Syngamy, Biology

Syngamy

The pollen tube grows to a very limited extent in the synergid. It releases the contents either through a terminal or a subterminal pore. The contents include the two male gametes along with the accompanying cytoplasm, some reserve nutrients and perhaps vegetative nucleus. One of the sperms enters the egg and the other to the central cell. The distance that the male gamete has to travel to come in contact with the egg or secondary nucleus is insignificant. The male gamete comes in contact with the plasma membrane of the egg that forms a bridge through which the male gamete enters.

Nuclear fusion is initiated by the joining of the outer membrane of the two nuclei. The inner membrane also fuses at localized areas forming a small bridge between the two nuclei. Enlargement of bridge causes eventual fusion of the male and egg nuclei (syngamy). Depending upon the stage of the male gamete at the time of nuclear fusion, three types have been recognized. (a) in pre-mitotic type-the male nucleus fuses with the egg before reaching the mitotic inter phase, (b) in post-mitotic type the male nucleus undergoes inter phase while in contact with the egg and the fusion is postponed until the initiation of the first mitosis in both, and (c) in intermediate cases, the fusion occurs when male nucleus is still at interphase. Generally, the male cytoplasm does not take part in fertilization. However, there are plants in which biparental inheritance of plastids has been demonstrated.

Posted Date: 1/23/2013 4:46:37 AM | Location : United States







Related Discussions:- Syngamy, Assignment Help, Ask Question on Syngamy, Get Answer, Expert's Help, Syngamy Discussions

Write discussion on Syngamy
Your posts are moderated
Related Questions
Define the Disc Electrophoresis? Disc electrophoresis has improved resolution and strong bands are obtained. It requires a two-gel system and several different buffers. The run

Abscission - Effects of Plant Growth Regulators Abscission of leaves and fruit is one of the more obvious characteristics of senescence. Leaves do not fall simply because they

MEDULL A OBLONGATA - Conical in appearance. Lower most part of hind brain. It's lumen is metacoel or 4th ventricle. An oval mass pons virolli lies above medula oblongeta. I

Which are the main cells of the nervous system? The major cells of the nervous system are the neurons. Besides the neurons the nervous system is also constituted of glial cells

Explain the Solubility in Water of dietary fibre? Fibres that dissolve in hot water are soluble and those that do not, are insoluble. Several structural features affect solubil

What are the three parts of a DNA nucleotide, and how are they connected to each other? The three types are a deoxyribose sugar, a phosphate group, and a nitrogenous base. The

EXTERNAL GENITALIA - Vestibule is covered by 2 pairs of lips labia majoris and labia minoris. At the anterior junction of labia minoris a small erectile clitoris presen

The Features of Retrograde Peri-Implantitis include: - Periapical Bone loss without gingival inflammation. - Microflora consisting mainly of streptococci and nonmotile organ

BLOO D CLOTTING - It is a nature's device to check the excessive loss of blood from an injury. Bleeding time is 1-3 minutes. Clotting time is 2-6 minutes. Process of

Observing the development of flowers into fruit Collect specimens of flowers in dissimilar stages of maturity from newly opened buds to specimens in which the petals have falle