Student Project Figures Figure 16 Figure 15. A drawing of the choanocyte chamber components involved in flow path, including; (1) prospopyle, (2) microvilli collar, (3) contact between apopylar velum of apopylar cells with chanocytes at apopylar opening and (4) reticuloapopylocyte (pressure regulation cell). Drawing credit to Hammer & Nickel (2014). Figure 16