Category:Carnegie Embryo 485

References

Kunitomo K. The development and reduction of the tail and of the caudal end of the spinal cord (1920) Contrib. Embryol., Carnegie Inst. Wash. Publ. 272, 9: 163-198.

Embryo No. 485, 13 mm Crown-Rump Length

Kunitomo K. The development and reduction of the tail and of the caudal end of the spinal cord (1920) Contrib. Embryol., Carnegie Inst. Wash. Publ. 272, 9: 163-198.

This specimen is cut in transverse section and is therefore well suited for the study of the spinal cord. There are 33 spinal ganglia, but at the thirty-third and thirty-second complete nerve-fibers can not be made out. The thirty-third, in particular, comprises such a small cell-group as to be hardly recognizable. There are 37 primitive vertebrae and a non-vertebrated tail portion 289 um long. As in the several specimens immediately preceding it, the few caudal vertebrae are fused together, showing no distinct boundaries. The non-vertebrated tail portion consists still of germinating mesenchymal cells, while the more cranially situated scleromeres are gradually becoming converted into precartilaginous tissue.