Embryonic and paralarval development of the central nervous system of the loliginid squid Sepioteuthis lessoniana

Publication Type:Journal Article
Year of Publication:2001
Authors:S. Shigeno, Tsuchiya, K., Segawa, S.
Journal:Journal of Comparative Neurology
Date Published:Sep
ISBN Number:0021-9967
Accession Number:WOS:000170256900006

The embryonic development of the central nervous system (CNS) in the oval squid Sepioteuthis lessoniana is described. It has three distinct phases: (1) The ganglionic accumulation phase: Ganglionic cell clusters develop by ingression, migration, and accumulation of neuroblasts. (2) The lobe differentiation phase: Ganglia differentiate into lobes. The phase is identified by the beginning of an axogenesis. During this phase, neuropils are first formed in the suboesophageal mass, then in the basal lobe system, and finally in the inferior frontal lobes and the superior frontal-vertical lobe systems. (3) The neuropil increment phase: After the shape of the lobes reached its typical form, neuropil growth occurs, specifically in the vertical lobe. The paralarval central nervous system (CNS) is characterized by neuronal gigantism of the giant fibers and some suboesophageal commissures and connectives. The neuropil formation in the CNS of S. lessonaina occurs somewhat earlier than in Octopus vulgaris, although the principal developmental plan is quite conservative among the other coleoids investigated. Some phylogenetic aspects are discussed based on the similarities in the morphologic organization of their brains. J. Comp. Neurol. 437:449-475, 2001. (C) 2001 Wiley-Liss, Inc.

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