Entry of pollen tube into the embryo sac, Biology

Entry of Pollen Tube into the Embryo Sac

The pollen tube enters the embryo sac through the filiform apparatus of ong of the synergids. Generally, one of the synergids degenerates before the entry of pollen tube and the tube invariably enters through such synergids. In Plumbago, where synergids are absent and the egg has the filiform apparatus, the tube enters directly into the egg. In several taxa, however, both the synergids remain healthy until the entry of pollen tube and the one that receives the pollen tube starts degenerating. It has been proposed that the degeneration of synergid and also of pollen tube cytoplasm is essential to prevent male gametes from a rejection or antigen-antibody type of reaction.

The choice of the male gamete involved in syngamy and triple fusion has long been a subject of speculation. Embryologists were curious to know which of the two male gametes participated in syngamy. Transmission electron microscopy and scanning electron microscopy have revealed that in certain plants the two male gametes are unequal in size and in the number of plastids and mitochonoria they contain. The plastid rich sperm seems to be preferentially involved in syngamy and the one with poor plastids fuses with the secondary nucleus. However recent studies indicate that heteromorphic sperms are not seen in other plants.

Posted Date: 1/23/2013 4:30:16 AM | Location : United States

Related Discussions:- Entry of pollen tube into the embryo sac, Assignment Help, Ask Question on Entry of pollen tube into the embryo sac, Get Answer, Expert's Help, Entry of pollen tube into the embryo sac Discussions

Write discussion on Entry of pollen tube into the embryo sac
Your posts are moderated
Related Questions

Why does oxygen concentration in the blood decrease during exercise? Why does carbon dioxide concentration in the blood change during exercise?

Define the Water Bath with Shaker? An electric water bath with a shaker that can hold test tubes as well as conical flasks. When on a non-shake mode, it acts as a simple water

Proteins destined to be secreted from the eukaryotic cell are synthesized by ribosomes bound to the RER (rough endoplasmic reticulum). As the protein is synthesized it is transloca

Which is the kind of gamete produced by a heterozygous individual? And what is the genotypical proportion of these gametes? The Heterozygous individuals, for instance, AA, prod

What are the Advanced surgical procedures The scope of implantology has widened to include many more clinical situations which would be hitherto contraindicated for implants du

What is Allantois One of the extraembryonic eggs found in the amniote animals. The allantois contains the metabolic wastes created by the developing embryo. May also be involved

Write a DNA palindrome or inverted repeat of at least 10 nucleotides in length.

What is a trace element and how are they important in organisms, give an example.