Sexual differentiation Flashcards
The bi-potential gonads are undifferentiated when?
The first five weeks of life
Maleness is determined by which gene?
SRY (Sex determining region of Y)
SRY is found on which part of the Y chromosome?
Short arm
In the presence of which transcription factor does the gonad differentiate into the testes at about week 6 of gestation?
TDF ( testes determining factor)
Seminiferous tubules are seen when?
8th to 9th week of gestation
When does the gonad differentiate into the testes?
About week 6 of gestation
The Mullerian Inhibiting Hormone (MIH) is produced by which cells?
Sertoli cells
The Mullerian Inhibiting Hormone (MIH) and Anti-mullerian hormone (AMH) are the same. T/F
T
What is the important function of MIH?
Causes the regression of mullerian (paramesonephric) duct ipsilaterally
Regression of the Mullerian duct occurs when?
7-8 weeks of gestation
Which cells produce testosterone?
Leydig cells
What stimulates testosterone production in the 8th to 10th week of gestation?
HCG
Testosterone is important in the development of which structure in males during the 8th to 10 weeks ofd gestation?
Wolffian ducts
Which substance causes regression of the mullerian duct?
MIH or AMH
Which structures originate from the Wolffian duct?
Epididymis, vas deferens, ejaculatory duct
Dihydrotestostserone (DHT) is a metabolite produced by enzyme 5-alpha reductace from which substance?
Testosterone
What is the effect of DHT in sexual differentiation?
It transforms the genital tubercle into the penis, and the urogenital sinus into the urethra and prostate gland
Which substance causes the development of Wolffian ducts?
Testosterone
In the first three months of life, stimulsation of gonadal steroidogensis is independent on fetal gonadotropins and depends on which hormone?
HCG
Which substances are involved in the desdent of the teste?
HCG and MIH/AMH
When does the testicles descend?
34-35th week of gestation
Which substance causes the genital tubercle to develop into the penis, and the urogenital sinus into the urethra and prostate gland?
DHT
Activation of both X chromosomes in the absence of TDF happens when?
9th week of gestation
What happens in the absence of MIF?
The paramesonephric duct develops into the uterus
When does the paramesonephric duct develop into the uterus?
9-20 weeks of gestation in the absence of MIH/AMH
The development of the paramesonephric duct into the uterus happens without the need for hormonal stimulation. T/F
T
What happens to the genital tubercle without DHT?
It develops into the labia minora and labia majora
What happens to the urogenital sinus without DHT?
It develope into the vagina?
When does the vagina develop?
8-14 weeks
Which structures in the male and female develop from the urogenital sinus?
Urethra and prostate of males
Lower 1/3 of vagina and urethra of females
Which structures in the male and female develop from the genital tubercle?
Glans penis and clitoris
Which structures in the male and female develop from the genital swellings?
Scrotum and labia majora
Which structures in the male and female develop from the geniral folds?
Penile urethra and corpora spongiosa in males
Labia minora in females
A male fetus unexposed to DHT
A. May have 5-alpha reductace deficiency
B. May have ambiguous external genitalia
C. Will have a testes and seminal vesicles
D. All of the above
D
In the absence of the testes determining factor (TDF), which events would you expect?
A. Wolffian duct regression
B. Mullerian duct transformation into fallopian tubes and uterus
C. Formation of genitsl tubercle into the clitoris
D. All of the above
D
The enxyme responsible for the conversion of testosterone to dihydrotestosterone is
A. Aromatase
B. 5-alpha reductase
C. Adenyl cyclase
D. None of the above
B
Which about sexual differentiation is true?
a. SRY gene is found in Chromosome Y
b. Genes for androgen receptors are found in chromosome X
c. Autosomal chromosomes don’t play arole in sexual differentiation
d. AOTA
e. A and B only
E
Which is true
a. Presence of AMH results in Mesonephric duct regression
b. Presence of Testosterone regulates normal…prostate
c. Presence of estrogen results in female genitalia
d. None are true
D
Genetic sex is determined by:
a. X or Y chromosome
b. Presence of internal genitalia
c. External genitalia
d. Parental social cues
A
hCG plays a role in:
a. testicular descent
b. sexual libido
c. steroidogenesis
d. AOTA
D
A female exposed to excess maternal adrenal androgens after the 20th week of fetal development will have?
a. Testis
b.
c. Ambiguous external genitalia
d. AOTA
C
Major site of degradation of sex steroids:
a. Brain
b. kidney
c. liver
d. heart
C
Prior to puberty, the expected profile of a 7-year old child is:
a. Low FSH, low LH, low estradiol
b. Low FSH, low LH, high estradiol
c. High FSH, high LH, low estradiol
d. high FSH, high LH, high estradiol
A
Which of the following is the correct sequence of female pubertal development:
a. Thelarche, Adrelarche, growth spurth, Menarch
b. Adrelarche, growth spurt, thelarche, menarche
c. Growth spurt, Menarch, Thelarche, Adrelarche
d. Menarche, Thelarche, Adrelarche, Growth Spurt
A
Which of the following is a characteristic of post-menopausal women?
a. Low estradiol, high FSH, High LH
b. Low estradiol, low FSH, low, LH
c. Normal estradiol, high FSH, high LH
d. Normal estradiol, low FSH, low LH
A
All of the following hormones attached to a membrane receptor except:
a. LH
b. FSH
c. GnRH
d. Estradiol
D
Effects of progesterone will include:
a. Secretion of nutrients for egg and sperm
b. Lobuloalveolar growth of the mammary gland
c. NOTA
d. A and B only
D
Dr. Buenaluz fears that she is nearing menopause. She may expect the following changes except:
a. An increase in transport globulins like thyroxine binding globulin
b. Increase in LDL
c. Decrease in bone mass
d. Decreased calcium absorption
A
Which of the following is the correct sequence of events in male pubertal growth
a. Testicular growth, pubic hair, growth spurt, penile enlargement
b. Penile enlargement, pubic hair, growth spurt, testicular growth
c. Testicular growth, pubic hair, penile enlargement, growth spurt
d. Testicular growth, penile enlargement, growth spurt, pubic hair
C
What is the normal adult testicular size:
a. 2cm long X2 cm wide
b. 2cm X3 cm
c. 5cm X3cm
d. 7cm X 5cm
C
The following are secreted by sertoli cells except:
a. Estradiol
b. Acid phosphatase
c. Androgen binding protein
d. Meiosis inhibiting factor
B
Which of the following substances ensures a high concentration of testosterone in the seminiferious tubule
a. Acid phosphatase
b. Androgen binding Protein
c. Anti-meiotic Hormone
d. Inhibin
B
Injecting male sterior hormones in preparation for a body building competition may result in
a. Testicular shrinkage
b. Muscle hypertrophy
c. Infertility
d. AOTA
A
Spermatogenesis begins at… A. Before birth B. Puberty C. After birth D. NOTA
B
The hormone that causes pubic hair growth in females is what?
DHEA
Development of seminal vesicles in utero
A. MIH B. HCG C. Testosterone D. Inhibin E. DHT
C
Stimulation of gonadal steroidogenesis
A. MIH B. HCG C. Testosterone D. Inhibin E. DHT
B
Secreted by Sertoli cells and sends (-) feedback to FSH
A. MIH B. HCG C. Testosterone D. Inhibin E. DHT
C
Prostate development and hypertrophy
A. MIH B. HCG C. Testosterone D. Inhibin E. DHT
E
Paramesonephric duct regression
A. MIH B. HCG C. Testosterone D. Inhibin E. DHT
A
What is the difference between male and female gametogenesis?
a. Sequence of events
b. Timing of events
c. Absence of mitosis or meiosis
d. All of the above
B
XY without androgen receptors
A. male
B. female
B
XX with exposure to androgens after 20th week
A. male
B. female
A
XY; exposure to androgens beyond 5th month of gestation
A. male
B. female
A
XY; exposure to androgens beyond 5th month of gestation
A. male
B. female
A. B
