The outer limiting "membrane" (OLM) of the vertebrate retina comprises a series of heterotypic adherens junctions between the photoreceptors and the supportive Müller cells. These junctions appear to support the photoreceptors, which in teleosts, anurans, and birds are motile, and thus help them maintain their orientation with respect to incoming light. In an unusual role for this type of junction, they also provide a semipermeable barrier, preventing the diffusion of some proteins out of the extracellular space that surrounds the inner and outer segments of the photoreceptors. Using immunoelectron microscopy, we examined the association of actin, myosin, alpha-actinin, and vinculin with the OLM junctions of the adult chicken retina. Vinculin was detected close to the plasma membrane in the cytoplasmic plaques of the junctions, as it was in the adherens junctions of the retinal epithelium. Labelling of actin, myosin, and alpha-actinin was spread more throughout the plaques and was distributed unevenly about the junctions; labelling was much more extensive in the Müller cells than in the photoreceptors. Thus, the junctions of the OLM show similarity to the other adherens junctions in that their cytoplasmic plaques contain actin, myosin, alpha-actinin, and vinculin. But the large aggregation of actin, myosin, and alpha-actinin in the Müller cells, and their resulting asymmetrical distribution about the junctions, is unusual, and possibly an adaptation for the special function of the OLM junctions, in providing both structural support for the motile photoreceptors and a semipermeable barrier.

Wound healing is a complex, long-lasting regulatory sequence that involves expression of a number of genes, which are active during the individual's development. Some of the phenomena differ from normal tissue turnover and growth only quantitatively. This article reviews the current data on corneal wound healing, with particular reference to mesenchymal matrix proteins and their integrin receptors, to growth factors and to proteolytic enzymes. Some inflammatory mediators are also discussed. The theoretical basis for therapeutic interventions is also discussed briefly, in the light of present knowledge.

The present results suggest the presence of several integrin heterodimers, acting as potential receptors for laminin, collagen, fibronectin, and vitronectin, in the anterior chamber angle.

Integrin complex alpha 6 beta 4 is a component of the hemidesmosome. In the unwounded cornea both the integrin subunits face the laminin-containing basement membrane, but the alpha 6 subunit is also located between the basal cells. While the migrating epithelium is known to be without hemidesmosomes, we investigated the distribution of alpha 6 beta 4 during epithelial healing. Epithelial abrasion 7.5 mm in diameter was mechanically created. The rabbits were killed 1-24 h or 2, 3, or 7 days later. Monoclonal antibodies against alpha 6, beta 4, and laminin A were used to detect their distributions by immunohistochemistry. Positive immunostaining for laminin A on the surface of the unepithelialized stroma indicated that basement membrane was intact after the epithelial abrasion. Three hours after corneal wounding, alpha 6, was detectable around the entire cell up to the leading edge of the migrating epithelium. In the peripheral wound, alpha 6, was also prominently present around the basal and suprabasal cells with only the superficial cell layers being negative. The beta 4 subunit showed a dissimilar distribution; it was not detectable subjacent to the leading edge. After 1 h the immunoreaction for the beta 4 subunit had faded 15 - 20 microns peripheral to the wound margin. Thereafter the subepithelial band was segmentally reassembled, starting from the periphery and progressing toward the central area of the wound. One week after epithelial wounding, immunolabeling for both integrin subunits was indistinguishable from that of the control cornea. Our results indicate that in addition to the beta 4 in the rabbit cornea, the alpha 6 subunit is also complex with another beta subunit during the epithelial healing phase. The results also suggest that basal cells 15 - 20 microns peripheral to the wound margin disassemble their HDs prior to the migration process.

An orbital nylon prosthesis was removed because of an infection caused by Staphylococcus aureus that was resistant to antimicrobials. It was processed for histopathology and immunohistochemistry. Within 3 weeks the implant had an extensive ingrowth of fibrovascular tissue containing chronic inflammatory cells, foreign body giant cells, and myofibroblasts. By using the indirect immunofluorescent method, this tissue was found to react with monoclonal antibodies (Mabs) against extradomain A of cellular fibronectin (EDA-cFN) and tenascin (TN). The presence of EDA-cFN and TN within the implant are indicative of an active healing process, since both of these proteins, scarce in adult tissues, have been shown to be reexpressed during tissue regeneration. The findings suggest that fibronectin plays a definite role in bacterial adherence and foreign body infections.