Module
8
Icon module 8
Embryonic phase

Synoptic table of the Carnegie stages 20 - 23

Stage 20
Approx. 49th day
18 - 22 mm
media/module8/carnegie/i1_kyotostad20.jpg

  1. Liver prominence
  2. Primordium of the eyelid
  3. Eye
  4. Auditory canal
  5. Elbow
  6. Fingers
  7. Toes being formed
  8. Straightening of the trunk
  9. Subcutaneous vessel network of the head
  10. Cervical flexure

Fig. synopimg20

Characteristic signs

  • Arms in pronation.

  • Separated fingers.

  • Gonadal gender determinable in female embryos.

© Professor Kohei Shiota, Kyoto University

Stage 21
Approx. 51rst day
22 - 24 mm
media/module8/carnegie/i1_kyotostad21.jpg

  1. Umbilical cord with physiologic hernia
  2. Nose
  3. Subcutaneous vessel network of the head
  4. Ear
  5. Elbow
  6. Pronation of the hands (pink arrow)
  7. Knee
  8. Supination of the feet (blue arrow)
  9. Toes

Fig. synopimg21

Characteristic signs

  • Subcutaneous vessel network of the head spreads out.

  • Hands and feet come closer and touch each other.

© Professor Kohei Shiota, Kyoto University

Stage 22
Approx. 53rd day
23 - 28 mm
media/module8/carnegie/i1_kyotostad22.jpg

  1. Umbilical cord with physiologic hernia
  2. Nose
  3. Subcutaneous vessel network of the head
  4. Ear
  5. Elbow
  6. Pronation of the hands
  7. Knee
  8. Supination of the feet
  9. Well-developed toes
  10. Remainder of the embryonic tail

Fig. synopimg22

Characteristic signs

  • Development of the eyelids and the external ear canal.

  • Tragus and antitragus.

  • Nasal septum.

  • Secondary palate.

© Professor Kohei Shiota, Kyoto University

Stage 23
Approx. 56th day
27 - 31 mm
media/module8/carnegie/i1_kyotostad23.jpg

  1. Umbilcal cord with hernia
  2. Nose
  3. Eye
  4. Eyelid
  5. Ear (a: tragus, b: antitragus )
  6. Mouth
  7. Elbow
  8. Finger
  9. Toes
  10. Atrophied embryonic tail bud
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
Spinal cord

Fig. synopimg23

Characteristic signs

  • Angle between the head and trunk amounts to 30°.

  • The head makes 50% of the embryo's size.

  • The head is rounded, the extremities lengthened and stand out from the body.

  • Chin.

  • Nasal pit.

  • Development of the external genital primordium.

© Professor Kohei Shiota, Kyoto University