Studying nonobstructive azoospermia in cystinosis: histologic examination of testes and epididymis and sperm analysis in a Ctns−/− mouse model

Capsule:
Male cystinosis patients are infertile. Male Ctns-/- mice (cystinosis mouse model) showed normal fertility compared with wild-type mice (measured by litter size). Also, histology of testes and epididymis as well as sperm analysis were similar in both groups.

Authors:
Martine T.P. Besouw, M.D., Ans M.M. van Pelt, Ph.D., Héloïse P. Gaide Chevronnay, Ph.D., Pierre J. Courtoy, M.D., Ph.D., Anna Pastore, Ph.D., Ellen Goossens, Ph.D., Olivier Devuyst, M.D., Ph.D., Corinne Antignac, M.D., Ph.D., Elena N. Levtchenko, M.D., Ph.D.
Volume 98, Issue 1 , Pages 162-165, July 2012

Objective:
To study the pathogenesis of male infertility in cystinosis due to nonobstructive azoospermia, using a Ctns−/− mouse model.

Design:
Observational case-control study.

Setting:
Academic research laboratory.

Animal(s):
Male C57BL/6 Ctns−/− mice were compared with C57BL/6 wild-type (wt) mice.

Intervention(s):
None.

Main Outcome Measure(s):
Fertility was studied using litter size (n = 3 vs. n = 2). After animals were sacrificed, testes, epididymis, and vas deferens were removed for testicular cystine measurements (n = 5 vs. n = 6), histologic studies (n = 3 vs. n = 3), and sperm analysis (n = 3 vs. n = 3).

Result(s):
Mean testicular cystine content was significantly higher in Ctns−/− mice compared with wt mice (26.6 ± 1.22 vs. 0.1 ± 0.01 nmol cystine/mg protein). Testes of Ctns−/− mice had lower weight compared with wt mice (0.096 ± 0.009 g vs. 0.112 ± 0.004 g), but mice fertility was similar (litter size 6.6 ± 1.4 vs. 6.3 ± 2.6 pups). Neither histologic nor sperm abnormalities were found.

Conclusion(s):
The Ctns−/− mouse model generated on C57BL/6 background is not suitable for clarifying the pathogenesis of male infertility in cystinosis. The etiology of nonobstructive azoospermia in these patients remains unclear.

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