Draw the diagram of a microsporangium and label its wall layers. Write briefly about the wall layers?

Mature microsporangium consist of two parts.
1) Microsporangial wall and
2) Sporogenous tissue
1. Microsporangial wall : Each microsporangium has four types of wall layers.
a) Epidermis b) Endothecium
c) Middle layers d) Tapetum
a) Epidermis : It is outer most single, one cell thickness thin walled layer. Stomium like epidermal cells helps in dehiscence of pollen sacs at maturity.
b) Endothecium : It is the hypodermal wall layer. Cells of this layer expand radially with fibrous thickenings. At maturity cells loss water and contract. It helps in dehiscence of pollen sacs.
c) Middle layers : 1-3 layers, thin walled layers present between endothecium and tapetum.
d) Tapetum : It is an innermost layer one cell thickness, and nutritive layer. Cells posses dense cytoplasm and are binucleate. It nourishes nutrients to developing sporogenous tissues.