Observations on the Ultrastructure of Extrusomes in Anteholosticha monilata (Ciliophora: Hypotrichida)

Abstract: By using scanning and transmission electron microscopy， the present study demonstrates a great number of extrusomes distributed in the cortical cytoplasm of a hypotrichous ciliate Anteholosticha monilata. The extrusive organelles in early phase were seen to be located in the deep part of the cytoplasm. There were three kinds of vesicles with different structural characteristics. The mature extrusomes moved towards the pellicle， which consisted three parts: a body consisting of strateform structures of uneven electron density， an elongated shaft located at the centre of the body and a cap including multilayer membrane-structure. The organelles broke through the pellicle and discharged part of their internal structural substances when suffered from the external stimulus， and the extruded structures were mushroom-shaped. The results indicated that the extrusomes play a protective/defensive role when the outer environment changes. Extrusomes may be originated from the vesicles of Golgi apparatus. In the close relationship of ciliates， their extrusomes may have similar characteristics in structure.

CSTR: 32200.14.cjcb.2012.02.0010