Calcium transport into the cells of the sea urchin larva in relation to spicule formation

Netta Vidavsky, Sefi Addadi, Andreas Schertel, David Ben-Ezra, Muki Shpigel, Lia Addadi, Steve Weiner

Research output: Contribution to journalArticlepeer-review


We investigated the manner in which the sea urchin larva takes up calcium from its body cavity into the primary mesenchymal cells (PMCs) that are responsible for spicule formation. We used the membrane-impermeable fluorescent dye calcein and alexa-dextran, with or without a calcium channel inhibitor, and imaged the larvae in vivo with selective-plane illumination microscopy. Both fluorescent molecules are taken up from the body cavity into the PMCs and ectoderm cells, where the two labels are predominantly colocalized in particles, whereas the calcium-binding calcein label is mainly excluded from the endoderm and is concentrated in the spicules. The presence of vesicles and vacuoles inside the PMCs that have openings through the plasma membrane directly to the body cavity was documented using high-resolution cryo-focused ion beam-SEM serial imaging. Some of the vesicles and vacuoles are interconnected to form large networks. We suggest that these vacuolar networks are involved in direct sea water uptake.We conclude that the calcium pathway from the body cavity into cells involves nonspecific endocytosis of sea water with its calcium.

Original languageEnglish
Pages (from-to)12637-12642
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number45
StatePublished - 8 Nov 2016
Externally publishedYes


  • Biomineralization
  • Cryo-FIB-SEM
  • Endocytosis
  • In vivo imaging
  • SPIM imaging

ASJC Scopus subject areas

  • General


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