Apparently there are at least two chapters of the original manga that have never been reprinted: "Jungle Kingdom" and "Chi-tan". I think these were turned into episodes of the original anime. Jungle Kingdom is English episode 93: Jungle Mystery or Japanese episode 102: Queen of the Devils' Place. "Chi-tan" is Japanese episode 165:A Great Fuss Over Babies, but this episode didn't make it into the English language version.
There is some info on Chi-tan here: http://www.astroboy-online.com/forums/s ... ht=chi-tan
http://www.astroboy-online.com/forums/s ... ht=chi-tan
I've never seen the 1963 anime, so does anyone have any info about these two stories?
I'm surprised that Tezuka Co. hasn't been able to track them down, though...