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.
Respiratory System. #5 Trachea. Sections of the trachea are shown and the esophagus may be included. Note the hyaline cartilage in the wall of the trachea and the lining of pseudostratified ciliated columnar epithelium. Cilia are clearly seen in some areas but goblet cells may not be obvious. Exocrine glands are found beneath the epithelium. Lymph nodes and diffuse, sub-epithelial lymphatic tissue are seen.