title: Alterations in bulk modulus of tracheae during development.
abstract: Tracheal dimensions, pressure-volume relationships, and bulk moduli, K, were determined in excised tracheae at different developmental ages: 21-, 27-1, and 31-day rabbit fetuses; 7-day pups; and adult rabbits 18 +/- 6 months of age. Alterations in tracheal dimensions paralleled the growth of the animal. At low segmental pressures such as 10 cm H2O, the tracheal segments became stiffer with age (K = 20.4 cm H2O for the 21-day fetus to K = 58.0 cm H2O for the adult). However, at segmental pressures greater than 15 cm H2O, the overdistended immature trachea became stiffer than even those of the adults. Developmental alterations in bulk modulus suggest significant changes in the material and mechanical properties of the wirways as a function of both pressure and developmental age.
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001699:Biometry; D004548:Elasticity; D005333:Fetus / Q000033:anatomy & histology / Q000502:physiology; D011312:Pressure; D011817:Rabbits; D014132:Trachea / Q000033:anatomy & histology / Q000254:growth & development* / Q000502:physiology*