In this article we will discuss about the asexual and sexual reproductive structure of oedogonium. This will also help you to draw the structure and diagram of oedogonium.
Asexual Reproduction of Oedogonium:
1. Zoospores and akinetes are the common means of asexual reproduction in Oedogonium.
2. Zoospores are formed in the cap cells singly, when the cell starts to function as zoosporangium.
3. In each zoosporangium develops a single, spherical to ovoid, uninucleate and multi-flagellate zoospore.
4. Zoospore comes out in the membranous vesicle formed by rupturing of the outer cell wall
5. On coming out of vesicle, zoospore settles on some substratum through its flagellar end. Its flagella withdraw and it germinates into new plant.
6. Akinetes are also formed in chain in some species of Oedogonium. These are the centres of reserve food.
Sexual Reproduction of Oedogonium:
1. It is of oogamous type.
2 Some species are monoecious or homothallic while others are dioecious or heterothallic.
3. Dioecious species are again of two types:
(a) In some, the male and female filaments are of normal size. These are known as macrandrous species.
(b) In others, the male filament is smaller in size, i.e., dwarf male or nannandrium. These are known as nannandrous species.
Antheridia:
1. Antheridia may develop in any cell possessing caps.
2 The cell divides into many small segments or chambers and each segment is known as antheridium (Fig. 27 A).
3. In each antheridium, two small, uninucleate and multi-flagellate structures are formed. These are known as antherozoids (Fig. 27B).
Oogonium:
1. Oogonium also develops in cap cells,
2. A single filament may contain many oogonia.
3. An oogonium is a spherical, uninucleate structure, which contains an egg (Fig. 28).
4. Below each oogonium, a slightly elongated or cylindrical cell is present. It is known as supporting cell or suffultory cell.
5. At the time of fertilization, a hyaline spot develops on one side of the egg. It is called receptive spot.
6. At the place of receptive spot, wall of the oogonium breaks up, antherozoids get in and perform the process of fertilization.
7. A thick-walled, reddish zygote develops after fertilization.
Dwarf Male:
1. Male cells in nannandrous species are called androsporangia.
2. Androsporangia are formed in the same way as antheridia in case of macrandrous species, i.e., by the division of a cap cell into many segments.
3. In each segment only one uninucleate and multiflagellate structure is present. It is known as androspore.
4. Species are known as gynandrosporous, if androspore and oogonium develop on the same filament.
5. If the androspore and oogonium develop on different filaments, the species is known as idioandrosporous.
6. Androspores develop into male filaments, which are smaller in size and are known as dwarf males (Fig. 29) or nannandria.
7. Androspore settles either on the oogonium or on the supporting cell or suffultory cell (Fig. 29).
8. At the tip of the androspore develops antheridia, each having two antherozoids.
9. Antherozoids are uninucleate, multi-flagellate and very small structures.