new_n_lost
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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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| mikky
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b
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| yoga
usmlelogy professor
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tough
may b a
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| po
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B. Female-type internal reproductive tract and female-type external genitalia?
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| tompat
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b
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| new_n_lost
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mikky wrote:
b
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| new_n_lost
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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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FORUM RULES-- Those who believe in telekinesis, raise my hand. I get enough exercise just by pushing my luck --P4U World.." The pure and simple truth is rarely pure and never simple."
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| Luckyall
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kindof late, but B 
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