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 local ized to basal laminae and granular cells of the hemolymph. Circulating gran ular cells increase in both number and size as pupal basal laminae break do wn after the initiation of adult development. Basal laminae of wing epithel ia break down as ecdysteroid levels rise during adult development, and lacu nin immunoreactivity concurrently passes from basal laminae to endocytic va cuoles of granular cells. Granular cells not only endocytose lacunin protei n that they salvage from the remnants of the old basal laminae but they als o express transcripts for lacunin. As new adult basal laminae form several days later, the number of circulating granular cells decreases as lacunin i mmunoreactivity appears in the new basal laminae. (C) 2001 Elsevier Science Ltd. All rights reserved.