A study on the digestive physiology of a marine polychaete (Eulalia viridis) through microanatomical changes of epithelia during the digestive cycle.
As for many invertebrates, the gut of marine polychaete species has key physiological functions. However, studies integrating microanatomical descriptions with physiological processes are scarce. The present investigates histological, histochemical and cytological changes in the alimentary canal during the digestive cycle of the marine annelid Eulalia viridis, a species that combines opportunist scavenging, predation and cannibalistic behavior. The gut is comprised of an eversible pharynx, esophagus, intestine and rectum. Three main phases of digestion were identified, namely, resting/secretory, absorptive and excretory. The intestinal epithelium is complex and exhibited the most significant changes regarding intracellular digestion, excretion and storage. Conversely, the pharynx and esophagus were chiefly important for enzyme secretion. The results also indicate the existence of two distinct types of secretory cells in the intestine, with likely distinct physiological roles. Some similarities have been found between the intestinal epithelia and the molluscan (especially cephalopod) digestive gland, as, for instance, the shedding of apical corpuscles by digestive cells at posterior stages of digestion. The findings indicate that the digestive process in this worm is complex and related to the many physiological roles that cells need to play in the presence of reduced organ differentiation.
1MARE-Marine and Environmental Sciences Centre/IMAR-Instituto do Mar,Departamento de Ciências e Engenharia do Ambiente,Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa,2829-516 Caparica,Portugal.
Ana P
AP
Rodrigo
1MARE-Marine and Environmental Sciences Centre/IMAR-Instituto do Mar,Departamento de Ciências e Engenharia do Ambiente,Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa,2829-516 Caparica,Portugal.
Maria H
MH
Costa
2Centro de Estudos do Ambiente e do Mar (CESAM)/Centro de Investigação Interdisciplinar Egas Moniz (CiiEM),Quinta da Granja,Monte de Caparica,2829-511 Caparica,Portugal.
António Pedro
AP
Alves de Matos
3Centro de Biologia Ambiental (CBA),Departamento de Biologia Vegetal, Faculdade de Ciências da Universidade de Lisboa,1749-016 Lisboa,Portugal.
Francisco
F
Carrapiço
1MARE-Marine and Environmental Sciences Centre/IMAR-Instituto do Mar,Departamento de Ciências e Engenharia do Ambiente,Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa,2829-516 Caparica,Portugal.
Pedro M
PM
Costa
D000818:Animals; D004068:Digestive System Physiological Phenomena; D004848:Epithelium / Q000502:physiology; D004947:Esophagus / Q000502:physiology; D005260:Female; D041981:Gastrointestinal Tract / Q000033:anatomy & histology / Q000502:physiology; D008297:Male; D011077:Polychaeta / Q000033:anatomy & histology / Q000502:physiology*
digestive cycle