Figure 5: Ovotestis of younger snails. (A) Portion of acinar space showing spermatids connected to thin threads (arrow) of acinar boundary. (B) Interacinar space between two acinar boundaries showing interstitial cell. Magnified view of the cytoplasmic part of an interstitial cell showing the RER (white arrow) is shown in box. A prominent elongated nutritive cell is shown in the acinar boundary (black arrow). (C) Acinar boundary with nutritive cell. Numerous membrane-bound secretory vesicles (arrow) are secreted into the acinar lumen. (D) Higher magnification of a portion of C, showing the secretory region packed with numerous mitochondria (black arrow) and RER (white arrow). ad = acinar boundary; ic = interstitial cell; n = nucleus; RER = rough endoplasmic reticulum; S = Sertoli cell; sd = spermatid; sg = spermatogonia.