Age-dependent properties and quasi-static strain in the rat sagittal suture.
We measured the morphology of and performed tensile tests on sagittal sutures from rats of postnatal age 2 to 60 days. Using the properties measured ex vivo and a pressure vessel-based analysis, we estimated the quasi-static strain that had existed in the suture in vivo from 2 to 60 days. Sutural thickness, width, and stiffness per length were notable properties found to be age dependent. Sutural thickness increased 4.5-fold (0.11-0.50mm) between 2 and 60 days. Sutural width increased transiently between 2 and 20 days, peaking around 8 days; at 8 days, mean sutural width was 75% larger than mean sutural width at two days (0.35+/-0.07 (SD) vs. 0.20+/-0.06 mm). Sutural stiffness per length increased 4.4-fold (8.77-38.3N/mm/mm) between 2 and 60 days. The quasi-static sutural strain estimated to exist in vivo averaged 270+/-190 muepsilon between 2 and 60 days and was not age dependent. These findings provide data on the age-dependent sutural properties of infant to mature rats and provide the first estimate of quasi-static sutural strain in vivo in the rat. The findings show that during development the rat sagittal suture, as a structure, changes significantly and is exposed to quasi-static tensile strain in vivo due to intracranial pressure.
Henderson
James H
JH
Biomechanical Engineering Division, Mechanical Engineering Department, Stanford University, Stanford, CA 94025-4038, USA. james.henderson@case.edu
Chang
Lillian Y
LY
Song
HanJoon M
HM
Longaker
Michael T
MT
Carter
Dennis R
DR
D000375:Aging / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena; D003393:Cranial Sutures / Q000033:anatomy & histology / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D013718:Tensile Strength