Matrix description and behavior of human primary osteoblasts seeded on an osteoid-like matrix.

<p>SEM (a) and TEM (b) views of the dense, 40 mg/mL, fibrillar collagen matrix (*). Scale bars: a: 1 µm, b: 100 nm. c, d: Cell adhesion over 72 hours and cell viability over 21 days analyzed by cell counting and MTT test, respectively. * = p<0.05. e–k: Osteoblast morphology. e, f: Hemalun staining of 5 µm-thick sections at 14 and 28 days, respectively; g, h: SEM observations at 14 and 28 days; i–k: TEM observations at 14 (i, j) and 60 days (k). i: The osteoblasts (OS) are organized into several layers and show a well-developed network of rough endoplasmic reticulum (white arrowheads) and are linked by means of tight junctions (black arrowhead); j: neosynthesized collagen (white arrow); k: cell extensions penetrating superficial region of the dense matrix (black arrows). Scale bars: e: 50 µm, f: 20 µm, g: 30 µm, h: 25 µm, i and j: 1 µm, k: 0.5 µm.