52030
Cell theory , first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann , states that all organisms are composed of one or more cells , that cells are the fundamental unit of structure and function in all living organisms , and that all cells come from pre-existing cells .
 Matthias Jakob Schleiden, Theodor Schwann
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Matthias Jakob Schleiden, Theodor Schwann