Quantification of Particle Uptake by Conjunctiva-Associated Lymphoid Tissue (CALT) in Chickens

Abstract

Tracer particle uptake by conjunctiva-associated lymphoid tissue (CALT) was quantified in the lower eyelids of 1-, 3-, 5-, and 7-week-old broiler chickens. CALT was measured histologically by computerized image analysis in all birds and in additional 1-day-old and 16-week-old chickens not subjected to uptake assessment. Suspensions of carbon or iron oxide were placed in contact with CALT for 5, 15, or 30 minutes (contact time). After eyelid removal, tracer uptake was scored by light microscopy, CALT was measured, and a mathematically derived uptake index was evaluated statistically. At each age examined, computer-generated measurements showed a significant increase in the proportion of CALT lymphoepithelium within proximal eyelids. Within the conjunctival sites evaluated, tracer uptake was significantly greater in lymphoepithelium than in non-lymphoepithelium at all ages and at all contact times. Uptake increased significantly between 3 and 5 weeks of age and between 5 and 15 minutes of tracer contact. Based on these uptake data for CALT in chickens, a minimal age-specific maturity is suggested that may influence function in mucosal immunity.

Head-associated lymphoid tissue [HALT] of the chicken: characterization of lymphocytes

“…These nodules were reported to resemble other constituents of the mucosal immune system such as the 14 gut-associated lymphoid tissue or bronchial-associated lymphoid tissue (Fix and Arp, 1991a). The lymphocytic clusters were noted at day of hatch.…”

“…Conjunctiva-associated lymphoid tissue (CALT) has been characterized in the chicken (Fix and Arp, 1991a) and has been described in the guinea pig (Chandler and Axelrod, 1980), rabbit (Axelrod and Chandler, 1979;Chandler and Axelrod, 1980) and turkey (Fix and Arp, 1989).…”

“…The CALT of the chicken (Fix and Arp, 1991a) has been described as a group of lymphoid nodules within the conjunctival folds and fissures and aggregated toward the medial canthus of the lower eyelid. These nodules were reported to resemble other constituents of the mucosal immune system such as the 14 gut-associated lymphoid tissue or bronchial-associated lymphoid tissue (Fix and Arp, 1991a).…”

“…Fix and Arp (12) have characterized the chicken's CALT as a group of lymphoid nodules within the conjunctiva which aggregate at the medial canthus position of the lower eyelid. In chickens, the lymphoepithelium lining of the CALT nodules was reported (13) to have the ability to take up foreign particles, such as carbon and iron oxide compounds, within 5-IS minutes of surface exposure of these particles.…”

“…In chickens, the lymphoepithelium lining of the CALT nodules was reported (13) to have the ability to take up foreign particles, such as carbon and iron oxide compounds, within 5-IS minutes of surface exposure of these particles. In turkeys (11), birds inoculated intraocularly with…”