Effectiveness of ultrasound as a contraceptive
in non-human primates
T.L. Tollner and C.A. VandeVoort
California National Primate Research Center and Dept. of Obstetrics and Gynecology
University of California, Davis
INTRODUCTION
RESULTS
Because of the loss of productivity and the personal and societal toll taken by surgery,
surgical complications, and the cost of anesthesia, a great need continues to exist for
nonsurgical methods of fertility control that are satisfactory, affordable, and
consistently available to users. In particular, new methods for male contraception are
needed because currently the only options for men are condoms (which have a high
misuse rate and are subject to supply disruptions in low-income countries) and
vasectomy (which is surgical and generally permanent).
Both surgery and
sterilization are psychological barriers for many men. We therefore seek to develop
impermanent, non-surgical methods of contraception for males. Owing to their
efficiency and cost-effectiveness, non-surgical, non-invasive methods are also sought
for control of feral and street populations of animals such as dogs, cats, and
monkeys.
Graph 1
Prof. M.S.Fahim at the University of Missouri demonstrated that brief applications of
testicular ultrasound waves were effective at reducing or eliminating sperm in rats,
cats, dogs, rabbits, monkeys, and man(1-5) . Prof. Fahim passed away in 1995 and this
research was not further pursued. We wish to replicate Dr. Fahim’s work in monkeys
to determine whether the effect can be confirmed in an independent laboratory with a
method that could be applied in men.
Semen Evaluation Results
Graph 2 Individual Total Normal Sperm Counts
Image 1 Semen pre- and post-ultrasound treatment
METHODS
Animals: 4 adult rhesus (Macaca mulatta) males (6-15 yrs, BW 10-15 kg)
Testicle size measurements collected and volume calculated.
Ultrasound exposure: 2.5W/cm-2 for 30m for all males, 3 times, every other day on a
Monday, Wednesday, Friday schedule.
Two methods of Ultrasound Application:
1) Cup method (N=2): Animal’s scrotum positioned in the cup and sound waves
emitted from the transducer at the base of the cup through a media solution of 3%
NaCl before radiating the testes.
2) Direct method (N=2): Application of the probe directly to the scrotum surface.
Semen collection: Male monkeys are
trained to chair restraint for electroejaculation, performed using defibrillation gel penile electrodes, with no
anesthesia (6).
Semen Evaluation: Semen quality was
evaluated a minimum of three times
over two months prior to ultrasound
exposure and weekly for 9 weeks
following exposure.
PHYSIOMED Elecktromedizin AG, model: Vetri-son portable unit(Schnaittach, Germany)
•  Evaluated for volume, sperm density, percentage of motile sperm, and total
numbers of sperm according to the WHO ’87 methods.
•  Sperm morphology: washed sperm samples from each male were layered onto
glass slides, dried, and stained using the method of Papanicolaou. Two hundred
sperm per male per treatment were scored for various categories of abnormal forms
according to Tollner et al. (7)
•  Computer assisted sperm analysis (CASA): Sperm were washed by centrifugation
in modified BWW medium with 0.3% BSA (mBWW) and resuspended into mBWW
for videomicrography as performed by Tollner et al. (8)
• Motion characteristics of the recorded sperm were analyzed using the HTM Ceros,
version 10.9d (Hamilton Thorne Biosciences, Inc.).
• At least 200 sperm per semen sample were analyzed for curvilinear velocity
(VCL), straight-line velocity (VSL), and amplitude of lateral head displacement
(ALH).
Table 1 Cup Direct
Animal
1
2
3
4
Ave. Testicle
% Inhibition* Volume (mm3) of TSC
2.0 x 105
95.3%
3.0 x 105
76.10%
2.9 x 105
No Inhibition
1.4 x 105
35.4%
* TSC (Total Sperm Count) averaged across five pre-treatment SEs divided by
TSC average across first five SEs following US treatment x 100.
The following trends were consistent across males following ultrasound treatment.
Cup Method...
•  Suppresses total sperm count for 7-8 weeks with a maximal average inhibition of
sperm numbers of 93%.
•  Results in transient reduction of % motility.
•  Reduces both VCL and ALH, measures of sperm vigor.
Both Methods...
•  Increase the number of sperm with tail defects
•  Reduce sample-to-sample variability in the total number of normally shaped sperm.
•  Result in a recovery in semen quality in weeks to months following ultrasound
treatment.
•  Produce no detectable undesirable side effects.
DISCUSSION
The cup method, a modification of methods used successfully in rats and dogs to
suppress spermatogenesis, results in reduction of semen quality in adult rhesus
monkeys. Unlike in other animal models, treatment did not induce azoospermia, yet
the numbers of sperm that were vigorously motile and with normal morphology were
exceedingly low. Within exposure method, ultrasound treatment appeared to be most
effective for males with smaller testes suggesting that higher levels of exposure may
be required to achieve contraception in individuals and animals with greater testicular
mass.
CONCLUSION
We confirm in a non-human primate species with testicles that compare in size with
those of men that ultrasound treatment results in reduced sperm numbers and quality.
This preliminary study provides a proof of principle that testicular ultrasound exposure
has the potential to be a viable approach for contraception in humans.
REFERENCES
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8.
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Dumontier, A, Burdick, A, Ewigman, B, et al. (1977). Effects of sonication on mature rat testes. Fertility and sterility, 28(2), 195-204.
Fahim, M S, Fahim, Z, & Azzazi, F. (1978). Effect of ultrasound on testicular electrolytes (sodium and potassium). Archives of andrology, 1(2), 179-84.
Fahim, M S, Fahim, Z, Der, R, et al. (1975). Heat in male contraception (hot water 60 degrees C, infrared, microwave, and ultrasound). Contraception, 11(5), 549-62.
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Sarason, R.L., C.A. VandeVoort, D.R. Mader, and J.W. Overstreet. 1991 Electro-ejaculation by direct penile stimulation of restrained but unanesthetized macaques. J. Med. Primatol. 20:122-125.
Tollner TL, Dong Q, VandeVoort CA. (2011). Frozen-thawed rhesus sperm retain normal morphology and highly progressive motility but exhibit sharply reduced efficiency in penetrating cervical mucus and hyualuronic acid gel. Cryobiology 62:15-21.
Tollner TL, Yudin AI, Treece CA, Overstreet JW, Cherr GN. (2008). Macaque sperm coating protein DEFB126 facilitates sperm penetration of cervical mucus. Human Reprod. 23:2523-34.
Acknowledgements:
This study was supported by a grant from
the Parsemus Foundation