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Monitoring Stem Cell Research 
Fig. 2: The phenotypes are distributed over a wide range of 
abnormalities. Most clones fail at two defined developmental stages, 
implantation and birth. More subtle gene expression abnormalities 
result in disease and death at later ages. 
Fig 2 Degree of Abnormalities in Clones: 
A Continuum without Defined Stages 
Fig 3: Parental epigenetic differences in normal and cloned 
animals 
A: The genomes of oocyte and sperm are differentially methylated 
during gametogenesis and are different in the zygote when 
combined at fertilization. Immediately after fertilization the paternal 
genome (derived from the sperm) is actively demethylated whereas 
the maternal genome is only partially demethylated during the next 
few days of cleavage. This is because the oocyte genome is in a 
different chromatin configuration and is resistant to the active 
demethylation process imposed on the sperm genome by the egg 
cytoplasm. Thus, the methylation of two parental genomes is 
different at the end of cleavage and in the adult. Methylated 
sequences are depicted as filled lollipops and unmethylated 
sequences as empty lollipops. 
PRE-PUBLICATION VERSION 
