イズミオオウズムシ(Bdellocephala brunnea)の再生と神経との関係 : II. 脳─神経索中の神経細胞の分布勾配と形態

概要

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The distribution and form of nerve cells in brain-nerve cords of Bdeallocephala brunnea have been studied to know the morphogenetic role of the nervous system. Special attention has been paid to the relation between the observed results and the curve of the head-frequency as well as the absence of the capacity of head regeneration in the postpharyngeal region. The nerve cells in the brain-nerve cords decrease gradually in number along the body axis. This distribution gradient of nerve cells corresponds closely to the head-frequency gradient of this species. Two different types of nerve cells are distinguishable by Heidenhain's iron hematoxylin staining: Long, slender spindle-shaped cells and round spindle-shaped ones. The former varies in length, and is characterized by a very strong affinity for hematoxylin. The latter may be classified according to the size as large, medium and small, and has a large nucleus with one or two nucleoli. The number of large nerve cells decreases from anterior levels posteriorly, remarkably in levels posterior to the pharyngeal base. The absence of the capacity of head regeneration in the postpharyngeal region seems to be a consequence of a small number of the nerve cells in the nerve cords.
社団法人日本動物学会の論文
1968-05-15