Nuclear type - endosperm, Biology

Assignment Help:

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.


Related Discussions:- Nuclear type - endosperm

Metanephridia - excretion, Normal 0 false false false E...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

What are the functions of biotin, What are the functions of biotin and pant...

What are the functions of biotin and pantothenic acid for the body? How are these vitamins obtained? Biotin (also called as vitamin B8) is a vitamin that acts in the metabolism

Phylum protozoa, PHYLUM  PROTOZOA Definition  and  Introduction  ...

PHYLUM  PROTOZOA Definition  and  Introduction  All  unicellular ( or  acellular )  eukaryotic  animals. Most  primitive (Gr. Protos = first=zoon= animals ) organisms

What is monera, What is monera? One of the 5 main kingdoms contains bac...

What is monera? One of the 5 main kingdoms contains bacteria and blue/green algae. Does NOT have a cell membrane, or in other words, is made of prokaryotic cells. Actually,

People who are at risk from drug-nutrient interactions, Determine People wh...

Determine People who are at risk from drug-nutrient interactions? People who are at risk from drug-nutrient interactions are the: 1. Persons who have a poor diet or in other

Zooology, green gland is excretory organ of which ortopodic phylem

green gland is excretory organ of which ortopodic phylem

Organ transplant rejection, ORGA N TRANSPLANT REJECTION - Major his...

ORGA N TRANSPLANT REJECTION - Major histocompatibility complex is responsible for stimulating the rejection of tissue MHC is set of genes that code for cell surface glycopr

Oxygen stratification - lake ecosystem, Oxygen Stratification - Lake Ecosys...

Oxygen Stratification - Lake Ecosystem In most lakes, oxygen stratification nearly parallels that of temperature during the summer season. The amount of oxygen is greatest on

Define major divisions & representing species of gymnosperm, What are the m...

What are the major divisions and representing species of the gymnosperms? This group of plants can be separated into conifers (pine, sequoia, cypress), that have flowers called

Germ layers - metazoa, Germ Layers - Metazoa The infolding of the blas...

Germ Layers - Metazoa The infolding of the blastoderm of the blastula forms a gastrula with two or more layers. The outer layer is the ectoderm' and the endoderm lines the inn

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd