What is ananplasia?

Answer 1

Most medical dictionaries say that anaplasia loss of the cellular microscopic features which distinguish one type from another. Anaplastic cells become smaller and simpler in structure and no longer combine to form recognizable tissues. It is a common feature of cancer and, in general, the greater the anaplasia the more malignant and dangerous the tumor.

It means that the tissues have lost their distinctive features and have reverted back to more primitive shapes.