This study evaluated the mechanical properties (Young's moduli, ultimate stress, ultimate strain) and histological composition (collagen, elastin, smooth/skeletal muscle, adipose) of the perineal body in postmenopausal ewes 280 days after ovariectomy — comparing 8 ewes with delayed estrogen replacement therapy (ERT, initiated at day 180 post-ovariectomy for 100 days) versus 7 ewes without ERT.
Mechanical properties did not differ significantly between groups (E0: 28 vs. 25 kPa; E1: 0.38 vs. 0.33 MPa; ultimate stress: 0.23 vs. 0.23 MPa; ultimate strain: 0.94 vs. 0.90). Delayed ERT was associated with higher collagen (33% vs. 23%, p<0.001) and elastin (6% vs. 5%, p<0.01) content, but these histological changes did not translate into measurable biomechanical reinforcement.
- Small sample size (n=15 ewes total) with no correction for multiple comparisons, limiting detection of small but clinically relevant effects. - Histology measured volume fractions only; fiber orientation, collagen crimp, crosslinking, and elastin integrity — key determinants of tensile behavior — were not assessed. - ERT was initiated late (180 days post-ovariectomy) and for a short duration (100 days), which may have blunted potential restorative effects.
Delayed estrogen therapy modestly increases perineal collagen and elastin but does not restore mechanical strength — suggesting early initiation of ERT may be more important for preserving pelvic floor tissue integrity. The quantitative mechanical and structural data from this ovine model (which closely mirrors human postmenopausal perineal tissue) can serve as input parameters for finite element models of pelvic organ prolapse.
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