Vijayan V K
Department of Human Anatomy, School of Medicine, University of California, Davis, CA 95616, U.S.A.
Int J Dev Neurosci. 1983;1(2):77-97. doi: 10.1016/0736-5748(83)90035-7.
Morphogenesis, distribution of cholinergic enzyme acetylcholinesterase and synaptogenesis in the dentate gyrus of the rhesus monkey during the pre- and postnatal periods of development were examined using histological, histochemical and ultrastructural methods. The pattern of neuronal differentiation in the dentate gyrus demonstrated distinct superficial-to-deep and lateral-to-medial gradients. The histochemical reaction for acetylcholinesterase was present on gestation day 120 as minimal staining in the supragranular band and in the inner one-third of the dentate molecular layer. At term, the laminar distribution of the enzyme assumed mature pattern although considerable enhancement in staining intensity was achieved postnatally. At term and at 9 months of postnatal age, the most pronounced enzyme activity was found in the supragranular band and in the inner one-third of the molecular layer. Synaptogenesis in the dentate molecular layer was characterized by the early formation of axo-dendritic contacts on dendritic trunks and branches followed by the appearance of synapses on simple and complex spines. Spines were detected infrequently on gestation day 132. On day 148, they ranged in morphology from short stubby protrusions to pedunculated, triangular processes. The majority of the spines exhibited flat postsynaptic surfaces. Complex, synapse-bearing U- and W-shaped spines were observed rarely at this age but appeared more frequently at term and at 15 months of postnatal age. However, at all ages, including 15 months postnatally, synapses on flat-surfaced simple spines predominated. Most synapses were of the asymmetric variety. With certain exceptions, these features of development of the rhesus dentate gyrus resemble the reported patterns of postnatal ontogenesis of this structure in the rat. However, the ingrowth of cholinergic afferents and the major modifications in synapse structure occur prenatally in the rhesus monkey during the second half of the gestation period. This temporal difference between the two species should receive consideration in the planning of neuroplasticity experiments designed to explore lesion-induced adaptations in afferent growth and synaptogenesis in the rhesus dentate gyrus.
利用组织学、组织化学和超微结构方法，研究了恒河猴出生前和出生后发育阶段齿状回的形态发生、胆碱能酶乙酰胆碱酯酶的分布和突触形成。齿状回中神经元分化模式显示出明显的由浅至深和由外侧至内侧的梯度。在妊娠第120天时，乙酰胆碱酯酶的组织化学反应表现为颗粒上层和齿状分子层内三分之一处有最小程度的染色。足月时，该酶的层状分布呈现成熟模式，尽管出生后染色强度有相当大的增强。在足月时和出生后9个月时，在颗粒上层和分子层内三分之一处发现最明显的酶活性。齿状分子层中的突触形成的特征是轴突-树突接触在树突干和分支上早期形成，随后在简单和复杂棘突上出现突触。在妊娠第132天时很少检测到棘突。在第148天时，它们的形态从短粗的突起到有蒂的三角形突起不等。大多数棘突表现出扁平的突触后表面。在这个年龄很少观察到复杂的、带有突触的U形和W形棘突，但在足月时和出生后15个月时更频繁出现。然而，在所有年龄段，包括出生后15个月，扁平表面简单棘突上的突触占主导。大多数突触是不对称类型。除了某些例外情况，恒河猴齿状回的这些发育特征类似于大鼠中该结构出生后个体发生的报道模式。然而，胆碱能传入纤维的长入和突触结构的主要变化在恒河猴妊娠后期发生在出生前。在设计探索恒河猴齿状回损伤诱导的传入生长和突触形成适应的神经可塑性实验时，应考虑这两个物种之间的这种时间差异。
