Ultrastructure of Haemocytes of the Freshwater Crab

Latha Nadkandi Padmanabhan, Sudha Devi Arath Raghavan*, Chandrashekar Sagar Bhadravathi Kenchappa 4 5 Department of Zoology and Research Centre, Mary Matha Arts and Science College, Mananthavady, Wayanad, Kerala, 6 India 670 645 7 Department of Neuropathology, National Institute of Mental Health and Neurosciences, Bangalore, Karnataka, India 560 8 029 9 10 E-mail: [email protected] 11 12 Abstract 13 The light and ultrastructural observations on haemocyte profile of the freshwater crab Travancoriana schirnerae 14 demonstrated three cell types: agranulocyte, granulocyte I and granulocyte II. Agranulocytes are the smallest of the 15 haemocyte types, comprised 38% of the haemocytes, devoid of granules and showed high nucleoprotoplasmic ratio. Their 16 cytoplasm contained numerous free ribosomes, vesicles of smooth endoplasmic reticulum, few mitochondria with parallel 17 cristae and vacuoles. Granulocytes I (37%) are the largest of the haemocyte types, characterized by the presence of 18 numerous granules (26 to 61) of varying size, shape and densities and organelles like mitochondria, free ribosomes and 19 peripheral vacuoles and displayed low nucleoprotoplasmic ratio. Granulocytes II (25%) contained large electron dense 20 granules (10 to 23) and organelles like free ribosomes and vacuoles and showed intermediate nucleoprotoplasmic ratio. 21 Unlike granulocytes, agranulocytes exhibited prominent pseudopodial projections suggesting a phagocytory function. This 22 study revealed the unusual occurrence of a binucleate agranulocyte and a rare phenomenon called clasmatosis of granulocyte 23 II, wherein part of the cell fragments off along with cytoplasmic contents devoid of nucleus. 24 25