PubMed · 14321616
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H HORTLING. 1965-08-05. [CRYPTORCHISM].. https://pubmed.ncbi.nlm.nih.gov/14321616/
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Estrogens are classically known to play a major role in female reproduction but there is now compelling evidence that they may also be involved in the regulation of male reproductive function. In humans, a decrease in sperm count and an increase in the incidences of testicular cancer, cryptorchidism and hypospadia have been observed in many countries over the last 50 years. Male reproductive alterations were also observed in wildlife. Such male reproductive disorders have been attributed to the increase in concentration of xenobiotics, and of xenoestrogens in particular, in the environment and in food. Epidemiological, clinical and experimental studies have suggested that excessive exposure to estrogens during fetal/neonatal life can lead to reproductive disorders in adulthood. Using an in vitro model we showed that estrogens directly affected the development of the fetal testis and we evidenced the existence of periods of sensitivity throughout development. Lastly, we clearly demonstrated that the fetal and neonatal testis is very sensitive to estrogens since the invalidation of estrogen receptor alpha leads to an increase of steroidogenesis and the invalidation of estrogen receptor beta enhances the development of the germ cell lineage in the male.
The latest figures from the Cancer Registry of Norway show that Norway has the highest incidence rate of testicular cancer in the world. They also show that the incidence rate continues to increase, as it has for the last decades in the western world. The reasons for this increase, which might also be true for urogenital abnormalities in men and reduced sperm quality, are uncertain. Data suggest, however, that these anomalies originate in foetal life, and that contributing factors are genetic, pregnancy-related and environmental. The potential importance of environmental factors must be taken seriously, and the authorities must take action to strengthen the research in this area.
The testicular dysgenesis syndrome (TDS) hypothesis proposes that the four conditions cryptorchidism, hypospadias, impaired spermatogenesis and testis cancer may all be manifestations of disturbed prenatal testicular development. The TDS hypothesis is based on epidemiological, clinical and molecular studies, all suggestive of an interrelation between the different symptoms. The aetiology of TDS is suspected to be related to genetic and/or environmental factors, including endocrine disrupters. Few human studies have found associations/correlations between endocrine disrupters, including phthalates, and the different TDS components. However, for ethical reasons, evidence of a causal relationship between prenatal exposure and TDS is inherently difficult to establish in human studies, rendering the recently developed animal TDS model an important tool for investigating the pathogenesis of TDS. Clinically, the most common manifestation of TDS is probably a reduced sperm concentration, whereas the more severe form may include a high risk of testis cancer. Clinicians should be aware of the interconnection between the different features of TDS, and inclusion of a programme for early detection of testis cancer in the management of infertile men with poor semen quality is recommended.