Genetical studies on the skeleton of the mouse xvi. Tail-kinks
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Tail-kinks (tk/tk) in the mouse is clue to a simple autosomal recessive gene with regular manifestation and full viability under laboratory conditions.
The major effects of the tail-kinks gene are confined to the axial skeleton. This is grossly affected in the cervical and upper thoracic and again in the caudal region; the intervening region is almost normal. Ribs are often involved and the manubrium sterol is usually fused to the next sternebra.
The distribution of abnormalities over the vertebral column is such that the small vertebrae at both ends are severely affected while the large ones in the middle are almost immune.
The abnormalities of the osseous skeleton are preformed in cartilage and are visible to the full extent as soon as chondrification sets in.
The abnormalities of the cartilaginous skeleton are preceded by defects in the membranous skeleton. These can be traced back to the 10-day stage (C.R..L. 4–5 mm.) when in the normal embryo the cervical sclerotomes have differentiated into anterior and posterior sclerotome halves which differ in tissue density whiletk/tk embryos do not yet show any signs of this differentiation. No differences have been discovered in 9-day embryos (C.R.L. about 3 mm.).
KeywordsVertebral Column Cervical Vertebra Cervical Region Thoracic Region Normal Embryo
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