Update: Here is some evidence for the medical part of the story from a doctor friend of mine - Dr.Vivek Chail. Though the reason for writing the story was more than just exploring medical possibilities through science fiction.
thnks for your mail/story link
your flow of thought is great.
comng to your ques..
1.is the medical possibility there, that the ova can be extrated from a human female and injected with sperm and placed in an artificial placenta like chamber and fed with appropriate nutrients.
the ova extracted frm human female and injected with sperm is the same as test tube baby..frst done in 1970s
the second part i would like to clarify that the placenta is a temporary organ that serves as a link between the deloping fetus and the uterus. The fetus develops in the uterus..i suppose you meant that as the "chamber"..still in rare cases the fetus can develop outside the uterus and this is known as an ectopic pregnancy..that is again dangerous to the mother..
as in your question..the "chamber" is still an enigma because you have multiple blood vessels and the blood flowing through those small channels should flow under regulated pressures at the same time performing many other processes to keep the fetus growing..if you can grow the "uterus" in a lab and maintain the othr parametrs under control conditions you story might be a reality..
2.Would it develop into an embryo and if DNA sequences are introduced later on to modify the traits can a 'more perfect' human being be formed.
there are certain cells known as stem cells and these are unique for any individual and can be used as a future reserve to grow organs..it is commercialised in bangalore and they preserve the cord blood and harvest stem cells..
the genetic make up is decided at the time of fertilisation..the maximum intervention is possbl at that time..later on DNA sequences may be modifiable still i have not heard much on that..you cant change DNA after birth still you can match and this helps in prediagnosing medical conditions and nature of future disease leading to preventive treatment..