Pleurolucina harperae, general anatomy, ctenidia, bacteria, oocytes and sperm. A Right side, with mantle removed, right demibranch and extended foot stained with methylene blue L 7 mm B Left demibranch and foot, critical point dried preparation. Scale bar = 1 mm C Cut section to show general anatomy, stained with methylene blue L 8 mm D Transverse section through single ctenidial demibranch. Scale bar = 100 µm E Surface of bacteriocytes and intercalary cells on lateral view of a ctenidial filament. Scale bar = 15 µm F Spirochaete bacteria on surface of bacteriocytes. Scale bar = 2 µm G, H Symbiotic bacteria contained in bacteriocyte. Scale bar = 5 µm I Developing oocytes. Scale bar = 500 µm J, K Sperm. Scale bars = 5, 2 µm respectively. aa anterior adductor muscle bz bacteriocyte zone cz ciliated zone dg digestive gland f foot lp labial palps me mantle edge ov ovary with oocyctes pa posterior adductor r rectum rd right demibranch st stomach tm thickened mantle ventral to anterior adductor muscle.