8.1 The Carnegie stages

Synoptic table of the Carnegie stages 11 - 13

Stage 11

Approx. 29th day

2.5 - 4.5 mm

`1 2 3`	`Neural tube Caudal neuropore Rostral neuropore that is just closing`

`4 5 6`	`Somites 2. pharyngeal arch 1. pharyngeal arch`

Characteristic signs:
Closure of the rostral neuropore Nasal placode Ophthalmic vesicle Auditory pit 13 – 20 somites

Stage 12

Approx. 30th day

3 - 5 mm

`1a 1b` `2 3 4 5 6`	`Maxillar process Mandibular process Second pharyngeal arch Third pharyngeal arch Somites Neural tube Heart`

`P M R`	`Prosencephalon (forebrain) Mesencephalon (midbrain) Rhombencephalon (hindbrain)`

Characteristic signs:Closure of the caudal neuropore Third pharyngeal arch Buds of the upper extremities Cervical sinus 21–29 somites

Stage 13

Approx. 32th day

4 - 6 mm

1a 1b 2 3 4 5 6 7 8 9 10 Maxillary process Mandibular process Second pharyngeal arch Third pharyngeal arch Fourth pharyngeal arch Somites Buds of the upper extremities Left cardiac ventricle Left cardiac atrium Body stalk Embryonic tail

Characteristic signs:Buds of the lower extremities Lens placode Auditory pit Fourth pharyngeal arch More than 30 somites

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