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.
Stratified squamous epithelium is found in areas where layers of epithelial cells are likely to be sloughed off. Examples of simple squamous epithelium: 1  Endothelium-lines the circulatory system. 2  Mesothelium-lines the peritoneal (abdominal), pleural (lung) and pericardial (heart) cavites.ogether with an underlying layer of connective tissue, they form mucous membranes. Epithelium may also line the surface of internal organs. An epithelial cells is said to be polarised as either side of the cell differs in terms of structure and function.