3631
The ultrastructural studies in the initial stage revealed significant lack of particles of perfused ruthenium red on the lamina rara externa and marked changes in epithelial cell cytoplasm .
 Chemical: ruthenium
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 Chemical: ruthenium