In this tissue-culture study, some effects of phagocytosis on the cell were investigated. Third-passage bovine trabecular-meshwork cells were incubated with latex microspheres for periods of up to 60 hr. Cells which had been involved in phagocytosis were found to settle at a faster rate than control cells, but if microspheres were added to the medium of recently settled cells, there was a reduction in their proliferative activity. Incorporation of tritiated proline remained unchanged, whereas uptake of tritiated glucosamine increased with the time period of phagocytosis. The fibronectin scaffold was more extensive and elaborate when cells were pre-incubated with microspheres before settlement. Exposure to a low concentration of microspheres promoted a higher uptake of a second presentation of 125I-labelled microspheres — an effect which was not seen if the original dose was too high.