"Our work challenges that dogma, held since early embryologists first observed mammalian eggs around 1827 and observed fertilisation 50 years later, that only an egg cell
fertilised with a sperm cell can result in a live mammalian birth.
One queen of the Q group which only had live cocoons in the cage managed to get into the cage and established a living egg cell
on the cocoons.
A key problem has been that human egg cells
appear more fragile than those of other species.
Scientists hope to fertilise the first human egg cells
grown in a lab from stem cells later this year, it emerged yesterday.
An electric current acts as a trigger for the egg cell
to start dividing as it grows like any normal embryo.
The researchers took bits of skin from the tails of mice, plucked out the nucleus of the skin cells, and inserted them into egg cells
from other mice whose own nuclei had been removed.
SCNTwhich is a technique of asexual reproduction, a.k.a., cloningactually creates a new embryo, not a "manufactured egg cell
." As an article published in the December 27, 2000, Journal of the American Medical Associationwritten by several bioethicists and biologists who strongly support SCNT researchput it, "CRNT [cell replacement through nuclear transfer] requires the deliberate creation and disaggregation of a human embryo." Thus, just as Dolly the cloned sheep began her biological existence as a cloned sheep embryo, assuming that human cloning can ever be done, the result of the process would be the creation of a nascent human organismnot an egg.
The patents include published United States patent applications numbers 20030224345, 20040199935, and 20040219563 which describe the fusion of the cytoplasm of egg cells
, or embryonic stem cells with somatic cells to reprogram the somatic cells back to a pluripotent stem cell state and the use of gene trap technology to identify and induce differentiation of stem cells.
Somatic cell nuclear transfer: Process in which the nucleus containing half a genome is removed from a human egg cell
and replaced with a nucleus containing a full genome from an adult cell of any kind from a donor.
The process of human cloning begins with removal of the nucleus from a human cell, such as a skin cell and transferring it to a woman's egg cell
from which the nucleus has been removed.
This phenomenon occurs by three methods: (i) fertilization of an unreduced egg by a reduced sperm nucleus (2n + n); (ii) union of a reduced egg cell
and an unreduced sperm nucleus (n + 2n); and (iii) fertilization of an unreduced egg by an unreduced sperm nucleus (2n + 2n).