Frequency - Word Form
 49 an
 47 transplantation
 45 from
 44 organs
 42 should
 41 have
 40 or
 40 organ
 39 not
 39 pig
 38 animals
 36 transplant
 35 animal
 34 must
 34 one
 34 survival
 32 also
 32 d
 30 transgenic
 29 ethical
 29 into
 29 s
 28 been
 28 can
 28 there
 27 at
 27 clinical
 26 cells
 26 may
 26 risk
 26 we
 25 2000
 25 has
 25 k
 25 m
 24 e
 24 such
 23 complement
 23 h
 23 health
 23 heart
 23 possible
 22 use
 21 7
 21 all
 21 antibodies
 21 case
 21 his
 21 pigs
 21 porcine