Growth of linear spicules in cultured primary mesenchymal cells of sea urchin embryos is bidirectional.
The growth of spicules of the sea urchin embryo was studied in a simple in vitro system in which primary mesenchymal cells attach to the substrata, migrate and fuse via filopodia, and subsequently deposit CaCO3, which in most cases is in the form of linear rods. The use of autoradiographs following 45Ca2+ pulse-chase labeling revealed that in such a system linear spicules that formed had two focal points of growth. Elongation occurred by addition of approximately equivalent amounts of Ca2+ to both ends of each rod. Multiform spicules having variable numbers of elongation sites (tips) also showed a similar pattern of Ca2+ deposition. Thus, the growth of both linear and relatively complex skeletal forms is apparently accomplished by the same basic mechanism.
Decker
G L
GL
Department of Biochemistry and Molecular Biology, University of Texas, M. D. Anderson Hospital and Tumor Institute, Houston 77030.
Lennarz
W J
WJ
D000818:Animals; D001345:Autoradiography; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003238:Connective Tissue / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology*; D008648:Mesoderm / Q000166:cytology*; D012016:Reference Values; D012617:Sea Urchins / Q000196:embryology*
D002118:Calcium