Development of somites and their derivatives in amphioxus, and implications for the evolution of vertebrate somites

Table 1 Synonyms for somite-related structures of amphioxus, anamniotes, and amniotes

Terms used in the present paper are in italics. ¹Present paper (without precedent). ² [15,68]. ³ [14]. ⁴ [3]; later in development, the myotome is generally termed ‘trunk muscle’. ⁵ [15]. ⁶ [15,68]. ⁷ [3]. ⁸ [69]. ⁹ [15]; ([14], considered this space as a subdivision of the myocoel). ¹⁰ [30]. ¹¹ [70]. ¹² [3]. ¹³ [71]; [3] later in development, the myotome is generally termed ‘trunk muscle’. ¹⁴[3] use the term ‘external cell layer’ alternatively with ‘lateral wall cells’. ¹⁵ [5]. ¹⁶ [72]. ¹⁷ [73] (name indicating later development as scale pockets in the dermis). ¹⁸ [71]; ([3] a region of sclerotome-derived cells (collectively the syndetome) gives rise to the tenocytes (myoseptal cells) at myotendinous junctions [5,38]). ¹⁹ [74]. ²⁰We will consider all chordate somitocoels homologous, although [3] have questioned that homology. The loose cells (collectively the arthrotome) in the amniote somitocoel are evidently sclerotome-related and give rise to the articular surfaces on the amniote axial skeleton [3]. ²¹ [33] Later in development, the myotome is generally termed ‘trunk muscle’. ²² [75].

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