Reproductive cloning

 

In reproductive cloning a somatic cell nuclear transfer(SCNT) is performed on a random cell from taken from a donor(donor nr 1) and an egg cell taken from another donor. In simpler terms, this means that a random cell is taken from a donor, then the nucleus is removed from that cell and placed in an egg cell, which has had its nucleus removed. The mentioned egg cell is taken from another donor this donor has to be fully developed in the sense that the egg cells have to be fully developed. The egg cell that now has the nucleus of donor nr 1 is placed in a petri dish where it is stimulated. Once it has begun dividing,

the embryo is placed in the uterus of a surrogate

mother. The surrogate mother is now pregnant

with a clone ofdonor nr.1.  SCNT is the most common

form of cloning and more than 18 mammals have been

cloned using this technique the first clone was the

sheep dolly who was born in Scotland the 5th of July

1996.

 

Since Dolly came into the world, it is among

other scientists have succeeded in cloning rats,

rabbits, cats, dogs, goats, pigs, cattle, horses

and rhesus monkeys. Despite this apparent success

and simplicity of the technique, there are significant

problems associated with cloning. Compared with

normal fertilized egg has the core transplanted

eggs a reduced ability to develop into blastocysts.

There is an increased rate of abortions. And among

the offspring are born, there is a high incidence of malformed offspring with reduced viability. Since Dolly was created, the researchers used not less than 277 nuclear transplanted eggs to produce 29 embryos. And of the embryos only three resulted in born lambs, only Dolly lived. Similarly, it has taken 9,000 attempts to produce 70 calves, and of the 70 calves about a third of them died too early. And as mentioned, scientists despite many attempts have not yet succeeded in cloning human cells.

The main reason for the many problems appears to be associated with the so-called re-programming of the genetic material necessary for the creation of a new individual.