Meaning of nine plus zero array

nine' plus" ze'ro array"

Pronunciation: [key]
— Cell Biol. Cell Biol.
  1. the arrangement of microtubules characteristic of basal bodies and centrioles, consisting of nine evenly spaced triplets between the outer and inner walls of the structure and having no central microtubules. Symbol: 9 + 0.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.