Morphological structure, type, cytochemical and phagocytotic characteristics of haemocytes from Octopus ocellatus gray
- WANG Jing,FAN Ting-jun*,JIANG Guo-jian,WU Zi-qiu,YANG Xiu-xia,CONG Ri-shan and YU Miao-miao
J4. 2007, 42(5):
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Haemocytes, as the frontier line of immune defence, play vital roles in the innate immune system of molluscans. In order to reveal characteristics of morphological structure, biological property and immunological function of cephalopod haemocytes, the morphological structure, type, cytochemical and phagocytotic characteristics of haemocytes from Octopus ocellatus gray were studied by vital staining, cytochemical and electron microscopic techniques. The findings show that Octopus haemocytes could be divided into four types, large hyalinocytes,hyalinocytes, with an average diameter of 11.64±0.82?μm, smooth cell surface and no pseudopodium, have a few small cytoplasmic granules. The small hyalinocytes, with an average diameter of 8.88±0.88?μm and a high nucleocytoplasmic ratio, have only a few small cytoplasmic granules, whose nucleus is positively stained by trypan blue. The small granulocytes, with an average diameter of 12 .82±1.54 μm and appearance of short pseudopodia, have a large number of small and homogeneous basophilic cytoplasmic granules. Some of the cells have small cytoplasmic vacuoles, which are unable to be stained by neutral red and can be derived from the desertion of the granule content. The large granulocytes, with an average diameter of 13.66±1.50?μm and appearance of many long pseudopodia, have a lot of differentsized basophilic cytoplasmic granules. Some of the cells have both large and small cytoplasmic vacuoles, which can not be stained by neutral red. The abundant basophilic granules in granulocytes may be related with active synthesis and secretion of certain kinds of materials such as proteins. The large granulocytes show characteristics of holocrine, and the small hyalinocytes are a transient type of residual cell bodies of large granulocytes after the holocrine process finished. The results of vibrio phagocytosis assay indicated that two kinds of granulocytes have obvious phagocytotic ability while two kinds of hyalinocytes do not. It implies that two kinds of granulocytes are key haemocytes in Octopus ocellatus to carrying out cell immunity. Two kinds of granulocytes not only relate with active synthesis and secretion of certain kind of materials, but also participate directly in phagocytosis and elimination of foreign pathogens. The results lay a solid foundation for studying the functions of haemocytes in Octopus nonspecific immune defense, and also have great scientific value in the enrichment of molluscan immunology.