The histological characteristics of the aggregated lymphoid nodules area in abomasum of Bactrian camels (Camelus bactrianus) of different ages.

The aggregated lymphoid nodules area (ALNA) in abomasum of Bactrian camels is a special immune structure discovered only in Bactrian camels in recent years (2003). The anatomy research found that there was a close relationship between degree of development, anatomical characteristics and age. To further establish the relationship between histological characteristics of this special structure and animal age, 24 Alashan Bactrian camels of the following four age groups were studied: young (1-2 years), pubertal (3-5 years), middle-aged (6-16 years) and old (17-20 years). Mucosal-associated lymphoid tissue (MALT) of ALNA in abomasum was particularly observed and analyzed by histology, histochemistry and statistical methods. The results showed that the average number of lymphoid nodules in reticular mucosal folds region of ALNA in abomasum from young group to old group was in order of 26.8, 32.7, 17.6 and 7.8, and in longitudinal mucosal folds region was 20.1, 26.0, 10.3 and 5.1. The number of lymphoid nodules in the four experimental groups first increased and then decreased with increasing age (P<0.01). In young and pubertal camels lymphoid nodules were distributed evenly on both sides of the axis of mucosal folds and mostly displayed round, oval or wedge shape. The number of lymphoid nodules, follicle-associated epithelium (FAE), reticular fibers and plasmocytes in mucosal folds gradually increased from 1 to 2 years and peaked at puberty. There were up to 37 visible lymphoid nodules in a mucosal fold. However, ALNA of middle-aged and old camels gradually degenerated as aging. Lymphoid nodules were unevenly distributed on both sides of the axis of mucosal folds, which mostly displayed oval or irregular shape. Lymphoid tissue in old camels mostly existed as diffuse form. Although germinal centers of the lymphoid nodules were still obvious, the number of reticular fiber and plasmocyte and lymphoid nodules gradually decreased. The results indicated that in accord with the anatomical results, there was a close relationship between histology characteristics of lymphoid tissue of ALNA in abomasum and animal age. In summary, the lymphoid tissue of ALNA in abomasums gradually increased from young to pubertal groups with increasing age, peaked in 3-5 year-old camels, and subsequently declined with age and when 17-20 years old this immunity structure had severely atrophied.

Age-related changes in the anatomical characteristics of Peyer's patches in small intestine of Bactrian camels (Camelus bactrianus).

The distribution, size, and appearance of Peyer's patches vary according to species. In order to determine the anatomical characteristics of Peyer's patches in small intestine of Bactrian camel, and age-related changes in the number of Peyer's patches, 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 exact number of Peyer's patches was recorded, and the appearance of Peyer's patches was described in detail. The results indicated that Peyer's patches of Bactrian camels not only have a particular anatomical location and distinct appearance but also change with age. They were distributed in the whole small intestine and there were four distinct types of Peyer's patches: nodular, faviform, cup-shaped, and cystic form Peyer's patches. However, the nodular and cystic form Peyer's patches are specific to Bactrian camel, which have not been found in other animals including Dromedary camel. In addition, the distribution density of Peyer's patches in ileum was the maximum, then was jejunum and duodenum. Further statistical analysis showed that the number of Peyer's patches was altered with age. The number peaked in 5-year-old camels and declined subsequently with age. However, there was little change in the size of Peyer's patches in different age groups; no age-related macroscopic variations in the shape or size of the Peyer's patches were found. Results obtained from this study provide the basic information to further study on the gastrointestinal mucosal immunity of Bactrian camel.

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 (0.5-2years); pubertal (3-5years); middle-aged (6-16years), and old (17-20years). 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.