Histological studies on some immune organs of oreochromis niloticus (tilapia nilotica)‎

الملخص EN

The thymus of Tilapia nilotica (Oreochromis niloticus) was covered by thin capsule with short trabeculae.

The parenchyma was differentiated into cortex and medulla; the cortex consisted of dense population of lymphoid cells and few epithelial reticular cells, while the medulla consisted of few lymphoid cells and abundant epithelial reticular cells.

Thymic corpuscle-like structures also detected in the medulla.

The parenchyma also contained pigmented macrophages and mast cells.

The kidney of Tilapia nilotica (Oreochromis niloticus) was differentiated into two parts; head and trunk kidneys.

Head kidney could not differentiated into cortex and medulla.

The subcapsular region contained haemopoietic tissue.

The haemopoietic elements were represented by different types of cells.

Non encapsulated melano-macrophage centres were found either sporadic or as clusters.

Corpuscle of Stannius was seen embedded in the parenchyma.

The trunk kidney was formed of nephrons and interstitial tissue which was represented by haemopoietic tissue, lymphoid tissue and melano-macrophages.

The spleen was surrounded by thin capsule.

The spleen was composed of red, ill developed white pulp and accumulation of melano-macrophages.

The subcapsular region occupied mostly by the red pulp.

Also the spleen contained haemopoietic tissue.

Some exocrine pancreatic acini were noticed at subcapsular region.

Melano-macrophage centres were found around the vascular channels and embedded in the parenchyma.