地鼠脊髓颈腰膨大部的运动细胞柱

THE MOTOR CELL COLUMNS IN THE CERVICAL AND LUMBAR ENLARGEMENTS OF THE SPINAL CORD OF THE MOLE-RAT

產在北京近郊的地鼠(地羊)的前足約當後足二倍。本研究取二個成長地鼠的脊髓,作切片觀察,注意比較頸、腰膨大部灰、白二質的形勢和前角運動細胞的數量,得到以下的結果:支配前肢的頸膨大部在切面上遠大於支配後肢的腰膨大部。與腰部相較,頸部的前角灰質面積廣闊,各細胞柱形體粗大,界限清明。特在頸部,前角灰質向外突成前、後外角;後者延伸特遠,内合支配趾肌的後後外側柱。此看支配肢肌的前角細胞在二膨大部各階段上的配佈,頸部總是高出腰部。在點定的16-18階段上總計前角細胞的數量,頸部約當腰部1.4-1.5倍。若單看支配肢體遠端的前角後部中細胞的總值,頸部超過腰部就達2.2-2.8倍。前足第三、四趾特別巨大。支配趾肌的後後外側柱在頸部比腰部粗而且長。大致說來,此柱中段的細胞較大、較多、更分出亞柱。這些跡象暗示控制巨大的第三、四趾的細胞似集中這個階段。地鼠前、後肢大小的懸殊反映到前角灰質發展的程度。這再次證明脊髓中樞的發展與所支配的周緣器官和動物的生活方式是相系的。

The forefoot of the mole-rat(Myospalax myospalax psilurus),found in the vicinity of Peking,is twice as large as its hindfoot.Serial sections of the spinal cords of two adult animals were compared as to the configuration of the white and gray matters and to the relative magnitude of the motor cells in the anterior horn of the cervical and lumbar enlargements.The results were as follows:The cervical enlargement innervating the foreleg is much larger in cross section than the lumbar enlargement which innervates the hindleg.As compared to the lumbo-sacral levels,the anterior horn of the cervical region is broader in area and its cell columns attain greater proportions with better delimitation.In the cervical enlargement,the gray matter of the anterior horn expands laterally to form the antero-external and postero-external angles.The latter thrusts far out and contains the retroposterolateral column supplying the digital muscles.At equal-spaced representative levels,the cervical enlargement consis-tently out-ranks the lumbar enlargement in the distribution of the motor cells in the anterior horn,which control the leg muscles.The sum total of such cells at all the levels of the cervical enlargement is 1.4-1.5 times that of the lumbar enlargement.Moreover,when taken separately,the total motor cells in the posterior part of the anterior horn of the cervical enlargement,which innervates the distal portion of the foreleg,are 2.2-2.8 times that of the lumbar enlargement.The third and fourth toes assume enormous size on the forefoot.The retroposterolateral column which supplies the digital musculature is larger and longer in the cervical intumescence.The cells in the middle segment of this column are generally larger-sized,more numerous and with better-defined subdivisions.These traits apparently suggest that the cells in control of the third and fourth toes are mainly located at this plane.The striking difference in the size of the fore and hind feet reflects itself in the differential development of the anterior horn cells in the cervical and lumbar enlargements.This goes to show once more that the motor centers of the spinal cord develop in correlation with the peripheral organs innervated as well as with the particular mode of life of the animal.