8 week embryonic heart and lungs

3D Model

Stages of normal human lung development: During the first stage (0-7 weeks, embryonic stage), the lung arises as a ventral diverticulum of the primitive foregut endoderm with the lobar and segmental bronchi appearing at the 5th week and arteries and veins developing as avascular buds. There then follows the pseudoglandular stage (8-17 weeks) when branching of the airways and vessels takes place.

References: 1-Netters atlas of human embryology (Updated Edition). 2-the anatomy of human of embryo electron microscope (1st Edition).