Talk:Carnegie stage 7

From Embryology

Sathananthan H, Selvaraj K & Clark J. (2011). The fine structure of human germ layers in vivo: clues to the early differentiation of embryonic stem cells in vitro. Reprod. Biomed. Online , 23, 227-33. PMID: 21665543 DOI.

The fine structure of human germ layers in vivo: clues to the early differentiation of embryonic stem cells in vitro

Abstract The fine structure of the three germ layers in human ectopic embryos (stage 7) have been documented by digital light and electron microscopy. The formation of ectoderm, endoderm and mesoderm and notochordal cells, and also the extraembryonic membranes, amnion and yolk sac, are imaged. The germ layers give rise to all the cells and tissues of the human body. Possible clues to the early differentiation of embryonic stem cells (ESC) in vitro were obtained, since these events are more or less mimicked in cultures of ESC derived from the inner cell mass of human blastocysts. The findings are discussed with reference to previous studies on the fine structure of ESC using the same technique. Copyright © 2011. Published by Elsevier Ltd.

PMID: 21665543 DOI: 10.1016/j.rbmo.2011.05.004

Carnegie Collection

7802 8206 8361 8602 8752 8756 9217

--Mark Hill 13:21, 22 August 2009 (EST) Updating carnegie stage pages with different format and new sets of images.

  • Now several different image sources for early (7-14) human embryos.
  • Initially will include the unlabelled versions of most images and will add links to labelled versions later.
  • I am still working on page format and general image layout.

UNSW Embryology Links

Image Terminology

  • BF - bright field image
  • SEM - scanning electron micrograph image
  • 1, 2, 3, 4 .... numbering reflects different images available.
  • a, b, c .... lettering reflects different version sizes available.
    • Generally: no letter = 1000px, a = 800px, b = 600px, c = 400px
  • all images have more detailed descriptions when opened individually.

(listed in order of length of notochordal process)

HEB-37. Summarized by Mazanec (1959). Chorionic cav- ity, 2.25 x 1.29 x 0.4 mm. Embryonic disc, 0.4 mm. Primitive streak, 0.104 mm, and node, 0.04 mm. Notochordal process, 0.032 mm. Stalk of umbilical vesicle (ibid., fig. 77). Median projection published (ibid., fig. 45).

//. R. 1. Described by Johnston (1940), who believed that a notochordal process (0.04 mm) and a prechordal plate (0.075 mm) were present. Florian in an appendix to the recorded in Streeter's horizon VII.

Goodwin. Described by Kindred (1933). Tubal. Chorion, 5.8 x 2.72 x 2.25 mm. Chorionic cavity, 2.44 x 2.25 x 0.75 mm. Embryonic disc, 0.588 mm in width. Primitive streak, 0.215 mm, and node, 0.078 mm. Notochordal process, 0.078 mm. No notochordal canal and no prechordal plate.

Pha I. Described by Mazanec (1949). Chorionic cavity, 7.872 x 5.475 x 2.032 mm. Embryonic disc, 0.66 x 0.52 mm. Primitive streak, 0.145 mm, and node, 0.06 mm. Notochordal process, 0.09 mm. No prechordal plate. Median projection published {ibid., fig. 51).
H. Schm. 10 (H. Schmid). Described briefly by Grosser (1931c). Embryonic disc (almost circular), 0.51 x 0.58 mm. Primitive streak, 0.14 mm, and node, 0.1 mm. Notochordal process, 0.1 mm. Probably belongs to stage 7, although a cavity in one section was thought to represent "Lieberkuhn's canal."

Bi24 (Bittmann). Described by Hill and Florian (1931b). Chorionic cavity, 3.05 x 3.036 x 3.029 mm. Embryonic disc (narrow type), 0.62 x 0.39 mm. Primitive streak, 0.28 mm, and node (Mazanec, 1959, fig. 105), 0.05 mm. Notochordal process, 0.105 mm, consists of median chord and lateral mesoblastic wings. Prechordal plate, 0.03 mm. Possible primordial germ cells in endoderm of region of cloacal membrane and in endoderm of umbilical vesicle caudally (Florian, 1931)- Politzer (1933) counted 41 germ cells in the region of the allanto-enteric diverticulum in this embryo, and 19 such cells in another presomite specimen (Bi 25). Dorsal and median projections published (Hill and Florian, 1931b, figs. 4 and 12; Florian, 1945, plate 5, fig. 43; Mazanec, 1959, fig. 50).

Manchester No. 1285 (fig. 7-1). Described by Florian and Hill (1935). Hysterectomy. Chorionic cavity, 4.28 x 3.28 mm. Embryonic disc (narrow type), 0.87 x 0.625 mm. Primitive streak, 0.39 mm, and node, 0.05 mm. Notochordal process, 0.125 mm. Prechordal plate, 0.03 mm. Connecting stalk at- tached to chorion at decidua capsularis (suggesting polar variety of velamentous insertion of umbilical cord). Dorsal and median projections published (Hill and Florian, 1931b, figs. 5 and 13; Florian and Hill, 1935, figs. 1-3; Mazanec, 1959, fig- 52). Specimen is housed in Department of Anatomy, University of Manchester.

Pha II. Summarized by Mazanec (1959). Chorionic cavity, 4.985 x 3.882 x 3.52 mm. Embryonic disc, 0.895 x 0.62 mm. Primitive streak, 0.37 mm, and node, 0.06 mm. Notochordal process, 0.13 mm. No prechordal plate. Median projection published (ibid., fig. 53) Thompson and Brash (1923) described a specimen that showed a notochordal process of 0.3 mm. It is described in the present work under stage 8.


Precise measurements of the notochordal process have not been provided in the accounts of die following embryos. The specimens are listed in order of year of publication. Debeyre (1912) described in detail a specimen that pos- sessed a chorionic cavity of 5.6 x 2.1 mm. Embryonic disc, 0.9 x 0.6 x 0.95 mm. Primitive streak stated to be 0.54 mm in length. Chorionic villi (0.4-1.6 mm) showed some branch- ing. Unsuitable plane of section makes it impossible to assess the specimen precisely.

Carnegie No. 1399

  • Mateer. Described by Streeter (1920). Hysterectomy. Angiogenesis in villi described by Hertig (1935). Chorion, 9 X 8 X 3.5 mm. Chorionic cavity, 6.1 x 5.6 x 2.5 mm. Embryonic disc, 1 x 0.75 mm. Primitive streak and groove present. Although the notochordal process was originally thought probably to be absent, Hill and Florian (1931b) have no doubt that it is present. More advanced than Hugo (Florian and Volker, 1929). A very small twin embryo was originally described but that "interpretation has become open to doubt" (Corner, 1955). Drawing of every section reproduced by Turner (1920). A median drawing (Davis, 1927, fig. 5A) and a projection have been published (Mazanec, 1959, fig. 56).

Ho (Hodiesne). Described by Fahrenholz (1927). Abor- tion. Chorionic cavity, 6.5 x 6 x 3 mm. Embryonic disc (deformed), 0.6 mm (0.725 mm by flexible scale). Primitive streak, 0.22 mm (0.345 mm by flexible scale). Notochordal process just beginning ("undoubtedly present," Hill and Florian, 1931b). Possible prechordal plate claimed (disputed by Waldeyer, 1929a, but supported by Hill and Florian, 1963). "Lieberkuhn's canal" (0.065 mm) is an artificial folding of the embryonic disc (Hill and Florian, 1931b). Dorsal and median projections published (Fahrenholz, 1927, figs. 32, 6 and 7; Mazanec, 1959, fig. 54). Debeyre (1933) described a specimen (0.9 mm) that possessed a primitive streak and probably belonged to stage 6 or stage 7. Large cells near the opening of the aliantois were identified as primordial germ cells.

Falkiner. Described by Martin and Falkiner (1938). Curettage. Embryo damaged and not in good condition. Measurements seem too small (see Mazanec, 1959). Chorionic cavity, 1.5 x 1.4 mm. Embryonic disc, 0.15 x 0.29 mm. Primitive streak, 0.07 mm. Notochordal process contains "no definite lumen." Cells rostral to notochordal process are "probably" the prechordal plate. Development "agrees most closely" with that of Bi I. Median projection published (Martin and Falkiner, 1938, fig. 8; Mazanec, 1959, fig. 39).

Gar (Green-Armytage). Described by West (1952). Hys- terectomy. Chorionic cavity, 3 x 2.6 x 2 mm. Embryonic disc (broad type), 0.56 x 0.69 mm. Primitive streak, node, and groove present. Short notochordal process. No noto- chordal plate. Said to resemble Hugo embryo. Trophoblast described by Hamilton and Boyd (I960).

7kfo/(Maliphant). Described by West (1952). Hysterectomy. Chorionic cavity, 3 x 1.8 mm. Embryonic disc (broad type), 0.45 x 0.6 mm. Primitive streak, node, and groove present. Notochordal process present (Mazanec, 1959); small cavity in node (West, 1952) or in notochordal process (Mazanec, 1959) "hardly sufficient to warrant the name chorda canal." No prechordal plate. Belongs either to stage 7 or to stage 8 (said to resemble Jones-Brewer I, which is in stage 8).

Carnegie No. 8602

  • Photomicrograph reproduced by Hertig, Rock, and Adams (1956, plate 10, fig. 53).
  • Chorion, 2.73 x 2.43 mm. Chorionic cavity, 1.83 x 1.33 mm. Embryonic disc, 0.3 x 0.06 mm.
  • Presumed age, 16-17 days.

Missen. Trophoblast described by Hamilton and Boyd (I960). Curettage. Chorion, 1.66 x 1.43 mm. Embryonic disc, 0.28 x 0.214 mm. Primitive streak and node. Notochordal process. Said to resemble No. 7801 and Edwards-Jones-Brewer (stage 6).

  • Presumed age, about 14 days.

Certain other embryos that probably belong to stage 7 but that have not been described in detail will not be referred to here. These include Fitzgerald, Fitzgerald-Brewer II, and Jones-Brewer II (Brewer and Fitzgerald, 1937).