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The anatomical characteristics of the aggregated lymphoid nodule area in the stomach of Bactrian camels (Camelus bactrianus) of different ages
The Veterinary Journal 184 (2010) 362–365
Contents lists available at ScienceDirect
The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl
The anatomical characteristics of the aggregated lymphoid nodule area in the stomach of Bactrian camels (Camelus bactrianus) of different ages Xiao-Hong Xu, Wen-Hui Wang *, Qiang Gao, Shan-Shan Qi, Wan-Hong He, Li-Feng Tai, Ying-Pai Zhaxi, Fei Guan Faculty of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu 730070, China
a r t i c l e
i n f o
Article history: Accepted 4 March 2009
Keywords: Bactrian camel Aggregated lymphoid nodule area (ALNA) Mucosal-associated lymphoid tissue (MALT) Stomach Ageing
a b s t r a c t 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. Ó 2009 Elsevier Ltd. All rights reserved.
Introduction Aggregated lymphoid nodules are important parts of mucosalassociated lymphoid tissue (MALT) in animals and play a vital role in mucosal immunity. The structures are mainly distributed in the ileum and appendix (Langman and Rowland, 1986; O’Leary and Sweeney, 1986; Owen et al., 1991) and normally there is little MALT in the gastric mucosa (Chen, 1993; Ma, 1995; Peng and Zhang, 2002). Previously, Wang (2003) reported a triangular, band-like, aggregated lymphoid nodule area (ALNA) in the cardiac gland region of the third compartment of the stomach of the Bactrian camel (Camelus bactrianus) (Wang and Chen, 2002a,b, 2003a,b; Wang, 2003). Such a structure has not been reported in other animals including the dromedary camel (Camelus dromedarius) (Getty, 1975; Dougbag and Berg, 1980; Liu et al., 1996; Eerdunchaolu et al., 1999; Wang et al., 2000; Peng and Zhang, 2002; Abdel-Magied and Taha, 2003). The mucosal folds of the ALNA are thicker than those of the adjacent non-ALNAs and form a distinct boundary. Wang (2003) described how the majority of the nodules were concentrated in
* Corresponding author. Tel.: +86 931 7632251; fax: +86 931 7631220. E-mail addresses: [email protected], [email protected] (W.-H. Wang). 1090-0233/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.tvjl.2009.03.003
the sub-mucosa and how there were extensive lymphoid accumulations between the gastric epithelium and glands. These findings suggest that, in addition to digestive activity, the stomach of the Bactrian camel also has role in immune function (Wang et al., 2006). The objective of the current study was to assess whether the morphological characteristics of the ALNA changed with age. Materials and methods All experimental procedures were approved by the welfare authority of Minqin County of Gansu Province. We investigated the ALNA in 40 clinically normal Alashan Bactrian camels which were divided equally into four age groups: young (0.5–2 years); pubertal (3–5 years); middle-aged (6–16 years), and old (17–20 years). All groups included both females and males and were held together for 1 week prior to the study. The animals were anaesthetised with sodium pentobarbital and then exsanguinated. The third compartment of the stomach was incised at the isthmus and at the origin of the duodenum and then opened along its major curvature. The mucosal surface was washed thoroughly, the numbers of longitudinal mucosal folds of the ALNA counted and their height and width measured using Vernier calipers. Given that the ALNA is approximately triangular (Van Kruiningen et al., 2002; Wang, 2003) its area was calculated for each animal following measurement of the length of the base and height of the structure. Following these measurements the ALNA was excised and weighed following the removal of extraneous connective tissue and the gastric lymph nodes and the absorption of water on the mucosa surface with filter paper.
X.-H. Xu et al. / The Veterinary Journal 184 (2010) 362–365
363
Data analysis was performed using the one-way ANOVA (SPSS for Windows version 11.5). Differences were considered statistically significant where P < 0.05.
Results Anatomical location of the aggregated lymphoid nodule area The ALNA was confined to a long, approximately triangularshaped region bordered on the right by gastric blood vessels and on the left by the attachment of the greater omentum (Fig. 1). The ALNA extended along the ventral wall of the isthmus, from the origin of the proximal enlargement and along the curvatura ventriculi minor. The mucosal folds of the ALNA were much thicker than and were clearly demarcated from those of adjacent non-ALNAs (Fig. 2). The overall shape and anatomical location of the ALNA was similar in all four age groups. Characteristics of the mucosal surface of the aggregated lymphoid nodule area
Fig. 2. Mucosal view illustrating the approximately triangular shape of the aggregated lymphoid nodule area (ALNA) along the ventral wall of the isthmus, from the origin of the proximal enlargement and along the curvature ventriculi minor: (A) glandular sac area of the second compartment of the stomach; (B) isthmus; (C) ALNA; and (D) non-ALNA of the cardiac glandular region of the third compartment.
The ALNA was clearly demarcated from the adjacent non-ALNAs. Based on the morphology of the mucosal folds, the ALNA could be divided into reticular and longitudinal regions. In the reticular region the folds were arranged in a ‘mesh-like’ structure. The surface area of each mesh unit gradually decreased in size distally and the mesh margins gradually extended to become longitudinally-orientated, approximately parallel folds distributed along the body of the third compartment (Fig. 3). Variation in aggregated lymphoid nodule area mucosal fold morphology with age Table 1 lists the average height, width and number of mucosal folds of the ALNA of the camels studied and indicates that the mucosal folds of both the reticular and longitudinal regions increase in height and width prior to puberty. These parameters then decrease with increasing age. The folds in the longitudinal region were more abundant in the young and pubertal age groups. The numbers of these longitudinal folds increased gradually prior to puberty, peaked at puberty, and decreased thereafter. The reticular region folds were lower, but wider than those in the longitudinal region. No significant differences were found in fold morphology among camels within the same age group (Fig. 4).
Fig. 3. Morphological features of the mucosal folds of the aggregated lymphoid nodule area (ALNA): (A) reticular mucosal fold area; (B) longitudinal mucosal fold area; and (C) non-ALNA of the cardiac glandular region of the third compartment.
Variation in the area and weight of the aggregated lymphoid nodule area with age As indicated in Table 2, the average area of the ALNA increased progressively before puberty, was largest in the pubertal age group, and decreased subsequently with age (P < 0.05). Table 2 also details how the average weight of the ALNA peaked (142.29 ± 13.57 g) at puberty before gradually declining with increasing age (P < 0.05). No significant differences were found in either of these parameters among camels within the same age group. Discussion
Fig. 1. Lateral view of the anatomical location of the aggregated lymphoid nodule area (ALNA) (C) within a long, approximately triangular-shaped area bordered on the right by gastric blood vessels and on the left by the attachment of the greater omentum: (A) glandular sac area of second compartment of stomach; (B) isthmus; (C) ALNA; (D) non-ALNA of cardiac glandular region of the third compartment; (E) fundic gland region of the third compartment; and (F) enlargement of duodenum.
The Bactrian camel is semi-feral, inhabiting semi-arid and arid regions (Su et al., 1990). Relative to other animals, immunological structures such as aggregated lymphoid nodules in the alimentary tract are all very developed (Alluwaimi et al., 1998; Wang, 2003; Wang and Chen, 2003c; Wang et al., 2006) and are thought to facilitate the survival of this species in extreme conditions. The finding of ALNAs in camels of varying age in this study provides further evidence of this species’ resistance to disease (Su et al., 1990). Aggregated lymphoid nodules, such as the ALNA, typically found along the intestinal tract, enhance the protective mucosal immune response of this organ. The location of the ALNA in the
364
X.-H. Xu et al. / The Veterinary Journal 184 (2010) 362–365
Table 1 Average height and width (±SD) of the mucosal folds in the reticular and longitudinal regions of the aggregated lymphoid nodule area (ALNA), and number of the mucosal folds in the longitudinal region of the ALNA of Bactrian camels at different ages. Numbera
Groups (years)
0.5–2 3–5 6–16 17–20 a b
10 10 10 10
Mucosal folds in the reticular region
Mucosal folds in the longitudinal region
Height (mm)
Width (mm)
Height (mm)
Width (mm)
Numberb
3.53 ± 0.33 4.89 ± 0.37 2.68 ± 0.31 1.92 ± 0.30
1.88 ± 0.12 2.43 ± 0.30 1.81 ± 0.23 1.52 ± 0.15
4.33 ± 0.14 5.01 ± 0.24 3.22 ± 0.34 2.13 ± 0.31
1.68 ± 0.33 2.04 ± 0.27 1.72 ± 0.25 1.43 ± 0.32
6–8 8–13 4–8 0–4
Refers to the number of camels in each group. Refers to the number of folds in the longitudinal region of the ALNA.
Fig. 4. Mucosal views illustrating the aggregated lymphoid nodule area (ALNA) of Bactrian camels of different ages. The mucosal folds of both the reticular and longitudinal regions are well developed before puberty (A), peak in terms of height and width at puberty (B) and decrease with advancing age (C and D). Mucosal surface of the ALNA of: (A) 6-months-old; (B) 4-years-old; (C) 7-years-old; and (D) 20-years-old Bactrian camels.
camel, at the proximal end of the third compartment, is likely to lead to constant exposure to foreign antigen and suggests a role in mucosal immunity. Our findings indicate that the anatomical distribution and overall shape of the ALNA differ from that of Peyer’s patches which are mainly found in the jejunum, ileum, and at the ileocecal orifice, and are tuberculous-, alveolate-, cupor cryptomere-shaped in Bactrian camels (Qi, S.-S., personal communication; Gao, Q., personal communication). Following our comprehensive examination of the area and weight, and of the height and number of the mucosal folds of the ALNA in camels of different ages we found the ALNA was quite developed before puberty, reached its peak of development at puberty and then regressed with increased age. Although remnants of
Table 2 Details of the average area and weight (±SD) of the aggregated lymphoid nodule area (ALNA) of Bactrian camels at different ages. Groups (years)
Numbera
Average area of ALNA (cm2)
Average weight of ALNA (g)
0.5–2 3–5 6–16 17–20
10 10 10 10
180.73 ± 12.81 260.79 ± 8.46 126.76 ± 8.52 64.56 ± 10.73
108.22 ± 12.54 142.29 ± 13.57 110.39 ± 10.80 86.74 ± 8.24
a
Refers to the number of Bactrian camels in each group.
the ALNA remained in 20-years-old animals, the germinal centres in the lymphoid nodules were not as prominent as in younger camels. More abundant lymphoid tissue is found in the taller, thicker mucosal folds of the ALNA, where nodules can be up to three rows thick (Wang, 2003). We speculate that the age-related development and regression of the ALNA reflects a changing contribution of this structure to the immunological protection of the alimentary tract in the Bactrian camel with mucosal immunity waning with increasing age (Koga et al., 2000; Katol et al., 2003). Interestingly, certain autoimmune diseases occur more frequently in older than in younger animals and vaccines stimulating mucosal immunity are more protective in younger camels (Miller, 1996; Schmucker et al., 1996; Bernstein et al., 1999; Castle, 2000). Although it is likely that even more advanced involution of the ALNA is present in camels >20-years-old, we did not examine animals in this age category and further work is required to confirm this. Previous studies of MALT in the alimentary tract of the Bactrian camel did not assess whether the morphology of these structures altered with age. In a study of 58 human patients, the number of Peyer’s patches peaked in subjects 15–25 years of age and then declined (Cornes, 1965). Van Kruiningen et al. (2002) found greater numbers of Peyer’s patches in the distal ileum of human patients 21–30 years of age than in older age groups. Furthermore, it is well known that the thymus of mammals and the Bursa of Fabricius of birds gradually regress. In recent studies we have also found that
X.-H. Xu et al. / The Veterinary Journal 184 (2010) 362–365
the number of Peyer’s patches in the intestinal tract of the Bactrian camel has the similar pattern of development to the ALNA (Qi, S.-S., personal communication; Gao, Q., personal communication). Gut-associated lymphoid tissue (GALT), which includes the Peyer’s patches, sacculus rotundus and appendix, is considered a lymphoid organ of mammals that is akin to the Bursa of Fabricius of avian species (Fichtelius et al., 1968) containing B lymphocytes (Reynolds and Morris, 1983, 1984; Gerber et al., 1986; Zhang et al., 1995). Conclusions The pattern of development of the ALNA of the Bactrian camel is similar to that of the Bursa of Fabricius in birds, peaking in size at puberty, before regressing with advancing age. It is interesting to speculate whether the ALNA may be a primary or secondary lymphoid organ and further studies are required to investigate the mechanisms through which this structure undergoes physiological atrophy. Conflict of interest statement None of the authors of this paper has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper. Acknowledgements We would like to thank Wei Hua for his great help in collecting specimens and Professor Ma Zhuo for his assistance with English. This study was supported by The National Natural Science Foundation of China (Grant No. 30671549) and The Natural Science Foundation of Gansu Province (Grant No. 3YS051-A25-017). References Abdel-Magied, E.M., Taha, A.A.M., 2003. Morphological, morphometric and histochemical characterization of the gastric mucosa of the camel (Camelus dromedarius). Anatomy, Histology and Embryology 32, 42–47. Alluwaimi, A.M., Fath El-Bab, M.R., Ahemed, A.K., 1998. Studies on the ileal lymphoid tissue (Peyer’s patches) in camels, Najdi sheep and cattle. Journal of Camel Practice and Research 5, 13–18. Bernstein, E., Kaye, D., Abrutyn, E., Gross, P., Dorfman, M., Murasko, D.M., 1999. Immune response to influenza vaccination in a large healthy elderly population. Vaccine 17, 82. Castle, S.C., 2000. Clinical relevance of age-related immune dysfunction. Clinical Infectious Diseases 31, 578. Chen, L.-Z., 1993. In: Histology. People’s Publishing House, Beijing, China, pp. 158– 183. Cornes, J.S., 1965. Number, size and distribution of Peyer’s patches in the human small intestine. Gut 6, 225–233. Dougbag, A.S., Berg, R., 1980. Histological and histochemical studies on the mucosa of the initial dilated and middle long part of the third compartment of the camel’s stomach (Camelus dromedarius). Anatomy, Histology and Embryology 148, 258–264. Eerdunchaolu, Takehana K., Kobayashi, A., Baiyin Cao, G.-F., Andren, A., Iwasa, K., Abe, M., 1999. Morphological characterization of gland cells of the glandular sac
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area in the complex stomach of the Bactrian camel (Camelus bactrianus). Anatomy, Histology and Embryology 28, 183–191. Fichtelius, K.E., Finstad, J., Good, R.A., 1968. Bursa equivalents of bursaless vertebrates. Laboratory Investigation 19, 339. Gerber, H.A., Morris, B., Trevella, W., 1986. The role of gut-associated lymphoid tissues in the generation of immunoglobulin-bearing lymphocytes in sheep. Australian Journal of Biomedical Science 64, 201. Getty, R., 1975. In: Sisson and Grossman’s The Anatomy of the Domestic Animals. W.B. Saunders, London, pp. 884–903. Katol, H., Fujihashil, K., Katol, R., Dohi, T., Fujihashi, K., Hagiwara, Y., Kataoka, K., Kobayashi, R., McGhee, J.R., 2003. Lack of oral tolerance in aging is due to sequential loss of Peyer’s patch cell interactions. International Immunology 15, 145–158. Koga, T., McGhee, J.R., Kato, H., Kato, R., Kiyono, H., Fujihashi, K., 2000. Evidence for early aging in the mucosal immune system. Journal of Immunology 165, 5352. Langman, J.M., Rowland, R., 1986. The number and distribution of lymphoid follicles in the human large intestine. Journal of Anatomy 194, 189–194. Liu, S.-W., Zhu, X.-R., Chen, H.-T., 1996. Histological studies on the gasters of Bactrian camels. Chinese Journal of Veterinary Science 16, 491–496. Ma, Z.-H., 1995. Anatomy Histology and Embryology of Domestic Animals. Agricultural Publishing House, Beijing, China. pp. 156–188. Miller, R.A., 1996. The aging immune system: primer and prospectus. Science 273, 70. O’Leary, A.D., Sweeney, E.C., 1986. Lymphoglandular complexes of the colon: structure and distribution. Histopathology 10, 267–283. Owen, R.L., Piazza, A.J., Ermak, T.H., 1991. Ultrastructural and cytoarchitectural features of lymphoreticular organs in the colon and rectum of adult BALB/c mice. American Journal of Anatomy 190, 10–18. Peng, K.-M., Zhang, R.-D., 2002. Histology and Embryology. Chinese Agriculture Publishing House, Beijing, China, pp. 134–145. Reynolds, J.D., Morris, B., 1983. The evolution and involution of Peyer’s patches in fetal and postnatal sheep. European Journal of Immunology 13, 627. Reynolds, J.D., Morris, B., 1984. The effect of antigen on the development of Peyer’s patches in sheep. European Journal of Immunology 14, 1. Schmucker, D.L., Heyworth, M.F., Owen, R.L., Daniels, C.K., 1996. Impact of aging on gastrointestinal mucosal immunity. Digestive Diseases and Sciences 4, 1183. Su, X.-S., Shui, S.-R., Chen, B.-H., 1990. Raising Camels. Chinese Agriculture Publishing House, Beijing, China, pp. 16–21. Van Kruiningen, H.J., Brian West, A., Freda, B.J., Holmes, K.A., 2002. Distribution of Peyer’s patches in the distal ileum. Inflammatory Bowel Diseases 8, 180–185. Wang, J.-L., Gao, L., Wang, G.-X., Li, H.-Y., Xie, Z.-M., 2000. Anatomical subdivisions of the stomach of the Bactrian camel (Camelus bactrianus). Journal of Morphology 245, 161–167. Wang, W.-H., Chen, H.-T., 2002a. Histology and histochemistry of the pyloric glandular region mucosa of the Bactrian camel. Chinese Veterinary Science 3, 29–32. Wang, W.-H., Chen, H.-T., 2002b. Study of the histology and histochemistry of the glandular sac areas of the stomach of the Bactrian camel in China. Chinese Veterinary Science 32, 2–6. Wang, W.-H., 2003. Observations on aggregated lymphoid nodules in the cardiac glandular areas of the Bactrian camel. The Veterinary Journal 166, 205–209. Wang, W.-H., Chen, H.-T., 2003a. Histology and histochemistry of the cardiac glandular region mucosa of the Bactrian camel. Acta Veterinaria et Zootechnica Sinica 34, 471–475. Wang, W.-H., Chen, H.-T., 2003b. Histology and histochemistry of the stomach of the Bactrian camel in China (Camelus bactrianus) – the fundic glandular region mucosa. Acta Veterinaria et Zootechnica Sinica 34, 372–375. Wang, W.-H., Chen, H.-T., 2003c. Observation on the histomorphology of the spleen in the Bactrian camel (Camelus bactrianus). Acta Veterinaria et Zootechnica Sinica 34, 268–272. Wang, W.-H., Chen, H.-T., Chen, Q.-S., Ma, J.-L., 2006. Study on mucosal associated lymphoid tissue in esophagus and stomach of the Bactrian camels. In: Proceedings of Veterinaria et Zootechnica Sinica Institute, Beijing, China, pp. 404–409. Zhang, H.-W., Cong, Y.-Z., Yu, S.-G., 1995. Study on the Peyer’s patches of goat lamb. Acta Zoologica Sinica 41, 190–196.
Contents lists available at ScienceDirect
The Veterinary Journal journal homepage: www.elsevier.com/locate/tvjl
The anatomical characteristics of the aggregated lymphoid nodule area in the stomach of Bactrian camels (Camelus bactrianus) of different ages Xiao-Hong Xu, Wen-Hui Wang *, Qiang Gao, Shan-Shan Qi, Wan-Hong He, Li-Feng Tai, Ying-Pai Zhaxi, Fei Guan Faculty of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu 730070, China
a r t i c l e
i n f o
Article history: Accepted 4 March 2009
Keywords: Bactrian camel Aggregated lymphoid nodule area (ALNA) Mucosal-associated lymphoid tissue (MALT) Stomach Ageing
a b s t r a c t 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. Ó 2009 Elsevier Ltd. All rights reserved.
Introduction Aggregated lymphoid nodules are important parts of mucosalassociated lymphoid tissue (MALT) in animals and play a vital role in mucosal immunity. The structures are mainly distributed in the ileum and appendix (Langman and Rowland, 1986; O’Leary and Sweeney, 1986; Owen et al., 1991) and normally there is little MALT in the gastric mucosa (Chen, 1993; Ma, 1995; Peng and Zhang, 2002). Previously, Wang (2003) reported a triangular, band-like, aggregated lymphoid nodule area (ALNA) in the cardiac gland region of the third compartment of the stomach of the Bactrian camel (Camelus bactrianus) (Wang and Chen, 2002a,b, 2003a,b; Wang, 2003). Such a structure has not been reported in other animals including the dromedary camel (Camelus dromedarius) (Getty, 1975; Dougbag and Berg, 1980; Liu et al., 1996; Eerdunchaolu et al., 1999; Wang et al., 2000; Peng and Zhang, 2002; Abdel-Magied and Taha, 2003). The mucosal folds of the ALNA are thicker than those of the adjacent non-ALNAs and form a distinct boundary. Wang (2003) described how the majority of the nodules were concentrated in
* Corresponding author. Tel.: +86 931 7632251; fax: +86 931 7631220. E-mail addresses: [email protected], [email protected] (W.-H. Wang). 1090-0233/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.tvjl.2009.03.003
the sub-mucosa and how there were extensive lymphoid accumulations between the gastric epithelium and glands. These findings suggest that, in addition to digestive activity, the stomach of the Bactrian camel also has role in immune function (Wang et al., 2006). The objective of the current study was to assess whether the morphological characteristics of the ALNA changed with age. Materials and methods All experimental procedures were approved by the welfare authority of Minqin County of Gansu Province. We investigated the ALNA in 40 clinically normal Alashan Bactrian camels which were divided equally into four age groups: young (0.5–2 years); pubertal (3–5 years); middle-aged (6–16 years), and old (17–20 years). All groups included both females and males and were held together for 1 week prior to the study. The animals were anaesthetised with sodium pentobarbital and then exsanguinated. The third compartment of the stomach was incised at the isthmus and at the origin of the duodenum and then opened along its major curvature. The mucosal surface was washed thoroughly, the numbers of longitudinal mucosal folds of the ALNA counted and their height and width measured using Vernier calipers. Given that the ALNA is approximately triangular (Van Kruiningen et al., 2002; Wang, 2003) its area was calculated for each animal following measurement of the length of the base and height of the structure. Following these measurements the ALNA was excised and weighed following the removal of extraneous connective tissue and the gastric lymph nodes and the absorption of water on the mucosa surface with filter paper.
X.-H. Xu et al. / The Veterinary Journal 184 (2010) 362–365
363
Data analysis was performed using the one-way ANOVA (SPSS for Windows version 11.5). Differences were considered statistically significant where P < 0.05.
Results Anatomical location of the aggregated lymphoid nodule area The ALNA was confined to a long, approximately triangularshaped region bordered on the right by gastric blood vessels and on the left by the attachment of the greater omentum (Fig. 1). The ALNA extended along the ventral wall of the isthmus, from the origin of the proximal enlargement and along the curvatura ventriculi minor. The mucosal folds of the ALNA were much thicker than and were clearly demarcated from those of adjacent non-ALNAs (Fig. 2). The overall shape and anatomical location of the ALNA was similar in all four age groups. Characteristics of the mucosal surface of the aggregated lymphoid nodule area
Fig. 2. Mucosal view illustrating the approximately triangular shape of the aggregated lymphoid nodule area (ALNA) along the ventral wall of the isthmus, from the origin of the proximal enlargement and along the curvature ventriculi minor: (A) glandular sac area of the second compartment of the stomach; (B) isthmus; (C) ALNA; and (D) non-ALNA of the cardiac glandular region of the third compartment.
The ALNA was clearly demarcated from the adjacent non-ALNAs. Based on the morphology of the mucosal folds, the ALNA could be divided into reticular and longitudinal regions. In the reticular region the folds were arranged in a ‘mesh-like’ structure. The surface area of each mesh unit gradually decreased in size distally and the mesh margins gradually extended to become longitudinally-orientated, approximately parallel folds distributed along the body of the third compartment (Fig. 3). Variation in aggregated lymphoid nodule area mucosal fold morphology with age Table 1 lists the average height, width and number of mucosal folds of the ALNA of the camels studied and indicates that the mucosal folds of both the reticular and longitudinal regions increase in height and width prior to puberty. These parameters then decrease with increasing age. The folds in the longitudinal region were more abundant in the young and pubertal age groups. The numbers of these longitudinal folds increased gradually prior to puberty, peaked at puberty, and decreased thereafter. The reticular region folds were lower, but wider than those in the longitudinal region. No significant differences were found in fold morphology among camels within the same age group (Fig. 4).
Fig. 3. Morphological features of the mucosal folds of the aggregated lymphoid nodule area (ALNA): (A) reticular mucosal fold area; (B) longitudinal mucosal fold area; and (C) non-ALNA of the cardiac glandular region of the third compartment.
Variation in the area and weight of the aggregated lymphoid nodule area with age As indicated in Table 2, the average area of the ALNA increased progressively before puberty, was largest in the pubertal age group, and decreased subsequently with age (P < 0.05). Table 2 also details how the average weight of the ALNA peaked (142.29 ± 13.57 g) at puberty before gradually declining with increasing age (P < 0.05). No significant differences were found in either of these parameters among camels within the same age group. Discussion
Fig. 1. Lateral view of the anatomical location of the aggregated lymphoid nodule area (ALNA) (C) within a long, approximately triangular-shaped area bordered on the right by gastric blood vessels and on the left by the attachment of the greater omentum: (A) glandular sac area of second compartment of stomach; (B) isthmus; (C) ALNA; (D) non-ALNA of cardiac glandular region of the third compartment; (E) fundic gland region of the third compartment; and (F) enlargement of duodenum.
The Bactrian camel is semi-feral, inhabiting semi-arid and arid regions (Su et al., 1990). Relative to other animals, immunological structures such as aggregated lymphoid nodules in the alimentary tract are all very developed (Alluwaimi et al., 1998; Wang, 2003; Wang and Chen, 2003c; Wang et al., 2006) and are thought to facilitate the survival of this species in extreme conditions. The finding of ALNAs in camels of varying age in this study provides further evidence of this species’ resistance to disease (Su et al., 1990). Aggregated lymphoid nodules, such as the ALNA, typically found along the intestinal tract, enhance the protective mucosal immune response of this organ. The location of the ALNA in the
364
X.-H. Xu et al. / The Veterinary Journal 184 (2010) 362–365
Table 1 Average height and width (±SD) of the mucosal folds in the reticular and longitudinal regions of the aggregated lymphoid nodule area (ALNA), and number of the mucosal folds in the longitudinal region of the ALNA of Bactrian camels at different ages. Numbera
Groups (years)
0.5–2 3–5 6–16 17–20 a b
10 10 10 10
Mucosal folds in the reticular region
Mucosal folds in the longitudinal region
Height (mm)
Width (mm)
Height (mm)
Width (mm)
Numberb
3.53 ± 0.33 4.89 ± 0.37 2.68 ± 0.31 1.92 ± 0.30
1.88 ± 0.12 2.43 ± 0.30 1.81 ± 0.23 1.52 ± 0.15
4.33 ± 0.14 5.01 ± 0.24 3.22 ± 0.34 2.13 ± 0.31
1.68 ± 0.33 2.04 ± 0.27 1.72 ± 0.25 1.43 ± 0.32
6–8 8–13 4–8 0–4
Refers to the number of camels in each group. Refers to the number of folds in the longitudinal region of the ALNA.
Fig. 4. Mucosal views illustrating the aggregated lymphoid nodule area (ALNA) of Bactrian camels of different ages. The mucosal folds of both the reticular and longitudinal regions are well developed before puberty (A), peak in terms of height and width at puberty (B) and decrease with advancing age (C and D). Mucosal surface of the ALNA of: (A) 6-months-old; (B) 4-years-old; (C) 7-years-old; and (D) 20-years-old Bactrian camels.
camel, at the proximal end of the third compartment, is likely to lead to constant exposure to foreign antigen and suggests a role in mucosal immunity. Our findings indicate that the anatomical distribution and overall shape of the ALNA differ from that of Peyer’s patches which are mainly found in the jejunum, ileum, and at the ileocecal orifice, and are tuberculous-, alveolate-, cupor cryptomere-shaped in Bactrian camels (Qi, S.-S., personal communication; Gao, Q., personal communication). Following our comprehensive examination of the area and weight, and of the height and number of the mucosal folds of the ALNA in camels of different ages we found the ALNA was quite developed before puberty, reached its peak of development at puberty and then regressed with increased age. Although remnants of
Table 2 Details of the average area and weight (±SD) of the aggregated lymphoid nodule area (ALNA) of Bactrian camels at different ages. Groups (years)
Numbera
Average area of ALNA (cm2)
Average weight of ALNA (g)
0.5–2 3–5 6–16 17–20
10 10 10 10
180.73 ± 12.81 260.79 ± 8.46 126.76 ± 8.52 64.56 ± 10.73
108.22 ± 12.54 142.29 ± 13.57 110.39 ± 10.80 86.74 ± 8.24
a
Refers to the number of Bactrian camels in each group.
the ALNA remained in 20-years-old animals, the germinal centres in the lymphoid nodules were not as prominent as in younger camels. More abundant lymphoid tissue is found in the taller, thicker mucosal folds of the ALNA, where nodules can be up to three rows thick (Wang, 2003). We speculate that the age-related development and regression of the ALNA reflects a changing contribution of this structure to the immunological protection of the alimentary tract in the Bactrian camel with mucosal immunity waning with increasing age (Koga et al., 2000; Katol et al., 2003). Interestingly, certain autoimmune diseases occur more frequently in older than in younger animals and vaccines stimulating mucosal immunity are more protective in younger camels (Miller, 1996; Schmucker et al., 1996; Bernstein et al., 1999; Castle, 2000). Although it is likely that even more advanced involution of the ALNA is present in camels >20-years-old, we did not examine animals in this age category and further work is required to confirm this. Previous studies of MALT in the alimentary tract of the Bactrian camel did not assess whether the morphology of these structures altered with age. In a study of 58 human patients, the number of Peyer’s patches peaked in subjects 15–25 years of age and then declined (Cornes, 1965). Van Kruiningen et al. (2002) found greater numbers of Peyer’s patches in the distal ileum of human patients 21–30 years of age than in older age groups. Furthermore, it is well known that the thymus of mammals and the Bursa of Fabricius of birds gradually regress. In recent studies we have also found that
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the number of Peyer’s patches in the intestinal tract of the Bactrian camel has the similar pattern of development to the ALNA (Qi, S.-S., personal communication; Gao, Q., personal communication). Gut-associated lymphoid tissue (GALT), which includes the Peyer’s patches, sacculus rotundus and appendix, is considered a lymphoid organ of mammals that is akin to the Bursa of Fabricius of avian species (Fichtelius et al., 1968) containing B lymphocytes (Reynolds and Morris, 1983, 1984; Gerber et al., 1986; Zhang et al., 1995). Conclusions The pattern of development of the ALNA of the Bactrian camel is similar to that of the Bursa of Fabricius in birds, peaking in size at puberty, before regressing with advancing age. It is interesting to speculate whether the ALNA may be a primary or secondary lymphoid organ and further studies are required to investigate the mechanisms through which this structure undergoes physiological atrophy. Conflict of interest statement None of the authors of this paper has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper. Acknowledgements We would like to thank Wei Hua for his great help in collecting specimens and Professor Ma Zhuo for his assistance with English. This study was supported by The National Natural Science Foundation of China (Grant No. 30671549) and The Natural Science Foundation of Gansu Province (Grant No. 3YS051-A25-017). References Abdel-Magied, E.M., Taha, A.A.M., 2003. Morphological, morphometric and histochemical characterization of the gastric mucosa of the camel (Camelus dromedarius). Anatomy, Histology and Embryology 32, 42–47. Alluwaimi, A.M., Fath El-Bab, M.R., Ahemed, A.K., 1998. Studies on the ileal lymphoid tissue (Peyer’s patches) in camels, Najdi sheep and cattle. Journal of Camel Practice and Research 5, 13–18. Bernstein, E., Kaye, D., Abrutyn, E., Gross, P., Dorfman, M., Murasko, D.M., 1999. Immune response to influenza vaccination in a large healthy elderly population. Vaccine 17, 82. Castle, S.C., 2000. Clinical relevance of age-related immune dysfunction. Clinical Infectious Diseases 31, 578. Chen, L.-Z., 1993. In: Histology. People’s Publishing House, Beijing, China, pp. 158– 183. Cornes, J.S., 1965. Number, size and distribution of Peyer’s patches in the human small intestine. Gut 6, 225–233. Dougbag, A.S., Berg, R., 1980. Histological and histochemical studies on the mucosa of the initial dilated and middle long part of the third compartment of the camel’s stomach (Camelus dromedarius). Anatomy, Histology and Embryology 148, 258–264. Eerdunchaolu, Takehana K., Kobayashi, A., Baiyin Cao, G.-F., Andren, A., Iwasa, K., Abe, M., 1999. Morphological characterization of gland cells of the glandular sac
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