Sequence of myelinization in the brain of the albino rat. A. Cerebral cortex, thalamus and related structures
Sequence of myelinization in the brain of the albino rat. A. Cerebral cortex, thalamus and related structures
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白化大鼠大脑中髓鞘化的序列。
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发表时间：
1963
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通讯作者：
S. Jacobson
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作者：
S. Jacobson
髓鞘是发育中的神经系统中的神经纤维被髓鞘包围的过程。在长达40年的时间里，Flechsig对大脑中的髓鞘形成模式进行了初步研究。根据Flechsig(1894)的说法，第一批有髓纤维发现于脊髓。然后髓鞘扩散到延髓、脑桥、中脑，最后进入端脑。大脑皮层也依次从投射中心开始，到联合中心结束。髓鞘束以下列方式出现：先投射后联结，外周先于中央，感觉先于运动。在投射中心，首先是感觉辐射，然后是皮质辐射，最后是骨痂和投射纤维的髓鞘。在Flechsig对髓鞘研究的推动下，对各种哺乳动物进行了调查：负鼠(朗沃西，‘28b)；大鼠(沃森，’03；蒂尔尼，‘33)；猫(Tilney和Casamajor，’24；朗沃西，‘28a；Windle等人，’34)；人类(Lucas Keene和Hewer，‘31和’33；朗沃西，‘30和’33；Pfeifer，‘34；Conel，’39，‘41，’47，‘51，’55，‘59)。许多方法可以用来研究皮质连接。这些染色包括正常纤维的髓鞘和轴突染色，变性轴突的Nauta和Glees染色，以及退化髓鞘的Marchi染色。在这项研究中，作者将根据出生后7-73天的白化大鼠的观察，通过跟踪大脑皮层、丘脑和中脑的髓鞘形成的时间顺序来证明大鼠大脑的联系。沃森(‘03)和蒂尔尼(’33)在老鼠身上研究了髓鞘化。这两项研究都表面上描述了脊髓、延髓和脑桥的髓鞘化，但在中脑、丘脑和大脑中的空间更少。这两项研究也都没有得到充分的说明。本研究详细介绍了丘脑和大脑的髓鞘形成，重点不仅放在某些年龄已经髓鞘的纤维上，而且还放在这些纤维的结构和连接上。对延髓、脑桥、小脑和中脑髓鞘形成的详细分析将在另一篇论文中提出。表1总结了由下列作者报告的各种哺乳动物的髓鞘形成：负鼠，朗沃西(‘28b)；大鼠，沃森(’03)，雅各布森(‘62)；猫，Tieh和Casamajor(’24)，Windle等人。(‘34)；人类，朗沃西(’30和‘33)，卢卡斯·基恩和休尔(’31和‘33)，以及道奇森(’62)。
Myelinization is the process by which a nerve fiber in the developing nervous system becomes surrounded by a myelin sheath. Over a period of 40 years Flechsig made the initial studies on myelinization patterns in the brain. According to Flechsig (1894), the first myelinated fibers are found in the spinal cord. Myelinization then spreads into the medulla, pons, midbrain, and finally into the telencephalon. The cerebral cortex also rnyelinates successively starting at the projectjon centers and ending at the association centers. Tracts myelinate in the following manner; projection before association, peripheral precede central, and sensory precede motor. In projection centers first the sensory radiation, then the corticofugal radiations, and finally the callosal and projection fibers myelinate. Following the impetus given to myelinization studies by Flechsig, investigations were made on various mammals: opossum (Langworthy, '28b) ; rat (Watson, '03; Tilney, '33); cat (Tilney and Casamajor, '24; Langworthy, '28a; Windle et al., '34); man (Lucas Keene and Hewer, '31 and '33; Langworthy, '30 and '33; Pfeifer, '34; Conel, '39, '41, '47, '51, '55, '59). Many methods may be used to investigate cortical connections. These include myelin and axon stains for normal fibers, the Nauta and Glees stains for degenerating axons, and the Marchi stain for degenerating myelin sheaths. In this study the author will demonstrate connections of the rat cerebrum by following the temporal sequence of myelinization in the cerebral cortex, thalamus, and midbrain based on observations of albino rats of 7-73 days postnatal. Myelinization has been studied in the rat by Watson ('03) and Tilney ('33). Both of these studies describe myelinization in the spinal cord, medulla and pons superficially, and devote even less space to the midbrain, thalamus and cerebrum. Both of these studies are also inadequately illustrated. The present study details thalamic and cerebral myelinization, with emphasis placed not only on fibers which have myelinated at certain ages, but also on the architecture and connections of these fibers. A detailed analysis of myelinization in the medulla, pons, cerebellum, and midbrain will be presented in a separate paper. Table 1 summarizes myelinization in various mammals as reported by the following authors : opossum, Langworthy ('28b); rat, Watson ('03), Jacobson ('62); cat, Tihey and Casamajor ('24), Windle et al. ('34); human, Langworthy ('30 and '33), Lucas Keene and Hewer ('31 and '33), and Dodgson ('62).