prosoplasia

[prŏs′ə-plāzhə]
n.
  1. Progressive transformation to a higher level of function or complexity, such as the change the cells of the salivary ducts go through to become secreting cells.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.