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This trend continues postnatally along an axis of increased growth from the head to the feet. Finally, in adults, the head represents approximately 12% of the body length. The cephalocaudal trend is also the trend of infants learning to use their upper limbs before their lower limbs. The proximodistal trend, on the other hand, is the prenatal ...
Gesell and his colleagues documented a set of behavioral norms that illustrate sequential & predictable patterns of growth and development. Gesell asserted that all children go through the same stages of development in the same sequence, although each child may move through these stages at their own rate [ 3 ] Gesell's Maturational Theory has ...
Mesoderm cells condense to form a rod which will send out signals to redirect the ectoderm cells above. This fold along the neural tube sets up the vertebrate central nervous system. The endoderm is the inner most germ layer of the embryo which gives rise to gastrointestinal and respiratory organs by forming epithelial linings and organs such ...
The Shh gene, and genes belonging to the BMP, Hox, T-box, FGF, and Wnt families, all play a pivotal role in cell signaling and differentiation to regulate and promote successful limb formation. Various other genes listed above, one example being Dach1, are DNA-binding proteins that regulate gene expression.
Some of the earliest ideas and mathematical descriptions on how physical processes and constraints affect biological growth, and hence natural patterns such as the spirals of phyllotaxis, were written by D'Arcy Wentworth Thompson in his 1917 book On Growth and Form [2] [3] [note 1] and Alan Turing in his The Chemical Basis of Morphogenesis (1952). [6]
[4] [5] [6] Pattern formation is genetically controlled, and often involves each cell in a field sensing and responding to its position along a morphogen gradient, followed by short distance cell-to-cell communication through cell signaling pathways to refine the initial pattern. In this context, a field of cells is the group of cells whose ...
Scientists have long known a gene called APOE4 is one of many things that can increase people’s risk for Alzheimer's, including simply getting older. The vast majority of Alzheimer’s cases ...
Cell division with no significant growth, producing a cluster of cells that is the same size as the original zygote, is called cleavage. At least four initial cell divisions occur, resulting in a dense ball of at least sixteen cells called the morula. In the early mouse embryo, the sister cells of each division remain connected during ...