Investigations on the conjunctival goblet cells and on the characteristics of glands associated with the eye in the guinea pig.

Abstract

OBJECTIVE: To investigate the distribution and density of conjunctival goblet cells (GC) and to study the anatomy and microscopic characteristics of glands associated with the eye in the guinea pig. PROCEDURES: Twenty-five guinea pigs were used. Meibomian gland openings were counted using biomicroscopy. Conjunctiva, eyelids and glands were embedded in glycol methacrylate and paraffin. Sections were stained with hematoxylin and eosin (H&E), periodic acid Schiff's reaction (PAS) and Alcian blue (AB). RESULTS: Highest GC densities were found in the bulbar and palpebral region of the nasal conjunctiva (GC index: 13.7-16.4%). Lowest GC densities (GC index: 0.0-1.0%) were found in 3/4 limbal regions (nasal and temporal upper eyelid, temporal lower eyelid). Guinea pigs have 27.1±3.0 (mean±SD) meibomian gland openings in the upper lid and 25.7±2.3 in the lower lid. Difference between upper and lower lid was significant (P=0.037). Two subconjunctival sebaceous glands occur temporal to each eye. The Harderian gland is very large. In the lacrimal gland three different cell types were distinguished both according to the cell structure and histochemical staining. CONCLUSIONS: Goblet cell densities are lower in guinea pigs than in dogs and horses. Positive staining with PAS and AB could be an indication that mucins are produced in the lacrimal gland. If so, they may contribute to the mucin layer of the tear film. Both the extraordinarily large Harderian gland and the subconjunctival sebaceous glands produce lipids and may contribute to the lipid layer of the tear film.