备用背根猫脊髓Ⅱ板层组织对鸡胚背根节神经突起生长的影响

用１０只存活５ｄ的单侧后肢备用根猫（切除Ｌ１～Ｌ５、Ｌ７～Ｓ２背根节，保留Ｌ６背根），取手术侧（实验组）和非手术侧（对照组）脊髓Ⅱ板层组织块及提取液分别与Ｈａｍｂｕｒｇｅｒ３５期鸡胚背根节进行悬滴培养，并以不加植块的背根节培养作参照。比较各组在同一观测时间的差异．结果：（１）各组背根节从培养２４ｈ到４８ｈ，其神经突起均明显增长；（２）同一观测时间内，对照组与参照组的神经突起少而短，从背根节迁出的细胞较多，而实验组神经突起多且长，迁出的细胞较少；（３）在两个观测时间，植块与提取液培养的实验组背根节神经突起平均长度均显著长于对照组者，而对照组与参照组背根节神经突起长度的差异无显著性．表明部分腰骶背根切除猫，其脊髓Ⅱ板层及其提取液的促神经突起生长活性增强．

THE NEURITE OUTGROWTH PROMOTING EFFECT OF SPINAL LAMINA Ⅱ FROM SPARED DORSAL ROOT CAT ON CULTURED DORSAL ROOT GANGLION OF CHICKEN EMBRYO

Our previous studies have confirmed the plasticity of spinal lamina Ⅱ after partial deafferentation in adult cat by quantitative electron microscopic method. In order to probe the mechanism of this plasticity, ten adult male cats received unilateral lumbosacral dorsal rhizotomy from L1 to S2 with sparing of L6 and allowed to survive for 5 days, were used. Tissue explants of spinal lamina Ⅱ from both operated and unoperated side of L4 to S2 spinal segment were cut respectively from five others.The tissue extract were made with Hanks Balanced salt solution. conditioned media contained 1/3 extract and 2/3 culture media. The tissue explants or the conditioned media were co-cultured with a dorsal root ganglion (DRG) of chicken embryo at Hamburger stage 35 by modified hanging drop culture technigue. A DRG co-cultured with an operated spinal lamina Ⅱ explant or conditioned media was named as the experimental group snd that with an unoperated spinal lamina Ⅱ explant or conditioned media as the control group. Another group of DRG cultured alone as the reference group. Tissue explants or conditioned media from one cat were used for one batch of cultures.Microphotographs of every DRG were taken at 24 h and 48 h of incubation and the average neurite length for each group were measured. The differences among all groups at the same test time were compared. The results were as follows: (1)There was a significant neurite outgrowth from 24 h to 48 h of the cultured DRGs in groups. (2)As compared with the control and the reference grorps, DRGs of the experimental group demonstrated much more and longer neurites and with lesscell migrated out from the DRGs. (3)The mean neurite length of the experimental group was statistically longer than that of the control and reference group. (4)The neurites of some DRGs in experimental grorp extended toward the explant of spinal lamina Ⅱ. (5)There was no significant difference of the mean neurite length between control and reference group. Our results revealed that the neurite outgrowth promoting activity increased in the spinal lamina Ⅱ of partial deafferented spinal cord of cat.