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Development of the Nervous System of Sea Urchin Embryos: Formation of Ciliary Bands and the Appearance of Two Types of Ectoneural Cells in the Pluteus
Author(s) -
NAKAJIMA YOKO
Publication year - 1986
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1986.00531.x
Subject(s) - cilium , anatomy , biology , axoneme , microbiology and biotechnology , ultrastructure , hemicentrotus , sea urchin , basal body , flagellum , biochemistry , gene
An ultrastructural study of the larval integument of the sea urchin, Hemicentrotus pulcherrimus , was conducted with special emphasis on the development of the nervous system in relation to the formation of ciliary bands. In the integument of 4‐armed pluteus larvae, cells associated with the ciliary band, which have 200 nm‐thick projections at their apices, and cells in the squamous epithelium, which have a cilium and long, fine radiating processes in the apical region, were observed. Both cell types have axons at their basal ends that form nerve bundles beneath the ciliary bands, where the axons make contact with ectodermal effector cells with motile cilia. The cilia and other apical projections of these ectoneural cells run parallel to the surface of the cells, and are under the hyaline layer. The axoneme of the cilium has a typical “9 + 2” microtubular arrangement, but generally has no dynein arms. These ectoneural cells are more frequent on the oral surface than on the antioral surface.