Fig. 15

Frontal histological sections of Zoea IV (Holländer stain). a - section showing the median portion of the pyloric stomach (PS) laterally flanked by the lobes of the midgut gland, see Fig. 2c for section plane; b - section of the anterior part of the midgut (MG) with the dorsal heart (H) and the ventral nerve cord (VNC) at the level of the suboesophageal ganglia. Dorsally, the VNC is crossed by muscles (Msc) associated with the maxillae; c - higher magnification of rosette-shaped tegumental glands of the mandible; d - the heart is surrounded by the pericardial cavity (PCav) into which the ostia (O) open. Asterisks identify putative trabeculae; E - cross section of musculature (asterisks and arrow) laterally to the heart (H) underneath the branchiostegites (Bst). Abbreviations: AA - anterior aorta, AC - anterior caecum, CEC - circumoesophageal connective, DG - digestive gland, H - heart, Lu – lumen of digestive gland, MA - mandibular adductor musculature, MG - midgut, Msc - musculature of the maxillae, PS - pyloric stomach, TeG - tegumental gland, VNC - ventral nerve cord