Nuclear type - endosperm, Biology

Nuclear Type - Endosperm

The primary endosperm nucleus divides. The cell wall is not laid. These nuclei and their division products form a large number of free nuclei. The first few divisions are synchronous as a result nuclei are seen in multiples of two i.e. 4, 8, 16, 32 and so on. Later the nuclear divisions are non-synchronous i.e. the nuclei may be seen in different stages of divisions and the number of endosperm nuclei are not in multiples of two. The free nuclei thus formed remain suspended in the cytoplasm of the embryo sac. After some time the nuclei become gradually pushed towards the periphery by an expanding central vacuole.

A large number of nuclei accumulate towards the micropylar and chalazal ends. The nuclei may increase in size either by the fusion of two or more or by their independent growth. The process of cell formation starts with the centripetally growing walls from the periphery proceeding towards the centre of embryo sac or from the apex progressing towards the base. To begin with a single layer of uninucleate cells is formed. Subsequent anticlinal and periclinal divisions of these cells lead to complete cellularization of the endosperm. In some plants only one or two peripheral layer of endosperm cells may develop and the entire embryo sac may remain in the he nuclear state or cell formation may be restricted only to the micropylar end of the embryo sac. In a few plants wall formation may not take place at all and the endosperm has free nuclei. Normally the endosperm cells are only uninucleate; sometimes more than one nucleus may be enclosed within a cell. The number may further increase by nuclear divisions.

The development of endosperm in coconut is interesting. When the fruit is young the embryo sac is filed with a clear fluid containing numerous free endosperm nuclei. Later, the periphery becomes jelly-like, containing several cells. As the fruit matures, and the cellular endosperm along the periphery becomes very massive, the central part contains a sweet liquid with a large number of nuclei. The cellular endosperm constitutes the edible copra rich in stored fat. In the betel nut and fruits of several other palms, the cellular endosperm becomes very hard and woody.

Posted Date: 1/23/2013 6:23:05 AM | Location : United States







Related Discussions:- Nuclear type - endosperm, Assignment Help, Ask Question on Nuclear type - endosperm, Get Answer, Expert's Help, Nuclear type - endosperm Discussions

Write discussion on Nuclear type - endosperm
Your posts are moderated
Related Questions
Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4

What is the difference between xylem and phloem? Both xylem and phloem are vascular tissues found in a plant. Xylem is a tubular structure, which is liable for water transport

Define Effect of feeding method on drug availability? The form in which a drug is administered or enters the body can influence its absorption, metabolism or excretion. This be

Q. What is the metagenesis? What are the other names of this procedure? Metagenesis is thekind of life cycle in which there are two different forms of individuals of the same s

Define Inadequate Dietary Intake - cause of anaemia is dietary? The commonest cause of anaemia is dietary inadequacy of iron. The dietary intakes arc usually half of the recomm

1. Discuss how nursing has changed over the last two (2) decades. 2. Review and summarise the philosophy of your enrolled nurse course and its relevance to your clinical practic

Alterations occurring in fish The skeletal muscle of fish consists of short fibers arranged between sheets of connective tissue. The connective tissue in the fish muscle is les

IAA Stimulates Cell Enlargement Cell wall contains layer of cellulose fibrils and are normally quite rigid. Thus for a cell to grow, there must be a mechanism for relaxing th

Introduction to Metabolism An organism have to be managed its cellular organization and internal equilibrium despite the external forces which act upon it. Cells take in nutrie

Define Renal Function & cardiovascular - change related with ageing? Changes associated with the cardiovascular and renal function: The progressive accumulation of athermanous