GLÂNDULA DIGESTIVA DE MYTELLA GUYANENSIS (BIVALVIA: MYTILIDAE) - MUDANÇAS CITOFISIOLÓGICAS NOS TÚBULOS - CICLO DIGESTIVO

Resumo

Cytophysiological evaluation of digestive tubules and tides synchronism of Mytella guyanensis, related to discontinuous feeding process, was performed in the present paper. Ten animals sampling, every two hours intervals over a 12 hour period were collected, fixed in alcoholic Bouin, imbedded in paraffin and stained in Masson's trichromic. The tubules presented digestive cells under the following morphophysiological changes or "phases": I - absorption; II - intracellular digestion; III - assimilation; IV - apocrine secretion; V - restauration and VI - holding phases. Basophilic secreting cells were under the following "phases": I - assimilative/absorptive; II - synthesizing; III - secretive merocrine; IV - secretive apocrine;V - restauration and VI - holding phases. Therefore, digestive gland behaves like a merocrine (when basophilic secretory cells secrete granules), like an apocrine (when acidophilic digestivecells eliminate the apical portion of cytoplasm and its secretion), or like a holocrine one (when allsecretory or digestive cells are eliminated). Ducts showed to participate in the food absorption process. Digestive cycle showed to be a consequence of morphophysiological modifications of acidophilic digestive cells, once they were massively present. As a conclusion, M. guyanensis presents a feeding cycle with coordinated intracellular and extracellular digestion and its digestive cycle is continuous, but cyclic and triphasic.