Department of Zoology, University of Melbourne, Melbourne, VIC, Australia.
Sex Dev. 2011;5(5):241-9. doi: 10.1159/000334053. Epub 2011 Nov 22.
Hypospadias is increasingly common, and requires surgery to repair, but its aetiology is poorly understood. The marsupial tammar wallaby provides a unique opportunity to study hypospadias because penile differentiation occurs postnatally. Androgens are responsible for penile development in the tammar, but the majority of differentiation, in particular formation and closure of the urethral groove forming the penile urethra in males, occurs when there is no measurable sex difference in the concentrations of testosterone or dihydrotestosterone in either the gonads or the circulation [corrected]. Phalluses were examined morphologically from the sexually indifferent period (when androgens are high) to well after the time that the phallus becomes sexually dimorphic. We show that penile development and critical changes in the positioning of the urethra occur in the male phallus begin during an early window of time when androgens are high. Remodelling of the urethra in the male occurs between days 20-60. The critical period of time for the establishment urethral closure occurs during the earliest phases of penile development. This study suggests that there is an early window of time before day 60 when androgen imprinting must occur for normal penile development and closure of the urethral groove.
尿道下裂越来越常见，需要手术修复，但病因知之甚少。有袋动物袋鼹鼠为研究尿道下裂提供了一个独特的机会，因为阴茎分化发生在出生后。雄激素负责袋鼹鼠的阴茎发育，但大多数分化，特别是雄性中尿道沟的形成和闭合，形成阴茎尿道，发生在睾丸或循环中睾酮或二氢睾酮的浓度没有可测量的性别差异时[更正]。在性未分化期（雄激素水平高时）到阴茎变得性别二态后很久，对阴茎进行了形态学检查。我们表明，阴茎的发育和尿道位置的关键变化发生在雄激素水平高的早期时间窗口内。雄性的尿道重塑发生在第 20-60 天之间。尿道闭合的关键时期发生在阴茎发育的最早阶段。这项研究表明，在第 60 天之前，必须有一个早期的时间窗口，以使雄激素印记发生，以实现正常的阴茎发育和尿道沟的闭合。
