FIGURE 8.

Fibrillin-2 immunostaining is revealed in P8 GT-8 mutant mice. A, P8 wild-type, heterozygous, and homozygous GT-8 skin sections were stained with anti-fibrillin-2 (pAb 0868) and with anti-fibrillin-1 (pAb 9543). Fibrillin-2 immunostaining was barely visible in wild-type sections, but long fibrillin-2-positive microfibril fiber bundles (arrows), inserting perpendicularly to the dermal-epidermal junction, were revealed in heterozygous and homozygous GT-8 sections. Fibrillin-2 immunostaining was more abundant in homozygous skin sections than in heterozygous skin sections. In contrast, fibrillin-1 immunostaining showed abundant long microfibril fiber bundles (arrows) in the wild-type skin sections, but in heterozygous and homozygous sections, fibrillin-1 immunostaining appeared fragmented, with very few long fibrils at the dermal-epidermal junction. Because early postnatal heterozygous skin sections showed abundant long fibrillin-1 microfibril fiber bundles (Fig. 4), microfibril assembly was apparently uncompromised. Therefore, P8 sections likely indicate that fragmentation of fibrillin-1 has occurred. B, P8 wild-type, heterozygous, and homozygous GT-8 sections of skeletal muscle and tendon were also examined, and similar results were obtained. Fibrillin-2 immunostaining was concealed in wild-type sections and revealed in heterozygous and homozygous skeletal muscle and tendon. In contrast, fibrillin-1 immunostaining appeared to be more fragmented in heterozygous and homozygous tissues than in the wild-type tissues. This was particularly noticeable in the skeletal muscle where fibrillin-1 immunostaining typically envelopes individual skeletal muscle fibers (arrows). Scale bars = 50 μm.