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The cells in blood islands are called hemangioblasts since they also differentiate into the endothelial cells of extraembryonic blood vessel structure .
 cells, blood islands, hemangioblasts, endothelial cells, extraembryonic blood vessel structure
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Anatomy 
Text: {0} 
Answer:
 cells, blood islands, hemangioblasts, endothelial cells, extraembryonic blood vessel structure