This study was conducted with the Iraqi Pin-tailed Sandgrouse (Pterocles alchata). For this purpose, five adult birds weighing between 195–250 g were dissected and the spleen was removed. The organs were placed in 0.9% normal saline and fixed in 10% formalin and then preserved in 70% alcohol. Histological sections were prepared using the paraffin wax method, which involves several steps: Dehydration, clarification and embedding. The present results show that the spleen is surrounded by a capsule of connective tissue containing collagen fibres and smooth muscle. A series of connective tissue trabeculae extend from this capsule and penetrate the parenchyma of the spleen. The parenchyma consists of two main regions: the white pulp and the red pulp, which are randomly distributed due to the absence of a marginal zone between them. The white pulp is composed of central arteries, sheathed arteries and lymphatic tissue represented by the peri-arterial lymphatic sheath (PALS), the peri-ellipsoid lymphatic sheath (PELS) and lymphatic nodules of two types – spherical and ovoid. The red pulp is formed by venous sinusoids and splenic cords. Plasma cells, lymphocytes and macrophages were also observed.
