Extracellular matrix remodeling in the human gubernaculum during fetal testicular descent and in cryptorchidic children.

PURPOSE: We evaluated extracellular matrix remodeling in human fetal and cryptorchidic gubernacula.

METHODS

Gubernacula were obtained from 40 normal human fetuses aged 15-29 weeks postconception (WPC) and from 39 children aged 1.3-10 years who had been submitted to orchiopexy. Total collagen and glycosaminoglycan (GAG) concentrations were assessed as μg hydroxyproline and μg hexuronic acid per mg dry gubernacular tissue, respectively, and proportions of sulfated GAG were determined by agarose gel electrophoresis.

RESULTS

Fetal age correlated with collagen (r = 0.77, P < 0.001) and GAG (r = -0.83, P < 0.01) concentrations, which varied from 10 to 50 μg/mg and 7.1-2.5 μg/mg, respectively. Collagen and GAG concentrations in cryptorchidic gubernacula varied from 80.0 to 120.0 μg/mg and from 0.8 to 1.0 μg/mg, respectively. These values did not correlate with patient's age, but when the testis was located more proximally, collagen content was lower. At 15-18 WPC, GAG consisted of 57.3% ± 13.5% chondroitin sulfate and 28.2% ± 10.1% dermatan sulfate, and at 25-28 WPC, 42.7% ± 8.7% and 71.8% ± 11.3%, respectively. GAG in postnatal gubernacula consisted mostly of dermatan sulfate.

CONCLUSIONS

From the 15th to the 29th WPC, the extracellular matrix of the gubernaculum undergoes extensive remodeling and this may contribute to testicular descent. Cryptorchidic gubernacula are markedly more fibrous than the corresponding fetal tissue, change little after birth, and have a lower collagen concentration when the undescended testis is abdominal in position.