A dominant gene will always be expressed when present, such as in the homozygous dominant genotype (RR), or heterozygous genotype (Rr). A recessive allele is only expressed wh â¦ en the genotype is homozygous recessive (rr).
(Lung alveoli, in contrast, are lined by very thin simple squamous epithelium .). Pseudostratified respiratory epithelium consists primarily of columnar ciliated cells. Ciliary beating sweeps mucus and the dust it carries up the bronchi and trachea toward the pharynx, where it can be swallowed.
This is a low power view of the trachea. The luminal surface of this organ is covered with a ciliated, pseudostratified columnar epithelium. This medium power view of the tracheal epithelium reveals its pseudostratified columnar architecture. Nuclei are seen at different levels within the epithelium giving the appearance of a stratified epithelium.