Male reproductive structure in flowering plant , Microsporogenesis

Male reproductive structure in flowering plant

• In flowering plants , Male and female reproductive organs are located on the  thalamus.

• The Reproductive structure  are found inside the flower.

• In flowering plants , Male reproductive structure is Stamen. It  is made up of two parts filament and anther.

• Out of two, Anther is for the formation of microspore or pollen grains or male gametophyte

Structure of Anther

• A typical anther is bilobed and dithecous. Each lobe of anther has two theca.

• Each theca of anther has two microsporangia therefore bilobed anther has four microsporangia therefore anther us tetragonal.

• When anther is young it is composed of sporogenous tissue . Anther is meant for the production of pollen grains.

• Pollen grains are formed inside the microsporangia therefore microsporangia is termed as pollensac. 

Structure of Microsporangia

• A typical microsporangia has four layers - epidermis , middle layer , endothecium and inner most layer tapetum.

• Former three layers are protective in function whereas the later innermost layer tapetum provides nutrition for developing pollen grains.

• The cells of anther are rich in cytoplasm and with more nuclei.

Microsporogenesis.

• When anther matures , it becomes cellular and still made up of sporogenous tissue.

👌👌Remember - Each cell of sporogenous tissue is capable of acting as a microspore mother cell but only few one cell performs the function of a microspore mother cell or pollen mother cells and rest are degerated to provide nutrition of active microspore mother cell.

• The microspore mother cell  undergoes the meiosis division and gives rise to pollen grains.

• These pollen grains are arranged in the form of microspore tetrad.

• Microspore mother cells divide repeatedly and form a large number of pollen grains.

• The formation of microspore from the microspore mother cell through the meiotic division is called microsporogenesis.

• When pollen grains are formed than anther dehydrated and dehisced. As a result , a large number of pollen grains are released.

• In most flowering plants when pollen grains are released, pollen grains have two cells - vegetative cell and generative cell. This is called two  celled stage  pollen grains.

• In the rest of flowering plants, generative cells divide and give rise to two male gametes . This is called three  celled pollen grains.

• Microspore, vegetative and generative cells are haploid whereas outside cells of anther or microsporangia are diploid.

• The vegetative cell has large , irregular shape nucleus. Vegetative cells is bigger and full of reserve food.

• The generative cell is small and spindle shaped with dense Cytoplasm and a nucleus. The generative cell float in cytoplasm of vegetative cells.

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