BIOCHEMISTRY

Pollen Development

DAPI staining

Toluidine Blue Sections

Electron Micrographs

Pollen Tube Growth

The mature male gametophyte is a tricellular pollen grain, containing two small sperm cells enclosed within a larger vegetative cell which will grow the pollen tube

Pollen development begins with meiosis, which creates four grains enclosed in a callose wall: the tetrad.  Breakdown of the callose releases the microspores.  These polarize, with a large vacuole at one end and a nucleus at the other, preparing the grain for an assymetric cell division.  The cell plate formed during pollen mitosis I has a distinctive hemisperical shape, and after division is completed the smaller generative cell detaches from the cell wall and in enveloped within the vegetative cell.  The generative cell undergoes another round of cell division to form the two sperm cells of the mature pollen grain.

Click on the links above to see images of pollen development using three different microscopy methods.