionic HRP-labeled central projection axonal terminals were found to be dense in the central part of laminae Ⅰ-Ⅱ from L4 to the rostral L6,and to scatter in the central part of gracile nucleus.Conclusion HRP-labeled primary afferent and efferent innervating acupoint "Taixi"(KI 3) are DRGs of L4-L6,the dorsolateral and mediolateral motoneuron columns of L4-L6,and the centrally projecting axonal terminals of laminae Ⅰ-Ⅱ of the spinal cord and the gracile nucleus.