Haemopoiesis in the head kidney of tilapia, Oreochromis niloticus (Teleostei: Cichlidae): a morphological (optical and ultrastructural) study

Abstract

The present work focused on the histological and ultrastructural studies on haemopoiesis in the kidney of tilapia, Oreochromis niloticus. Haemopoietic tissue was found mainly in the head kidney and a small amount occurred in the mesonephros. The haemopoiesis of tilapia had the following series: erythropoiesis, granulopoiesis, thrombopoiesis, monopoiesis and lymphoplasmopoiesis. Erythropoiesis includes proerythroblasts, basophilic erythroblasts, polychromatic erythroblasts, acidophilic erythroblasts and young and mature erythrocytes. The proerythroblasts were the largest cells in the erythropoietic series. During the maturation process both the nuclear and cellular size decreased gradually due to the chromatin condensation and the progressive substitution of cytoplasmic matrix with a large amount of haemoglobin. Granulopoietic series consisted of cells with variable shape and size at different stages of maturity from myeloblasts to mature granulocytes. The promyelocytes were the largest cells in the series and were characterised by the appearance of primary (azoruphilic) granules. The maturation process involved the appearance of specific granules in the heterophilic, eosinophilic and basophilic series. It is important to mention that eosinophilic granulocytes were the dominant granulopoietic series in the haemopoietic tissue (Ht) of tilapia. Lymphopoietic series consisted of lymphoblasts, large lymphocytes, small lymphocytes and active and inactive plasma cells. Thrombopoietic series consisted of thromboblasts, prothromboblasts and thrombocytes. Thrombocytes of tilapia were nucleated and possessed a spindle shape. Melanomacrophage centres were dominant among the Ht of the head kidney. Also, monocytes were detected and shown to be large cells with an indented nucleus and cytoplasm containing numerous vesicles of different sizes and a few lysosomes.

Erythrocytes in teleost fishes: a review

“…Beginning from proerythroblast, the cells of the erythroid line are recognizable based on morphological criteria. The same stages were found by Kondera (2011) in C. carpio andAbdel-Aziz et al (2010) in Oreochromis niloticus. According to Murad and Houston (1992), the maturation of Carassius auratus erythrocytes required 16-20 days.…”

Immune-Related Functions of theHivepGene Family in East African Cichlid Fishes

“…Consistent with an elevated immune response upon Vibrio vaccination, we found an increased lymphocyte production in the head kidney, the organ where clonal lymphocyte production takes place (Rombout et al 2005; Abdel-Aziz et al 2010). We also found a higher proportion of lymphocytes both in blood and spleen, indicating lymphocyte migration toward peripheral organs.…”

Impaired growth and erythrocyte nuclear lesions of immature Oreochromis niloticus exposed to waterborne crude oil: Persistent responses

“…In tilapia, head kidney (pronephros) is a major site of hematopoiesis whereas the trunk kidney (mesonephros) functions primarily in excretion (Abdel-Aziz et al 2010). The same authors maintain that head kidney accommodates various erythroblasts including young, mature as well as aging erythrocytes suggesting that it remains an active site of erythropoietic process.…”