Kristt D A
Brain Res. 1978 Jul 21;150(3):467-86. doi: 10.1016/0006-8993(78)90814-4.
Newborn (P-0 and P-1) through 6-day-old (P-6) rats were studied using light microscopic (Golgi) and ultrastructural methods. Previous studies demonstrated that early-formed synapses are concentrated at specific cortical depths, i.e. in strata. The present study shows that the synaptic stratum in the marginal zone corresponds to a dense fiber plexus and few somata (Cajal-Retzius cells). Axons in this zone almost exclusively form synapses on distal branches of dendrites originating in deeper lamina. In newborn neocortex there is a second synaptic stratum located deep to the cortical plate. It contains numerous axosomatic and axoproximal dendritic synapses as well as the most highly differentiated somata and proximal dendrites. By age P-6 there are 3 synaptic strata; one each in the marginal zone, cortical plate and 'subplate' layers. For all 3 strata a neuron's most differentiated dendrites are directed towards, traverse or run within, the nearest synaptic stratum. We conclude that, throughout the first postnatal week, the most mature dendrites of a given neuron generally occur at depths where synapse density is highest. At P-0 the most mature somata are similarly related to synaptic density.
使用光学显微镜（高尔基染色法）和超微结构方法对新生（P-0和P-1）至6日龄（P-6）的大鼠进行了研究。先前的研究表明，早期形成的突触集中在特定的皮质深度，即层中。本研究表明，边缘区的突触层对应于一个密集的纤维丛和少量的体细胞（卡哈尔-雷茨乌斯细胞）。该区域的轴突几乎仅在起源于更深层板的树突远端分支上形成突触。在新生的新皮质中，有第二个突触层位于皮质板下方。它包含大量轴体和轴近端树突突触，以及分化程度最高的体细胞和近端树突。到P-6时，有3个突触层；分别位于边缘区、皮质板和“亚板”层。对于所有这3个层，神经元分化程度最高的树突都指向、穿过或位于最近的突触层内。我们得出结论，在出生后的第一周内，给定神经元最成熟的树突通常出现在突触密度最高的深度。在P-0时，最成熟的体细胞与突触密度也有类似的关系。
