A PLANIMETRIC STUDY OF MORPHOLOGICAL VARIABILITY IN THE DIGESTIVE DIVERTICULA OF LITTORINA LITTOREA (LINNAEUS) AND MYTILUS EDULIS LINNAEUS

The inter-and intratubular morphological variability in thedigestive diverticula of Littorina littorea and Mytilus edulishas been investigated by planimetric procedures. Five parametershave been measured: mean epithelial thickness (MET), mean diverticularradius [MDR], mean luminal radius (MLR), MLR/MET ratio and MET/MDRratio. The results indicate that irrespective of the patternof tubule organization within the digestive diverticula (whethertubule types are clustered or not), variability between individualsis greater than that between zones of the digestive gland. Thishas implications for the design of sampling strategies in investigationsof the morphology of digestive diverticula in physiologicaland pathological studies. The variability in the epithelialthickness within diverticular sections is of minor relevancein assessing the overall condition of the digestive gland inthese studies, because variability in epithelial thickness betweentubules is significantly greater than within tubules in bothspecies. (Received 10 March 1989; accepted 16 October 1989)