Pseudoglandular period of developing lung (human, embryo, low magnification)

Stain: Trichrome (Goldner). Cross-sectioned future bronchial tubes (1) of varying sizes. Note the apical position of the nuclei in these epithelial cells with light-stained basal parts (glycogen). The surrounding mesenchyme becomes more condensed (↓) around the epithelium and in between numerous small blood vessels (*) are present. The future visceral pleura (2) and the pleural cavity (X) filled with red blood cells (3) are indicated (artifactual due to preparation procedures).