title: Effects of maturation and aging on the pressure-bearing region of the plantaris longus tendon of the bullfrog (Lithobates catesbeianus).
abstract: The plantaris longus tendon (PLT) in bullfrog develops a fibrocartilage-like tissue in the area that is functionally subject to compressive forces. The aim of this study was to analyze the modifications of the pressure-bearing region in bullfrog PLT with different ages (7, 180, and 1,080 days after the end of metamorphosis) using histomorphometric, ultrastructural and biochemical methods. Weak basophilia and cells with a fibroblastic phenotype were observed in the compression region at 7 days of age. On the other hand, a large area of intense tissue basophilia associated with a chondroblast-like cell population was noted at the other ages. Collagen fibers exhibited a three-dimensional network-like arrangement at all ages. The number of connective tissue cells increased between 7 and 180 days of age and was reduced in older animals. The 180-day-old animals presented a well-developed pericellular matrix rich in proteoglycans. The mean diameter of collagen fibrils increased from 7 to 180 days and was the same at 1,080 days. Glycosaminoglycan content was higher in 7-day-old animals. A higher amount of hydroxyproline was observed at 180 and 1,080 days. The swelling test showed a significant increase of wet weight in 7-day-old animals. In conclusion, the alterations that occur in the pressure-bearing of bullfrog PLT are the result of physiological alterations of the animal with the maturation and aging.
authors.affiliation: Programa de Pós-graduação em Ciências Biomédicas, Centro Universitário Hermínio Ometto, Av. Dr. Maximiliano Baruto, 500 Jd. Universitário, 13607-339, Araras, SP, Brazil.
authors.forename: Valdenilson José
authors.initials: VJ
authors.lastname: Zorel
authors.forename: Jymenez
authors.initials: J
authors.lastname: De Morais
authors.forename: Andrea Aparecida
authors.initials: AA
authors.lastname: de Aro
authors.forename: Laurecir
authors.initials: L
authors.lastname: Gomes
authors.forename: Marcelo Augusto Marretto
authors.initials: MA
authors.lastname: Esquisatto
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D006025:Glycosaminoglycans / Q000032:analysis; D006909:Hydroxyproline / Q000032:analysis; D008853:Microscopy; D046529:Microscopy, Electron, Transmission; D011892:Rana catesbeiana / Q000033:anatomy & histology / Q000502:physiology*; D013710:Tendons / Q000737:chemistry / Q000502:physiology / Q000648:ultrastructure*; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D006025:Glycosaminoglycans; D006909:Hydroxyproline
keywords: aging; collagen fibers; extracellular matrix; glycosaminoglycans