Reproductive dysgenesis in wildlife: a comparative view

Abstract

Abnormal reproductive development in males has been linked to environmental contaminant exposure in a wide variety of vertebrates. These include humans, rodent models, and a large number of comparative wildlife species. In human males, abnormal reproductive development can manifest as a suite of symptoms, described collectively as testicular dysgenesis syndrome (TDS). TDS is also described as demasculinization or feminization of the male phenotype. The suite includes cryptorchidism, in situ germ cell carcinoma of the testis and overt testicular cancer, reduced semen quality, and hypospadias. In this paper, we review examples of TDS among comparative species. Wildlife exposed to environmental contaminants are susceptible to some of the same developmental abnormalities and subsequent symptoms as those seen in human males with TDS. There are additional end points, which are also discussed. In some cases, the symptoms are more severe than those normally seen in humans with TDS (i.e. oocytes developing within the testis) because some non-mammalian species exhibit greater innate reproductive plasticity, and are thus more easily feminized. Based on our review, we present an approach regarding the ontogeny of TDS. Namely, we suggest that male susceptibility to the androgynizing influences of environmental contaminants originates in the sexually undifferentiated embryo, which, in almost all species, including humans, consists of bipotential reproductive tissues. These tissues can develop as either male or female and their ultimate direction depends on the environment in which they develop.

‘Idiopathic’ partial androgen insensitivity syndrome in 28 newborn and infant males: impact of prenatal exposure to environmental endocrine disruptor chemicals?

“…Several epidemiological studies have documented a deterioration in male reproductive health in the last few decades (13,14,16,(40)(41)(42)(43)(44)(45)(46)(47), and a similar phenomenon has been reported in numerous wildlife species (48)(49)(50)(51)(52). In addition, the evidence from wildlife observations, registers of genital malformations and diethylstilbestrol (DES)-exposed human male fetuses, and experimental data from animals and cells all have increased the suspicion that fetal exposure to EDCs could adversely affect fetal male sex differentiation (9-11, 15, 23, 49-53).…”

Misconceptions about falling sperm counts and fertility in Europe

“…Since the publication of Carlsen's meta-analysis, 11 there has been widespread anxiety about the negative impact of environmental pollutants on human reproduction. Given the well-known adverse effects of occupational exposures on reproduction in Misconceptions about declining male fertility ER te Velde and JP Bonde 197 certain professions 46 and the results of studies in wildlife where feminisation and sterility of male animals occur in highly polluted areas, 47 the concern about adverse effects of environmental pollutants is not only understandable but fully warranted. However, the panic-stricken viewpoint of the authors of the Science Policy Briefing is not the appropriate approach to advance.…”

Cypermethrin exposure and effects on the reproductive male system: a literature review

“…The observation of effects at extremely low doses but not at higher ones difficult to duplicate the precise effects seen in wildlife in laboratory animals (MCKINLAY et al, 2008). The main hypothesis is that very low doses of EDs fail to trigger the mechanisms, which would normally detoxify them, but they can disrupt sensitive stages of an organism's development, especially during embryogenesis (THAYER et al, 2001;EDWARDS et al, 2006). CP was synthesized for the first time in 1974 and introduced on the market from 1977.…”