BACKGROUND AND OBJECTIVES: Detailed information on how an epithelial differentiation and elastic structures occurred in the developing eustachian tube would be helpful in understanding both normal physiology and pathology of the tubotympanum. This study was undertaken to establish elastic structures such as cartilage, elastic fiber, and collagen fiber in the embryonic mouse eustachian tube at a stage when epithelial differentiation is taking place. MATERIALS AND METHOD: Thirty four mice (BALB/c mouse), aged from gestational day 11 to postnatal day 21, were investigated using Verhoeff stain, Masson trichrome stain and alpha-1 antitrypsin immunohistochemistry. RESULTS: The cartilage-like structures were first found after birth, however, matured cartilages appeared at postnatal day 7. The elastic fibers and collagen fibers surrounding cartilage were abundantly found about 5 days after birth. alpha-1 antitrypsin, which is an strong inhibitor of elastase, began to be immunolabelled at gestational day 16. Its expression has been significantly increased after birth. CONCLUSION: Although the epithelial differentiation and maturation in eustachian tube occured at late embryonal stage, the elastic structures have developed and matured after birth. These findings might be a explanation to why young children are highly susceptible to otitis media.
Animals ; Cartilage ; Child ; Collagen ; Elastic Cartilage ; Elastic Tissue ; Elasticity ; Eustachian Tube* ; Humans ; Immunohistochemistry ; Mice ; Otitis Media ; Pancreatic Elastase ; Parturition ; Pathology ; Physiology

OBJECTIVE: To explore the postmortem changes of biomechanical properties of underwater corpses and value for estimating postmortem interval. METHODS: SD rats were sacrificed by cervical vertebra dislocation and stored in the water at constant temperature. The vessel wall, skin, muscle, small intestine and colon were sampled at different postmortem time points (0h, 6h, 12h, 18h, 24h, 30h, 36h, 42h, 48h, 60h, 72h, 96h, 120h, 144h, 168h, 192h). The biomechanics properties of different soft tissues including ultimate load, strain, maximum stress were measured by electronic universal material testing machine. RESULTS: Except for the vessel wall, the biomechanics properties of skin, muscle, small intestine and colon showed linear decrease gradually after death. Each tissue displayed its obvious "window period" for PMI estimation. CONCLUSION The time-sequential changes of biomechanical property parameters of soft tissue in underwater corpses are significantly correlated with PMI and it could be a simple and quantitive new technology for estimating PMI. The specific heat capacity of the heat-eliminating medium around the corpses probably is one of the physical factors to influence algor mortis, autolysis, putrefaction and biomechanics properties.
Animals ; Biomechanical Phenomena ; Cadaver ; Elastic Tissue/physiology* ; Forensic Pathology/methods* ; Intestines ; Male ; Muscles ; Postmortem Changes ; Rats ; Rats, Sprague-Dawley ; Skin ; Stress, Mechanical ; Time Factors ; Weight-Bearing