Question

Give an account microgametogenesis in angiosperm.

Need long question type answer​

Answer 1

Answer

Microgametogenesis. Microgametogenesis is the process in plant reproduction where a microgametophyte develops in a pollen grain to the three-celled stage of its development. In flowering plants it occurs with a microspore mother cell inside the anther of the plant.

Answer 2

Microsporogenesis in Angiosperms

Microsporangium

The terminal part of the stamen bears the anther. It consists of two lobes. Each lobe has two chambers or loculi, called the pollen sacs or microsporangia. Thus a typical anther is tetrasporangiate. The four pollen sacs appear to lie in the four corners of an anther. The pollen sacs or microsporangia develop hypodermally in anther from strips of archesporial cells.

The transverse section of a mature anther shows the following:

Wall of the anther: The anther wall consists of four layers. These are epidermis, endothecium, middle layers and tapetum.

Epidermis: This is the outermost layer. It is only one cell in thickness.

Endothecium: This layer is situated just below the epidermis. It is a single layer of radially elongated cell with fibrous thickening. Because of the presence of fibrous thickenings, the endothecium is also called fibrous layer. In between these cells, a few cells without thickening are also present. These thinned wall cells collectively form the stomium or line of dehiscence.

Middle layers: The middle layers consist of three to four layers of thinned wall cells. These layers are situated below the endothecium. These layers generally degenerate to provide nourishment to the growing microspore mother cells.

Tapetum: Tapetum is the innermost layer of the wall and is multinucleate. The tapetal cells provide nutrition to the developing microspores. Tapetum secretes both enzymes and hormones. Tapetum is of two types-Secretory or glandular tapetum.and amoeboid or plasmodial tapetum.

Pollen chamber: The pollen chamber forms the central cavity of anther lobe. The process of microsporogenesis takes place in the pollen chamber.