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Anatomy Week 11 BT > Embryo V > Flashcards

Embryo V Flashcards

1
Q

What early embryonic layer is of principle concern in the genitourinary system?

A
  • Mesoderm, specifically intermediate mesoderm
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2
Q

What does the intermediate mesoderm forms into?

A

Urogenital ridges that are located on either side of the vertebral column

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3
Q

What part of the urogenital ridge gives rise to for genital system?

A
  • The more medial part of the ridge along the more central part of the axis
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4
Q

What are the 3 progressive kidney states as they develop from in weeks 4-10 from intermediate mesoderm?

A
  1. Pronephros (1st)
  2. Mesonephros (2nd)
  3. Metanephros (3rd)
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5
Q

What is the pronephros?

A
  • non-functional kidney that quickly regresses
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6
Q

What is the mesonephros?

A
  • 2nd kidney but 1st funcitonal kidney
  • developes a mesonephric duct on the lateral side that drains into the cloaca of the hindgut
  • has both filtration and collecting system
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7
Q

What aspect of mesonephros regression differs in males and females?

A

Males: mesonephric duct is retained and contributes to the formation of the male genital tract

Female: duct regresses completely after a short period

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8
Q

When does the metanephros become funcitonal?

A

around week 10

Note: this is the final kidney

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9
Q

What does the mesonephric duct (Wolffian) drain into?

A

Cloaca (future urinary bladder)

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10
Q

What are the functional kidney filtration system works in the up to week 8 or 9 and what does it consist of?

A

Mesonephros

  • Bowman’s capsule
  • glomerulus
  • vascular loop
  • mesonephric dutule that drains to the duct
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11
Q

When does the the development of the final kidney begin and what does it develop from?

A
  • w4 -5 (not functional until week 10)

Develops from 2 distinct masses

  1. Ureteric Bud => MESONEPHRIC DUCT
  2. Metanephric blastema => INT. MESODERM
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12
Q

T or F: the Ureteric Bud of the mesonephric duct and metanephric blastema MUST be in good contact for a kidney to form

A

TRUE, this is the cause of the most common newborn kidney defect

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13
Q

What is the most common newborn kidney defect and what are its consequences?

A
  • Renal Agenesis

- Asymptomatic because the other kidney compensates in size

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14
Q

What part of the kidney is the ureteric bud responsible for?

A
  • The drainage system
    1. Collecting Tubules
    2. Minor Calyces
    3. Major Clayces
    4. Renal Pelvis
    5. Ureter
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15
Q

What are the two most common abnormalities in ureteric developement?

A
  1. Double Ureter

2. Ectopic openings

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16
Q

What are the two different types of double ureter and their causes?

A
  • Partial: typically results from a single ureter that tried to split
  • Complete: simultaneous developement of two ureteric buds

**This is typically UNILATERAL and ASYMPTOMATIC

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17
Q

What is ectopic ureter and what is its manifestation in males and females?

A
  • one ureter opens into bladder but the other open in some other location

Females: most commonly drains to vaginal canal, urethra, or vestibule

Males: most common sites are prostatic urethra, neck of bladder, or around trigone of the bladder

**CLINICALLY SIGNIFICANT because the person has URINARY INCONTINENCE

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18
Q

What forms the functional unit of the kidney?

A
  • metanephric mass/blastema

- leads to formation of the cortex and medulla and nephron

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19
Q

What is unilateral renal agenesis?

  • Causes?
  • Frequency?
  • Symptoms?
A
  • Ureteric bud and metanephric blastema fail to develope or integrate properly –> results in the kidney never developing
  • MOST COMMON of newborn renal defects
  • Usually clinically Asymptomatic
  • More common on LEFT SIDE, more common in MALES
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20
Q

What is unilateral hypoblastic kidney?

  • Causes?
  • Frequency?
  • Symptoms?
A
  • smaller than normal kidney that is properly formed the other kidney compensates
  • SECOND most common
  • Usually Asymptomatic
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21
Q

What is Supernumerary Kidney?

  • Causes?
  • Frequency?
  • Symptoms?
A
  • caused by splitting of the metanephric blastema
  • Rare
  • Asymptomatic
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22
Q

What is polycystic Kidney Disease?

  • Causes?
  • Symptoms?
A
  • Collecting ducts dilate to form fluid-filled cysts (appearance manifested by end of trimester 3)
  • Total Renal Failure after birth
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23
Q

What is bilateral renal agenesis and its consequences?

- symptoms?

A
  • Kidneys don’t form
  • ONLY cause of OLIGOHYDRAMNIOS (lack of enough amniotic fluid), because the fetus can swallow but not excrete fulid
  • Usually accompanied by Potter Sequence and Hypoplastic lung
  • Usually stillborn
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24
Q

What is Potter Sequence and what causes it in Renal Bilateral agenesis?

A
  • Pulmonary Hypoplasia
  • Limb Defects
  • Facial Deformities

This is secondary to oligohydramnios

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25
Q

What is the final position of the kidney in the adult and what causes its ascent?

A
  • T12-L3

- diminution of the body curvature and differential growth of the body in the lumbar and sacral regions

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26
Q

What is pelvic (ecotopic) kidney?

  • causes?
  • Symptoms?
A
  • kidney fails to ascend and remains in the pelvic cavity

- asymptomatic (unless the kidney undergoes rotation causing ureter knot)

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27
Q

What is horshoe kidney?

  • causes?
  • Symtoms?
A
  • kidneys get to close while passing through the arterial fork and fuse
  • Get stuck on IMA
  • Asymptomatic
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28
Q

What divides the hindgut and what spaces are created as a result of this division?

A
  • Urorectal septum (mesoderm)

Cloaca is divided into:

  • Anorectal Canal
  • Urogenital sinus
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29
Q

What cloaca derivative gives rise to the bladder?

A

Urogenital SInus

30
Q

What do the superior, middle and inferior parts of the urogenital sinus give rise to?

A

Upper: allantois (connects to yolk sac)
Middle: bladder
Inferior: Urethra (all of female, most of male) and male prostate

31
Q

T or F: both mesonephric ducts and ureters arise from the same structure

A

False, the uteric bud arises from the mesonephric duct, the uteric bud then gives rise to the ureters

32
Q

What is the relationship of the mesonephric ducts to the ureters and what is the adult derivative of the mesonephric duct?

A
  • Mesonephric duct = loops around the urethra in a downward facing U shape
  • Vas Deferens
33
Q

How do gonads get to the medial part of the urogenital ridge?

A
  • Migration of Primordial Germ Cells from the allantios along the connecting stalk to the medial part of the urogenital ridge
34
Q

T or F: by week 4-10 you can determine whether your baby is a boy or a girl

A

False, w4-7 is the indifferent stage of development gonads can’t be distinguished as male or female

***Until w11-12 external genitalia won’t be formed meaning it can’t be detected on ultrasound

35
Q

What are the 3 important components of the indifferent gonad?

A
  1. Primordial Germ Cells (PGCs)
  2. Primary Sex Cords
  3. Two duct systems
36
Q

What do the primary sex cords hold and what do they become at puberty in males and females?

A
  • PGCs
    Males:
    Seminiferous Tubules (after they hollow out and lengthen)

Females:
Primordial (1st gen.) Follicles (after they break up into small segments)

37
Q

What does the mesonephric duct do in females?

A

Nothing, it regresses

Mesonephtic duct = Wolffian duct ~ WOLFMAN duct only retained in males

38
Q

What does the paramesonephric duct give rise to in females?

A

Genital Tract (uterine tube, uterus, upper vaginal canal)

39
Q

When is sex determined?

A

7th week

40
Q

What is the timing and sequence of the steps required to make testis?

A
  • SRY gene on Y chromosome triggers:
    1. TDF - Testis determining factor which stimulates LEYDIG and SERTOLI cell formation
    2. LEYDIG cells produce TESTOSTERONE (opens up sex cords to seminferous tubules)
    3. SERTOLI produces MIF (mullerian inhibiting factor) drives paramesonephrenic duct regression
    4. DHT is formed from Testosterone via 5alpha-reductase 2 enzyme
41
Q

What produces mircogenitalia or ambiguous genitalia?

A

Low levels of DHT

42
Q

What is produced by low levels of MIF?

-Physical characteristics?

A
  • Male with female characteristics (male intersexuality)

- Clitoris, rudimentary vagina

43
Q

What causes elongation and coiling of the primary sex cords to become seminiferous tubules?

A

Testosterone

44
Q

What do the mesonephric tubules form and what induces this transformation?

A
  • Forms male genital tract

- MIF induces this while getting rid of the paramesonephric duct

45
Q

T or F: like the the testi in the male, several factors are needed to induce development of the the ovary

A

False, ovary is the default in the absence of Y chromosome and TDF

46
Q

What happens to the mesonephric duct system and primary sex cords in the absence of TDF and Testoterone?

A
  • Mesonephric system regress
  • Primary sex cord degenerates
  • 2nd generation of sex cord forms
47
Q

What is housed in the 2nd generation sex cords in the female?

A
  • Primordial Follicles which themselves house primary oocytes
48
Q

What structure in the female is left in tact in the absence of MIF, and what does this structure give rise to?

A
  • Paramesonephric ducts

- Gives rise to the female genital tract

49
Q

What drives the growth of the external Genitalia and prostate gland?

A

DHT from testosterone

50
Q

What two remnnants of paramesonephric ducts are left over in the adult male?

A
  • Utriculus prostaticus (male vagina)

- Appendix Epididymis

51
Q

What does the mesonephric (wolffian duct) form?

A
  • epididymis
  • vas deferens
  • seminal vesicle
52
Q

What drives the development of the paramesonephric duct and what does it develop into?

A
  • Estrogen

Develops into:

  1. Uterine Tube
  2. Uterus
  3. Cervix
  4. Upper Vaginal canal
53
Q

What structure in the female has a DUAL DEVELOPMENT and how is this so?

A
  • Vaginal canal

Upper Vaginal Canal:
- paramesonephric ducts (mesoderm)

Lower Vaginal Canal:
- urogenital sinus (endoderm)

54
Q

What are the only two small remnants of the mesonephric ducts in the female?
- When do they become clinically significant?

A
  1. Epo/paraophoron on ROUND ligament
  2. Gartner’s cyst - near vaginal canal
  • Only clinically significant when they get infected
55
Q

T or F: the paramesonephric tubercle derives from the paramesonephric duct

A

False, it develops from the urogenital sinus (endoderm)

56
Q

What hollows out to become the cavity of the uterus, cervix, fornices, and upper vaginal canal?

A
  • uterovaginal complex formed by the fusion of the paramesonephric ducts and uterine septum
57
Q

What is the most common defect in uterine developement?

A

Bicornate Uterus

  • two ducts failed to fuse and you end up with a double horned uterus
58
Q

What are the 3 components of indiffernent genitalia?

A
  • Genital Tubercle
  • Urogenital Folds
  • Lateral Genital Swellings
59
Q

In males, what drives differentiation of the 3 indifferent structures and what do these structures become?

A

DHT drives differentiation of genitalia

  • Genital Tubercle –> Glans of the Penis and part of the Shaft
  • Urogenital Folds —> Shaft of the Penis (folds fuse at midline)
  • Lateral Genital Swellings —> Scrotum (swellings fuse at midline)
60
Q

In the females, what drives differentiation fo the 3 indifferent structures ans what do these structures become?

A

Estrogen

  • Genital Tubercle - clitoris
  • Urogenital Folds - labia minora (by not fusing)
  • Lateral Genital swellings - labia majora (by not fusing)
61
Q

What developmental defect presents with abnormal openings on the ventral aspect of the scrotum, shaft of penis, or glans penis?
- Cause?

A

Hypoplasia

  • Lateral Genital Swellings and/or Urogenital folds fail to fully fuse at the midline
62
Q

What diseases presens with failure of tissue to fuse on the dorsal aspect of the penis and/or holes in the bladder?

A

Epispadias - openings on dorsal penis
Exstrophy of bladder - open bladder

  • If it is confined to the penis then those tissues failed to form
  • If it extends to the bladder, then the lateral body folds failed to fuse
63
Q

What guides the gonad to the scrotal sac?

A
  • gubernaculum (band of CT)
64
Q

What is the processus vaginalis?

A
  • an extension of parietal peritoneum through the inguinal canal and scrotal sac
65
Q

What remains of the obliterated processus vaginalis in an adult male?

A
  • Tunica vaginalis - serous membrane that reduces friction
66
Q

What could be the cause of a bowel herniation into a newborn’s scrotum? what has happened?

A
  • Congenital Indirect Inguinal Hernia

- A piece of bowel has herniated into a patent PROCESSES VAGINALIS

67
Q

What is hydocele and varicocele, and how can they be diffentiated?

A
  • Hydrocele and Varicocele both result from fluid filling the serous cavity of the tunica vaginalis
  • Hydrocele is clear serous fluid (transmits light)
  • Varicocele is blood (no light transmission)
68
Q

What is female intersexuality?

-causes?

A
  • Internal Female reproductive organs, Female 46, XX genotype, but external genitalia is masculinaized (hypertrophy)

Cause: congenital adrenal hyperplasia - production of excess androgen

69
Q

What is male intersexuality?

-causes?

A
  • male 46,XY genotype but have female-like genitalia with micropenis and microscrotum

Cause: 5alpha-reductase deficiency or low levels of MIF

70
Q

What causes Androgen Insensitivity Syndrome?

-causes?

A
  • Male 46,XY genotype, with testis in labia majora or inguinal canal
  • Female genitalia extenally with rudimentary vagina
  • Present as normal females

Cause: mutation in androgen receptor (AR) gene that renders it inactive

Anatomy Week 11 BT (8 decks)

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