Famiglietti E V
Department of Anatomy, University of Calgary, Faculty of Medicine, Alberta, Canada.
J Comp Neurol. 1992 Feb 22;316(4):422-46. doi: 10.1002/cne.903160404.
Polyaxonal (PA) amacrine cells are a new class of amacrine cell bearing one to six branching, axon-like processes that emerge from the cell body or dendritic trees within 50 microns of the cell body. These slender processes of uniform caliber branch at right angles and in many respects closely resemble the axons of Golgi type II cells found elsewhere in the brain. Of the four types of polyaxonal amacrine cell that we have recognized in rabbit retina, two have been described previously in brief communications. One of these, the PA1 amacrine cell with its interstitially displaced cell body, located in the inner plexiform layer (IPL), has been analyzed extensively in two preceding reports. This paper concerns PA2, PA3, and PA4 amacrine cells. Type 2 polyaxonal (PA2) amacrine cells, identified in Golgi preparations of whole-mounted rabbit retinas, have smaller cell bodies (9-14 microns) than the other three types and these are always displaced to the ganglion cell layer (GCL) or the inner border of the inner plexiform layer (IPL). The dendritic fields of PA2 cells are also smaller than those of other PA amacrine cells, and most of their sparse dendritic branching is narrowly stratified at the border of strata (S) 4 and 5. Some members of this more heterogeneous amacrine cell "type" are bistratified, however, and more highly branched with terminal branches rising to end in S1. PA2 amacrine cells bear a scattering of small dendritic spines and may also exhibit complex dendritic appendages arising at the ends of terminal branches in proximal regions of the dendritic tree. PA2 cells emit one to three axons from the proximal dendritic tree, and about half of the cells bear a single axon. Type 3 polyaxonal (PA3) amacrine cells resemble PA1 cells in the large size of their cells bodies (11-16 microns) and dendritic fields, but differ from the latter in placement of cell bodies, which is in the GCL, and dendritic and axonal stratification, which is multistratified, ranging from S4 to S1, with a concentration in S3 or S4 and a variable contribution to S1. PA3 cells differ from PA1 cells in several other respects, including dendritic branching which occurs at higher frequency and is biased toward temporal retina, and in characteristic bristling dendritic spines, clustered in the intermediate regions of the dendritic tree, that are longer, more variable in appearance and more tightly clustered than the small, uniform spines of PA1 cells that are clustered on proximal dendrites.(ABSTRACT TRUNCATED AT 400 WORDS)
多轴突（PA）无长突细胞是一类新的无长突细胞，具有一到六个分支，轴突样突起从细胞体或距细胞体50微米内的树突树发出。这些口径均匀的细长突起呈直角分支，在许多方面与大脑其他部位发现的高尔基II型细胞的轴突非常相似。在兔视网膜中我们识别出的四种多轴突无长突细胞类型中，有两种先前已在简短通讯中有所描述。其中之一，即PA1无长突细胞，其细胞体位于内网层（IPL）且间隙移位，在前两篇报告中已进行了广泛分析。本文涉及PA2、PA3和PA4无长突细胞。在兔视网膜整装片的高尔基染色标本中识别出的2型多轴突（PA2）无长突细胞，其细胞体（9 - 14微米）比其他三种类型的小，且这些细胞体总是移位到神经节细胞层（GCL）或内网层（IPL）的内边界。PA2细胞的树突野也比其他PA无长突细胞的小，其大部分稀疏的树突分支在第4层和第5层的边界处呈狭窄分层。然而，这种更具异质性的无长突细胞“类型”的一些成员是双分层的，并且分支更多，末端分支上升到第1层结束。PA2无长突细胞有分散的小树突棘，并且在树突树近端区域末端分支的末端可能还会出现复杂的树突附属物。PA2细胞从近端树突树发出一到三条轴突，约一半的细胞有一条轴突。3型多轴突（PA3）无长突细胞在细胞体（11 - 16微米）和树突野的大小上与PA1细胞相似，但在细胞体位置上与后者不同，其细胞体位于GCL，树突和轴突分层是多层的，范围从第4层到第1层，集中在第3层或第4层，对第1层的贡献可变。PA3细胞在其他几个方面与PA1细胞不同，包括树突分支发生频率更高且偏向颞侧视网膜，以及在树突树中间区域有特征性的竖起的树突棘，这些树突棘比聚集在近端树突上的PA1细胞的小而均匀的树突棘更长、外观更可变且聚集更紧密。（摘要截于400字）
