Events after sperm and egg fusion, Biology

Events after Sperm and Egg Fusion

The entry of the sperm into the egg activates the egg. The activation of egg results in two types of responses.

(1) The early responses and

(2) The late responses.

The early response for the entry of the sperm into the egg is the prevention of polyspermy i.e. the entry of or fusion of more than one sperm into the egg. Polyspermy may result in several abnormalities such as polyploidy, abnormal mechanism of chromosomal separation during cell division and ultimate death of the embryo. Organisms have evolved different types of mechanisms for prevention of entry of more than one sperm into egg. Generally any one of the three different strategies may be involved in the prevention of polyspermy. For instance in fishes the sperm can enter into the egg only through the narrow opening the micropyle, the rest of the egg being covered by the impermeable chorion. In sea urchins and mammals there is a restriction on the number of sperm that are able to penetrate the extracellular coats and fuse with the egg. In mammals the sperm have to migrate the long female reproductive tract to reach the egg and further, the structural changes in zona pellucida block polyspermy. Certain animals such as salamanders do permit the entry several sperm into the egg but only the nucleus of one of the sperm can fuse with the egg to form the zygote nucleus; other sperm nuclei degenerate.

Posted Date: 1/25/2013 12:18:00 AM | Location : United States







Related Discussions:- Events after sperm and egg fusion, Assignment Help, Ask Question on Events after sperm and egg fusion, Get Answer, Expert's Help, Events after sperm and egg fusion Discussions

Write discussion on Events after sperm and egg fusion
Your posts are moderated
Related Questions

Catastrophism Once-popular belief which events in the history of earth had occurred in the past a sudden events and by processes different from those operating today. The periods

Differentiation of Tissues - Root Apex New cells generated from the divisions of meristematic cells start expanding and differentiating further. Epidermis, cortex and stele a

Amoeboid Tapetum - Tapetum It is also known as invasive or periplus modial tapetum. This type of tapetum is more prevalent in the monocotyledons (Arum) than in the dicotyledon

HACCP Control Measure HACCP Control Measure :  Any action or activity that can be used to prevent, eliminate or reduce a significant hazard.

Why is ridge mapping required and what is its alternative The selection of the implant diameter apart from the mesiodistal space available also depends on the buccolingual widt

How cell divides?

Classification of Living Organisms – Species You have by now already come across the word 'species'. The word has a definite meaning in biology. Although the living world is v

is the leukamia dangerous

Zygotic or Suspensor Polyembryony Cleavage of the apical cells of the globular or filamentous proembryo produced by the zygote may result in two or more embryos in a seed. Th