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Human Structure - Block 2 - Week #5 - Flashcards - JTC > Development of the Genital System | B2, WK5 > Flashcards

Development of the Genital System | B2, WK5 Flashcards

1
Q

Which develops first: External or internal genitals?

A

Internal (External takes longer)

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2
Q

The urinary and genital systems are derived from _______________________-

A

intermediate mesoderm (intermediate mesenchyme)

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3
Q

Intermediate mesoderm forms a _______________ ________________ (2 words), which differentiates into what 2 structures?

A

Urogenital ridge
1. nephrogenic cord
2. genital ridge

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4
Q

T/F: Up until week 6, the genital system develops differently for Male/Female, regardless of chromosomal composition of the embryo

A

False
Up until week 6, the genital system develops similar for Male/Female, regardless of chromosomal composition of the embryo

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5
Q

What is genotypic sex?

A

Sex of individual based on chromosomes
46 XX, 46 XY
[don’t forget about 45X (turner syndrome) and 47 XXY [Klinfelter syndrome]

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6
Q

What is phenotypic sex?

A

Based on the appearance of internal/external genitalia (i.e., phenotype = physical)

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7
Q

How is phenotypic sex first determined? (list/describe the process)

A

Y chromosomes have SRY genes. These genes produce SRY protein (or testis determining factor)
1. SRY protein produced in developing gonad
2. SRY protein starts cascade of factors that initiate male-like phenotypic sex development

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8
Q

What happens (in terms of phenotypic sex) when an embryo has XX chromosomal pattern OR the Y chromosome does not contain the SRY gene

A

Female-like phenotypic sex will be produced

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9
Q

Genital (gonadal) ridges form _____________ to mesonephros and are initially at level of _______ vert.

A

Medial
T10

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10
Q

During the 5th-6th week, what cells migrate from the yolk sac to the genital ridges? What happens if these cells don’t migrate?

A

Primordial germ cells [oocytes/sperm]
If they don’t migrate - gonads will NOT form

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11
Q

What is the outer part of the gonad? inner part?

A

Outter: cortex
Inner: medulla

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12
Q

The ____________________________ (3 words) are found in the medulla of developing gonad.

A

Primitive (primary) sex cords

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13
Q

By the 6th week - What two duct systems form?

A
  1. Mesonephric (wolffian) ducts
  2. Paramesonephric
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14
Q

What are Mesonephric (wolffian) ducts?

A

Form most of the phenotypic-male duct system

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15
Q

What are Paramesonephric (Mullerian) ducts?

A

Form most of the phenotypic female duct system

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16
Q

SRY protein starts its work at week 7 - what does this do/mean?

A

Differentiation of genitalia during Wk 7 – SRY protein influences the gonad to become a testis

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17
Q

Under influence of SRY protein, medullary portions of _______________________ develop

A

Primitive sex cords (testis cords)

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18
Q

What does the testis cord form?

A

Seminiferous tubules & rete testis

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19
Q

What do sustentacular (sertoli) cells secrete?

A

Anti-mullerian hormone (AMH) [or Mullerian Inhibiting Substance (MIS)]

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20
Q

What does AMH (MIS) induce?

A

degeneration of paramesonephric ducts

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21
Q

The paramesonephric ducts degenerate, but what about the mesonephric duct?

A

This duct remains, will form most of the reproductive duct system associated w/ the testis

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22
Q

How does the prostate and bulbourethral glands form?

A

Form from endodermal ‘buds’ off of urethra

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23
Q

What pulls the testis down from its lumbar placement into the scrotum?

A

Gubernaculum!

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24
Q

3rd - 7th month of development - where are the testes located?

A

Testis at level of deep inguinal ring

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25
Q

9th month of development - where are the testes located?

A

Testis pulled into scrotum

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26
Q

What gets “pulled” with the testis as it descends?

A

Its innervation (T10/T11)

27
Q

The kidneys _________________ while the testes start to ________________.

A

Kidneys: ascend
Testes: descend

28
Q

T/F: The descent of the testes occurs throughout entire fetal period

A

TRUE

29
Q

What is cryptorchidism?

A

“Hidden testis”
-Undescended testis

30
Q

Why does cryptorchidism occur more commonly in preemies?

A

Born before 9th month, so it has not descended yet

31
Q

What other increased risks are associated with cryptochidism?

A

Testicular cancer
Fertility problems (b/c of temp regulation that is needed)

32
Q

What is testicular Hydrocele?

A

Fluid-build up in either tunica vaginalis or part of patent process vaginalis

33
Q

T/F: Testicular hydrocele typically occurs in 3-5 yr olds and needs medical attention, as it will not regress on its own

A

FALSE:
typically occurs in 1 yr olds AND typically regresses on its own
(emphasis on typically)

34
Q

Absence of the Y-chromosome and SRY gene will yield

A

Female-like development

35
Q

During the 7th week, the testis cords of gonads degenerate and a secondary set of cords called ______________________ develop in the __________________
[differentiation of ovaries]

A

cortical cords ; cortex

36
Q

Cortical cords form what?

A

Follicular cells of ovarian follice

37
Q

Does the medulla of the ovary have sex cells? {Think about gross anatomy and histo}

A

NO

38
Q

In female development, absence of AMH yields

A

-degeneration of mesonephric ducts
-development of paramesonephric ducts

39
Q

What forms the uterus and superior part of the vagina?

A

Inferior (caudal) ends of paramesonephric ducts that fuse (during 2nd trimester)

40
Q

What forms the uterine tubes?

A

Unfused superior forms of paramesonephric ducts

41
Q

The inferior part of the vagina is formed from?

A

Sinovaginal bulbs (off of UG sinus) that fuse – OUTGROWTH of urethra

42
Q

The vagina separates from the bladder when?

A

When the inferior part of the vagina forms

43
Q

Where do the ovaries descend from?

A

T10 region –> to pelvic cavity
(posterior to broad ligament)

44
Q

What are uterine malformations typically caused by?

A

Partial atresia of one of the paramesonephric ducts

(atresia: a body part that is tubular in nature does not have a normal opening, or lacks the ability to allow material to pass through it.)

45
Q

What is uterus didelphys?

A

Double uterus & double cervix – fundus malformation

46
Q

What does this pic show?

A

Bicornuate Uterus

47
Q

Why are uterine malformations (such as uterus didelphys) harmful?

A

Causes issues for the development of offspring (i.e., uterus can’t expand as fetus grows)

48
Q

What occurs when sinovaginal bulbs fail to form?

A

Vaginal Atresia

49
Q

Vaginal atresia is when…

A

The superior vagina forms but the inferior part does not (so, no connection to the outside body)

50
Q

External genitalia are undifferentiated until about week ____. They are phenotypically differentiated by about week _____.

A

12
20

51
Q

What are the three sets of primordia (external genitalia) found at week 6?

A
  1. Urethral (urogenital folds)
  2. Labioscrotal swellings
  3. Gentical tubercle (phallus)
52
Q

Under the influence of testosterone - what happens to the following?
-Genital tubercle
-Urethral folds
-Labioscrotal folds

A

-Genital tubercle: enlarges, forms the glans of penis
-Urethral folds: fuse to form the ventral surface of the penis (encloses penile urethra)
-Labioscrotal folds: fuse to form the scrotum

53
Q

In the absence of testosterone (or lack of tissue response to testosterone), the embryonic folds remain

A

Unfused

54
Q

Under NO influence of testosterone - what happens to the following?
-Genital tubercle
-Urethral folds
-Labioscrotal folds

A

-Genital tubercle: becomes clitoris
-Urethral folds: becomes labia minora
-Labioscrotal folds: labia majora

55
Q

What is hypospadias?

A

Disorder where irethra found on inferior (ventral) surface of penis instead of glands

56
Q

What causes hypospadias?

A

Incomplete fusion of urethral folds

57
Q

What is epispadias?

A

Disorder when urethral opening is on the DORSUM of penis

58
Q

What is epispadias usually associated with?

A

Bladder exstrophy (Ventral body defect - bladder inside out, sticks out of abdominal wall)

59
Q

What is 46 XY DSD?

A

XY genotype w/ ambiguous external genitalia or variable phenotypic female-like external genitalia

Testicular tissue may be present

60
Q

What usually causes 46 XY DSD?

A

A reduction in male hormones in development
OR
Tissues don’t respond to androgens (insensitivity)

61
Q

What is 46 XX DSD?

A

XX genotype
Ambiguous or phenotypic male-like external genitalia

62
Q

What are the phenotypic characteristics of 46 XX DSD?

A

Clitoris may be enlarged
Labia may be partially or completely fused

63
Q

What is 46 XX DSD due to exposure of XX fetus to excessive androgens?

A

-Occurs when pregnant individuals produce or are exposed to abnormal amounts of androgens

64
Q

What is Conginital adrenal hyperplasia (CAH)?

A

Fetal adrenal gland produces EXCESSIVE amounts of androgens (most common cause of 46 XX intersex)

Human Structure - Block 2 - Week #5 - Flashcards - JTC (7 decks)

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