Morphometry of transport tissues in a freshwater crustacean

Gills and fenestra dorsalis of the syncarid crustacean Allanaspides helonomus were examined with the electron microscope. Their epithelia were characterized using morphometric measurement, with a view to assessing potential for ion transport and respiratory activity. The results obtained show distinctions between the paired gills and allow the possibility that one gill of each pair is respiratory and the other osmoregulatory. The fenestra dorsalis has been tentatively assigned a transport function, although the nature of its transport load remains uncertain. The detailed morphometric analysis provided useful insights into the nature of the tissues studied.