Preclinical evaluation for noninvasive reversal following long-term vas occlusion with styrene maleic anhydride in langur monkeys

Nirmal K. Lohiya, Boomi Manivannan, Pradyumma K. Mishra, Seshadri Sriram, Satish S. Bhande, Subbarayalu Panneerdoss

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


A preclinical evaluation for reversal through a noninvasive approach following long-term vas occlusion with styrene maleic anhydride (SMA) has been attempted in langur monkeys at the level of semen parameters, sperm functional tests, semen biochemistry, histology and ultrastructure of reproductive organs, hematology and serum clinical biochemistry including antisperm antibodies (ASA), prostate-specific antigen (PSA) and testosterone. Noninvasive reversal through palpation, percutaneous squeezing and electrical stimulation, forced vibratory movements and suprapubic percussion in the inguinal segments and per-rectal digital massage was attempted in seven langur monkeys after 540 days following vas occlusion. The results revealed instant azoospermia reversal on the same day of reversal with impaired sperm quality, which showed gradual improvement and normospermia with normal motility and viability after 60-90 days of reversal. Sperm functional tests, including ultrastructure of spermatozoa, indicative of sterility in the initial ejaculations, reached normalcy after 90-120 days of reversal. The seminal plasma biochemistry indicative of obstructive azoospermia regained a normal pattern after 90-120 days of reversal. The morphology of testes that showed focal degeneration during 540 days of vas occlusion and that of vasa deferentia that showed exfoliation of epithelial cells resumed to normal morphology comparable with control animals after 150 days of reversal. The morphology of the epididymis, seminal vesicle and prostate did not show appreciable changes following vas occlusion and after noninvasive reversal compared with those of control animals. Hematology, serum clinical chemistry, ASA, PSA and testosterone fluctuated within control limits, indicating safety of the procedure at the level of accessory reproductive organs. The results suggest that noninvasive reversal is feasible even after long-term vas occlusion with SMA and is safe without adverse side effects.

Original languageEnglish (US)
Pages (from-to)214-226
Number of pages13
Issue number3
StatePublished - Mar 2005
Externally publishedYes


  • Langur monkeys
  • Male contraception
  • Noninvasive reversal
  • Spermatogenesis
  • Styrene maleic anhydride
  • Vas occlusion

ASJC Scopus subject areas

  • Obstetrics and Gynecology
  • Reproductive Medicine


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