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1 The detailed structure of the thymus. (A) Hematoxylineosin-stained thymic lobe. The undivided pale-stained medulla is surrounded by lobulated heavily stained cortical lobules. (B) Schematic illustration of the avian thymus. Thymic dendritic cells are located in the epithelial-free zone of the thymic medulla, concentrated around the blood vessels. (C) The densely packed cortical thymocytes result in basophilic staining. The large, pale nuclei belong to the epithelial reticular cell (ERC) (outlined). Granules show different electron densities, and the membrane-bound vesicles contain a fine flocculated substance. (D) Attachment spots between the cortical thymocytes and the ERC. epith, Epithelial reticular cells, M, medulla, C, cortex. (B) Adapted from Nagy et al., Dev Comp Immunol; 2016. 58: 47À59
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... During poultry embryonic development, the spleen becomes a secondary lymphoid organ, providing an indispensable microenvironment for the interactions between lymphocytes and nonlymphocytes. Due to the underdeveloped lymphatic vessels and lymph nodes in poultry, the contribution of spleen to the poultry entire immune system can be more important than the mammalian counterpart (27). If the spleen is not well-developed, there will lack enough mature lymphocytes to resist pathogens (13). ...
As the largest peripheral lymphoid organ in poultry, the spleen plays an essential role in regulating the body’s immune capacity. However, compared with chickens and ducks, information about the age- and breed-related changes in the goose spleen remains scarce. In this study, we systematically analyzed and compared the age-dependent changes in the morphological, histological, and transcriptomic characteristics between Landes goose (LG; Anser anser) and Sichuan White goose (SWG; Anser cygnoides). The results showed a gradual increase in the splenic weights for both LG and SWG until week 10, while their splenic organ indexes reached the peak at week 6. Meanwhile, the splenic histological indexes of both goose breeds continuously increased with age, reaching the highest levels at week 30. The red pulp (RP) area was significantly higher in SWG than in LG at week 0, while the splenic corpuscle (AL) diameter was significantly larger in LG than in SWG at week 30. At the transcriptomic level, a total of 1710 and 1266 differentially expressed genes (DEGs) between week 0 and week 30 were identified in spleens of LG and SWG, respectively. Meanwhile, a total of 911 and 808 DEGs in spleens between LG and SWG were identified at weeks 0 and 30, respectively. Both GO and KEGG enrichment analysis showed that the age-related DEGs of LG or SWG were dominantly enriched in the Cell cycle, TGF−beta signaling, and Wnt signaling pathways, while most of the breed-related DEGs were enriched in the Neuroactive ligand−receptor interaction, Cytokine−cytokine receptor interaction, ECM−receptor interaction, and metabolic pathways. Furthermore, through construction of protein-protein interaction networks using significant DEGs, it was inferred that three hub genes including BUB1, BUB1B, and TTK could play crucial roles in regulating age-dependent goose spleen development while GRIA2, GRIA4, and RYR2 could be crucial for the breed-specific goose spleen development. These data provide novel insights into the splenic developmental differences between Chinese and European domestic geese, and the identified crucial pathways and genes are helpful for a better understanding of the mechanisms regulating goose immune functions.
... MD is not a novel lymphoid organ in ducks. It has already been known that it is one of avian lymphoid organs [8]. Meckel's diverticulum is composed of a large amount of aggregated lymphoid follicles within the tunica mucosa. ...
The intestine plays an important role in mediating between the bird and its nutritional environment. The yolk stalk, also known as Meckel's diverticulum, is a landmark between the jejunum and ileum. This work aimed to investigate the anatomical, histological, and electron microscopical features of cellular components of the Meckel’s diverticulum (MD) in adult geese. The intestine was dissected from the bird’s body cavity, and Meckel’s diverticulum was exposed and prepared for light and electron microscopical examinations. Our results revealed that the MD mucosa is thrown up into villi and crypts, and the mucosal epithelium is a columnar epithelium with goblet cells as well as intraepithelial lymphocytes. Lymphoid follicles and numerous immune cells were demonstrated within the lamina propria. The mucous glands were also observed within the lamina propria and amongst the lymphoid follicles. The lining epithelium of MD appeared with different staining affinities: dark cells (electron-dense) and light cells (electron-lucent) contained few mitochondria and more secretory vesicles, while dark cells contained more mitochondria and fewer secretory vesicles. Immunohistochemical analysis of MD revealed positive immunoreactivity for several markers, such as CD 117, chromogranin, PLCβ, cytokeratin, MHC II, and S 100. Taken together, our findings suggest that MD is considered an immune organ in adult geese.
... Morphological evaluations of the thymus, bursa of Fabricius, CT, and spleen were conducted using H&E staining. The morphological structure of these organs at the specified age corresponds with the descriptions found in the literature (Olah et al., 2014). ...
... Within the thymus, young thymocytes primarily undergo proliferation and gradual selection in the cortex with only the mature ones entering the medulla. Conversely, in the bursa, the migration of B cells follows the opposite direction (Olah et al., 2014). The present study conducted a morphometrical analysis of the thymus and bursa of Fabricius, but no significant impact of early feeding on the ratios of the cortex to the medulla in these organs was observed. ...
Under commercial conditions, chicks hatch within a 24 to 48 h window, a period known as the hatching window. Subsequently, they undergo various treatments before finally being transported to the broiler farm. These procedures may delay the chicks’ access to food and water, sometimes receiving them as late as 72 h after hatching. Previous studies have indicated that fasting during this initial period is detrimental, leading to impaired body growth, compromised immune system response, and hindered muscle development. The objective of this study was to assess the impact of early posthatch feeding on immune system organs and selected hematological, biochemical, and hormonal parameters. The experiment utilized Ross 308 broiler eggs incubated under typical commercial hatchery conditions. The experimental group's eggs were hatched in HatchCare hatchers (HC) with immediate access to feed and water, while the control group's eggs were hatched under standard conditions (ST). Thirty chickens from each group were assessed on the 1st (D1), 7th (D7), 21st (D21), and 35th (D35) day after hatching. On D1, the HC group exhibited lower hemoglobin, hematocrit, and total serum protein values, suggesting that early access to water prevents initial dehydration in newborn chicks. Conversely, the ST group showed a stress reaction on D1 due to feed deprivation, leading to an almost 2-fold higher serum corticosterone concentration compared to the HC group. However, this increase did not result in a significant change in the heterophil/lymphocyte ratio. Furthermore, the HC group displayed an increase in triglyceride concentration and a decrease in HDL concentration on D1. On D7, the HC group exhibited an increased relative weight of the bursa and a higher CD4⁺ cell number in the cecal tonsil (CT), indicating a more rapid development of these organs resulting from early stimulation of the gastrointestinal tract. However, early feeding did not influence the numbers of Bu-1⁺, CD4⁺, and CD8⁺ cells or the germinal center (GC) areas in the spleen. In conclusion, early feeding contributes to the welfare of newborn chicks by reducing dehydration and stress levels and stimulating the development of gut-associated lymphoid tissue.
... Yang et al. [50] found that the mixture of organic acids and essential oils had no significant effect on the performance and size of Bursa of the 21-and 42-day-old broilers. Contradictorily, when analyzing the immune-stimulating effect of essential oils of peppermint and eucalyptus added to water at a dose of 0.25 mL/L [67] found an increase in the weight of Bursa of chickens treated with those essential oils and concluded they are capable of implementing an immune response in broilers. ...
This study aimed to evaluate the effects of essential oils from the fruits of Citrus sinensis and Xylopia aromatica, included in broiler feed, on blood parameters, the biometrics of digestive organs, bone analyses, and the biochemical profiles of the viscera, as well as the histomorphometry of the small intestine. In this study, 180 one-day-old male chicks of the Cobb 500 strain were fed a corn and soybean meal over three treatments and six replications, and the experimental design was completely randomized. The data were subjected to an analysis of variance and a Tukey test at a 5% significance level. The effect of the experimental diets on performance, blood parameters, biometrics of the digestive organs, bone analysis, and biochemical profiles of the viscera, as well as the histomorphometry of the small intestine, were evaluated. The compounds identified in the essential oil of X. aromatica were sylvestrene, α-pinene, and β-pinene, while in C. sinensis they were limonene and myrcene. The essential oils of C. sinensis and X. aromatica had no significant effect on performance at 14 days. The effects of the presence of the essential oils of C. sinensis and X. aromatica on the response were beneficial: there were reductions in liver lipids, cholesterol, and triglycerides, and in the depths of the crypts in the jejunum of chickens. So, the essential oils from the fruits of C. sinensis and X. aromatica can be used in broiler chickens to improve the lipid profiles of birds without affecting their performance.
... The spleen is the largest lymphoid organ in birds that contains a large number of immunocompetent cells and can effectively induce innate and adaptive immune responses. Hence, the global profile of miRNA expression in the spleen provided a good overview of the host response to CAstV infection [18,19]. The transcriptional regulation of host miRNAs after CAstV infection in chickens, especially in the spleen, can be used as a tool to study pathogen-host interactions and can therefore provide insights into the pathogenic and immune mechanisms of CAstV. ...
miRNAs represent ubiquitous regulators of gene expression and play an important and pivotal regulatory role in viral disease pathogenesis and virus–host interactions. Although previous studies have provided basic data for understanding the role of miRNAs in the molecular mechanisms of viral infection in birds, the role of miRNAs in the regulation of host responses to chicken astrovirus (CAstV) infection in chickens is not yet understood. In our study, we applied next-generation sequencing to profile miRNA expression in CAstV-infected chickens and to decipher miRNA-targeted specific signaling pathways engaged in potentially vital virus-infection biological processes. Among the 1354 detected miRNAs, we identified 58 mature miRNAs that were significantly differentially expressed in infected birds. Target prediction resulted in 4741 target genes. GO and KEGG pathway enrichment analyses showed that the target genes were mainly involved in the regulation of cellular processes and immune responses.
... It is located in the ventral orbit, posteromedial to the eyeball (Wight et al., 1971;Mobini, 2012;Kaiser and Balic, 2015). Since it is loosely connected to the periorbital fascia, it may remain in orbit after eye removal (Dyce et al., 2010;Olah et al., 2014, Figure 1). The HG was first introduced in 1964 ( Dyce et al., 2010). ...
Infectious bronchitis virus (IBV) replicates primarily in the epithelial tissues of the respiratory tract, particularly the trachea. However, little is known about IBV replication and immune responses in relation to head-associated lymphoid tissue (HALT), such as the Harderian gland (HG) and choanal cleft, as well as respiratory (turbinate) tissues. Furthermore, few studies have looked into the role of the HG, choanal cleft, pharyngeal tissues, and turbinate in innate, cellular, and mucosal immune responses of commercial broiler chickens and laying hens infected with IBV, compared to the studies about the effects on the trachea. This review article overviewed the role of avian HALT, conjunctival-associated lymphoid tissue (CALT), concerning the anatomical, physiological, and immune responses to infectious bronchitis disease in chickens. The HG, choanal cleft, and turbinate in innate, mucosal, and cellular immune responses play a significant role in avian protection through virulent or attenuated vaccines of IBVs. The IBV viruses could not reach the trachea in chickens vaccinated with IBV vaccine due to the inhibition of viruses by HALT and respiratory tissues by innate, mucosal, and cellular immunity. It can be concluded that other than the trachea, the HALT and respiratory tissues play an important role in the infectivity and immune induction against IBVs due to their proximity to the upper air passages. Keywords: Avian immunity, Chicken, Harderian gland, Infectious bronchitis, Turbinate
... Plasma cells are also present around lymphocytic aggregations in interfollicular portions (figure 2) (figure3). (13) reported that Lamina propria is full of lymphocyte, macrophage and mast cells and the Lymph nodules at the base of lamina propria contain big germinal centers. (14) also mentioned that The caecal tonsil is comprised of multiple tonsillar units that are made up of secondary lymphoid follicles with intermittent T cell areas positioned round the center and fossula branches into many crypts with close connections towards the caecal lumen. ...
The anatomy and histology of caecal tonsils among different birds’ species is vital to understanding the relationship between the physical structure and gut health. the current article intended to reviewing the morphological differences of cecum and caecal tonsils in five local domesticated birds .
... Plasma cells are also present around lymphocytic aggregations in interfollicular portions (figure 2) (figure3). (13) reported that Lamina propria is full of lymphocyte, macrophage and mast cells and the Lymph nodules at the base of lamina propria contain big germinal centers. (14) also mentioned that The caecal tonsil is comprised of multiple tonsillar units that are made up of secondary lymphoid follicles with intermittent T cell areas positioned round the center and fossula branches into many crypts with close connections towards the caecal lumen. ...
veterinary immunity researchers enteric infections. the current works will provide a considerable assistance for biological and in birds may explain the immunological variation and the resistance of different bird types to some and protective role of caecal tonsils as apart of immune system and the morphological differences of the anatomy and histology of caecal tonsil in different birds’ species is crucial, due to the defense tonsillar villi, lymphoid tissue organization, and cellular distribution.In conclusion: Understanding the histological and cellular differences like the thickness of caecal wall, length and shape of length, breadth, and symmetry among different birds’ species. also, the current review summarized collected, analyzed and explained in this review Results revealed that caecum differ in shape, performed through researches and articles databases and internet indexes websites, then papers domesticated birds An extensive search related to caeca and caecal tonsils anatomy and histology intended to reviewing the morphological differences of cecum and caecal tonsils in five local understanding the relationship between the physical structure and gut health. the current articleز
... Plasma cells are also present around lymphocytic aggregations in interfollicular portions (figure 2) (figure3). (13) reported that Lamina propria is full of lymphocyte, macrophage and mast cells and the Lymph nodules at the base of lamina propria contain big germinal centers. (14) also mentioned that The caecal tonsil is comprised of multiple tonsillar units that are made up of secondary lymphoid follicles with intermittent T cell areas positioned round the center and fossula branches into many crypts with close connections towards the caecal lumen. ...
The anatomy and histology of caecal tonsils among different birds’ species is vital to understanding the relationship between the physical structure and gut health. the current article intended to reviewing the morphological differences of cecum and caecal tonsils in five local domesticated birds
An extensive search related to caeca and caecal tonsils anatomy and histology performed through researches and articles databases and internet indexes websites, then papers collected, analyzed and explained in this review
Results revealed that caecum differ in shape, length, breadth, and symmetry among different birds’ species. also, the current review summarized the histological and cellular differences like the thickness of caecal wall, length and shape of tonsillar villi, lymphoid tissue organization, and cellular distribution.
In conclusion: Understanding of the anatomy and histology of caecal tonsil in different birds’ species is crucial, due to the defense and protective role of caecal tonsils as apart of immune system and the morphological differences in birds may explain the immunological variation and the resistance of different bird types to some enteric infections. The current works will provide a considerable assistance for biological and veterinary immunity researchers
... The adaptive immune systems of aves and mammals differ greatly, particularly in the development of B cells since aves possess a unique organ, the bursa of Fabricius. The bursa is the initial site of B-cell development prior to its involution of the bursa at 12 weeks of age (1). Avian species also rely on gene conversion (2) to generate diversity in their naïve repertoire. ...
The mechanisms of B-cell diversification differ greatly between aves and mammals, but both produce B cells and antibodies capable of supporting an effective immune response. To see how differences in the generation of diversity might affect overall repertoire diversity, we have compared the diversity characteristics of immunoglobulin genes from domestic chickens to those from humans. Both use V(D)J gene rearrangement and somatic hypermutation, but only chickens use somatic gene conversion. A range of diversity analysis tools were used to investigate multiple aspects of amino acid diversity at both the germline and repertoire levels. The effect of differing amino acid usages on antibody characteristics was assessed. At both the germline and repertoire levels, chickens exhibited lower amino acid diversity in comparison to the human immunoglobulin genes, especially outside of the complementarity-determining region (CDR). Chickens were also found to possess much larger and more hydrophilic CDR3s with a higher predicted protein binding potential, suggesting that the antigen-binding site in chicken antibodies is more flexible and more polyreactive than that seen in human antibodies.
