The morphological characteristies and distribution of the choline acetyltransferase (ChAT)-like immunoreactive neuronal elements in the sacral and coccygeal spinal cord of the cat were studied by avidin-biotin combined immunohistochemical technique. The results were as follows:1. The ChAT-positive neuronsIn the ventral horn, ChAT-positive motoneurons were located in the motor columns. These neurons can be divided into three types: the large multipolar neurons, the medium-sized multipolar neurons and the small motoneurons. The color of anti-ChAT reaction product in the large and medium-sized motoneurons varied from light to moderate brown, but the small motoneurons were heavily stained.In the intermediate zone, three groups of ChAT-positive parasympathetic preganglionic neurons were observed in 3 areas: the intermediolateral nucleus (IL) in the lateral part of lamina Ⅶ, the intermediomedial nucleus (IM) dorsal-lateral to the central canal, the intercalated nucleus (IC) looated between IL and IM. The somata of these neurons were round, oval, and fusiform in shape. In the lamina Ⅶ, there were some prominent ChAT medium-sized multipolar neurons named partition cells, scattered among the extended fibers of the parasympathetic preganglionic cells. In the vicinity of the central canal could be observed small CHATpositive cells.In the ventral part of the dorsal commissural nucleus region, a number of ChAT-positive cells were present. They were round, oval and fusiform in shape and small in size (averaging 11.91?m?17.38?m). Occasionally, they were observed in the dorsal part.In addition, some of the ChAT-positive neurons were scattered in laminae Ⅲ-Ⅴ.2. The ChAT-positive fibers and terminals.The ChAT-positive punctate structures were observed throughout the sacral and coccygeal spinal cord resembling terminal branch and terminals. The density of the distribution of the punctate structures was arranged, from high to low, in the following order: the ventral horn, intermediate zone, central gray matter and dorsal commissural nucleus region, and the dorsal horn. In the dorsal horn, many of these punctate structures Were concentrated in two laminae, the major one being lamina Ⅲ and a minor one lamina Ⅰ. But in lamina Ⅱ, they were rare. In the ventral horn such punctate structures were often closely contacted with large and medium-sized ChAT-positive motoneuronal somata and dendrites. Some axonal terminal branch with varicosities closely surrounded a somata and bases of dendrites, and formed contacts with the same somata and its dendrites. In the intermediate zone, there were many transverse fibers associated among the parasympathetic preganglionic nuclei.

In the present study the projections were traced from the red nucleus and the region of the griseum centrale mesencephali to the inferior olivary complex (IOC) by using the method of anterograde transport of the WGA-HRP in the cat. The results has led to the following conclusions: 1.Both injected regions have positive projections to the ipsilateral IOC. No labeled cells were found in the IOC. 2. The projections from the red nucleus to the IOC terminated in the dorsal lamina of the principal olive and the dorsal end of the caudal half of the medial accessory olive. The projections from the region of the griseum centrale mesencephali to the IOC terminated in the whole medial accessory olive, ventral lamina of the principal olive and the connecting part between the ventrolateral end of ventral lamina and dorsal lamina of the principal olive. The most heavily labeled regions were the dorsal lamina of the principal olive among the regions receiving projection from the red nucleus and the medial accessory olive among those receiving fibers from the griseum centrale mesencephali region, the other regions were more lightly labeled.3. Some labeled regions of the IOC in the present study overlapped with those regions receiving fibers from the spinal cord reported by others. In the present study the labeled area is more extensive than those reported in the literature.

Using Nissl method, Kluver and Barrera method and rapid Golgi method, we found that there were large, medium and small-sized neurons in lamina V of medullary dorsal horn Of the cat, the medium-sized neurons were most numerous and the large-sized neurons were least in number. According to the dendritic branching pattern and the number of spines, the lamina Ⅴ neurons could be divided into two categories——the radiate neuron and bushy neuron. The former contained three subcategories: pyramidal, polygonal and bipolar neurons. Spiny and smooth types were found in pyramidal and polygonal neurons. Considering with the results of neurophysiologic research and intracellular injection of HRP by others, we presume that different types of neurons in lamina Ⅴ might also differ functionally. In addition, according to the results of transganglionic transport of HRP from the peripheral and retrograde transport of HRP from the thalamus, it was assumed that some neurons in lamina V received messages from the primary afferent in lamina Ⅴ, Ⅳ, and Ⅲ, and thence, transmitted them to the thalamus.

After a injection of kainic acid or WGA-HRP into the red nucleus, the degenerated or HRP labeled terminals in lamina V of the contralateral trigeminal subnucleus caudalis (Vc) were examined electron microscopically. It was found that the degenerated and HRP labeled terminals contained vesicles of spherical or mixed type, and formed symmetrical synapses with medium- or small-sized dendrites. These findings suggested that the descending rubral fibers might be inhibitory in regulating the activity of the neurons, and supposed to be sensory in nature. Thus the red nucleus might play certain role in modulation of the oro-facial somatosensory transmission (including pain) in lamina V of Vc, besides the rubrospinal influence on the involuntary motor functions of the spinal anterior horn. The technique for tracing neural connections with electron microscope was discussed as well.

The indirect pathway of the somatic afferent elements from trigeminal nerve (TGN) to nucleus tractus solitarii (NTS) was studied with the light and electron microscopic HRP transganglionic and retrograde tracing. After HRP was injected into NTS at the level of obex, the retrogradely labeled cells were mainly found in the interstitial nucleus buried in the spinal tract of TGN along caudal subnucleus. The interstitial nucleus was also the terminating area of the primary afferent fibers of lingual and inferior orbital nerves. Under electron microscope, it was found that the primary afferent terminals of lingual and inferior orbital nerves formed synapses on the dendrites of neurons in the interstitial nucleus. Moreover, in cellular architecture, the interstitial nucleus and the superficial laminae of the caudal nucleus of TGN were similar and continuous with each other. Hence, the pathway from the TGN to NTS via the interstitial nucleus is consisted of two neurons and the sensations transmitted through this pathway may be considered to be somatic. It is presumed that this pathway composed of two neurons might modulate the visceral afferent function in NTS when certain points in the skin area innervated by TGN were acupunctured.

Objective To observe the co-localization of phosphate activated glutaminase(PAG) and parvalbumin(PV) in neurons,and the connections between preprodynorphin-like immunoreactive(PPD-LI) or preproenkephalin(PPE)-LI terminals and coexistent neurons of PAG-LI and PV-LI in the mesencephalic trigeminal nucleus(Vme) of the rat. Methods In the present study,the immunofluorescence histochemical double-staining and triple-staining technique were used.The staining results were observed under a confocal laser scanning microscope. Results Many neuronal cell bodies through the whole rostrocaudal extent of Vme showed PAG-LI and PV-LI.The majority of them were large pseudounipolar neurons.A considerable number of PV-LI neurons expressed PAG-LI,cell counts showed that more than 95% of PV-I neurons were immunostained with PAG-LI.Confocal laser scanning microscope further revealed that axonal varicosities with PPD-LI or PPE-LI were found to make close contact with neuronal cell bodies of Vme showed both PAG-LI and PV-LI. Conclusion The present results indicated that the glutamate and PV are involved in the transmission of the trigeminal proprioceptive sensory singals from the Vme to the higher centers,simultaneously,dynorphin-and enkephalin-immuoreactive terminals may also exert modulatory influence on the primary afferent cell bodies of the Vme.;

Objective To investigate whether the serotonin(5\|HT)\|like immunoreactive axons synapse upon the second\|order neurons on the central pathway of the trigeminal proprioception in the rat. Methods Electron microscopic double\|labeling of retrograde tract\|tracing technique combined with immunohistochemistry. Results Following the injection of wheat germ agglutinin\|horseradish peroxidase (WGA\|HRP) into the dorsomedial part of the principal sensory trigeminal nucleus(Vpdm) of the rat and the immunostaining for 5\|HT, there were neurons retrogradely labeled by WGA\|HRP and axon terminals with 5\|HT\|like immunoreactivity(5\|HT\|LI) in the dorsomedial part of the subnucleus oralis of the spinal trigeminal nucleus and its adjacent lateral reticular formation(Vodm\|LRF).At the electron microscopic level,the 5\|HT\|immunostained axonal profiles were observed to make synaptic contacts with the WGA\|HRP\|labeled neurons.Both the axon\|somatic and axon\|dendritic synapses were found.These synapses were mainly of symmetric type although the asymmetric ones were also seen.Conclusion\ The present results provided a morphologic basis for the serotoninergic terminals which might be involved in the regulatory effect for the trigeminal proprioceptive information transmission.\;[

Previous studies showed that the Vodm-LRF-including the dorsomedial part of the subnucleus oralis of the spinal trigeminal nucleus and its adjacent lateral reticular formation--contained the second-order neurons on the central pathway of the trigeminal proprioceptive sensation of the rat and the "zone-shaped area"-including the caudolateral part of the supratrigeminal nucleus (Vsup-CL). The dorsomedial part of principal sensory trigeminal nucleus (Vpdm) and two newly found nuclei: the areaventral to the motor trigeminal nucleus (AVM) and the area dorsal to the superior olivary nucleus (ADO)-contained the third order neurons of this pathway. Parvalbumin (PV) is one of the calcium-binding proteins, In this pathway, many PV-like immunoreactive (PV-LI) neurons were observed in Vodm LRF and the "zone-shaped arena", hut there has been no reports so far regarding whether these PV-LI neurons are projection neurons responsible for the transmission of proprioceptive information or the interneurons serving the modulatory function, in the present study, our aim was to solve the problem by a double labeling study by using retrograde tracing method combined with immunofluorescence histochemistry. The results showed that: (1) following the unilateral Fluoro-Gold (FG) injections into the ventral posteromedial nucleus (VPM) of the thalamus and the separated parts of the "zone-shaped area", viz, Vpdm, ADO and AVM, many FG-labeled neurons were always found contralaterally in the "zone-shaped area" and ipsilaterally in the Vodm-LRF, respectively; (2) in either the "zone-shaped area" or the Vodm-LRF, a substantial number of the FG retrogradely labeled neurons showed PV-LI. In the Vsup-CL, Vpdm, AVM and ADO, about 57%, 55%, 11% and 4% of the neurons projecting to the VPM of the thalamus showed pV-LI, respectively. Of the total population of PV-LI neurons in the Vsup-CL, Vpdm. AVM and ADO, about 23%, 79%, 53% and 16% were labeled by FG, respectively. Most of these PV/FG double-labeled neurons were medium- to small-sized, round, piriform or irregular in shape. On the other hand, in the Vodm-LRF, approximately 33%, 34% and 50% of the neurons which projected to the Vpdm, AVM and ADO expressed PV-LI, respectively. The percentage of PV/FG double-labeled neurons to the total number of the PV-LI neurons in Vpdm, AVM or ADO were 26%, 17% or 11%, respectively, The present results indicated that PV might play an important role in the transmission of the trigeminal proprioceptive information of the rat from Vndm-LRF to the contralateral VPM of the thalamus through the "zone-shaped area".

HRP solution was injected into the dorsal commissural nucleus (DCN) of segment L_6 or S_1 of the spinal cord and laterodorsal tegmental area(TLD)——take the Barrington's nucleus as its center and lateral parabrachial nucleus (PBL) of the rostral pons in different individuals of the rats. After HRP was injected into the DCN, labelled neurons and dense terminals were found in Barrington's nucleus, and labelled terminals appeared in the PBL. When the unilateral TLD was injected the labelled cells and terminals were found in the DCN and bilateral intermediate zone (IM), and formed a band of labelled neurons and terminals. When the PBL was injected the labelled neurons were observed in the DCN and bilateral IM. A few labelled neurons were found in lamina Ⅰ in the latter two experimental groups.Based on the present and previous studies, the authors got the following understandings:1. Morphylogically, the present study for the first time demonstrated that, the micturition reflex arch through the pontine consists of following parts: the primary afferent neurons of the bladder→secondary relay neurons of DCN→Barrington's nucleus→IM (mainly IML) parasympathetic preganglionic neurons→parasympathetic postganglionic neurons.2. According to the present and previous researches, the authors conjecture that, the secondary fibers of visceral sensation of the pelvic organs originate from the neurons of DCN, IM and lamina I and project into the PBL.3. According to the facts mentioned above, we presume that the DCN and bilateral IM constitute a complex and named it the 'visceral field', and which is closely associated with the pelvic organs. This field has widespread connections with the peripheral efferent and afferent nerves. On the other hand, i t contains a lot of relay neurons projecting into Barrington's nucleus and PBL and receives the terminals of descending fibers of the neurons of the Barrington's nucleus. The descending fibers also project into the Onuf's nucleus.In addition, the present study disscussed the complicated functions of the DCN systematically.

2?l 10% ricin were injected into the pelvic nerve of cats. After 3～5 survival days 20% HRP solution was injected into the ipsilateral lateral parabrachial nucleus, 2～3 days later the animals were perfused with paraformaldehyde and glutaraldehyde, the brain and spinal cord were removed and processed for light and electron microscopy. It was confirmed that the primary afferent terminals (degenerated) of pelvic nerve formed axo-dendritic and axo-somatic synapses with the retrograde labelled neurons projected to the lateral parabrachial nucleus which were located in the dorsal commissure nucleus (DCN), intermediolateral nucleus (IML) and lamina Ⅰ of sacral spinal cord. Hence, the secondary afferent pathway of pelvic visceral sensation, as. indicated at the ultrastructural level, might originate from DCN, IML and lamina Ⅰ of sacral spinal cord and project to the lateral parabrachial nucleus.