Abstract
Purpose: :
It was hypothesized that conjunctival epithelial stem cells reside at the fornix, a finger-like invagination similar to the intestinal crypt. The mechanisms controlling cellular differentiation and migration from the fornix remain unclear. This study investigated the cellular differentiation and migration of integrin signal-dependent pathways found in the fornix, palpebral conjunctiva, bulbar conjunctiva epithelia and the mucocutaneous junction (MCJ).
Methods: :
Balb/c mice were sacrificed in accordance with the ARVO Statement for Use of Animals in Ophthalmic and Visual Research. Eyelid tissues were studied using single- and double-labeled immuno-histochemistry with antibodies against paxillin, cofilin, profilin-1, focal adhesion kinase (FAK), gelsolin, cytokeratin (CK) 4, integrin beta1 and integrin alpha6.
Results: :
Paxillin was expressed with the greatest intensity at the fornix , with diminishing intensity along the basal layer of palpebral conjunctival and bulbar conjunctival epithelia, ending at the MCJ. Cofilin was strongly expressed in all layers of the fornix and bulbar conjunctival epithelia, as well as the basal layer of MCJ. Weak expression was noted along the basal layer of the palpebral conjunctiva epithelium and along ductal epithelia of Meibomian glands. Profilin-1 was expressed at the superficial layer of the skin epidermis and MCJ, but not at the fornix, palpebral conjunctival or bulbar conjunctival epithelia. FAK was expressed in the supra-basal and basal cell layers along the palpebral conjunctival, fornix and bulbar conjunctival epithelia, with the greatest intensity of expression at the fornix. FAK was weakly expressed in the basal layer of the MCJ. Gelsolin was expressed in all layers of fornix, and in the supra-basal and basal layers of the palpebral conjunctival epithelium. Weak expression was detected in the MCJ. Integrin beta1 and integrin alpha6 were expressed in the basal layer of the fornix, bulbar conjunctival, palpebral conjunctival epithelia and MCJ .
Conclusions: :
The diminishing expression of paxillin along the basal layer from the fornix towards the MCJ and limbus suggested that cells migrate from the fornix to form bulbar and palpebral conjunctiva. These results provide insight that the integrin signal-dependent pathway may contribute to the special environment of fornix.
Keywords: conjunctiva • differentiation