Noun:

மாவித்தி,

megaspore தமிழ் அர்த்தத்தின் உதாரணம்:

பூக்கும் தாவரங்களில், இரண்டாவது உயிரணு ஒன்று, மாவித்திக்குழியத்தில் இருக்கும் வேறொரு கருவுடன் இணைந்து பல்மடிய நிலையிலுள்ள வித்தகவிழையத்தை உருவாக்கும்.

சூலானது உட்புறமாக மாவித்திக் குழியம் (megasporocyte) என்னும் பகுதியையும், அதனைச் சூழ்ந்திருக்கும் மூலவுருப்பையகம் (nucellus) என்னும் பகுதியையும், வெளிப்புறமாக ஒரு உறை போன்று பாதுகாப்பிற்காக அமைந்த சூலுறை (integument) என்ற பகுதியையும் கொண்ட ஒரு அமைப்பாகும்.

பின்னர் சூலின் உட்புறமாக இருக்கும் மாவித்திக் குழிய உயிரணுவில் ஏற்படும் ஒடுக்கற்பிரிவு எனப்படும் கலப்பிரிவு செயல்முறை மூலம், ஒருமடிய மாவித்தி (Megaspores) எனப்படும் சூல்முட்டை உயிரணுக்களை உருவாக்கும்.

மாவித்திர, பிலியந்தலை இல் வசிக்கும் இவர் பௌத்த மதத்தைச் சேர்ந்தவர்,.

megaspore's Usage Examples:

7, C) immediately above the megaspore.

The fructification consists of long, lax spikes, with whorled sporophylls; indications of megaspores have been detected in the sporangia.

The endosperm detached from a large Ginkgo ovule after fertilization bears a close resemblance to that of a cycad; the apex is occupied by a depression, on the floor of which two small holes mark the position of the archegonia, and the outgrowth from the megaspore apex projects from the centre as a short peg.

The spores of this genus are curiously winged, and intermediate in size between the microspores and megaspores of Lepidostrobus; the question of homospory or heterospory is not yet decided.

Each sporophyll bears a megasporangium, attached to its upper surface at the proximal end, containing a single large megaspore (fig.

Each sorus includes both microsporangia, with numerous spores, and megasporangia, each of which contains a single megaspore with a complicated wall.

Some Calamites were heterosporous, sporangia with microspores and megaspores being found in the same cone.

These are with few exceptions foliar structures, known in comparative morphology as sporophylls, because they bear the spores, namely, the microspores or pollen-grains which are developed in the microsporangia or pollen-sacs, and the megaspore, which is contained in the ovule or megasporangium.

In the megasporangium, on the other hand, the four megaspores, which arise from a single mother-cell, are nourished at the expense of the other sporogenous cells and of the tapetum.

The single megaspore enclosed in the nucellus is filled with tissue (prothallus) before fertilization, and contains two or more archegonia, consisting usually of a large egg-cell and a small neck, rarely of an egg-cell only and no neck (Gnetum and Welwitschia).

At an early stage of development a large cell makes its appearance in the central region of the nucellus; this increases in size and eventually forms three cells; the lowest of these grows vigorously and constitutes the megaspore (embryo-sac),which ultimately absorbs the greater part of the nucellus.

These latter bear spores of two kinds, microspores and megaspores, in separate sporangia.