The middle layer in a microsporidian spore wall that lies under the exospore and outside the plasma membrane, containing chitin and proteins.
Source:PMID:19457051
Comment
Microsporidian biology uses the term endospore differently than GO:0043593 endospore coat which is for a spore formed inside of another cell. Microsporidian endospore refers to the inner layer of the spore wall itself.