Histomorphometric changes during prenatal development of the spleen in different gestational phases of the dromedary camel (Camelus dromedarius)

The spleen functions as the principal secondary lymphoid organ and plays a critical role in filtering blood and initiating immune responses to antigens. The present study examined the prenatal histological and histometric development of the spleen across the three trimesters of gestation. Sixteen camel fetuses were collected and allocated to first, second, and third trimester groups by measuring the crown vertebral rump length (CVRL) of each fetus. Tissue samples were taken from the spleen and processed for histological investigations. In the first trimester, the spleen exhibited a thin capsule, small lymphoid nodules, and a network of developing blood sinuses. In the second trimester, the capsule differentiated into an outer collagenous layer and an inner smooth muscle layer with well-developed and branched trabeculae. The lymphoid nodules in the stroma increased both in number and size. During the third trimester, the trabeculae showed increased branching and contained smooth muscle layer. The white pulp structures appeared spherical, with prominent central arterioles. The thickness of the capsule increased significantly (p < 0.05) from 21.3 μm in the first trimester to 54.6 μ in the second trimester, whereas no significant increase was noted in the third trimester (55.2 μ). The diameter of the lymphoid nodules increased significantly (p < 0.05) from 133.0 μ to 161.6 μ in the second and third trimesters, respectively. These observations suggest a progressive increase in the size of these nodules during fetal development. It is concluded that the structural changes in the camel spleen during embryonic development were similar in trend to those of other domestic animals. This study provides novel baseline quantitative data on the morphometry of the splenic capsule and lymphoid nodules during prenatal development of the camel spleen, offering a reference for future studies on lymphoid organ maturation in camelids.