Difference between Nucellus and Tapetum

Nucellus and tapetum are nutritive layers found in the ovary and anther, respectively. They both provide nutrients to the female and male gametophyte, however, they differ in their location and structure.

What is Nucellus?

The nucellus is a mass of cells, present centrally in the ovule of female gametophytes. It forms several layers of diploid cells just inside the integuments. The ovules contain the megaspore mother cells which divides meiotically to produce megaspores.

The nucellus protects the developing embryo by providing nourishment. In angiosperms, the nucellus tends to generate while giving nutrients to the embryo, this makes a cavity for the embryo and endosperm to grow.

The nucellus often differs in its shape and size, which makes it characteristic of plant species.

Nucellus in Angiosperms and Gymnosperms

What is Tapetum?

The tapetum is a nutritive layer of cells present in the anther of the male gametophytes. The cells of the tapetum are polynucleate and big in size. The layer is located between the sporogenous layer and the anther wall. The chief function of the tapetum is to provide nourishment and regulatory molecules to the developing pollen grains.

Other functions of the tapetum include synthesis of sporopollenin, synthesis of callase enzyme for separation of the microspore tetrads, and synthesis of pollenkitt and tryphine that acts as a binding material for the pollen grains.

The tapetum cells are of two types, amoeboid and glandular. The glandular tapetum remains intact around the anther locule, while the amoeboid tapetum disintegrates and forms a multinucleate plasmodium around the pollen sac.

Refer: Functions of Tapetum

Let us find out the differences between nucellus and tapetum now.

Nucellus

Tapetum

Description

The nucellus is a central mass of cells present in the ovules.

The tapetum is a layer of tissues present inside the anther walls.

Functions

The nucellus provides nourishment to the developing embryo and endosperm.

  • The tapetum layer acts as a nutritive tissue for the developing pollen grains.
  • It also helps in the formation of pollen walls.

Found within

It is found in female gametophytes.

It is found in male gametophytes.

Surrounds

It surrounds the embryo sac.

It surrounds the pollen mother cells or the microspores.

Enclosed by

It is enclosed within the integuments.

It is enclosed within the anther walls.

Ploidy

It is always diploid in nature.

It is diploid in nature but becomes multinucleate due to abnormal mitosis.

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Frequently Asked Questions

What is the difference between nucellus and endosperm?

The nucellus is a diploid tissue surrounding and protecting the embryo sac, whereas the endosperm is a triploid tissue that provides nourishment to the embryo.

What are the two types of tapetum?

The two types of tapetum are plasmodial and secretory.

What is the function of the tapetum?

The main function of the tapetum is to provide nutrients and regulatory molecules to the developing pollen grains.

Is sporopollenin secreted by tapetum?

The precursor for the formation of sporopollenin is secreted by the tapetum and deposited inside the anther locules.

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