Development of the Reproductive System (Brauer) Flashcards Preview

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Flashcards in Development of the Reproductive System (Brauer) Deck (52)
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1
Q

What are primordial germ cells

A

Cells of the epiblast that are initially localized w/in the walls of the yolk sac but migrate up the dorsal mesentery into the genital ridge of the intermediate mesoderm. They develop into oogonia and spermatogonia.

2
Q

How are somatic support cells formed

A

Primordial germ cells stimulate cells from the coelomic epithelium of the genital ridge to proliferate and delaminate into Somatic support cells

3
Q

What do somatic support cells develop into in males & females

A

Males - Sertoli cells

Females - Follicle cells

4
Q

What are the two sets of reproductive ducts that form within the intermediate mesoderm

A

Mesonephric ducts (Wolffian) & Paramesonephric ducts (Mullerian)

5
Q

What structures are derived from the mesonephric duct

A

Epididymis

Vas Deferens

Seminal Vesicle

Ejaculatory duct

Mesonephric duct is lost in females so only male structures formed

6
Q

What structures are derived from the Parameonephric duct

A

Oviduct

Uterus

Upper Vagina

Parameonephric duct is lost in males so only female structures formed

7
Q

What is the role of SRY in sex determination

A

It is the testis-determining factor gene which is located on the Y chromosome. In it’s absence, development is female.

8
Q

What is the effects of SRY in males

A
  1. Turns on SOX9 expression in somatic support cells which triggers them to differentiate into Sertoli cells
  2. Suppresses Wnt4 (pro-female gene)
9
Q

What is the effects of the abscent of SRY in females

A

Since the SRY gene is abscent, somatic support cells express Wnt4 and FOXL2 (supresses SOX-9)

10
Q

What do a subset of intertubular cells differentiate into in males

A

Leydig cells (recruited by Sertoli cells)

11
Q

What is the role of Sertoli cells in male development

A

They express Anti-Mullerian hormone (AMH) which causes the paramesonephric duct to degenerate

12
Q

What are the remnants of the paramesonephric duct

A

Appendix testis & proststic utricle

13
Q

What do Fetal Leydig cells do

A

They produce testosterone which triggers the mesonphric tubules and ducts to form:

  • Effernet ductules
  • Epididymis
  • Vas deferens
  • Seminal vesicles
14
Q

How are external male genitalia developed

(penis, scrotum, prostate & testicular descent)

A

Testosterone is converted to dihyrotestosterone (DHT) by 5-alpha-reductase

15
Q

What is the role of adult Leydig cells

A

Produce androgens that initiate and maintain:

Spermatogenesis

Masculinization of the brain

Male sexual behavior

16
Q

What germ layers are semial vesicles formed from

A

Intermediate mesoderm of urogenital ridge

Seminal vesicles are buds coming of the mesonephric duct hence deried from intermediate mesoderm

17
Q

What germ layers are prostate glands from

A

Endoderm buds of urogenital sinus

18
Q

What is the urogenital plate

A

The roof of the phallic portion of the urogenital sinus that is lined by endoderm. It expands along the lower surface of the genital tubercle as the genital tubercle enlarges

19
Q

What germ layer are the bulourethral glands formed from

A

Endodermal buds

20
Q

How is the genital tubercle form?

A

Ectodermal-covered mesoderm swelling at ventral and cranial end of phallic portion of urogenital plate.

21
Q

What is the glans plate?

A

Remnants of cloacal membrane at the ventral end of urogenital place and adjacent genital tubercle

22
Q

What are the pair of swellings that develop on either side of the urogenital plate through aan expansion of mesoderm underlying the ectoderm

A

Urogenital folds

23
Q

Fusing of the urogenital folds with each other forms what structure

A

Urethra

24
Q

What promotes lengthening and growth of the genital tubercle to form the penis & fusion of labioscrotal swellings to form the scrotum

A

dihydrotestosterone (DHT)

25
Q

What is hypospadias

A

A common male birth defect that is a result of the failure of the urogenital (urethral) folds to close properly

26
Q

What is Epispadias

A

Opening of the urethra on the superior aspect of the penis. Cause is unknown but may be due to improper ventral body closure or formation of too large of a cloacal membrane to be covered when it ruptures

27
Q

In females, what gene is expressed and promotes the female reproductive system?

A

WNT-4 & FOXL2

28
Q

What suppresses SOX-9 in females?

A

FOXL2

29
Q

What is the effect of the suppression of SOX-9

A

No SOX-9 = No Sertoli cells = No AMH = paramesonephric ducts retained

30
Q

What blocks oocytes in meiosis-1?

A

Follicle cells

31
Q

Absence of Leydig cells in females means what?

A

Mesonephric duct system is lost

32
Q

Fusion of the inferior paramesonephric ducts form what

A

Uterus

33
Q

The unfused superior portion of the paramesonephric ducts form what

A

Uterine tubes

34
Q

What is didelphys

A

Double uterus

35
Q

How is the vagina formed

A

Contact of paramesonephric duct to the urogenital sinus stimulates proliferation and formation of sinuvaginal bulb which is eventually canalized

36
Q

What germ layer is the vagina derived from

A

Whole thing is endodermally derived with the exception of the upper vaginal fornix which is mesodermally derived.

37
Q

What is vagina agensesis

A

Lack of a vagina due to failure of normal sinuvaginal bulb development and/or canalization

38
Q

What do the urogenital folds and labiosacral folds develop into in females

A

Urogenital folds - labia minora

Labioscrotal folds - labia majora

39
Q

What does the phallic segment of the urogenital sinus contain in females

A

Urogenital plate

Glans plate

Genital tubercle

Same as in males

40
Q

What is the broad ligament?

A

Peritoneal fold that attaches the uterus, fallopian tubes, and ovaries to the pelvis

41
Q

How does the broad ligament form?

A

Remaining tissue from the uterus and oviduct forms a double fold of peritoneum

42
Q

What does the round ligament of ovary connect?

A

Ovary to uterus

43
Q

What is the embryological origin of the round ligament of ovary?

A

Superior gubernaculum

44
Q

What does the round ligament of uterus connect?

A

Uterus to labia majora

45
Q

What is the embryological origin of the round ligament of uterus?

A

Inferior gubernaculum

46
Q

What is the term for the congenital condition in which development of chromosomal, gonadal and anatomical sex is atypical

A

Disorders of sex development (DSDs)

47
Q

What is it called when an individual has testes but their phenotype appears female

A

46, XY DSDs

48
Q

What are some causes of 46, XY DSDs

A
  1. Inadequate testosterone synthesis
  2. Androgen insensitivity syndrome
  3. 5 alpha-reductase deficiency
  4. Mutation in AMH or AMH receptor
49
Q

What are the characteristics of androgen insensitvity syndrome

A
  1. Common cause is loss of functional androgen receptors (X linked recessive)
  2. They have testes but no spermatogensis. Testosterone levels may be high due to a lack of negative feedback.
  3. At puberty, the testosterone is metabolized to estradiol initiating female secondary sexual characteristics
  4. Produce AMH so paramesonephric system is supressed = no uterus or uterine tube and the vagina is short and ends blindly.
  5. Testes usually found in inguinal or labial regions
  6. Increased risk of tumor formation in gonads
50
Q

What are the characteristics of 5- alpha-reducatse deficiency

A
  • Autosomal recessive
  • Have a 46 XY genotype
  • Normal testis and duct system since there is AMH and testosterone
  • Underdeveloped male external genitalia due to deficieny in DHT
51
Q

What are the characteristics of 46 XX DSDs

A
  • Presence of ovaries
  • Fetus produces excess androgens
  • Maculinzation of the female external genitalia; may even exhibit fusion of labia giving appearance of a scrotum.
  • Most common cause is congenital adrenal hyperplasia
52
Q

How does Congenital adrenal hyperplasia cause of 46 XX DSDs?

A

Deficiency in 21-hydroxylase leads to excess ACTH production (lack of negative feedback). Excess ACTH causes an excessive production of androgens.