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
Explain E. coli - Microbiological Study of Water? It is always present in human intestine so its presence indicates the faecal pollution and possible presence of other human or

Natural versus Artificial (Man-made) Environment The environments discussed so far are, natural environments. In several instances man has greatly altered the natural condition


Which is true of the resting membrane potential? A. It requires few ions to be distributed unevenly. B. It has the same value in all cells C. Only nerve and muscle cells h

Term Translation or protein synthesis, is quite similar in eukaryotes and prokaryotes. We will look at the details of the process in prokaryotes and consider the differences in euk

B o vi n e spongiform encephalopathy (BSE) Bovine spongiform encephalopathy (BSE) is a transmissible, neurodegenerative, fatal brain disease of cattle characterized by post

With response to synthesis of fatty acids and triacylglycerol, the pentose pathway supplies: -NADPH and glycerolaldehyde 3 P -NADPH and glucose -NADPH and ribulose 5 P

Do algae reproduce sexually or asexually? There are algae that replicate sexually and there are algae that replicate asexually. In unicellular algae reproduction is usually

What are some mechanisms by which pathogenic bacteria cause diseases? Why is this knowledge important? Pathogenic bacteria have characteristics called as virulence factors that

Assessment of Peripheral Vascular Perfusion (Beside Test) Burger's Postural Test Perform in daylight.  Place patient supine with both legs elevated and knees