|MadSci Network: Cell Biology|
First of all, some basic genetics. Human males are XY and females are XX. You are correct in noting that two female pronuclei, if they could be used to make an embryo, would make only females, as there would be no source of the Y chromosome, which causes males to develop.
If sex chromosomes were the only consideration, yes, two sperm nuclei could produce XX (female), XY (male) and YY (inviable) offspring.
The main problem to carrying out the experiment that you suggest is a
phenomenon called imprinting. For some reason, genes inherited from the
mother and genes inherited from the father are "marked" or "imprinted",
leading them to be expressed differently during embryonic development. We
know this because there are genetic diseases caused by inheriting a deletion
(a chromosome rearrangement in which a segment of a chromosome has broken in
two places and rejoined, resulting in a missing segment). One such disease
is Prader-Willi syndrome:
If a child inherits a specific deletion from the father, they get this syndrome.
If they inherit the same deletion from the mother, they get a different
genetic disease called Angelman syndrome:
Oddly enough, it is possible to get Prader-Willi or Angelman Syndrome even if the child does not inherit a deletion. If they inherit both copies of chromosome 15 from the mother they get Prader-Willi; if they inherit both copies of chromosome 15 from the father they get Angelman's.
This and other such observations in humans, mice, and other mammals show that there are several parts of the genome that contain imprinted genes. It is necessary to get one set of these from the mother and one set from the father for normal development. This is the main barrier to the experiment that you suggest.
This is discussed in some of my prior answers to Mad Sci (search the archive using "Szauter").
Here is a good article on the subject:
Here are some links to news articles connected to imprinting:
For help on terminology, see the MGI Glossary:
Thank you for an interesting question.
Mouse Genome Informatics
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