Victorian Wife wrote on Sent: Monday, July 22, 2002 5:36 PM
>I have never heard of two
>fully formed embryos fusing back together into one embryo (it might but I
>haven't heard about it and would suspect to be very very rare if at all if
>you apply stringent scientific criteria to was is separate in the first
>place).
Consider:
"Cysts, called teratomas, composed of bits of hair and teeth and
foetal bones are sometimes discovered in adults. Either they are
errant cells that have reverted to a primitive embryological state
or the remnant of a vanished identical twin. Dead fetuses have
also been found inside living children. There is a well-known case
in 1949 of such a 'foetus-in-foetu', in which five fetuses were
removed from the brain of an infant girl in Philadelphia; several
less spectacular cases have been reported since, including a six-
pound foetus round during the autopsy of an elderly man. These
events probably accidents of timing during early pregnancy.
Identical twinning is thought to occur on or before the fourteenth
day after conception. If the division happens early in that cycle,
the embryos will be in separate placentas, like nearly all
fraternal twins By the end of the fourth day, the chorion, which
is the outer placental membrane, will have formed, and if the
zygote divides after that time, as is the case with two-thirds of
MZ twins, they develop in a single placenta. If the division
occurs between the fifth and the eight day, the twins will still
be encased in separate amniotic sacs, but if they divide after the
eighth day there will be nothing between them. Half of these late-
splitting twins die, often strangling in each others umbilical
cords. It is thought that by the twelfth day the division is
likely to be incomplete, resulting in conjoined or Siamese twins,
which occur in abut one out of 400 MZ births, foetus-in-foetu, and
teratomas. These are, however, only theories. One can also make
the case that the twinning process got stuck at the beginning and
never advanced. These abnormalities are far more prevalent in
girls than in boys, since male twins (like all boys) are more
likely to miscarry." Lawrence Wright, Twins, (London: Phoenix
Books, 1997), p. 78-79
MZ=Monozygotic
People have also been found with fraternal twin fusions, in which the person
has two different tissue types in different parts of his body.
glenn
see http://www.glenn.morton.btinternet.co.uk/dmd.htm
for lots of creation/evolution information
anthropology/geology/paleontology/theology\
personal stories of struggle
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