Role of hormones, genes, and environment in human cryptorchidism

Prevalence of cryptorchidism among Bulgarian boys

BACKGROUND

Cryptorchidism is the most common congenital defect of the male urogenital system. It may be an important cause for male infertility. The data about its prevalence in South-eastern European countries and especially for the Balkan region are still incomplete.

OBJECTIVE

The aim of the present study was to establish the prevalence of the abnormality in the Bulgarian population living in the different areas of the country.

METHODS

In a population-based cross-sectional study in Bulgaria 6200 Caucasian boys (aged under 1 year to 19 years) from five regions of the country were included. One physician examined all children in order to reduce the inter-observer error.

RESULTS

The prevalence of cryptorchidism was 1.52% for the total group. It was 3.2% for boys under one year of age, 2.1% for those between one and ten years and dropped significantly in older boys (0.6%). No regional or seasonal trends were established.

CONCLUSIONS

Our study suggests a relatively higher prevalence of cryptorchidism in Bulgaria for children younger than one year of age, while the overall prevalence is comparable to those reported for other countries. The prevalence of cryptorchidism did not differ significantly from the prevalence reported thirty years ago.

The orl rat with inherited cryptorchidism has increased susceptibility to the testicular effects of in utero dibutyl phthalate exposure

Phenotype results from interactions between genetics and environment, but for most environmental chemical exposures, such interactions are theoretical. The phenotypic response of the testis to in utero dibutyl phthalate (DBP) exposure was compared between two strains of Long-Evans (LE) rats, the orl substrain with inherited cryptorchidism and an outbred (wt) strain. orl and wt LE rats were exposed daily between gestational day (GD) 12 and GD21 to DBP dose levels ranging from 50 to 200 mg/kg by oral gavage and sensitive phthalate testicular end points examined at either GD19, GD21, or postnatal day (PND) 21. At 50 mg/kg DBP, GD19 expression of Cyp17a1, Insl3, and Scarb1 was significantly reduced in orl but not wt testis. At GD21, statistically significant differential strain effects (orl more sensitive than wt) were observed for testicular expression of Scarb1 at 50 and 200 mg/kg DBP and Star at 200 mg/kg DBP. Similarly, DBP exposure disproportionately increased GD21 seminiferous cord diameters and numbers of multinucleated germ cells in the orl strain. At PND21, body weight-corrected testis weights were lowered significantly by DBP exposure at all dose levels in the orl strain but not in wt rats. While the frequency of undescended testes after 200 mg/kg DBP exposure in the orl strain appeared increased, these data were not statistically significant. These results demonstrated enhanced sensitivity of the orl rat to phthalate exposure as compared to its parent strain, a potentially important model of the effects of gene-environment interaction on development of male reproductive malformations.