Phasic activity in the digestive diverticula of the lamellibranch Cyclina sinensis.

Abstract

The canal system and digestive processes of the digesive gland of Cyclina sinensis were studied in a low intertidal population. Specimens were collected from a low-tide level at the estuary of the Tsuri-River, Fukuoka Prefecture, in February, August and November 1981. The sections were examined after staining with haematoxyline and eosin, Azan or Halmi's trichrome. The gland consisted of branched canal system, which contained four kinsd of canals, main and lateral ducts, secondary duct and blind-ending tubule. The main ducts communicating with the somach were two on each side in this species. The tubule consisted of two kinds of the cells, digestive cell and darkly-staining basophyl cell. The darkly-staining cells were always present at three crypts in cross section of the tubule, and these three groups of darkly-staining cells extended continuously through the length of each tubule to meet at the apex. The cell was smaller and appeared triangular in section, bore a long beating flagellum. The digestive cell was larger, granulated and lacked cilia or flagellum. The cell varied in shape from flattened to cuboidal or columnar in accordance with the state of intracellular digestion. Differences in the morphological appearance of digestive gland tubules were attributed to the changes within the digestive cells, which make up the tubules. These morphological variations could be recognized as five distinct tubule types (holding, absorption, digestion, breakdown, final stage of breakdowm).