Testis-Like Steroidogenesis: DISCUSSION(4)

28 Apr

T europaea is one of four species of the genus Talpa known to have ovotestes. Of interest is how this phenotype could have arisen in the ancestor of the genus Talpa and what advantage this phenotype conveyed in order for it to be conserved in every female of all four of the species examined. Because the basic form of the ovotestis is found in at least four species of mole, Sanchez et al. have argued that it is an evolutionarily primitive condition resulting from an ancient mutation. It seems likely that female moles have evaded the common costs of exceptional androgen production on reproductive success by the reciprocal, seasonal inversion of the two component tissues of the gonad; persistently high levels of testosterone during spring would be expected to be disruptive to folliculoge-nesis and estrus. However, these considerations leave open the question of what benefits might accrue from higher testosterone production in autumn. buy birth control online

In a comprehensive review of the natural history of moles, Gorman and Stone write, ‘‘there is no doubt that the medullary (i.e., interstitial) tissue is endocrine in nature and involved in the synthesis of hormones, but what hormones and to what purpose is as yet unknown’’ (pp. 60-61). The authors then add, ‘‘One possibility is that for most of the year the medullary (interstitial) tissue produces male hormones and that these are responsible for the aggressive nature of the female and for the masculine appearance of her genitalia.’’