The number of b1b-chains (DP11–18) was almost similar to that of b1a-chains, whereas the number of b2-chains (DP 19–27) was comparatively small and b3-chains(DP ≥ 28) occurred in almost trace amounts. In general, at all matu-rities, b1b-, b2-, and b3-chains were some what more abundant inthe clusters from A-type granules than from B-type granules.