Carnegie stages

Carnegie Stages refer to a standardized system of 23 stages used to provide a unified developmental chronology of the embryo. The stages are based on the external and/or internal morphological development of the embryo, and not on the size or the number of days of development. The system was first introduced by George Linius Streeter and is named after the Carnegie Institution of Washington where Streeter worked.

Etymology[edit | edit source]

The term "Carnegie Stages" is derived from the Carnegie Institution of Washington, where the system was first developed. The institution itself is named after Andrew Carnegie, a Scottish-American industrialist and philanthropist.

Development of the Stages[edit | edit source]

The Carnegie Stages were developed by George Linius Streeter, an American anatomist and embryologist. Streeter was interested in the development of the human embryo and sought to create a system that would standardize the stages of embryonic development. The stages are based on the morphological characteristics of the embryo, rather than the number of days since fertilization, which can vary. This makes the Carnegie Stages a more accurate and reliable system for embryonic development.

Stages[edit | edit source]

The Carnegie Stages consist of 23 stages, each representing a specific phase in the development of the human embryo. The stages are as follows:

Stage 1: Fertilization
Stage 2: Beginning of the first cell division
Stage 3: Morula
Stage 4: Blastocyst
Stage 5: Implantation
Stage 6: Formation of the primitive streak
Stage 7: Gastrulation
Stage 8: Neurolation
Stage 9: Formation of the somites
Stage 10: Formation of the neural tube
Stage 11: Formation of the foregut and hindgut
Stage 12: Formation of the heart tube
Stage 13: Formation of the pharyngeal arches
Stage 14: Formation of the limb buds
Stage 15: Formation of the liver bud
Stage 16: Formation of the kidney bud
Stage 17: Formation of the eye and ear buds
Stage 18: Formation of the nasal pit
Stage 19: Formation of the lung buds
Stage 20: Formation of the genital tubercle
Stage 21: Formation of the digits
Stage 22: Formation of the external ear
Stage 23: Completion of organogenesis

Related Terms[edit | edit source]

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