Theaters of drama taking from theaters of anatomy

"The ordinary citizen, in order to be admitted to the anatomy, had to purchase an entrance ticket. This was another international custom. It appears quite likely that the sale of tickets to those wishing to attend public anatomies preceded the same of ordinary theater tickets by sever years and may even have encouraged theatrical confraternities to follow suit. This, incidentally, is only one of a number of aspects suggesting, it seems to me, that studies of the history of the stage should include the anatomical theaters."

-p. 32, William Heckscher's Rembrandt's Anatomy of Dr. Nicholas Tulp, 1958

The full text of the book can also be found HERE