Semen concentration

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... 

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, ... 

In addition, it has been suggested that short-term exposure to phytoestrogens during adulthood does not affect male sex hormone concentrations or semen quality (Mitchell et al, 2001). 

No effect on weight gain, serum testosterone at age 11 months, libido, sperm mobility, semen volume, and sperm concentration. No histopathology of liver, lung, kidney, or spleen. No tissue residues — except for one bull slaughtered at age 5 months <20 pg/kg FW in muscle, 20 in liver and kidney, 40 in subcutaneous fat, and 80 in renal and omental fat... 

Occupational exposure to 1,2-dibromoethane has been reported to produce adverse effects both on spermatogenesis (sperm concentration) and seminal fluid production (semen volume) in human males (Ratcliffe et al. 1987 Takahashi et al. 1981, Ter Haar 1980). 

Radioactivity ( H or "C-1,2-dibromoethane) was detected in spermatozoa collected approximately 1 week following the initial oral dose (Amir 1973). These results indicate that 1,2-dibromoethane exerts spermicidal action during the process of spermiogenesis and sperm maturation. This conclusion was supported by the evidence that the percentage of sperm abnormalities was highest when little 1,2-dibromoethane radioactivity could be detected in sperm. In addition, reduction in sperm concentration was more pronounced in adult bulls than in young bulls, and the period of recovery was longer in adult animals (Amir 1975). In another study, bulls were fed 2 mg/kg/day 1,2-dibromoethane for 12 months followed by 4 mg/kg 1,2-dibromoethane every other day until they reached the age of 14-16 months. The semen samples examined revealed low sperm density, structural abnormalities, and low mobility (Amir and Volcani 1965). Sperm production returned to normal as early as 10 days postexposure (Amir and Lavon 1976 Amir et al. 1977). 

One study directly evaluated semen and testicular endpoints in men consuming soy phytoestrogens. Mitchell et al. (2001) reported a study of 14 young men (18 to 35 years old) who consumed 40 mg per day of soy isoflavones (in a tablet form) for two months. The subjects were followed for two months before and three months after taking the supplement. The isoflavone supplement did not change testicular or ejaculate volume, or sperm concentration, count, or motility. 

Meeker JD, Stapleton HM (2010) House dust concentrations of organophosphate flame retardants in relation to hormone levels and semen quality parameters. Environ Health Persp 118 318-323... 

Studies on health effects of PAEs in humans have remained controversial due to limitations of the study design. Some findings in human populations are consistent with animal data, suggesting that PAEs and their metabolites produce toxic effects in the reproductive system. Some studies associate monoesters PAEs with semen parameters, sperm DNA damage, and hormones in human population, but none of them are statistically significant. Urinary monomethyl phthalate (MMP), monobenzyl phthalate (MBzP), mono- -butyl phthalate (MBP), MEHP, and monoethyl phthalate (MEP) were associated with poor sperm morphology and vigor, and with low sperm concentration, motility, and linearity [31-35]. However, it is not yet possible to conclude whether phthalate exposure is harmful for human reproduction. 

Hauser R, Meeker JD, Duty S, Silva MJ, Calafat AM (2006) Altered semen quality in relation to urinary concentrations of phthalate monoester and oxidative metabolites. Epidemiology 17 682-691... 

Liu HX, Qin WH, Wang GR, et ah Some altered concentrations of elements in semen of workers exposed to trinitrotoluene. Occup Environ Med 52(12) 842-845, 1995... 

Cardoso Rde C., A. R. Silva, D. C. Uchoa, and L. D. da Silva. Cryopreser-vation of canine semen using a coconut water extender with egg yolk and three different glycerol concentrations. Theriogenology 2003 59(3-4) 743-751. 

The prostaglandins are a group of modified C20 fatty acids first isolated from human semen and initially assumed to be secreted by the prostate gland. They are now known to occur widely in animal tissues, but only in tiny amounts, and they have been found to exert a wide variety of pharmacological effects on humans and animals. They are active at very low, hormone-like concentrations and can regulate blood pressure, contractions of smooth... 

It appears that small groups of kallikreins may represent enzymatic cascade pathways in certain tissues. For example, it is very likely that at least three kallikreins, hK2, hK3, and hKl 1, which are present in seminal plasma at relatively very large concentrations, may coordinately act as a cascade enzymatic pathway, involved in semen liquefaction or other activities. In contrast, another group of kallikreins, including hK5 and hK7 and possibly many others, seem to be involved in skin desquamation. Similar cascade pathways may be operating in the breast, testis and other tissues. 

Bird et al. (1983) found that when captive American kestrels Falco sparverius) were fed 8 mg kg-1 of mirex for 69 days, there was a decline in sperm concentration and a slight increase in semen volume. An overall net decrease of 70% in sperm number was observed. The investigators... 

Reduced sperm concentration and increased semen volume Bird et al. (1983) 69 days... 

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