Development of Male and Female Gametophytes

Introduction

Male gametophytes is the stage that produces male gametes and are derived from microspores. On the other hand, female gametophytes are derived from megaspore and produce female gametes.

The Process of Gametophytes

Gametophytes is the process present in every plant and some algae species. It is one or two phases of the multicellular life cycle of algae or plants. This is their evolution that transforms their next generation. This process of development of male and female gametophytes includes many stages. These stages help them to produce the other lifecycle with this alteration. There are very basic types in which the plant and some algae versions evolve. These types distinguish themselves by the chromosomal quantities and pairing status. 

The phases of alteration include: 

• Sporophyte:

In this generation, plants and algae undergo multiple diploid pairing of the chromosomes. Here, the chromosomes present, have the pairing in the set of two chromosomes distinctively. This is the non-sexual phase of development of male and female gametophytes, where an organism goes through to produce the next generation. 

•    Gametophyte: 

This is the sexual phase of generation. These are the haploid generation. In this generation, the organism produces gametes and haploids as reproductive cells. These cells take the major responsibility to produce the advent generation. Here, the reproductive cells i.e. haploids and gametes act as the eggs and sperms which undergo the reproduction procedure. In this phase, the reproductive cells undergo the cell division procedure without losing the set of chromosomes. This is the process of mitosis by which denotes the development of male and female gametophytes definition ingeniously. 

The involvement of the procedure in the gametophytes two major kinds of sex organs is present. These sex organs have the thorough responsibility of the production for the altering generation.

 Types of Reproductive Organs

Pistil- It is the female reproductive part of flower. Pistil has three parts the stigma, style and ovary. The stigma serves as a landing platform for pollen grains.     

• Ovary

These are the female reproductive organs that produce eggs. These are the multicellular female organs that act like a human ovary. This is because it has the liability to generate the haploid egg cells. 

Stamen – It is male reproductive part of a flower.Stamen is  the long and slender stalk called the filament, and the terminal generally bilobed structure  called the anther.

•       Anther

 These are the male reproductive organs. They are multicellular which function like the human testis and produce the haploid sperm cells. These gametophytes are part of all the gametes present in this haploid phase of development.

Female Gametophyte (Embryo sac) of Angiosperm

The female gametophytes are very large and consist of multicellular structures. The female gametophytes play a crucial role in the development of male and female gametophytes. This is because they carry the two-fold responsibility of supporting the male gametes and nurturing the embryo. The female gamete consists of eight nuclei that exist between the angiosperms in a contrast state.

The female gametes provide the physical base for seed fertilization and with a molecular base. Development of female gametophyte in Angiosperm

The development of the female gametophytes undergoes two distinct features. These features differentiate by the quantity of the cellular haploids and involvement of the procedure. These processes are:

       Megasporogenesis:

In this process, the female gametophytes, the development of megaspores from the megasporocyte undergoes the meiosis.  A single haploid female gametophyte forms a multicellular tetrad of haploid megaspore. In this procedure of meiosis, only a single megaspore survives while the other three dissolve. This surviving megaspore grows and functions as the embryo sac. 

•       Megagametogenesis:

This is the second phase of the female gametophyte where the mitosis function takes place. Here the haploid cells generate  8 nucleates which act as embryo sacs. The polar nuclei moves to the center and fuses the prime diploid cells in the center. The production of triploid endosperm undergoes the fusion of diploid cells and sperm.

Male Gametophytes (Pollen grains) of Angiosperm

The development of male and female gametophytes classification consists of the major functional and production factors. The male gametophytes generally grow and transform into pollen grains. Here, the microspore mother cell modifies itself to the pollen grains. The four microspores here form the maturation state into the pollen grains. The inner layer of the microspore gets its nourishment from the tapetum. The pollen grains consist of two major cells:

•       Vegetative cells 
•       Generative cells

After the maturity state, the microsporangium bursts to release the pollen from one another. There are two layers in the pollen grains. The upper layer is its exine and is very thin. The inner layer of the pollen grain is intine which is thick in nature and functions to protect the pollen from damage. The development of male gametophytes takes place in two stages:

•       Pre-pollination stage 
•       Post-pollination stage

When the germination starts in the pollen sac before pollination, it is known as the pre pollination stage. Three celled stages found in some angiosperm plants before pollination. Three celled are vegetative, two male gametes form by division of generative. Most angiosperm plants have three celled stages after fertilization is called the post pollination stage. Post pollination is the pragmatic phase of pollination to fertilization. These stages affect the male gametophytes’ health and quantity of the pollen grains. The male gametes support each other in developing during the pre-pollination state. In the post-pollination state, they attain sustainability and survival to produce the next altering generation.

Development of Male Gametophyte in Angiosperm

The development of male gametophytes depicts the germination procedure within the pollen sac. The mitosis procedure goes through precocious germination where the single large vacuole forms the two daughter nuclei. The small cell present here is the generative cells (generative cells divide and form two male gametes) and large cells are the vegetative cells. These cells have the cytoplasm in sufficient amounts which are their food reserve. The reserves help the male gametophytes in the development and assemble all the generative cells in mid-section.

Conclusion

The discussions about the development of male and female gametophytes have large and very detailed aspects. The scriptural description with categorical explanation makes the subject and the topic easy to understand. This note has discovered the basic structure of the chapter gametophytes.