Artificial Insemination

Artificial insemination (AI) is when sperm is placed into a female's uterus (intrauterine), or cervix (intracervical) using artificial means rather than by natural copulation.

Modern techniques for artificial insemination were first developed for the dairy cattle industry to allow many cows to be impregnated with the sperm of a bull with traits for improved milk production.

Artificial insemination is used in animals to propagate desirable characteristics of one male to many females or overcome breeding problems, particularly in the cases of horses, cattle, pigs, pedigreed dogs, and honeybees. Semen is collected, extended, then cooled or frozen. It can be used on site or shipped to the female's location. The small plastic tube holding the frozen semen is referred to as a "straw". To allow the sperm to remain viable during the time before and after it is frozen, the semen is mixed with a solution containing glycerol or other cryoprotectants. An "extender" is a solution that allows the semen from a donor to impregnate more females by making insemination possible with fewer sperm. Antibiotics, such as streptomycin, are sometimes added to the sperm to control some venereal diseases.

Artificial insemination of farm animals is very common in today's agriculture industry, especially for breeding dairy cattle (75% of all inseminations) and swine (up to 85% of all inseminations). It provides an economical means for a livestock grower to breed their herds with males having very desirable traits.

Human Artificial Insemination
In humans artificial insemination is usually part of an infertility treatment; either the woman's partner's sperm (artificial insemination by husband, AIH) or donor sperm (artificial insemination by donor, AID) can be used. Earlier, a popular form of artificial insemination was AIC, in which the sperm of the husband and a donor were mixed. The advantage of this procedure was that it could not be conclusively stated that the husband was not the father of the child. This was important in an age where artificial insemination was considered to be immoral and tantamount to adultery, with the resulting child being considered as illegitimate and having no inheritance rights. With the acceptance of artificial insemination in society, the popularity of AIC waned.

The woman's menstrual cycle is closely observed, using ovulation kits, ultrasounds or blood tests. When an ovum is released, semen from a donor is inserted into her body. Just as with in vitro fertilization, the male donor is recommended not to ejaculate for a few days before the procedure. This is to ensure a higher sperm count. After the donation the sperm must immediately be “washed” in a laboratory. The process of “washing” the sperm increases the chances of fertilization and removes any chemicals in the semen that may cause discomfort for the woman. A chemical is added to the sperm that will separate the most active sperm in the sample. If the procedure is successful, she conceives and bears to term a baby as normal, making her both the genetic and gestational mother.

Of course, there are various gradations of treatment, and more technical procedures are sometimes needed. For example, semen can be injected directly into a woman's uterus to improve the chance of conception in a process called intrauterine insemination.

Artificial insemination has become a significant issue in recent years, particularly in debates revolving around surrogate parenting. Legal issues have arisen in cases where the gestational (and possibly genetic) mother decides to keep the child. Likewise, there have been debates over the rights of sperm donors.

History
Many people think of artificial insemination as a modern technology but it has a long history. Thus, apparently artificial insemination was attempted on Juana, wife of King Henry IV of Castile. In 1677 the Dutch scientist Leeuwenhoek saw spermatozoa through the newly invented microscope. More than 100 years later in 1780 an Italian priest and physiologist named Lazzaro Spallanzani performed an experiment in his laboratory that revolutionized the way scientists thought. Until this point scientists had a very primitive understanding of conception largely based on how plants grew. They speculated that the embryo was the "product of male seed, nurtured in the soil of the female." Spallanzani's experiment on dogs proved for the first time that there must be physical contact between the egg and sperm for an embryo to develop. With this new knowledge Spallanzani experimented on frogs, fish, and other animals and was successful.

Efforts to develop practical methods for AI were started in Russia in 1899. Papers on artificial insemination in horses had been published by 1922. By the mid 1940's artificial insemination had become an established industry. In 1949 improved methods of freezing and thawing sperm were developed. The idea for adding antibiotics to the sperm solution came in 1950 from Cornell. Improved methods of sperm collection were developed in the 1970's and 1980's. Research to improve methods of artificial insemination continues and is usually studied under animal science curriculums.