Figure 4. Buccal-lingual sections of the M1 in a 36-week-old rat stained with Azan (A,C,D) or treated for detecting GDF-5 (E,H), -6 (F,I), and -7 (G,J) transcripts. (A) Apically, one-fourth of the root is fully covered by thick cellular cementum. Small rectangles of C and D indicate the areas enlarged in C and D, respectively. (B) The fluorescent green line of labeled calcein is almost undetectable in the alveolar bone (ab), dentin (d), and cementum (cc) in the area outlined by the red rectangle in Fig. 4A. (E,F) GDF-positive cells are not visible in the periodontal tissues in sections hybridized with the GDFs mRNA probe. ab, alveolar bone; cc, cellular cementum; d, dentin; pdl, periodontal ligament; pul, pulp. Bar = 500 µm (A and B), 50 µm (C-J).