Category:Carnegie Embryo 467

From Embryology

This Embryology category includes pages and images that relate to the Carnegie Collection Embryo No. 467. Do not know exact staging, but is before stage 17. This embryo was classified as Carnegie stage 16 occurring in Week 6.

Stage 16 Links: Week 6 | Head | Lecture - Limb | Lecture - Gastrointestinal | Lecture - Head Development | Science Practical - Gastrointestinal | Science Practical - Head | Carnegie Embryos | Category:Carnegie Stage 16 | Week 6 | Next Stage 17
  Historic Papers: 1906 | 1908 | 1948 stages 15-18


thumb|fig. 1 Spaulding MH. The development of the external genitalia in the human embryo. (1921) Contrib. Embryol., Carnegie Inst. Wash. Publ. 81, 13: 69 – 88.

9 mm (fig. 1, plate 1). The earliest stage that I have studied is shown in an embryo 9 mm long. In this specimen the genital tubercle is a very low conical eminence between the umbilical cord and the base of the tail. Its apex is separated from the rest of the tubercle by a pair of converging depressions which unite in the midventral line to form a longitudinal groove extending to the caudal border, giving to the entire groove a Y-shape. Caudal to the arms of the Y and lateral to its stem is a pair of broad, swollen areas. This condition is slightly different from the stage described by Keibel (1896) of the beginning development of the genitalia in a 3-mm. embryo. In his specimen he described the cloacal tubercle as consisting of a pair of eminences separated by the cloacal membrane. The difference between the stage described by Keibel and my first stage may be accounted for entirely by the difference in the size of the two specimens.

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