Vegetative Cell

What is a Vegetative cell? Vegetative cell definition

In microbiology, vegetative cells are the normally growing cells forming the endospores.

The nature of spores is so that they are dehydrated and inactive metabolically, and It can stay viable for centuries. Under favourable conditions, spores can germinate into the vegetative cells in a matter of 90 minutes. Typically, vegetative cells are gram-positive cells, and a few are gram-negative cells. Their microscopic appearance is non-refractile.

Vegetative cell Example

Vegetative cells are any cells of the body except those which take part in the production of gametes. These cells are produced from the cells which pre-exist through the process of asexual reproduction. In bacteria, the normal living cells are vegetative cells. The vegetative cells of multicellular entities are referred to as somatic cells. The vegetative cells of Fungus go on to form the fungal hyphae. In fungi, the vegetative cells comprise a thick cell wall.

Vegetative cell Shape

As vegetative cells comprise the reserves of food, they are bigger typically, possessing a nucleus that is irregularly shaped which assists in the production of proteins, helping in sustaining the generative cell which is developing.

Vegetative cell and Generative cell

Through the process of asymmetric cell division of the microspores, generative cells are the second type of cells that are produced. Subsequent to the process of cell division, the collection of the droplets of osmiophilic lipid in the vegetative cell’s cytoplasm that lines the cell wall of the generative cell. Additionally, the vegetative cells exhibit the gathering of amyloplasts loaded with starch in their cytoplasm following cell division.

Generative cells are mainly involved in serving as reproductive cells of the pollen grains. Hence, after pollination, they develop two sperm cells in the angiosperms, of which one sperm cell unites with the egg leading to the formation of the zygote, developing into the seed later. The second sperm cell unites with the central cell (binucleate), which forms a primary endosperm cell. The process is referred to as double fertilisation.

Vegetative cell Ploidy – Vegetative cell is haploid or diploid?

The process of vacuolation is co-occurred by the displacement of the microspore nucleus to an eccentric place against the wall of the microspore. Here, the nucleus experiences first pollen mitosis leading to the formation of 2 unequal cells. After the release of the microspores from the tetrads, an unequal division of the microspore can be seen, which forms the large vegetative cell (n) and the small generative cell (n), each comprising a haploid nucleus.

The vegetative cells comprise the majority of the younger pollen grain and the generative cell. On the other hand, it inherits the trace quantity of the microspore cytoplasm found in the vegetative cell. Subsequently, the generative cell detaches from the pollen grain wall, engulfed by vegetative cells, thus forming a characteristic “cell inside a cell” structure. This engulfed generative cell splits further by the process of mitosis, forming two sperm cells enclosed completely in the cytoplasm of the vegetative cell before shedding the pollen in the pollen tube.

In various plants, for instance, corn, the generative cell experiences a mitotic division in the pollen grain, which forms two sperm cells (n).

Vegetative cell Function

The known function of the vegetative cells in pollen grains is the extension of the pollen tube for the transportation of two sperm cells into the embryo sac for the process of fertilisation. In other words, the vegetative cells, following pollination, produce pollen tubes by serving as the pollen tube cell. It is involved in delivering the sperm cells to the ovule. The pollen tube carries sperm nuclei from the stigma to the ovule of the flowers of the angiosperms.

However, it does not experience fertilisation by uniting with egg cells. Hence, the vegetative cells are referred to as non-reproductive cells. Neither does the physiology nor the morphology of the vegetative cell appear as that of the reproductive cell, as in the case of the generative cell. Once the pollen tube ruptures, releasing the sperm cells, the pollen tube experiences destruction.

All in all, the mature pollen grain comprises generative as well as vegetative cells. The vegetative cells carry out metabolic activities, storing reserve food for pollen grains and delivering gametes to the embryo sac of the ovule.

Vegetative cell of Pollen grain

One of the two types of cells found in the pollen grains in higher plants is vegetative cells, the second being the generative cells. Both these cells are a result of the asymmetric cell division of the nucleus of the microspore, which forms by meiosis at the earlier phases of the development of the pollen.

The pollen grains which fall on the stigma, the receptive surface of the pistil, undergoes germination if it belongs to the same species, thus producing pollen tubes. Each of these develops in style towards the ovule. The pollen tube comprises 3 haploid nuclei, one of which, the so-called vegetative or tube nuclei, apparently channels the functions of the structure that is growing.

Vegetative cells and Endospores

Cells begin as vegetative cells, performing all the activities necessary for growth. Under hostile conditions, if they are capable, it converts from vegetative cells into endospores. As a result, endospores are actually formed inside the vegetative cell, and then these cells lyse, thus releasing the endospores.

Endospores are thick-walled, ovoid or round, extremely refractile, metabolically inert resistant structures. The spores are not mandatory parts of the bacterial life cycle. The endospores do not show any sign of life, being referred to as cryptobiotic.

The process of conversion of the vegetative cell into an extremely protective endospore is through sporulation, which usually takes place when the arrival of the cell is somehow threatened.

Endospores can stay in the dormant state until the environmental conditions get better, which leads to a chemical change initiating the expression of genes. The conversion of endospores into vegetative cells that are metabolically active occurs in three different stages:

• Activation – a preparatory stage which is identified by heat-application
• Germination – endospores turn active metabolically and start to act on water
• Outgrowth – complete emergence of vegetative cells from the endospore shells

To summarise, the endospores take form by the vegetative cells responding to the environmental factors, which signify limiting factors for vegetative growth, for instance, the exhaustion of important nutrients. It germinates and turns into vegetative cells when there is a relief from environmental stress. As a result, the endospore-formation is a means of survival as opposed to a mechanism of reproduction.

Difference between Vegetative cell and Endospore – Vegetative cell vs Endospore

Listed below are a few important differences between vegetative cells and endospores:

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