Age-dependent histomorphometric evolution of the corpus spongiosum.

Purpose: To quantify the age-dependent changes in the relative volume of elastic fibers, collagen fibers and the proportion of collagen types I/III in the corpus spongiosum of rats.

Methods: Forty-eight rats, raised under similar conditions, were divided into four groups (G1 to G4) and underwent penectomy at the ages of 6, 9, 12 and 24 months, respectively. Histological sections from the middle segment of the penis were stained with Weigert's resorcin-fuchsin, Masson's trichrome and Picrosirius red, the volumetric density of elastic fibers, collagen fibers and the proportion of collagen types I and III in the corpus spongiosum were determined by stereological analysis.

Results: A reduction in the proportion of collagen I/III between the groups G3 and G4 (p < 0.048) was observed. In the volumetric analysis of elastic fiber, we observed a significant rise between the groups G2 and G3 (p < 0.03) and a reduction of the volume between the groups G3 and G4 (p < 0.01). However, there was no difference in the quantity of total collagen between the groups (p > 0.54).

Conclusions: Aging in rats did not change the quantity of total collagen but reduced the proportion of collagen types I/III and the volume of elastic fibers.