Student Project Figures Figure 16 Cross section showing the body plan of a juvenile sponge with a leuconoid aquiferous system. Mesophyll shown in blue and populated with cell types.  Archeocyte (a ), choanocyte chamber ( cc ), endopinacoderm ( en ), exopinacoderm ( ex ),ostium ( o ), osculum ( os ), sclerocyte ( s ), spicule ( sp ), and spherulouscell ( sph). From Degnan et al, 2015.  Figure 16 Figure 17 Figure 18 Figure 19 Figure 20