Semen

Research in physiology carried out in the 1930s established that the lipid fraction of semen contains small amounts of substances that exert powerful effects on smooth mus cle Sheep prostate glands proved to be a convenient source of this material and yielded a mixture of structurally related substances referred to collectively as prostaglandins We now know that prostaglandins are present m almost all animal tissues where they carry out a variety of regulatory functions... 

Transport. Transcobalamin II dehvers the absorbed vitamin 3 2 to cells and is the primary plasma vitamin B22-binding transport protein. It is found in plasma, spinal fluid, semen, and extracellular fluid. Many cells, including the bone marrow, reticulocytes, and the placenta, contain surface receptor sites for the transcobalamin II—cobalamin complex. 

The male barrier contraceptive device is known as the condom, or mbber, and is widely available in most countries. The condom is a mbber or latex sheath, sometimes packaged with a lubricant and spermicide, which serves as a cover for the penis and a receptacle for semen. The method is very effective if the condom is of good quaUty, remains on, and is replaced for each subsequent intercourse. It was reported that 6 biUion condoms were used in 1990 (101). Usage appears to be increasing as adjunctive use with other methods of contraception for prevention of HIV or other sexually transmitted diseases. By rough estimate, condoms may have been used in more than 13 biUion acts of sexual intercourse that risked unwanted pregnancy, HIV, and/or other sexually transmitted diseases (101). 

While considerable attention is given to the question of male fertility, the incidence of infertility or sub-fertility in the population is difficult to measure and it is not known to what extent measures of semen quality, for example, are indicators of male fertility as such. 

The issue of whether sperm counts are declining has been the focus of most media attention. A debate still continues as to whether the reported changes in sperm quality are genuine. In 1992, an article described the meta analysis of available data on semen quality in normal men, taken from reports published between the period 1938-1990. This analysis showed a 50% decline in sperm concentration... 

Controversy will continue to persist over allegations that sperm counts are declining. Prospective studies on semen quality in fertile men involving centres in... 

Europe, the USA and Japan are under way. In these studies, semen analysis methodology and subject selection criteria have been standardised to address whether there are region-specific differences in semen quality. These data can then be used as a reference point for any studies on future decline in sperm counts. More importantly, it still remains to be demonstrated whether the reported decrease in semen quality is sufficient to compromise fertility. 

It is widely accepted that men with testicular cancer have a higher incidence of abnormalities associated with impaired spermatogenesis, both in the cancerous testis but also in the contralateral testis. Men diagnosed as having testicular cancer often have very poor semen quality, with sperm concentrations of less than 10 million/ml compared to healthy men with > 50 million/ml." It is thought that gonadal function is abnormal even before testicular cancer develops, ... 

Zeugungs-. generative, procreative. -flUssIg-keit,/. seminal fiuid. -mittel, n. aphrodisiac, -stoff, m. semen. 

Perhaps the most common and well-publicized use of DNA fingerprinting is that carried out by crime laboratories to link suspects to biological evidence— blood, hair follicles, skin, or semen—found at a crime scene. Thousands of court cases have now been decided based on DNA evidence. 

Alec Jeffryes, an English geneticist, discovered in the 1980s how to apply this principle to forensics. To do this, it is necessary to locate that portion of the DNA molecule in which the base sequence differs significantly from one individual to another. That part of the molecule is cut out by a "restrictive enzyme" in much the same way that trypsin splits a protein molecule into fragments. The DNA sample obtained in this way from a suspect can be compared with that derived from blood, hair, semen, saliva, and so on, found at the scene of a violent crime. 

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