Explain the structure of microsporangium and write the functions of its different layers

A sporangial is a structure which contains microspores which are the pollen sacs giving rise to male gametes in an angiosperm is a microsporangium. 

Microsporangium - 

circular in outline in the transverse section and is usually surrounded by four wall layers. 

Epidermis- 

The outermost is the single layer of the epidermis. 

The second layer is endothecium, where cells develop thickenings. 

The middle layer is made up of 2-4 cells. The innermost layer is tapetum, which provides nutrition to the developing pollen cells. 

Cells of the tapetum may be multinucleate. Outer three layers are protective in function and also help in dispersal of pollen by dehiscing themselves. 

There are four pollen sacs present inside the microsporangium comprising compact sporogenous tissue and these tissues undergo meiotic divisions to form microspore tetrads that further divide to form pollen grains.

Final Answer Hence, this is the structure of microsporangium.