Light and electron microscopic study of the eyelids, conjunctiva-associated lymphoid tissue and lacrimal gland in Bilgorajska Goose (Anser anser)

Abstract

Normal structure of the accessory organs of the eye is essential for normal eye physiology. Among the most important accessory organs of the eye are the eyelids, the conjunctiva-associated lymphoid tissue (CALT) and the lacrimal gland (LG). The aim of this study was to demonstrate the histological structure of the eyelids and LG by histochemical and ultrastructural analysis. The study was performed on 13 adult female Bilgorajska geese. Eyelid samples were stained with the Alcian blue (AB pH 2.5) and periodic acid-Schiff (PAS) methods. Staining methods used for LG were AB pH 2.5, aldehyde fuchsin (AF), PAS and Hale's dialysed iron (HDI). Within the connective tissue of the eyelids, well-developed, diffuse, CALT follicles were observed, mostly under the conjunctival epithelium. Numerous lymphocytes were present within loose connective tissue. Staining of the eyelids with the PAS method demonstrated the presence of goblet cells of a mucous nature, and AB pH 2.5 staining indicated the presence of sulfated acid mucopolysaccharides. PAS staining of LG revealed the presence of secretory cells containing weakly PAS-positive granules. All epithelial cells of the corpus glandulae and the duct systems reacted positively to AB pH 2.5. HDI staining detected the presence of carboxylated acid mucopolysaccharides. Transmission electron microscopy investigations revealed two types of secretory epithelial cells in LG. Both types of LG cells contained drop-like secretory vesicles of different sizes with low or high electron density in cytoplasm, as well as small and large lipid vacuoles, and numerous small primary lysosomes.

Histological, histochemical and ultrastructural studies on Harderian and lacrimal glands of the Capercaillie (Tetrao urogallus majorL.)

“…The AB-positive cells were observed in both the glandular and ductal epithelium. AB-positive cells were also observed both in the corpus of the glandule and within the main duct in HG and LG in chickens [32], domestic ducks [5], domes-tic geese [4], Bilgorajska geese [28], fowl [8] and ospreys [30]. In the present study, the HDI staining showed the presence of carboxylated acid mucopolysaccharides in the HG and LG.…”

“…In Capercaillies, the LG was uniform, undivided, flattened in shape and bright red in colour. According to Klećkowska-Nawrot et al [28], the LG in Bilgorajska geese was bright red in colour and had a triangular shape. On the other hand, the gland was oval in shape and of bright red colour in the African black ostrich [26].…”

The differences in the eyelids microstructure and the conjunctiva‐associated lymphoid tissue between selected ornamental and wild birds as a result of adaptation to their habitat

“…The mammalian third eyelid moves passively, whereas in birds it moves actively due to the presence of two muscles—the quadratus third eyelid muscle ( m. quadratus membranae nictitans ) and the pyramidal third eyelid muscle ( m. pyramidalis membranae nictitans ). The role of the third eyelid is to protect, moisten and clean the cornea (Hall et al., ; Klećkowska‐Nawrot, Goździewska‐Harłajczuk, et al., ; Klećkowska‐Nawrot, Nowaczyk, et al., ; Nomina Anatomica Avium, ). The free margins of the third eyelid possess characteristic thick folds, which enable the removal of fluids and detritus from the corneal surface (Klećkowska‐Nawrot, Goździewska‐Harłajczuk, et al., ; Nomina Anatomica Avium, ).…”

“…In birds, the CALT is assumed to play a key role in the protection of the eyes by initiating and regulating immune responses as well as participating in the mucosal immunity of the nasopharynx (Khan et al., ; Seo et al., ; Siebelmann et al., ; Steven & Gebert, ; Steven et al., ). In mammals, the lacrimal apparatus and CALT moisturize the eye and supply the cornea and superior and inferior conjunctival sacs with nutrients and antibodies to maintain their health (Dartt, ; Jochems & Phillips, ; Klećkowska‐Nawrot, Goździewska‐Harłajczuk, et al., ; Klećkowska‐Nawrot, Nowaczyk, et al., ; Maggs, ). In humans, the CALT is present in the form of organized lymphoid follicles and diffuse lymphoid tissue (lymphocytes and plasma cells) located in the upper and lower eyelids (Klećkowska‐Nawrot, Goździewska‐Harłajczuk, et al., ; Knop & Knop, ; Siebelmann et al., ).…”

“…In birds, the CALT is present within the conjunctival fornix of the lower eyelids and the ocular epithelium of the third eyelid (Fix & Arp, ). It is present in the form of lymphoid follicles (termed as the follicle‐associated epithelium FAE) that are formed by specialized cells essential in antigen uptake in other mucosal lymphoid tissues, which are located directly under the conjunctival epithelium (Bayraktaroglu, Kormaz, Aşti, Kurtdede, & Altunay, ; Fix & Arp, ; Klećkowska‐Nawrot, Goździewska‐Harłajczuk, et al., ; Klećkowska‐Nawrot, Nowaczyk, et al., ). The number and size of the lymphoid follicles increase in response to an exposure to pathogens (Chodosh & Kennedy, ; Klećkowska‐Nawrot, Goździewska‐Harłajczuk, et al., ; Siebelmann et al., ).…”