Shahid Bahonar University of Kerman and Iranian Biotechnology Society Agricultural Biotechnology Journal 2228-6705 18 3 2026 08 23 Developmental dynamics of spleen morphogenesis and histogenesis in local Iraqi Awassi sheep fetuses: Insights from light and scanning electron microscopy Developmental dynamics of spleen morphogenesis and histogenesis in local Iraqi Awassi sheep fetuses: Insights from light and scanning electron microscopy 453 476 5453 10.22103/jab.2026.27153.1896 FA Aisha Ayoub Essa Department of Anatomy and Histology, College of Veterinary Medicine, Al-Qasim Green University, Babylon, 51013, Iraq Jafar Ghazi Abbas Al-Jebori Department of Anatomy and Histology, College of Veterinary Medicine, Al-Qasim Green University, Babylon, 51013, Iraq 0009-0007-8070-8234 Journal Article 2026 05 10 ObjectiveSpleen plays an important role in the hemopoietic function in embryonic life. During the hepatic growth stage, spleen produces blood cells along with liver while in myeloid stage, it produces the blood cells along with liver and bone marrow. Destruction of older erythrocytes, lymphocytes and thrombocytes take place in spleen. The aim of this study was to investigate the prenatal morphological and histological development of the spleen in local Awassi sheep used light and scanning electron microscopy. Materials and methodsThirty spleen specimens were collected from healthy pregnant Awassi ewes at different stages of gestation. Fetal age was determined using the fetal crown rump length (CRL) equation and the specimens were classified into three groups: Group 1: 50–60 days, Group 2: 90–100 days, and Group 3: 130–140 days. For scanning electron examination, small spleen blocks (~1 mm³) were fixed. SEM was used to observe the splenic surface at multiple magnifications. Data analysis of histological and morphological parameters was performed using SPSS version 24. Results In group 1, spleen a tiny reddish bloody patch then appeared reddish in color more cohesive while, by scanning electron microscopy and histologically revealed an immature surface structure with incomplete development of the cortex and the trabeculae were undeveloped yet reflecting early splenic differentiation. In group 2, the spleen showed an increase in size and the trabecula extend from capsule to parenchyma, clear differentiation of white pulp and red pulp, indicating progressive structural maturation. In group3, spleen was more development with advancement of gestation and become relatively similar to that in postnatal periods and consist of the splenic capsule, trabeculae, red pulp, white pulp with present of cellular components and increased in trabecular network by light and scanning microscope examination. Conclusion These findings highlight the progressive prenatal maturation of the spleen and underscore its pivotal role in immune system development. Deviations from these normal microstructural patterns may indicate pathological or immunological disorders. ObjectiveSpleen plays an important role in the hemopoietic function in embryonic life. During the hepatic growth stage, spleen produces blood cells along with liver while in myeloid stage, it produces the blood cells along with liver and bone marrow. Destruction of older erythrocytes, lymphocytes and thrombocytes take place in spleen. The aim of this study was to investigate the prenatal morphological and histological development of the spleen in local Awassi sheep used light and scanning electron microscopy. Materials and methodsThirty spleen specimens were collected from healthy pregnant Awassi ewes at different stages of gestation. Fetal age was determined using the fetal crown rump length (CRL) equation and the specimens were classified into three groups: Group 1: 50–60 days, Group 2: 90–100 days, and Group 3: 130–140 days. For scanning electron examination, small spleen blocks (~1 mm³) were fixed. SEM was used to observe the splenic surface at multiple magnifications. Data analysis of histological and morphological parameters was performed using SPSS version 24. Results In group 1, spleen a tiny reddish bloody patch then appeared reddish in color more cohesive while, by scanning electron microscopy and histologically revealed an immature surface structure with incomplete development of the cortex and the trabeculae were undeveloped yet reflecting early splenic differentiation. In group 2, the spleen showed an increase in size and the trabecula extend from capsule to parenchyma, clear differentiation of white pulp and red pulp, indicating progressive structural maturation. In group3, spleen was more development with advancement of gestation and become relatively similar to that in postnatal periods and consist of the splenic capsule, trabeculae, red pulp, white pulp with present of cellular components and increased in trabecular network by light and scanning microscope examination. Conclusion These findings highlight the progressive prenatal maturation of the spleen and underscore its pivotal role in immune system development. Deviations from these normal microstructural patterns may indicate pathological or immunological disorders. https://jab.uk.ac.ir/article_5453_8ae5780d22688d976ebce9d8fb3db81c.pdf