Primary mesenchyme cell-ring pattern formation in 2D-embryos of the sea urchin.
Primary mesenchyme cell (PMC) migration during PMC-ring pattern formation was analyzed using computer-assisted time-lapse video microscopy in spread embryos (2D-embryo) of the sea urchin, Mespilia globulus, and a computer simulation. The PMC formed a near normal ring pattern in the 2D-embryos, which were shown to be an excellent model for the examination of cell behavior in vivo by time-lapse computer analysis. The average migration distance of the ventro-lateral PMC aggregate-forming cells (AFC) and that of the dorso-ventral PMC cable-forming cells (CFC) showed no significant difference. All PMC took a rather straightforward migration path to their destinations with little lag time after ingression. This in vivo cell behavior fitted well to a computer simulation with a non-diffusable chemotaxis factor in the cyber-cell migration field. This simulation suggests that PMC recognize their destination from a very early moment of cell migration from the vegetal plate, and implicates that a chemoattractive region is necessary for making the PMC migration pattern. The left- and right-lateral AFC and dorso and ventral CFC were each derived from an unequally divided one-quarter segment of the vegetal plate. This suggests that AFC and CFC have a distinctive ancestor in the vegetal plate, and the PMC are a heterogeneous population at least in terms of their destination in the PMC-ring pattern.
Katow
H
H
Marine Biological Station, Graduate School of Science, University of Tohoku, Aomori, Japan. hkatow@mail.cc.tohoku.ac.jp
Nakajima
Y
Y
Uemura
I
I
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008648:Mesoderm / Q000166:cytology*; D018715:Microscopy, Video / Q000379:methods; D012617:Sea Urchins / Q000166:cytology / Q000196:embryology*