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

(N/A) In a transverse section,a typical microsporangium appears near circular in outline. It is surrounded by four wall layers:
$(A)$ Epidermis: It is the outermost protective layer. It is single-layered and provides protection to the internal tissues.
$(B)$ Endothecium: It is located below the epidermis. Cells of this layer possess fibrous thickenings of $\alpha$-cellulose. They help in the dehiscence of the anther to release pollen grains.
$(C)$ Middle layers: These are $2-3$ layers of thin-walled cells located between the endothecium and the tapetum. They provide support and are generally ephemeral.
$(D)$ Tapetum: It is the innermost wall layer. It consists of cells with dense cytoplasm and generally more than one nucleus. It provides nourishment to the developing pollen grains.
In the center of the microsporangium,there is a group of compactly arranged homogenous cells called the sporogenous tissue. The cells of the sporogenous tissue undergo meiotic divisions to form microspore tetrads. This process is known as microsporogenesis.