Morphology, Morphometry and Histogenesis of the Prenatal Dromedary (Camelus Dromedarius) Spleen

Prenatal gross morphologic, morphometric and histologic developmental features of the dromedary spleen were studied. The dromedary gestation period (13 months) was categorized into four (1-4) phases and ten developing spleens per growth phase were sampled. Splenic topographical anatomy was noted before being eviscerated from each foetus. Morphologic and morphometric features of the eviscerated spleens were immediately documented and 2 – 4 mm thick samples were collected for histological analysis. The developing spleen was dark brown in colour, semilunar shaped and significantly increased (p<0.05) in size and weight across the four phases of prenatal development. The full-term dromedary spleen was observed to have unique histological features. Its capsule had an inner smooth muscle and an outer predominant connective tissue layer. The pumping of stored blood from the muscular capsule and trabeculae was proportionate to the body’s requirement. The splenic venous return was characterized by blood flow from the red pulp (venous sinusoids) to the peritrabecular sinuses, subcapsular sinuses and finally to the splenic veins. The dromedary has a sinusal type of spleen and has both open and closed types of circulation. The presence of closed circulation and absence of marginal sinus could be the reason for dromedary main health problems of blood parasites; Trypanosoma evansi. It was concluded that most of the salient features of the postnatal spleen were already evident in the first growth phase and became developed by the second phase. Other growth phases were mainly characterized by increase in sizes.