Category:Carnegie Embryo 211

This Embryology category shows pages and images that relate to the Carnegie Collection Embryo No. 449. This embryo would be early fetal development Week 9 based upon the CRL 33 mm.

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. 211, 33 mm Crown-Rump Length

Embryo No. 211 has 34 vertebra and 31 spinal ganglia. The vertebral column curves ventrally at the thirty-first and thirty-second vertebra. The caudal end of the chorda dorsalis is undergoing regression and appears to be branching. The caudal end of the spinal cord may be divided into three portions: (1) the primordiinn of the conus medullaris, which includes the primordium of the ventriculus terminalis; (2) the filum terminale; (3) the coccygeal medullary vestige. The first extends about the length of the thirtieth and thirty-first vertebrae, tapering gradually towards its caudal end. The ventriculus terminalis, which is included in the conus medullaris, expands in the medial part dorsoventrally and transversely. The upper part of this cavity, which marks the entrance of the central canal, narrows slightly; the caudal end narrows sharply and forms a canal which terminates blindly at the end of the conus medullaris. The wall of the ventriculus terminalis consists of gray and white substance and the cavity is lined with a layer of ependymal cells. The dorsal wall is thicker than the ventral wall. The filum terminale extends from the caudal end of the conus medullaris, wathout definite boundaries, to a level between the thirty-second and thirty-third vertebrae. Its caudal end is represented by a slender bundle of nerve-fibers, and in its cranial portion there is a strand of ependymal cells. The large coccygeal medullary vestige is situated dorsal to the thirty-third and thirty-fourth vertebrae and its wall is thrown into a number of folds. At the caudal end it has two processes, one extending ventrally, the other dorsally. The latter enters into a rounded eminence at the caudal end of the embryo which represents a tail-bud, termed by Unger and Brugsch caudal tuberck. The post-anal swelling is well developed, while the coccygeal tubercle is scarcely to be made out.

Cite this page: Hill, M.A. (2026, October 2) Embryology Carnegie Embryo 211. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Category:Carnegie_Embryo_211

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© Dr Mark Hill 2026, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G