Structure of Microsporangium

In transverse section a typical microsporangium appears near circular in outline. It is generally surrounded by four wall layers - the epidermis, endothecium, middle layers and the tapetum. The outer three wall layers perform the function of protection and help in dehiscence of anther to release the pollen. The innermost wall layer is the tapetum. It nourishes the developing pollen grains. Cells of the tapetum possess dense cytoplasm  and generally have more than one nucleus. When the anther is young, a group of compactly arranged homogenous cells called the sporogenous tissue.

SPOROGENOUS TISSUE

It is compactly arranged homogenous cells which are present at centre of each microsporangium when the anther is young.

Microsporogenesis – Process by which 4 haploid microspores are produced from each diploid sporangenous cell after meiotic division.

As the anther develops, the cells of the sporogenous tissue undergo meiotic divisions to form microspore tetrads. Each cell of the sporogenous tissue is known as pollen mother cell (PCM) or microspore mother cell. The process of formation of microspore from a pollen mother cell through meiosis is called microsporogenesis.

The microspores are formed in form of microspore tetrad. As the anther mature and dehydrate, the microspores dissociate from each other and develop into pollen grain.