THE ORIGINS OF THE DESCENDING PRO-PRIOSPINAL TRACT AND THE CONNEC-TIONS OF THE NUCLEUS DORSOLA-TERAL FUNICULUS IN THE SPINAL CORD OF THE RAT / 解剖学报

HRP solution was injected into the right side of the thoracic spinal cord of the rat with a micropipette to observe the neurons which give rise to the descending propiospinal tract. Labeled neurons were distributed throughout the bilateral Rexed's laminae Ⅰ-Ⅹ of the spinal cord in the segments rostral to the site of HRP application. The greatest number of the labeled cells were consistently found in lamina Ⅶ (including the intermediolateral nucleus), and then in laminae Ⅷ and Ⅳ. Our results verified the existence of the nucleus of the dorsolateral funiculus and its intraspinal connections in the spinal cord of the rat. This nucleus gives rise to the descending projections to the lower spinal segments.

THE DISTRIBUTION OF NEURONS CONSTITUTING THE SUPERIOR MESENTERIC PLEXUS OF THE CAT—A HRP STUDY / 解剖学报

The origin of nerves innervating the small intestine and oral part of the colon of the cat was studied by means of the retrograde axonal transport of HRP. Twelve adult cats were used in this experiment. The proximal cut end of the superior mesenteric plexus was immersed in HRP solution, in order to localize the neurons which contribute fibers to this plexus. Neurohistochemical procedures were processed according to Mesulam's tetramethylbenzidine (TMB) method. HRP labeled cells or fibers can be identified bilaterally in the following places: 1. The dorsal motor nucleus of the vagus nerve; about 80% of the labeled cells were found in a region from 0.4mm below to 2.0 mm above the obex, approximately at the rostral two-thirds of the middle segment of this nucleus. 2. The reticular formation of medulla; only a few cells labeled and 92% of them were located in an area from 0.2, mm to 2.7 mm above the obex. 3. The coeliac-superior mesenteric ganglion complex; almost all of the labeled cells were concentrated in the caudal part of it, near the origin of the superior mesenterie plexus. 4. The nodose ganglion; most of the oval or round labeled cells were of medium or small size, their diameters vary from 30 to 40?m, and the average total numbers of the labeled cells were 661 in the left and 695 in the right ganglion respectively. 5. The spinal ganglia; small round or oval labeled cells (25～45 ?m in diameter) were found in the left T_2 to L_5 and right T_2 to L_4 ganglia, with the most heavily labeled segments at T_(13) and L_1 (left, mean 365; right, mean 34% of all labeled cells). The average total number of the labeled Cells were 1872 in the left and 1698 in the right side. 6. Transganglionic labeled fibers were seen in the gracile nuclei of one cat, suggesting that HRP molecules are transported retrogradely in the peripheral process and anterogradely in the centrally projecting process of the same neuron of spinal ganglia.

SYMPATHETIC PREGANGLIONIC NEURONS IN THE RABBIT SPINAL CORD PROJECTING TO THE SUPERIOR CERVICAL GANGLION——HRP STUDY / 解剖学报

The purpose of this research work is to find out the longitudinal distribution of the preganglionic neurons which project to the superior cervical sympathetic ganglion (SCSG). Experiments were performed on 12 adult rabbits and a monkey. Under sodium pentobarbital anesthesia, 20 microliters of 10% HRP were injected slowly into the rabbit's SCSG. In the monkey, 20 microliters of 15% HRP was injected.After a postoperative survival time of 3～6 days, the animals were perfused through,the ascending aorta with a cold fixative mixture composed of 2% paraformaldehyde and 1.25% glutaraldyhyde in 0.1mol phosphatebuffer at pH 7.4. The spinal cord segments C_1～L_3 were cut serially in transverse plane on a cryostat at 48 micra.The HRP reaction product was demonstrated according to Mesulam's (1976) benzidine blue reaction method, and counterstained with neutral red.HRP labeled neurons in the spinal cord were located exclusively on the side ipsilateral to the injected SCSG. The total number of labeled cells were 7908 in 12 rabbits, but the number of labeled cells varied from animal to animal. The highest amount was 1690 (423~#) and the lowest amount was 71 (425~#). The longitudinal distribution of the labeled cells in 12 rabbits was 12 segaments of the spinal cord (C_6～T_9), but the largest proportion (86.18%) of them was concentrated from T_1 to T_4, especially at the level of T_2 and T_3 (56.22%), and with a peak at T_2 (29.10%).In cross section of the spinal cord. HRP-labeled cells were concentrated in four cell groups, they are: nucleus intermediolateralis pars principalis (ILp), nucleus intermediolateralis pars funicularis (ILf), nucleus intercalatus (IC) and nucleus intercalatus pars paraependymalis (ICpe). The latter is subdivided into dorsal portion and ventral portion. HRP positive cells were mainly located in the ILp, In 12 rabbits about 92.99% cells were located in it. A small portion of labeled cells(6.25%) were seen in the ILf. A few labeled neurons could be detected within,the IC (0.68%) and ICpe (0.08%). Furthermore, occasionally, very few labeled cells were found at the dorsol portion of the anterior horn.In the monkey, generally speaking, the pattern of the distribution of labeled cells was the same as the rabbit.

RELATIVE POSITIONS OF THE WHITE AND GRAY COMMUNICATING RAMI / 解剖学报

The rami communicantes in five adult cadavers were examined.All the rami were taken down serially in three cadavers;each pair was cut transversely into two parts to be separately sectioned and treated by the Weigert-Pal and Ranson's pyridine silver methods.Their components were observed under microscope for the presence or absence of the myelin sheath in order to identify a filament as of white or gray ramus. On the thoraco-lumbar levels,the shallower or lower ramus was coarser of the pair and its junction with the respective spinal nerve was also farther from the corresponding intervertebral foramen.It was composed mainly of myelinated fibers and hence designated as the white ramus.On the other hand,the deeper or upper member of the two was relatively slender and its junction with the pertinent spinal nerve was nearer to the foramen.This branch contained chiefly unmyelinated fibers and represented the gray ramus.The oblique ramus,which occurred occasionally and consisted mainly of myelinated elements,was also clas- sified with the white ramus. The White rami were definitely distributed from thoracic 1 to lumbar 3.The gray rami of the cervical 6-8 and lumbar 4-5 also contained a number of mye- linated fibers and even some sympathetic cells were aberrated into them.The upper cervical and lower sacral gray rami contained but rarely any myelinated elements. Thus,the white and gray communicating rami were formed not purely of myelinated or unmyelinated fibers,but a mixture of both,with,however,the predominence of one kind.In general,it is possible to ascertain the relative positions of the two rami in a cadaver under dissection.