Relationship of distraction rate with inferior alveolar nerve degeneration-regeneration shift

Distraction osteogenesis is an important technique for the treatment of maxillofacial abnormities and defects. However, distraction osteo- genesis may cause the injury of the inferior alveolar nerve. The relationship between distraction rate and nerve degeneration-regeneration shift remains poorly understood. In this study, 24 rabbits were randomly divided into four groups. To establish the rabbit mandibular distraction osteogenesis model, the mandibles of rabbits in distraction osteogenesis groups were subjected to continuous osteogenesis dis- traction at a rate of 1.0, 1.5 and 2.0 mm/d, respectively, by controlling rounds of screwing each day in the distractors. In the sham group, mandible osteotomy was performed without distraction, Pin-prick test with a 10 g blunt pin on the labium, histological and histomorpho- metric analyses with methylene blue staining, Bodian＇s silver staining, transmission electron microscopy and myelinated fiber density of inferior alveolar nerve cross-sections were performed to assess inferior alveolar nerve conditions. At 28 days after model establishment, in the pin-prick test, the inferior alveolar nerve showed no response in the labium to a pin pricks in the 2 mm/d group, indicating a severe dysfunction. Histological and histomorphometric analyses indicated that the inferior alveolar nerve suffered more degeneration and in- juries at a high distraction rate （2 mm/d）. Importantly, the nerve regeneration, indicated by newborn Schwann cells and axons, was more abundant in 1.0 and 1.5 mm/d groups than in 2.0 mm/d group. We concluded that the distraction rate was strongly associated with the inferior alveolar nerve function, and the distraction rates of !.0 and 1.5 mm/d had regenerative effects on the inferior alveolar nerve. This study provides an experimental basis for the relationship between distraction rate and nerve degeneration-regeneration shift during dis- traction osteogenesis, and may facilitate reducing nerve complications during distraction osteogenesis.

Reproductive Ecology of Rhynchanthus beesianus W. W. Smith （Zingiberaceae）in South Yunnan, China： A Ginger with Bird Pollination Syndrome

Rhynchanthus beesianus W. W. Smith （Zlnglberaceae） Is an eplphytlc tropical ginger with a very conspicuous floral display, but almost no fruit set under field conditions. The reproductive ecology encompassing phenology, floral biology, and pollination and breeding systems was Investigated In an evergreen broadleaved forest In Yunnan Province, Southwest China. The flowers possess a typical bird pollination syndrome, but no effective pollinators were observed during 138 h of observation. Female Black-breasted Sunbird （Aethopyga saturata） and bumblebees visited R. beesianus regularly, but they all played roles as nectar robbers. No fruit was found In the bagging treatment, and fruit set following manual self-pollination （（57.55 ± 4.08）%） was comparable with cross-pollination （（64.32 ± 4.42）%）, suggesting that R. beeslanus is self-compatible but spontaneous self-pollination In this species does not occur. Seed set of open-pollination （（26.42 ± 3.11）%） was significantly lower than manual self-pollination （（73.41± 4.16）%） and cross-pollination （（75.56 ± 4.52）%）, confirming that R. beeslanus was dependent on animals for fertilization and suffered a serious pollinator-limitation.