['The purpose was to examine human osteoblasts immunohistochemically in order to clarify the significance of the innervation for alveolar bone growth.', 'Unstained sections available from 21 normal human mandibles (foetal gestational ages: 14-22 weeks).', 'Before sectioning in 1980-1990, the mandibular tissue had been fixed in 4% neutral-buffered formaldehyde for 5 days. Tissue blocks were then decalcified in equal parts of 2% citric acid and 20% sodium citrate for 7-15 days, dehydrated, embedded in paraffin, and sagittally cut into 4-mum-thick serial sections and mounted on Superfrost Plus microscope slides. Sections were dried overnight at 40 degrees C. In the present study, paraffin sections were deparaffinized and treated with Tris-EDTA (Merck, Germany), pH 9.0, and immunohistochemically tested with polyclonal rabbit anti-PGP 9.5, and the EnVision +/HRP dual link (K4065; DAKO Denmark A/S, Denmark) method.', 'A pronounced protein gene product (PGP) 9.5 activity was registered in osteoblasts from alveolar bone in all specimens. In all cases, the activity was intense at the top of and labially to the alveolar bone, while less or no activity was observed on the inner lingual aspects of the alveolar processes. Osteoclasts and osteocytes reacted vaguely or negatively.'] Are immunohistochemical PGP 9.5 positivity in human osteoblasts may indicate that compensatory and dysplastic craniofacial growth under control by peripheral nerves?