Schlessinger A R, Cowan W M, Gottlieb D I
J Comp Neurol. 1975 Jan 15;159(2):149-75. doi: 10.1002/cne.901590202.
The dentate gyrus of the rat contains about 600,000 granule cells. These small neurons are generated over a prolonged period from the 14th day of gestation until some time after the second postnatal week. The majority of the cells pass through their last phase of DNA synthesis in the postnatal period, and during the peak period of cell generation, between the fifth and seventh days after birth, up to 50,000 granule cells are formed each day. Contrary to earlier reports, most of the cells pass through their last mitotic division either within the stratum granulosum itself, or within the hilar region of the developing gyrus. The precursor population of cells in the hilar region must therefore constitute a pool of true neuroblasts. The origin of this pool of cells has not been definitely established but it seems probable that its cells are derived from the neuroepithelium lining the lateral ventricle adjacent to the region from which the hippocampal pyramidal cells are generated. Examination of the final location of granule cells labeled at different stages reveals three distinct morphogenetic gradients in the gyrus. The cells in the dorsal blade tend to be formed earlier than those in the ventral blade; cells in the more caudal (or temporal) portions of the gyrus are generated earlier than those in more rostral (or septal) regions; and in all regions the more superficial neurons in the stratum granulosum are formed earlier than the deeper granule cells. The bearing of some of these findings on the development and organization of the connections of the dentate gyrus is discussed.
大鼠的齿状回包含约600,000个颗粒细胞。这些小神经元在较长时期内产生，从妊娠第14天直到出生后第二周的一段时间。大多数细胞在出生后阶段经历DNA合成的最后阶段，在细胞生成的高峰期，即出生后第五天至第七天之间，每天可形成多达50,000个颗粒细胞。与早期报道相反，大多数细胞在颗粒层本身内或在发育中的回的门区完成其最后一次有丝分裂。因此，门区的细胞前体群体必定构成了真正的神经母细胞池。这个细胞池的起源尚未明确确定，但似乎其细胞可能源自与海马锥体细胞产生区域相邻的侧脑室衬里的神经上皮。对在不同阶段标记的颗粒细胞的最终位置进行检查，揭示了回中的三个不同的形态发生梯度。背侧叶片中的细胞往往比腹侧叶片中的细胞形成得早；回中更靠尾侧（或颞侧）部分的细胞比更靠前侧（或隔区）区域的细胞产生得早；并且在所有区域中，颗粒层中较浅的神经元比较深的颗粒细胞形成得早。讨论了其中一些发现对齿状回连接的发育和组织的影响。
