Change in the adhesive properties of blastomeres during early cleavage stages in sea urchin embryo

Blastomeres of sea urchin embryo change their shape from spherical to columnar during the early cleavage stage. It is suspected that this cell shape change might be caused by the increase in the adhesiveness between blastomeres. By cell electrophoresis, it was found that the amount of negative cell...

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Bibliographic Details
Published in:Development, growth & differentiation growth & differentiation, 2001-02, Vol.43 (1), p.43-53
Main Authors: Masui, Mizuko, Kominami, Tetsuya
Format: Article
Language:English
Subjects:
Animals
Calcium - pharmacology
Cell Adhesion
cell contact
Cell Lineage
Cell Nucleus - physiology
cell surface
Echinoidea
Embryo, Nonmammalian - metabolism
Embryo, Nonmammalian - physiology
Fertilization
pseudopodia
Pseudopodia - physiology
sea urchin
Sea Urchins - embryology
Time Factors
timing mechanism
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Summary:Blastomeres of sea urchin embryo change their shape from spherical to columnar during the early cleavage stage. It is suspected that this cell shape change might be caused by the increase in the adhesiveness between blastomeres. By cell electrophoresis, it was found that the amount of negative cell surface charges decreased during the early cleavage stages, especially from the 32‐cell stage. It was also found that blastomeres formed lobopodium‐like protrusions if the embryos were dissociated in the presence of Ca2+. Interestingly, a decrease in negative cell surface charges and pseudopodia formation first occurred in the descendants of micromeres and then in mesomeres, and last in macromeres. By examining the morphology of cell aggregates derived from the isolated blastomeres of the 8‐cell stage embryo, it was found that blastomeres derived from the animal hemisphere (mesomere lineage) increased their adhesiveness one cell cycle earlier than those of the vegetal hemisphere (macromere lineage). The timing of the initiation of close cell contact in the descendants of micro‐, meso‐ and macromeres was estimated to be 16‐, 32‐ and 60‐cell stage, respectively. Conversely, the nucleus‐to‐cell‐volume ratios, which are calculated from the diameters of the nucleus and cell, were about 0.1 when blastomeres became adhesive, irrespective of the lineage.
ISSN:0012-1592
1440-169X
DOI:10.1046/j.1440-169x.2001.00555.x