Embryologie und Wirbelsäule – Teil 2

The precursors of the components of the vertebral column arise initially from different cellular condensations of axial mesenchyme. This relates to a biodynamic metabolic field called a densation field, which is characterised by fluid loss and small, closely packed cells with a rather spherical shape. The neural tube, which is the main formative apparatus of the entire embryo, grows preferentially longitudinally and arches dorsally away from the aorta. One consequence of this expansion is the development of buckling in the notochord. Intervertebral discs or vertebral bodies arise according to whether the notochord is pulled dorsally or not.

Intervertebral discs and vertebral bodies arise medially between the dorsal rami of the dorsal aorta, whereas vertebral arches and ribs arise laterally between the craniocaudally arranged trunks of the neurovascular conduction pathways.

Cartilaginous skeletal structures arise in a  so-called contusion field. This denotes a metabolic field in which the more spherical cells of the former densation field are flattened into a disc shape.

As these cells have an increasingly high osmotic pressure, they absorb water from their surroundings and begin to swell (with a now enlarged cross-section). This swelling growth leads to a piston-like function of the growing cartilage in a so-called distusion field.