Experimental Study of Effect of Aluminum on Learning and Memory and the Changes of Synaptic Interface Constructure in Hippocampus CA3 Area in Rats / 解剖科学进展

Objective　To study the effect of aluminum on learning and memory and the synaptic interface constructure in hippocampus CA3 area in rats. Methods　The electrical maze were used to test the behavioral reaction of rats. Some parameters of synaptic interface structure were measured by the method of ultrastructural quantitative analysis in hippocampus CA3 area in the rats. Results　The time coming through the E-maze prolonged siginificantly in the experimental group compared with the normal control (P＜0.01), meanwhile the cyto-apparatus demonstrated the pathogenetic changes. Amounts of synapse obviously reduced and the post-synaptic density turned thinner in experimental group than in the control group (P＜0.01). Conclusion　Aluminum can cause the malfunction on learning and memory, which related to the plastic of synapse.

DISTRIBUTION OF AFFERENT FIBERS IN VENTRAL SPINAL ROOTS TO THE SPINAL CORD AND MEDULLA OBLONGATA / 解剖学报

After severance the ventral spinal roots in 10 dogs, the distribution of the anterograde degeneration was studied by means of Nauta's technique with the following conclusions:1. After sectioning the ventral roots, degenerating fibers (including preterminal and terminal fibers) appeared regularly in the spinal cord and medulla oblongata. This confirms that there are afferent fibers which project into the central nervous system via the ventral spinal roots.2. These degenerating fibers ascended not only in the posterior funiculi, but also in the gray matter, so that the preterminal and terminal degenerations of the terminal branches or collateral branches were found in the columna grisea posterior of the thoracic and cervical segments above the surgically operated segments of the spinal cord.3. The preterminal and terminal degenerations were found in the reticular areas of the nucleus gracilis of the medulla oblongata and around the non-cluster cells.4. Degenerating fibers were unequally distributed, most of them located ipsilaterally. The degenerating fibers decreased in number in rostral segments.5. Afferent fibers in ventral roots differ from those in dorsal roots in distribution:a) From the operated segment and to far more rostral segments, afferent fibers of the ventral root were distributed in a more medial position in the spinal dorsal gray column, viz, "medial tendency", and then ascended after interposing into the funiculi gracilis. This is different from the afferent fibers of the dorsal root in the control group which were distributed in "equal tendency" in the dorsal column and took a "lateral addition fashion" of entering the funiculi gracilis.b) Apparently, much more afferent fibers in ventral roots projected contralaterally than those in the dorsal roots.c) It was also characteristic that the afferent fibers in ventral roots projected further toward the rostral segments of the spinal cord.

OBSERVATIONS ON THE NEURONS IN THE SPINAL VENTRAL ROOTS OF THE INFANTS / 解剖学报

Spinal ventral roots of 10 infants were examined. Eight pairs of spinal ventral roots were cut off from 10 infant cadavers including the following segments: C_6, C_7,T_5, T_(11), L_3, L_5, S_1, and S_2. Serial longitudenal sections were prepared and stained with Niss's method. The presence of sensory neurons were recorded and their num- ber were counted. The results were as follows:Nerve cells in the spinal ventral roots were found in all the cases examined.The minimal number was 58 cells in No. 8, and the maximal number was 203 in No. 10. There were altogether 1,446 cells found in 117 spinal roots, and no cell in 35 roots. The highest number of nerve cells observed in a single root was 83.The nerve cells were scattered all over the spinal ventral root from its attachment to the spinal cord to its junction with the dorsal root. More cells were found in its distal extremity close to the spinal ganglion. They appeared singly, in groups of two or three, or in a cluster looking like a small ganglion. They were usually distributed among the nerve fibers, or around the blood vessels, or beneath the epineurium of the ventral root. They were ovoid in shape, with the long axis paralleling the course of nerve fibers. Nuclei were round in shape, Nissl granules were evenly distributed in the cytoplasm. They were different in sizes, ranging from 15 to 60 ?m. There were 808 cells (56%) more than 30～50 ?m. 607 cells (42%) less than 30 ?m, which accounted 98% of the total cell population.