【作者】 徐永平；

【导师】 张涌；

【作者基本信息】 西北农林科技大学 ， 临床兽医学， 2002， 博士

【摘要】 本论文从解剖学、组织学及细胞学方面对山羊胚胎中神经系统的形成和发育进行了系统的研究。主要结果如下： 1．山羊胚胎脑和脊髓生长发育具有快慢交替的阶段性变化规律。发育早期脑的生长速度要快于同期脊髓的生长速度。出生前，大脑在长、宽、高三个方向上的发育表现出不均衡的特点。脊髓不同节段直径的变化表明，各个节段的生长高峰期的出现的时间、数量和增长趋势都不一致。 2．山羊胚胎脊髓的神经管到E6w末才形成了完整的三层同心圆结构。脊髓神经管的组织发生和脊髓灰质的形成在时间上交互重叠。脊髓灰质结构中，有些结构发生早，而神经元分化发育较晚，如侧角、胶状质；有些结构发生虽然晚，但其中的神经元胞体分化发育则较早，如Clarke氏背核；有些结构发生早，神经元分化发育也早，如腹角运动神经元。 3．发现了光镜下发育中神经元胞体形态变化经历以下几个阶段：①未分化细胞，仅见到细胞核，着色较深，聚集形成核团原基。②不成熟神经元，神经元开始发育，细胞核的增大，着色变浅，少数神经元胞体轮廓模糊，其数量逐渐增多，此类细胞数量的增加方式与核团自身特点有关。③幼稚神经元，神经元胞体变大，着色较深，轮廓清晰，细胞核着色变浅，有的成较大的淡染泡状核，中央核仁明显。④成熟期神经元，胞体着色变浅，尼氏颗粒开始出现，并不断变大增多，细胞核多为淡染的泡状核，神经元胞体逐渐具备成熟神经元的特点。不同核团中的神经元发育变化的时间有很大的差异，这种差异与相应的核团的结构特点相适应。同一核团内，不同神经元个体的发育不完全同步，但其变化规律是一致的。 4．发现山羊脑内各脑区的核团发生和形成的时间略有差异，延髓和脑桥内部的核团多在E6w以前形成。但脑桥的耳蜗神经核和前庭神经核，其发生和形成持续的时间略长一些。中脑灰质结构的形成从E6w初～E8w，持续时间较长，明显晚于脑桥和延髓。间脑内灰质结构的形成于E6w末～E12w。端脑内部结构的形成始于E6w末，到E8w时端脑内的结构基本都已出现，但是大脑皮质全部形成一直持续到E12w以后。小脑皮质形成于E6w末，其外颗粒层这个次级生发中心在E21w仍然存在，说明小脑皮质的结构要到出生以后才能全部形成。 5．山羊脑干内各灰质核团的形成和发育的次序不完全一致：①有的神经核团形成早，其神经元分化和发育较晚，如延髓的下橄榄核、三叉神经脊束核和孤束核；脑桥的上橄榄核、三叉神经脑桥核和脑桥核；中脑的脚间核和黑质。②神经核团形成较晚，但其神经元分化和发育较早，如延髓的舌下神经核和疑核及延髓的网状结构；脑桥的前庭神经核、耳蜗神经核及脑桥的网状结构；中脑的E-W核、前丘和中央灰质。③有些核团形成早，其神经元分化和发育也较早，如延髓的迷走神经背核：脑桥的三叉神经运动主核、外展神经核、面神经核；中脑的动眼神经核、滑车神经核、三叉神经中脑核和红核。 6．耳蜗核的形成要早于前庭神经核，与前庭系和听觉系在种系发生的过程中规律相反；而前庭神经核的发育要早于耳蜗神经核，这与种系发生过程中出现的规律相似。 山羊中枢神经系统的形成和发育 7．山羊中脑灰质中，脑神经核团的形成和发育最早，其中卜w核的形成和发育要晚一点；红核的形成比黑质略晚一些，但红核的神经元的发育则比黑质早得多；中央灰质的形成较晚，其内部神经元的发育与黑质相似；脚间核形成于mW初，其内部神经元的发育直到朋W才开始；前丘形成于田W，其内部分层到m7。才较为明显，但灰质层内的神经元的发育与中央灰质相似，早于脚间核，这些结构内神经元发育分化的顺序为脑神经运动核、红核一前丘，黑质、中央灰质一脚间核。 8．山羊小脑的外颗粒层形成于胚胎E6。末，外颗粒层逐渐增厚，到ESW不再变厚，E12W，外颗粒层开始变薄，E14W又开始增厚，直到E18W达到最厚以后，再次变薄，到出生前一周外颗粒层已经较薄，有4—5层细胞。山羊小脑的蒲肯野氏细胞可能在胚胎ESW以前就己聚集定位，到E14W，其轮廓与内颗粒层其它细胞区别开来，到出生前，己经比较成熟。小脑核的神经元在胚胎期发育分化早于浦肯野氏细胞，它形成于E7W，从ESW开始发育，E14W内多数神经元胞体轮廓清楚：到出生前小脑核的神经元远比浦肯野氏细胞成熟。 9．山羊胚胎间脑内的灰质结构形成顺序依次为后丘脑、底丘脑一丘脑一上丘脑～下丘脑；神经元发育分化的顺序为底丘脑核一丘脑一后丘脑一下丘脑和上丘脑（绢核）。出生前山羊胚胎下丘脑内的神经元发育很不成熟，多数核团难以根据细胞构筑特征来区分界限，山羊胚胎下丘脑灰质结构发育顺序为外侧带一内侧带一室周带。 10．山羊端脑内纹状体比大脑皮质形成的早。纹状体中，苍白球内的神经细胞定位和发育比尾壳核早，但其中大部分神经元与尾壳核的神经元一起开始发育，并且神经元发育分化要比尾壳核的晚一些。新皮质内各层神经元发育顺序依次为：内锥体层一外锥体层、多形层一内颗粒层一外颗粒层；海马皮质锥体细胞的发育较早，按由深到浅的次序发育，而海马皮质中更多还原

【Abstract】 The histogenesis and development of central never system were observed in anatomic, histological and cytological level in prenatal goat. The results as follows:1. The brain and the spinal cord has the fast and slow alternant phases developmental rule in goat embryo. The growth speed of the brain was faster than the spinal cord. The develop are unbalanced on three dimension in the brain. The growth fastigium in different spinal cord segment weren’t consistent in the timing, quantity and growth mode in the goat embryo.2. The three stratum round structure of were finished in the sixth weekend in the embryical goats. The overlapped time is longer between the histogenesis of never duct and the forming of spinal cord of prenatal goat. The forming time was incompletely consistency with the developing time of spinal cord: Some structure occur early and the neurons emerge lately such as the substantia gelatinosa. Some structure occur lately, and the neurons emerge earlier, such as the dorsal nucleus of Clarke’s.3.The the general features developmental change of perikaryon has went through hereinafter several phase by staining with hematonylin and eosin: ?Undifferetiation neurons has dark- staining cell nucleus, which got together to form the analge of gray nucleus. ?Immatured neurons had developed, which cytonucleus is biger and its staining color became light. A few newrons whose outline were dim appeared firstly then its number were increased. The increased mode were related with the characteristic of the gray neucleus themselves. ?The youthfull neurons has enlarged perikaryon which outline became distinct. The staining color of cytonucleus became light till to a bigger light-staining and bubble-shaped nucleus which had central nucleolus appeared. ?The riped neurons had a bigger light-staining and bubble-shaped nucleus which had central nucleolus appeared. The Nissi’s body in cytoplasm of neuron formed gradually, then they became bigger and increased, which made the body of neuron had characteristics of mature neuron.with enlargement of nucleus.then the body of neuron enlarged and their outlin became distinct gradually; during this process.the staining color of nucleus becime light till to a bigger light-staining and bubble-shaped nucleus which had central nucleolus appeared.With appearance of bubble-shaoed nucleus,the Nissi’s body in cytoplasm of neuron formed gradually.then they became bigger and increased.which made the perikaryon had characteristics of mature neuron. The number of riped neuron is increased showed that the variational rufe of different neuron body are identical in spite of the time of their morphological change were inconsistent. In addition, the bigger difference in time of developmental change of neuron among different nucleus was adapt to their structural characteristics.4.The time of genesis and forming of gray nucleus of brain regions in embryo goat had a little difference. The gray nucleus in medulla oblongata and pons has been formed in the 6th weeks. But the genesis and forming time of the cochlear mucleus and the vestibular nucleus was later. The forming of gray matter of mesenceohalon need longer time, which formed at beginning of 6 week to 8 week, this is obvionsly late than medulla oblongata and pons. The formation of gray matter in diencephalon began at the 6th week and last to the 8th week. The gray matter structure of telencephalon formed at the end of the 6th week, and all structure appeared at the 8th week, but the complete formation of cortex was lasting to the 12th week. The cortex of cerebeelum formed at the end of the 6th week, but it’s total formation was complete after birth.S.The development and differentiation rules of the brain stem nerve nuclei are similar to the spinalis in goat embryo. That is: some structures generation is earlier than the neurons differentiation, ie, Nucleus olivaris inferior, Nucleus tr. spinalis and Nucleus tr. solitarii in the medulla oblongata, Nucleus olivaris superior, Nucleus pontine in the pons, Nucleus intepeduncuaris and su更多还原