The role of the yolk syncytial layer in determination of the plane of bilateral symmetry in the rainbow trout,Salmo gairdneri Richardson

✍ Scribed by Long, Wilbur L.

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: English
• Weight: 663 KB
• Volume: 228
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402280110

✦ Synopsis

Abstract

Two types of morphogenetic cell movements are required for construction of a teleost embryo from the blastodisc. These are epiboly and convergence. Convergence is responsible for building the embryonic shield, thereby converting the radially symmetrical blastodisc to a bilaterally symmetrical one. Control of the convergence movement in rainbow trout, Salmo gairdneri, blastodiscs was investigated by marking the plane of bilateral symmetry with chalk. The blastodiscs were removed from their underlying yolk syncytial layers (YSL) and younger, radially symmetrical, blastodiscs were used to replace them. The newly transplanted blastodiscs formed planes of bilateral symmetry which matched the marked YSL substratum. Therefore, the YSL from an older, bilaterally symmetrical egg can impart its bilateral symmetry to a young, radially symmetrical blastodisc. This ability suggests that the YSL has the role of directing the cell movements which establish the embryonic shield during normal morphogenesis.