Petit T L, LeBoutillier J C, Gregorio A, Libstug H
Department of Psychology, University of Toronto, Ont., Canada.
Brain Res. 1988 Jun 1;469(1-2):209-19. doi: 10.1016/0165-3806(88)90183-6.
The pattern of dendritic development of layer V pyramidal cells in the neocortex of the rat was studied using a variety of quantitative techniques in an attempt to determine what rules govern dendritic differentiation. Animals were sacrificed on postnatal days (P) 1, 3, 5, 7, 10, 15, 20, 25, 30 and 60, their brains impregnated with the rapid Golgi technique, and cells from the sensorimotor cortex examined for maximal apical and basilar dendritic field, number of dendritic branches at 20 micron intervals from the cell body, number of apical and basilar branch types (branching order), length of dendritic branch segments, and dendritic spine density. Primary dendrites are formed early in development, with no new ones formed after P7-10. Once a dendritic segment has bifurcated, all further development appears to occur at the tip, i.e. the trunk does not seem to undergo additional elongation, and new branches do not appear to form from the trunk. There is a plateau in dendritic differentiation close to the cell body after approximately P20; however, there is a continued increase in the length of terminal dendritic branches in the distal portions of the dendritic field into adulthood. During early development, dendrites bifurcate on reaching approximately 20-30 microns; however, during adulthood additional length is added to terminal dendrites without branching. Dendritic spines increase dramatically early in development, and then decline on proximal dendrites but continue to increase on terminal branches into adulthood. These results suggest that the terminal portion of the dendritic field remains plastic into adulthood, and that during development several general rules govern the pattern of dendritic differentiation.
利用多种定量技术研究了大鼠新皮质V层锥体细胞的树突发育模式，试图确定哪些规则支配树突分化。在出生后第1、3、5、7、10、15、20、25、30和60天处死动物，用快速高尔基技术对其大脑进行染色，并检查感觉运动皮质中的细胞，以确定最大顶树突和基底树突场、距细胞体20微米间隔处的树突分支数量、顶树突和基底树突分支类型（分支顺序）的数量、树突分支段的长度以及树突棘密度。初级树突在发育早期形成，出生后第7 - 10天之后不再形成新的初级树突。一旦一个树突段发生分叉，所有进一步的发育似乎都发生在尖端，即树干似乎不会再额外伸长，并且新的分支似乎也不会从树干形成。在大约出生后第20天左右，靠近细胞体的树突分化出现一个平台期；然而，树突场远端部分的终末树突分支长度在成年期持续增加。在发育早期，树突在达到约20 - 30微米时发生分叉；然而，在成年期，终末树突会增加额外的长度而不发生分支。树突棘在发育早期急剧增加，然后在近端树突上减少，但在终末分支上持续增加直至成年。这些结果表明，树突场的终末部分在成年期仍保持可塑性，并且在发育过程中有几个一般规则支配着树突分化模式。
