Structure of the Eurasian moorhen spleen: A comprehensive study using gross anatomy, light, and transmission electron microscopy

Abstract

The spleen is the largest secondary lymphoid organ with major roles in the removal of blood-borne antigens. The Eurasian moorhen is a wild aquatic bird that revealed the adaptation to harsh environmental conditions. Information regarding the structural features of moorhen's spleen is lacking. The present study aimed to describe the composition of moorhen's spleen using anatomical dissection, histology, histochemistry, immunohistochemistry, and transmission electron microscopy. The spleen appeared as a brownish red sickle-shaped organ close to the proventriculus and gizzard. The splenic capsule was very thin, and the trabeculae were poorly developed. The white pulp formed of the periarteriolar lymphoid sheath, lymphoid follicles, and periellipsoidal lymphatic sheath. The red pulp composed of sinusoids and cords and contained various types of blood cells. Blood vessels were observed within the splenic capsule and inside the parenchyma. Notably, penicillar capillaries (PCs) appeared branched and surrounded by welldeveloped ellipsoids. Direct connections were observed between PCs and splenic sinusoids suggesting a closed type of circulation. Ultrastructurally, intercellular spaces and vascular channels were evident in the wall of PCs. Ellipsoid-associated cells, lymphocytes, monocytes, and heterophils were observed within splenic ellipsoids. Ellipsoids were thus suggested as a crucial component of moorhen's spleen. Numerous MafB-immunoreactive (IR) macrophages were seen within the red pulp. Splenic cords contained the highest number of PHH3-IR cells, while CCASP3-IR cells were exclusive to follicles of the white pulp. In conclusion, the structure of moorhen's spleen revealed species-specific features.The findings of the present study could help to improve the immunity of domestic birds. Highlights• The Eurasian moorhen is a wild aquatic bird adapted to harsh environmental conditions with no known information about the cellular composition of its spleen.• The Eurasian moorhen's spleen revealed numerous penicillar capillaries surrounded by well-developed ellipsoids and appeared directly connected to the splenic sinusoids forming a closed type of circulation.• Immunohistochemical staining revealed site-specific staining for macrophages, proliferating, and apoptotic cells within moorhen's spleen.

Post-Hatch Age Related Development of Spleen of Broiler Chicken: A Biometric and Histomorphometric View

“…Zhang et al 5 reported a similar architecture of the spleen in adult broiler chickens in general. The trabeculae were poorly developed in other avian species like in ostrich, a non-flying bird (Struthio camelus) spleen 22 , Japanese quail (Coturnix coturnix Japonica) spleen 23 Eurasian moorhen (Gallinula chloropus, also known as the "swamp chicken") spleen 24 and Red-Legged Partridge (Alectoris chukar) spleen 25 . A significantly increasing trend in histomorphometrical parameters of capsule, white pulp and lymphatic nodules was observed in broiler chicken until post-hatch day 35.…”

Anatomical, histochemical, and immunohistochemical observations on the gastrointestinal tract of Gallinula chloropus (Aves: Rallidae)

“…The wall thickness of different segments of the moorhen digestive tract was determined in microscopic images taken using the × 4 objective lens. The average number of glucagon, somatostatin, PHH3, and C.CASP3 IR cells per the area of 1 mm 2 of the mucosa of the esophagus, proventriculus, isthmus, ventriculus, duodenum, jejunum, ileum, ceca, and rectum were analyzed in microscopic images taken using the × 10 objective lens with the help of the area measurement and particle counting sections of the ImageJ software (National Institutes of Health, Bethesda, MD, USA) as previously described [ 31 ].…”

Recent Advances of Emerging Spleen‐Targeting Nanovaccines for Immunotherapy

“…[ 34 ] The trabeculae, a branching network inside of spleen, emerge from all directions to support the arteries, veins, and splenic pulps. [ 35 ] Anatomically, the splenic pulps are constituted by three sub‐regions ( Figure ): red pulp (RP), white pulp (WP), and marginal zone (MZ). [ 36 ] (i) The RP mainly contributes to the capture of pathogens in the blood by various leukocytes such as DCs, MΦs, neutrophils, and NK cells.…”