The anatomical characteristics of the aggregated lymphoid nodule area in the stomach of Bactrian camels (Camelus bactrianus) of different ages

The aggregated lymphoid nodule area (ALNA) in the third compartment of the stomach of Chinese Alashan Bactrian camels is a recently described species-specific anatomical structure. To further establish the relationship between this structure and animal age, 40 Bactrian camels of the following four age groups were studied: young (0.5–2 years); pubertal (3–5 years); middle-aged (6–16 years), and old (17–20 years). The ALNA in the third stomach compartment was measured and weighed for each group as was the height and number of mucosal folds. The exact anatomical location and the mucosal characteristics of the ALNA were also recorded. The results indicated that the ALNA not only has a particular anatomical location and distinct mucosal structure, but also changes with age. The structure was found along the ventral wall of the isthmus, from the origin of the proximal enlargement and along the curvatura ventriculi minor, forming a triangular band-like region. The mucosal folds containing the ALNA were much thicker than adjacent folds that did not contain this structure. Statistical analysis indicated that the ALNA enlarges prior to puberty, peaks in size at puberty, and then regresses. A small, vestigial ALNA was found in 20-years-old camels, although the germinal centres of the lymphoid nodules were not as obvious at this time. The data indicated that changes in ALNA structure occurs with development and ageing.