Why does the paratially transplanted liver grow to full size not larger?

Answer 1

It can grow to full size as liver cells divide.
Ususally healthy liver is not large (ie: it's not palpable).
[No doubt the transplant liver is healthy liver.]

Answer 2

The same reason the original liver grew to full size and not larger. The cells in the liver get signals from their environment (i.e. the rst of the organs oaround it) to let the cells know whether it is appropriate to divide or not. When it reaches the edge of the liver's "border" the cells sense this and stop dividing.

Answer 3

Genetic pre-programming!