Surface and ultrastructural characterization of the haemocytes in the scallop Argopecten irradians
ZHANG Wei-Zhu 1,4 , WU Xin-Zhong 2 , WANG Ming 3 1. Department of Chemistry and Biology, Chuzhou University, Chuzhou 23900, Anhui, China 2. College of Animal Sciences, Zhejiang University, Hangzhou 310029, China 3. College of Veterinary Medicine, China Agricultural University, Beijing 100094, China 4. South China Sea Institute of Oceanology, the Chinese Academy of Sciences, Guangzhou 510301, China
Light, transmission electron and scanning electron microscopical studies were carried out to characterize the haemocytes in the scallop Argopecten irradians. Fore kinds of haemocytes were recognized: typeⅠsmall hyalinocytes, size of (2.38±0.08) μm, percentage of 30%-35%; typeⅠlarge hyalinocytes, size of (4.41±0.33) μm, percentage of 15%-20%; typeⅡsmall granulocytes, size of (4.15±0.26) μm, percentage of 20%-25%; typeⅡ large granulocytes, size of (8.26±0.52) μm, percentage of 25%-30% according to cell size, granular features, and some structural and functional characteristics. There might be 5 types of surface structures in the haemocytes under scanning electron microscopy:round shape cells, pear or spindle shaped cells, pinecone-like cell, amoeba-like cells and large shaped cells. Granulocyte types showed larger sizes and smaller N/C ratios than hyalinocytes. The mean haemocyte number was about(3.75 ± 0.65)×10 7 cells/ml of haemolymph. Differential haemocyte counts identified the haemocyte population containing 44.7% granular cells and 55.3% agranular cells. Three types of granules were distinguished: typeⅠ, with high electron-dense, size of 0.1-0.6 μm, with or without membrane surrounding it; typeⅡ,with low electron-dense, size of 0.1-0.5 μm, usually surrounded by a membrane; type Ⅲ, with medium electron-density, size of 0.2-1.0 μm, usually surrounding by a membrane. We suppose that the typeⅠgranules might be formed by engulfing the foreign materials (microorganisms, or other granules) or internal waste materials (organelles or fragments); the typeⅡ granules might be formed by primary lysosomes, probably originating in the Golgi complex or endoplasmic reticulum; and the type Ⅲ granules might be the secondary lysosomes and formed by fusion of two kinds of typeⅠand typeⅡgranules or the matured typeⅠgranules which absorbing some hydrolases in it.