BIOCHEMISTRY

Anther sections stained with toluidine blue

1 µm thick sections of embedded Arabidopsis anthers stained with toluidine blue.
The dark shell around each pollen grain is the exine of the pollen coat, which is secreted by the surrounding tapetal cells of the anther and forms a protective meshwork over each gain.  Within the pollen grain we can distinguish the dark-staining nucleolus within the homogeneously lighter-staining nucleus (black arrows). 

The polarized microspore stage is characterized by the large vacuole (v) present in each grain, which disappears during and after pollen mitosis I.  The curved cell plate (white arrows) stains dark purple.

After pollen mitosis 1 the generative cell detaches from the pollen cell wall and floats free in the cytoplasm of the larger vegetative cell.  It can be recognized by its dark staining cell wall cell (black arrowhead, bicellular).  The generative cell divides during pollen mitosis II to give rise to the two smaller, highly elongaged sperm cells (black arrowhead, tricellular).  Scale bars are 20 µm

Below is a close-up view of a toluidine blue-stained pollen grain late in pollen mitosis I.  Note the curved cell plate.   To the right is an electron micrograph of the curved cell plate in another pollen grain.  N = generative nucleus

To see more electron micrographs, click here.

To view some raw images of toluidine-blue stained pollen sections, click here

To return to the pollen development overview page, click here.