1

Development of organs – general embriology

Elongation of the blastocyst

Primitive streak and primitive node

(stria primitiva, nodus primitivus)

Lamina neuralis (with blue) and

the sulcus neuralis.

On both sides of sulcus neuralis

somites start to develop.

2

su: diffuse, epitheliochorial

ca: zonaria, endotheliochorial

eq: diffuse, epitheliochorial

ru: cotyledonaria (multiplex),

synepitheliochorial

ho: discoidea, hemochorial

Types of placenta

Fetal cotyledon + maternal caruncula = placentome

3

4

Bending of the embryo and formation of somites Early differentiation of mesoderm

and closure of neural folds

Single mesoderm and chorda dorsalis

Paraxial mesoderm and lateral plate mesoderm

Separation of lateral plate mesoderm

Intermedier mesoderm (in the middle),

somatopleura (next to ectoderm),

and splanchnopleura (next to entoderm).

Differentiation of entoderm,

early entodermal structures

5

Latero-lateral folding of the embryo

Cranio-caudal folding of the embryo

Colors:

- blue: ectoderm

- red: mesoderm

- yellow: entoderm

Videos about folding:

- https://www.youtube.com/watch?v=qMnpxP6EeIY

- http://www.indiana.edu/~anat550/genanim/latfold/latfold.swf

6

Development of body cavities

canalis

pleuroperitonealis

Common thoracic and abdominal cavity

Adhesion of plica pleuropericardiales

/n. phrenicus (with black) and v. cardinalis

communis (with pink) are embedded into to fold/

Formation of diaphragm: septum transversum (ventrally, orange), pleuroperitoneal folds (from both sides, blue),

mesenterium dorsale (in the midline), and mesodermal-derived muscle-cell ingrowth (circularly, red)

The entodermal-derived

lungs gradually grow into

the thoracic cavity