Pit (botany)

Bordered pits in the wood of Picea abies. The top section is a cross-sectional view with bordered pits shown between adjacent cells, and the bottom section is a radial view with numerous bordered pits shown.

Pits are relatively thinner portions of the cell wall that adjacent cells can communicate or exchange fluid through. Pits are characteristic of cell walls with secondary layers. Generally each pit has a complementary pit opposite of it in the neighboring cell. These complementary pits are called "pit pairs".[1]

Pits are composed of three parts: the pit chamber, the pit aperture, and the pit membrane. The pit chamber is the hollow area where the secondary layers of the cell wall are absent. The pit aperture is the opening at either end of the pit chamber. The pit membrane is the primary cell wall and middle lamella, or the membrane between adjacent cell walls, at the middle of the pit chamber.[2]

The primary cell wall at the pit membrane may also have depressions similar to the pit depressions of the secondary layers. These depressions are primary pit-fields, or primary pits. In the primary pit, the primordial pit provides an interruption in the primary cell wall that the plasmodesmata can cross. The primordial pit is the only aperture in the otherwise continuous primary cell wall.[3]

Pit pairs are a characteristic feature of xylem, as sap flows through the pits of xylem cells.[4]

  1. ^ Jeremy Burgess (1985). Introduction to Plant Cell Development. CUP Archive. p. 91. ISBN 9780521316118.
  2. ^ Ray F. Evert (2006). Esau's Plant Anatomy: Meristems, Cells, and Tissues of the Plant Body: Their Structure, Function, and Development (third, illustrated ed.). John Wiley & Sons. p. 76. ISBN 9780470047378.
  3. ^ Katherine Easu (1977). Anatomy of Seed Plants. Plant Anatomy (2nd ed.). John Wiley & Sons. p. 51. ISBN 0-471-24520-8.
  4. ^ B. A. Meylan, Brian Geoffrey Butterfield (1972). Three-dimensional Structure of Wood: A Scanning Electron Microscope Study; Volume 2 of Syracuse wood science series (illustrated ed.). Syracuse University Press. p. 12. ISBN 9780815650300.