Right- and left-handedness.

The Left–Right Polarity Puzzle: Determining Embryonic Handedness

W henever symmetry is broken in nature to yield only one of two equally probable outcomes, whether in physics, chemistry, or biology, there is an intriguing problem to be solved. Physicists from M. and P. Curie to T.-S. Lee and C.-D. Yang puzzled over such phenomena at the atomic level. Organic chemists puzzled over the handedness of molecules for many years after Pasteur showed that grape juic...

The development of handedness in left/right asymmetry.

The development of handed asymmetry requires a special mechanism for consistently specifying a difference between left and right sides. This is to be distinguished from both random asymmetry, and from those left/right differences that are mirror symmetrical. We propose a model for the development of handedness in bilateral animals, comprising three components. (i) A process termed conversion, i...

Development of left/right handedness in the chick heart.

The chick heart tube develops from the fusion of the right and left areas of precardiac mesoderm and in almost all cases loops to the embryo's right-hand side. We have investigated whether any intrinsic difference exists in the right and left areas of precardiac mesoderm, that influences the direction of looping of the heart tube. Chick embryos incubated to stages 4,5 and 6 were cultured by the...

Left-Handedness

Science in the Making: Right Hand, Left Hand. III: Estimating historical rates of left-handedness.

The BBC television programme Right Hand, Left Hand, broadcast in August 1953, used a postal questionnaire to ask viewers about their handedness. Respondents were born between 1864 and 1948, and in principle therefore the study provides information on rates of left-handedness in those born in the nineteenth century, a group for which few data are otherwise available. A total of 6,549 responses w...