Our goal here is to set out the types of unitary decisions made by heart progenitor cells, from their appearance in the heart field until they form the simple heart tube. This provides a context to evaluate cell fate, lineage and, finally, morphogenetic decisions that configure global heart form and function. Some paradigms for cellular differentiation and for pattern generation may be borrowed from invertebrates, but neither Drosophila nor Caenorhabditis elegans suffice to unravel higher order decisions. Genetic analyses in mouse and zebrafish may provide one entrance to these pathways.

Fashioning the vertebrate heart: earliest embryonic decisions

We demonstrated previously that a single injection of recombinant human macrophage colony-stimulating factor (rhM-CSF) is sufficient for osteoclast recruitment and survival in osteopetrotic (op/op) mice with a deficiency in osteoclasts resulting from a mutation in M-CSF gene. In this study, we show that a single injection of recombinant human vascular endothelial growth factor (rhVEGF) can similarly induce osteoclast recruitment in op/op mice. Osteoclasts predominantly expressed VEGF receptor 1 (VEGFR-1), and activity of recombinant human placenta growth factor 1 on osteoclast recruitment was comparable to that of rhVEGF, showing that the VEGF signal is mediated through VEGFR-1. The rhM-CSF–induced osteoclasts died after injections of VEGFR-1/Fc chimeric protein, and its effect was abrogated by concomitant injections of rhM-CSF. Osteoclasts supported by rhM-CSF or endogenous VEGF showed no significant difference in the bone-resorbing activity. op/op mice undergo an age-related resolution of osteopetrosis accompanied by an increase in osteoclast number. Most of the osteoclasts disappeared after injections of anti-VEGF antibody, demonstrating that endogenously produced VEGF is responsible for the appearance of osteoclasts in the mutant mice. In addition, rhVEGF replaced rhM-CSF in the support of in vitro osteoclast differentiation. These results demonstrate that M-CSF and VEGF have overlapping functions in the support of osteoclastic bone resorption.

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Vascular Endothelial Growth Factor Can Substitute for Macrophage Colony-Stimulating Factor in the Support of Osteoclastic Bone Resorption

Object. The author discusses the successful preliminary experience of treating selected cases of basilar invagination by performing atlantoaxial joint distraction, reduction of the basilar invagination, and direct lateral mass atlantoaxial plate/screw fixation. Methods. Twenty-two patients with basilar invagination—in which the odontoid process invaginated into the foramen magnum and the tip of the odontoid process was above the Chamberlain, McRae foramen magnum, and Wackenheim clival lines—were selected to undergo surgery. In all patients fixed atlantoaxial dislocations were documented. The 16 male and six female patients ranged in age from 8 to 50 years. A history of trauma prior to the onset of symptoms was documented in 17 patients. Following surgery, the author observed minimal-to-significant reduction of basilar invagination and alteration in other craniospinal parameters resulting in restoration of alignment of the tip of the odontoid process and the clivus and the entire craniovertebral junction i...

Treatment of basilar invagination by atlantoaxial joint distraction and direct lateral mass fixation

Msg1 and Mrg1, founding members of a gene family, show distinct patterns of gene expression during mouse embryogenesis.

The nail is considered to be a specialised modification of the skin – an ‘epidermal appendage’. However, the phrase ‘hanging on by your fingernails’ belies a vital aspect of nail microanatomy that has

The nail as a musculoskeletal appendage--implications for an improved understanding of the link between psoriasis and arthritis.

Human Nutrition and Dietetics. By SIR STANLEY DAVIDSON, R. PASSMORE and J. F. BROCK. Fifth edition. Pp. 597, illustrated. Edinburgh and London: Churchill Livingstone, 1972. £6.00. The Acute Abdomen in Rhyme. By SIR ZACHARY COPE. Fifth edition. Pp. 108, illustrated. London: H. K. Lewis, 1972. £0.50. Multiple Sclerosis. A reappraisal. By D. McALPINE, C. E. LUMSDEN and E. D. ACHESON. Second edition. Pp. 653, illustrated. Edinburgh and London: Churchill Livingstone, 1972. £6.00. The UFA W Handbook on the Care and Management of Laboratory Animals. Edited by UFAW. Foreword by C. W. HuME. Fourth edition. Pp. 624, illustrated. London: Churchill Livingstone, 1972. £7.00. Clinical Electroencephalography. By L. G. KILOH, A. J. MCCOMAS and J. W. OSSELTON. Third Edition. Pp. 239, illustrated. London: Butterworths, 1972. £6.50.

M. Allen

Papers

The Upper Cervical Spine. Regional Anatomy, Pathology and Traumatology. A Systematic Radiological Atlas and Textbook.