Histogenesis And Development Of Central Never System In Prenatal Goat

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...