Figure 3. Immunocytochemistry reveals A. willeyana LC3A⁺ cells. (A) A low magnification image of a section illustrating the inner choanosome and the outer ectosome of A. willeyana. Near the outermost ectosome layer is a larva (L) containing LC3A-positive cells. Also clearly visible in this section are spherulite-forming ectosomal LC3A⁺ cells (vertical arrows). (B) A magnification of the boxed region in A detailing the LC3A⁺ cells in the larva (L), and the larger mature cells in the ectosome. (C) An adult LC3A⁺ cell (black arrow) in close proximity to a larva illustrates the clear difference in size between differentiated spherulite-forming cells and larval LC3A⁺ cells (white arrowheads). (D) Developing larvae (DL) and relatively mature larvae (L) contain LC3A⁺ cells suggesting that the process of autophagy is active throughout development in A. willeyana. However LC3A⁺ cells in larval stages do not have the same morphology as fully differentiated adult spherulite-forming cells, suggesting that these larval cells are not forming spherulites. (E) An image from the deeper choanosome layer where there can be many LC3A⁺ cells. (F) A magnified view of the boxed region in (E) illustrates the rounded morphology of these spherulite-forming cells.