What is more acceptable?

There are more sodium ions outside the cell


There are more sodium ions outside of the cell

  • Can you explain please? May 28, 2017 at 15:53
  • There's also the possibility of more sodium ions on the outside of the cell, which would normally be taken to imply those additional ions are very close to (or "touching") the outer surface of the cell, as opposed to just anywhere (in the general vicinity). That "right next to the outer edge" sense might perhaps be more strongly suggested by your second example (including of, but not on the). May 28, 2017 at 18:18

1 Answer 1


outside the cell
outside of the cell
on the outside of the cell

of these three only "on the outside of the cell" might imply direct contact with the cell wall.

Since you are probably talking about osmotic pressure, any of the three can be used without loss of understanding since the reader will probably already know how osmotic pressure works.

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