Pollen Grains and Male Gametophyte in Angiosperms

In a typical angiosperm, 4 pollen sacs are present in the anther.

The microsporogenesis takes place at anther.

Myosotis yields the smallest pollen grain.

Sporogenous cells divide to form microspore mother cells.

The tapetal cells provide nourishment to young microspore mother cells either by forming a plasmodium (amoeboid or invasive type) or through diffusion (parietal or secretory type).

Pollen grains begin to germinate, while still in the anther lobe.

Exine is thin at germ pores.

Sporopollenin is resistant to chemical and biological decomposition and cutinizes exine. Pollen grains are well preserved as fossils because of the presence of sporopollenin.

Pollen grain is the male gametophyte of angiosperms.

The larger cell of pollen grain is called vegetative cell.

Thin-walled hypodermal cells constitute the stomium or line of dehiscence.

The pollen sacs develop hypodermically from archesporial cells.

Endothecium lies below epidermis followed by 1-3 layers of parenchyma cells which are followed by tapetum.

Pollinium is found in calotropis.

4 haploid microspores are produced from each diploid microspore mother cell in a process called microsporogenesis.