For fertilization to occur, the male must ejaculate sperm inside the woman's vagina during sex (of course, insemination can occur without intercourse through "artificial" means). There are many things (intentional and unintentional) that can interrupt or prevent the processes of fertilization and embryo-development from occurring. This Web Site as a whole focuses on oral means of interruption of these processes. This section of the Web Site focuses of the interruptions of this process in relation to the male. Above and throughout are links to related pages within the larger site. Enjoy the tour through male contraception!

 
   

 

Release of Sperm and Formation of the Embryo:
As described in Normal Reproductive Cycles, spermatozoa are produced inside the testes of the male. Sperm cells then mature in the epididymis. From the epididymis, sperm travel through the vas deferens and join with seminal fluid from the seminal vesicle to produce semen ejaculate. When this occurs inside the female, sperm cells then travel from the upper vagina through the cervix and into the uterus. If the female has ovulated, the sperm cells can meet with the ovum as they continue to travel into the uterine tubes...
...Sperm cells attempt to break through the corona radiata and zona pellucida of the ovum. Through hydrolysis and the acrosomal reaction (Normal Reproductive Cycles), one sperm is able to penetrate the ovum to form the zygote. The zygote then implants itself into the endometrium of the uterus, and the embryo develops. (For interruption in this process, see Post-Intercourse Female Contraceptives.) (Carlson, 1999)
The above images were taken from www.advancedfertility.com/embryos.htm.

 

Common Contraceptive Methods:

The creation of new life is not merely a biological issue for humans. When individuals create a potential or born child, emotional, financial, psychological, physical, ethical, and interpersonal issues are often raised. While biology favors reproduction as a consequence of heterosexual intercourse, many individuals make use of various contraceptive methods to prevent unintended and unplanned pregnancies.

The most common contraceptive method in the U.S. is the condom. The condom, if properly used, has the potential to prevent semen from entering the vagina during sex. It also has the potential to prevent most sexually transmitted infections. (Elizabeth, 2002)

Other planned and intentional interruptions in the reproductive process include the Pre-Fertilization Pill, the diaphram, the sponge, female injections, surgical vasectomy, the "rhythm method," the Morning-After Pill, RU486, and surgical abortion. Each of these methods of contraception carries several considerations, including affordability, ease of use, availability, reversibility, ethics, and effectiveness. Of these methods, only two are ones in which males can directly participate: surgical vasectomy and the rhythm method. Surgical vasectomy is not always reversible. (Elizabeth, 2002)
These images were taken from http://www.babysimage.com and www.sfaf.org/prevention/gallery/necessty.jpg?116,46.

 

Experimental Male Contraceptives:
Surgical vasectomy, condoms, and the rhythm method remain the only widely available contraceptive methods in which men can participate directly. Surgical vasectomy is considered by some men to be invasive and is not universally reversible. Condoms, while they provide protection against sexually transmitted infections, are not necessarily the method of choice or preference for monogamous, committed partners. The rhythm method is both impractical and highly unreliable. This often leaves the responsibility of contraception on the female partner. There are, however, many possibilities for male contraception on the horizon which give men full control over contraception; these methods vary in effectiveness, invasiveness, and reversibility. (Lissner, 1994)
Heat:  

As opposed to the female gonads (ovaries), the testes are externally located. Evolutionarily this is due to the need for sperm to exist at a temperature lower than normal body temperature. Sperm cells cannot exist at body temperature or higher. A few experimental methods use this fact to control male fertility. Suspensory briefs use natural body heat or outside heat to control fertility. Specially designed underwear either pushes testes into the inguinal canals or applies heat; either way, testes are at or above body temperature. This should hypothetically lower sperm count.

The other contraceptive method involving heat depends on the regular heating of the testes through hot baths. From clinical trials, both of these methods appear to be reversible and effective. (http://www.reproline.jhu.edu/english/1fp/1advances/conrad_men.htm)

Non-scalpel Vas Occlusion:  

Some research has been done exploring the possibility of blocking or rendering ineffective sperm through methods related to the vas deferens. In the method of RISUG (Reversible Inhibition of Sperm Under Guidance), a chemical called styrene malic anhydride (SMA) is injected into the vas deferens, hardens, and renders sperm ineffective by rupturing sperm cell membranes. This method is easily reversible and holds none of the negative side effects of surgical vasectomy.

Three methods, medical-grade polyurethane (MPU) injection, medical-grade silicone rubber (MSR) injection, and the shug (a rubber plug), rely on blocking the vas deferens and preventing sperm form leaving the male body. Each of these methods is reversible and highly effective. (http://www.conrad.org/)
Hormone Therapy:
Often called the "male pill," researchers are currently attempting to develop exogenous hormones that would render males temporarily infertile. These hormones would be designed to inhibit the production and/or release of endogenous hormones that are critical for spermatogenesis. The effect of these hormones on general and sexual male functioning is not yet known. (Lissner, 1994)
Oral Contraceptives:
Probably the ideal contraceptive method for males would come in the form of a non-hormonal pill. Not only would this method be effective and reversible, but it would also be non-invasive, non-surgical, and taken with ease. There are a number of oral contraceptives being explored, but, as with the above methods, experimental studies are still very much in progress; condoms, rhythm method, and surgical vasectomy remain the only readily available male cantraceptive methods in this country. (Shulman, 2002)
These images were taken from http://www.911pictures.com/firepix.htm and matweb.hcuge.ch/selected_images/selected_medical_images.htm.

 

Types of Male Oral Contraceptives:

Tripterygium wilfordii:

(http://www.bloomingbulb.com/products/ProductDetail.asp?ProductKey=411)

Chemical Description:

-vine used in China to treat fever; contains triptolide, tripdiolide, triptolidenol, tripchlorolide, 16-hydroxytriplide, and T7/19, all of which contribute to infertility.

Mechanism:

-unknown; daily dosage reduces sperm count and causes sperm to be immotile.

History:

-discovered in 1980s to cause temporary infertility; studies thus far have focused on mechanism.

Effectiveness, Reversibility, and Side Effects:

-not enough studies have been done, but it appears to be effective and reversible; possible side effects of effective dose include immuno-suppression. (http://www.malecontraceptives.org)

 

 

 

Gossypol:

 

 

(http://www.angelfire.com/la/guwapo/images/cotton1.jpg)

Chemical Description:

-molecule found in cottonseed oil.

Mechanism:

-unknown

History:

-crude cottonseed oil was found to cause low fertility in coupls in a 1929 study in China; extensive research took place by Chinese government in 1970's, where problems of irreversibility and hypokalemia were found; clinical trials continue in Austria, Brazil, Chile, China, the Dominican Republic, and Nigeria.

Effectiveness, Reversibility, and Side Effects:

-effective, but sometimes irreversible for at least a year; side effects include hypokalemia (low potassium levels in blood). Possibly effective in low dose combined with low dose of tripterygium wilfordii without side effects of either. (Lissner, 1994)

Sugar Pill:

 

 

Ovum and zona pellucida. (http://www.unifi.it/inifi.anatistol/istologia/embriol/gam3.htm)

Chemical Description:

-synthetic sugar molecule.

Mechanism:

-acts like sugar molecules of the zona pellucida of egg; sperm enzyme HEX-B binds to synthetic sugar and leaves sperm functionally inactive.

History:

-developed by Dr. Joseph Hall of Norfolk University; has been tested in vitro with bull, ram, and rat sperm; has been tested in vivo with rats; human trials scheduled to begin in 2002.

Effectiveness, Reversibility, and Side Effects:

-appears to be 98% effective and fully reversible; possible complications include the risk of the molecule binding to other enzymes in the body. (http://www.malecontraceptives.org)

Nifedipine:

 

 

 

Photograph of nifedipine under microscope. (http://micro.magnet.fsu.edu/pharmaceuticals/pages/nifedipine.html)

Chemical Description:

-high blood pressure and migraine medication.

Mechanism:

-blocks calcium channels in sperm cell membranes; sperm membranes become loaded with cholesterol, rigid, and unable to bind to zona pellucida of the egg.

History:

-has been on the market for 20 years as a high blood pressure medication; recently discovered by Dr. Susan Benoff to have contraceptive effects on male patients; drug companies don't want to advertise its contraceptive effects and, therefore, funding for research is difficult to find; Dr. Benoff is attempting to develop a drug similar to nifedipine that she can patent for contraceptive use.

Effectiveness, Reversibility, and Side Effects:

-appears to be effective and fully reversible; because it has been mostly used by people with high blood pressure, its effects on men with low to normal blood pressure are unknown. (Family Health International, 1998 and Lissner, 1994)

 

Return to the Process of Normal Fertilization

 

See how Brown University Students View Male Contraception