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Segmentation in biology is the division of some animal and plant body plans into a linear series of repetitive segments that may or may not be interconnected to each other. This article focuses on the segmentation of animal body plans, specifically using the examples of the taxa Arthropoda , Chordata , and Annelida .
The nervous system segmentation confers several developmental advantages to the vertebrate body as humans possess a body plan that is bilaterally segmented at the nervous system level. The segmentation is involved at all levels of the human nervous system with increasing level of complexity in the innervation from the brain to limbs. [1]
A key discovery was the existence of groups of homeobox genes, which function as switches responsible for laying down the basic body plan in animals. The homeobox genes are remarkably conserved between species as diverse as the fruit fly and humans, the basic segmented pattern of the worm or fruit fly being the origin of the segmented spine in ...
Ed Lewis, Christiane Nüsslein-Volhard and Eric F. Wieschaus identified and classified 15 genes of key importance in determining the body plan and the formation of body segments of the fruit fly D. melanogaster in 1980. [60] For their work, Lewis, Nüsslein-Volhard, and Wieschaus were awarded the Nobel Prize in Physiology or Medicine in 1995. [61]
Earthworms are a classic example of biological homonymous metamery – the property of repeating body segments with distinct regions. In biology, metamerism is the phenomenon of having a linear series of body segments fundamentally similar in structure, though not all such structures are entirely alike in any single life form because some of them perform special functions. [1]
A gap gene is a type of gene involved in the development of the segmented embryos of some arthropods. Gap genes are defined by the effect of a mutation in that gene, which causes the loss of contiguous body segments, resembling a gap in the normal body plan. Each gap gene, therefore, is necessary for the development of a section of the organism.
Like all arthropods, chelicerates have segmented bodies with jointed limbs, all covered in a cuticle made of chitin and proteins. The chelicerate body plan consists of two tagmata, the prosoma and the opisthosoma – excepting the mites, which have lost any visible division between these sections
The gap genes are part of a larger family called the segmentation genes. These genes establish the segmented body plan of the embryo along the anterior-posterior axis. The segmentation genes specify 14 parasegments that are closely related to the final anatomical segments. The gap genes are the first layer of a hierarchical cascade of the ...