The extracellular matrix protein lacunin is expressed by a subset of hemocytes involved in basal lamina morphogenesis

The extracellular matrix protein of Manduca sexta known as lacunin is localized to basal laminae and granular cells of the hemolymph. Circulating granular cells increase in both number and size as pupal basal laminae break down after the initiation of adult development. Basal laminae of wing epithelia break down as ecdysteroid levels rise during adult development, and lacunin immunoreactivity concurrently passes from basal laminae to endocytic vacuoles of granular cells. Granular cells not only endocytose lacunin protein that they salvage from the remnants of the old basal laminae but they also express transcripts for lacunin. As new adult basal laminae form several days later, the number of circulating granular cells decreases as lacunin immunoreactivity appears in the new basal laminae.