Figure 1 in Apocrine secretion of the egg hull in oogenesis and exclusion of sperm organelles at fertilization make reproduction in Chitonida (Mollusca) unique

Figure 1. (A) Scanning electron micrograph (SEM) of oocyte type with closed hull cupules (C) found in some species of Acanthochitona and Cyanoplax. The example is Cyanoplax dentiens. Scale bar = 40 µm. (B) Transmission electron micrograph (TEM) of section of later stage oocyte (O) of A. garnoti showing characteristic form of closed cupules (C). FC, follicle cell. Scale bar = 10 µm. (C) TEM of forming hull cupule (H) of A. garnoti showing three areas of microapocrine secretion (arrows) from surface of oocyte (O). FN, follicle cell nucleus. Scale bar = 5 µm. (D) TEM of one region of microapocrine secretion release below the forming hull (H). Note elongate apical blebs (AB), like microvilli, extending from cell membrane of oocyte (O). Micro-aposomes are pinched off and released into the intercellular space, where the hull is forming. Note also: rare Golgi vesicle exocytosis (arrow). Scale bar = 1 µm. (E) TEM detail of