Tezuka In English Discussion Forums

I probably ought to check my pile of books about Tezuka for this, but I was thinking that as far as I know, Tezuka's Shojo manga have happy endings, whereas some shonen have sad or tragic endings. I admit, offhand, I can only say that I am familiar with Ribon no Kishi as far as girls' comics go, though I have far more familiarity with the boys' comics, such as Mighty Atom, Dororo, Umi no Toriton, Jungle Emperor, & a few others.

I can think of more than a few episodes in the B&W Mighty Atom that have sad endings, but not one in Ribon no Kishi. Did Tezuka write fairy tales for girls while writing more realistic stuff for boys? Was he preparing boys for the adulthood & the cold, hard facts of life, while merely entertaining girls?