ABC model a model for specification of floral organs especially in Arabidopsis thaliana. It views the floral primordium as comprising four whorls whose developmental fate is determined by the concentric and combinatorial activity of three classes of gene, denoted A, B, and C, which encode transcription factors. Class A determines the fate of whorls 1
Abbe refractometer a refractometer in which the critical angle for total reflection at the interface of a film of liquid between two similar glass prisms is used in determining the refractive index of the liquid. [After Ernst Abbe (1840–1905), German physicist famous for his researches in optics.]
Aarskog–Scott syndrome or Aarskog syndrome or faciogenital dysplasia an extremely rare genetically heterogeneous developmental disorder in which individuals have widely spaced eyes, anteverted nostrils, a broad upper lip and a ‘saddlebag’ or ‘shawl scrotum’. The X-linked form has been ascribed to mutations in the FGD1 gene. [After Dagfinn Aarskog (1928– ), Norwegian paediatrician, and Charles