Draw the T.S. of a mature anther and explain briefly.

Explanation

A mature anther internally contains four microsporangia, two in each anther lobe. Each microsporangium consists of an outer anther wall and an inner anther locule.
(i) Anther wall: It is the protective covering of anther or microsporangium. It is composed of epidermis, endothecium, middle layer and tapetum.
(1) Epidermis : It is the outermost protective layer of anther, composed of a single layer of cells. The cells are often stretched and flattened in a mature anther.
(2) Endothecium : It is the uniseriate layer composed of radially elongated cells with callose thickening on their inner tangential walls. Along the line of dehiscence of anther lobe, endothecium is composed of thin walled cells called stomium.
(3) Middle layers : These are 2-3 concentric layers of cells present in between the endothecium and tapetum. In mature anther the cells of middle layers are flattened and collapsed due to the pressure exerted in the anther locule.
(4) Tapetum : This is the innermost layer of anther wall composed of secretory cells. These cells secrete nutrients for developing microspore mother cells/ pollen grains in the anther locule.
(ii) Anther locule : It is the sporangia! cavity containing a number of microspore tetrads / pollen grains formed from microspore mother cells by meiosis. (Microspores after the separation from tetrad are called pollen grains)