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Local axon collaterals of lamina I projection neurons in the spinal cord of young rats
Author(s) -
Szucs Peter,
Luz Liliana L.,
Lima Deolinda,
Safronov Boris V.
Publication year - 2010
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.22391
Subject(s) - lamina , spinal cord , biology , anatomy , neuroscience , commissure , axon , biocytin , lumbar spinal cord , dorsum , central nervous system
Large, mediolaterally oriented neurons in lamina I of the spinal cord, frequently referred to as marginal cells of Waldeyer , are known to project to supraspinal targets via the anterolateral tract (ALT). Although dendritic organization of lamina I neurons has been extensively studied, little is known about their local axonal morphology and branching. With the help of oblique illumination, we visually identified large lamina I neurons in the isolated lumbar enlargement (L1–L6) of the spinal cord of P14–P20 rats. By using intracellular and cell‐attached biocytin injections, we achieved extensive axonal and dendritic labeling in 77 lamina I cells, 40 of which were identified as ALT projection neurons. In the majority of the cases (n = 28), the main axon of these projection neurons gave rise to one or more thin collaterals on the ipsilateral side. Based on their trajectory and location, these collaterals could be divided into three major categories: dorsal, lateral, and ventral. Lamina I projection neurons had dorsal (n = 5), lateral (n = 8), or ventral (n = 6) collaterals only or a combination of these collateral types (n = 9). Our results suggest that lamina I ALT projection neurons can additionally function as local‐circuit and propriospinal neurons participating in intra‐ and intersegmental spinal cord processing. J. Comp. Neurol. 518:2645–2665, 2010. © 2010 Wiley‐Liss, Inc.