Table of Contents
Can a sperm fuse with another sperm?
If more than one sperm fuses—a condition called polyspermy—multipolar or extra mitotic spindles are formed, resulting in faulty segregation of chromosomes during cell division; nondiploid cells are produced, and development usually stops.
What do you think would happen if multiple sperm fused with one egg?
To ensure that the offspring has only one complete diploid set of chromosomes, only one sperm must fuse with one egg. If this mechanism fails, multiple sperm can fuse with the egg, resulting in polyspermy. The resulting embryo is not genetically viable and dies within a few days.
What is fertilization by 2 or more sperm called?
Polyspermy results from multiple sperm fertilizing an egg, leading to an offset number of chromosomes within the embryo. Polyspermy, while physiologically possible in some species of vertebrates and invertebrates, is a lethal condition for the human zygote.
Can sperm only fertilize an egg from the same species?
Fertilization is the culminating event in sexual reproduction and requires the recognition and fusion of the haploid sperm and egg to form a new diploid organism. Specificity in these recognition events is one reason why sperm and eggs from different species are not normally compatible.
Is Polyspermy possible in humans?
Polyspermy is very rare in human reproduction. The decline in the numbers of sperm that swim to the oviduct is one of two ways that prevents polyspermy in humans. The other mechanism is the blocking of sperm in the fertilized egg. Only two cases of human polyspermy leading to birth of children have been reported.
What triggers acrosome reaction?
The acrosome reaction that occurs after sperm capacitation, is an exocytotic event induced by a Ca++ influx. Binding of the sperm receptor to ZP3, a zona glycoprotein acting as ligand, triggers the molecular events leading to acrosomal exocytosis.
What prevents multiple sperm from fertilizing an egg?
Human ovum. The zona pellucida is seen as a thick clear girdle surrounded by the cells of the Corona radiata. The cortical reaction is a process initiated during fertilization that prevents polyspermy, the fusion of multiple sperm with one egg.
How is polyspermy harmful?
In general, the entry of more than two spermatozoa into the egg cytoplasm, referred to as polyspermy, causes aberrant effects on meiosis completion or embryo development and hence embryonic death, due mainly to excess male centrosomes delivered into the egg.
Can polyspermy result in twins?
Identical twins result from a fertilized egg (an egg that has fused with a sperm cell) dividing in two. A likely cause of the above scenario is polyspermy, in which one egg is fertilized by multiple sperm cells.
What will happen if the acrosome of a sperm is removed?
Sperm that are unable to go through the acrosome reaction properly will not be able to fertilize an egg.