modified midgut cells secrete chitin and protein whereas modified foregut tissue ( valvula cardiaca ) appears to be adapted to provide structural integrity ( extensive junctions , microtubules ) , movement ( muscles , possibly microtubules ) , a store of energy ( glycogen deposits ) and possibly a lipidic secretion ( from smooth endoplasmic reticulum ) to lubricate the passage of the membranes .
C0007634
cells
C0230789
smooth endoplasmic reticulum