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<11>In a genotypic male, the testes fail to develop, and do not secrete
testosterone or Müllerian regression factor. Which of the following best
describes the in utero reproductive system development of this individual ?
A. Both male- and female-type internal reproductive tracts and male-type external genitalia
B. Female-type internal reproductive tract and female-type external genitalia
C. Female-type internal reproductive tract and male-type external genitalia
D. Male-type internal reproductive tract and female-type external genitalia
E. Male-type internal reproductive tract and male-type external genitalia
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D)Complete androgen resistance results in feminization of affected male fetuses. It is characterized by an XY genotypic male with phenotypically female external genitalia and a vagina that ends as a blind sac.
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11>The correct answer is B. The description is that of gonadal dysgenesis. In the absence of testosterone, the Wolffian ducts will regress and fail to differentiate into normal male internal reproductive tracts. In the absence of Müllerian regression factor, the Müllerian ducts will automatically differentiate into oviducts and a uterus. Differentiation of the male external genitals is dependent on adequate dihydrotestosterone (via an action of 5 a-reductase on testosterone). In the absence of testosterone, female-type external genitalia will develop.
Selective dysgenesis of the Sertoli cells could produce the situation described in choice A. Normal Leydig cells would secrete testosterone and produce normal male-type internal and external tracts. However, the absence of Müllerian regression factor, which is secreted by the Sertoli cells, would allow formation of female-type internal structures as well.
Female-type internal reproductive tract and male-type external genitalia (choice C) would not be likely to occur under any circumstances.
The situation described in choice D could occur with 5 a-reductase deficiency. Normal male-type internal tracts can form because there is no requirement for dihydrotestosterone. Müllerian regression factor will prevent differentiation of female-type internal tracts. Since differentiation of the normal male external genitals requires dihydrotestosterone, 5 a-reductase deficiency will lead to feminization.
The situation described in choice E is normal, and would not occur in the individual described who has testicular dysgenesis.
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These questions very confusing for me...Is there any easy way to remember this?
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what I understand is that leydig cells secrete testosterone that gets converted to DHT that acts on the wolfian duct that causes the external and internal genitalia in males to develop.The sertoli cells also secrete MIF that will cause the mullerian duct to regress and thus female genitalia are not formed in males.this is the normal.
