WordNet

axis of a compound leaf or compound inflorescence
of or relating to the spine or spinal cord; "spinal cord"; "spinal injury"
a genus of plants with pods that ripen underground (see peanut) (同)genus Arachis

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背骨の / せき髄麻酔

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/02/28 06:30:17」(JST)

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The dark rachis of a turkey feather

Rachis /ˈreɪkɨs/ is a biological term for a main axis or "shaft".

In zoology/microbiology

In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually forms the supporting axis of the body and is then called the spine or vertebral column. Rachis can also mean the central shaft of pennaceous feathers.

In the gonad of the invertebrate nematode C. elegans, rachis is a term used to describe the central cell-free core or axis of the gonadal arm of both adult males and hermaphrodites where the germ cells have achieved pachytene and are attached to the walls of the gonadal tube. The rachis is filled with cytoplasm.^[1]

Vertical fern rachis with horizontal leaflets, "pinnae" attached, each with rachillae and pinnules

The inflorescence of Buddleja paniculata is arranged along a central rachis

In botany

In plants, a rachis is the main axis of a compound structure. It can be the main stem of a compound leaf, such as in Acacia or ferns, or the main, flower-bearing portion of an inflorescence above a supporting peduncle.

A ripe head of wild-type wheat is easily shattered into dispersal units when touched or blown by the wind. A series of abscission layers forms that divides the rachis into dispersal units consisting of a small group of flowers (a single spikelet) attached to a short segment of the rachis. This is significant in the history of agriculture, and referred to by archaeologists as a "brittle rachis", one type of shattering in crop plants.

References

^ Tim Schedl (9 August 2012). Germ Cell Development in C. elegans. Springer. p. 11. ISBN 978-1-4614-4015-4. Retrieved 6 August 2013.

English Journal

An efficient plant regeneration and Agrobacterium-mediated genetic transformation of Tagetes erecta.

Gupta V1, Ur Rahman L.
Protoplasma.Protoplasma.2014 Dec 12. [Epub ahead of print]
Tagetes erecta, L. an asteraceous plant of industrial and medicinal value, contains important compounds like pyrethrins, thiophenes and lutein, possessing immense potential for insecticidal, nematicidal and nutraceutical activities. Considering the importance and demand for these natural compounds,
PMID 25504508

Nanomechanical properties of bird feather rachises: exploring naturally occurring fibre reinforced laminar composites.

Laurent CM1, Palmer C2, Boardman RP3, Dyke G4, Cook RB5.
Journal of the Royal Society, Interface / the Royal Society.J R Soc Interface.2014 Dec 6;11(101):20140961. doi: 10.1098/rsif.2014.0961.
Flight feathers have evolved under selective pressures to be sufficiently light and strong enough to cope with the stresses of flight. The feather shaft (rachis) must resist these stresses and is fundamental to this mode of locomotion. Relatively little work has been done on rachis morphology, espec
PMID 25339689

Detection of progressive idiopathic scoliosis during growth using back surface topography: A prospective study of 100 patients.

De Korvin G1, Randriaminahisoa T2, Cugy E3, Cheze L2, de Sèze M4.
Annals of physical and rehabilitation medicine.Ann Phys Rehabil Med.2014 Dec;57(9-10):629-39. doi: 10.1016/j.rehab.2014.09.002. Epub 2014 Sep 19.
The progression of adolescent idiopathic scoliosis is typically monitored via regular radiographic follow-up. The Cobb angle (as measured on whole-spine radiographs) is considered as the gold standard in scoliosis monitoring.OBJECTIVE: To determine the sensitivity and specificity of back surface top
PMID 25267453