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Fine structural studies of the nervous system and the apical organ in the planula larva of the sea anemone Anthopleura elegantissima
Author(s) -
Chia FuShiang,
Koss Ron
Publication year - 1979
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1051600303
Subject(s) - biology , cilium , nervous system , anatomy , nerve plexus , tuft , microbiology and biotechnology , microtubule , plexus , motile cilium , apical cell , morphogenesis , central nervous system , basal body , columnar cell , apical membrane , epithelium , neuroscience , flagellum , biochemistry , materials science , genetics , gene , composite material
The nervous system of the planula larva of Anthopleura elegantissima consists of an apical organ, one type of endodermal receptor cell, two types of ectodermal receptor cells, central neurons and nerve plexus. Both interneural and neuromuscular synapses are found in the nerve plexus. The apical organ is a collection of about 100 long, columnar cells each bearing a long cilium and a collar of about 10 microvilli. The cilia of the apical organ are twisted together to form an apical tuft. The ciliary rootlets of the apical organ cells are extremely long, reaching to the basal processes of the cells adjacent to the mesoglea. All three types of sensory cells are tall and slender in profile and are identified by the presence of one or more of the following features: microtubules, small vesicles, membrane‐bound granules and synapses. The interneurons are bipolar cells with somas restricted to the aboral end, adjacent to the apical organ. All synapses observed are polarized or asymmetrical. A diagram including all the elements of the nervous system is presented and the possible functions of the nervous system are discussed in relation to larval behavior.