Embryology

Question 1

Intermediate mesoderm will give rise to:

Answer 1

GU

Question 2

Intermediate mesoderm will later be called:

Answer 2

urogenital ridge (2, on either side of midline)

*name change once arranged cranial-caudally

Question 3

How does GU develop in earlier stages?

Answer 3

cranial-caudal, along full length of UG ridge

Question 4

How do gonadal/genital parts develop in earlier stages?

Answer 4

along medial + central portion of UG ridge

Question 5

What are the 3 stages of kidney development (start in 4th week)?

Answer 5

1. pronephros (non-functional, disappears early)
2. mesonephros (functional from week 5 to ~week 9)
3. metanephros (functional begining in 2nd trimester)

Question 6

mesonephros consist of:

Answer 6

nephron

mesonephric duct

Question 7

During kidney development, as _____ portion is developing, ____ portion is regressing.

Answer 7

caudal

crainial

Question 8

Separate draining systems that exist during kidney development?

Answer 8

mesonephrus

Question 9

Mesonephric duct is aka

Answer 9

Wollfian duct

Question 10

What portion of the mesonephros does NOT regress?

Answer 10

mesonephric duct

Question 11

What are the 2 parts of metanephros?

Answer 11

ureteric bud (grows out of mesonephric duct)

metanephric blastema/mass

Question 12

Metanephric duct drains into

Answer 12

cloaca

Question 13

What would causes congenital absence of kidney on 1 side?

Answer 13

ureteric bud or metanephric blastema/mass fail to develop

Question 14

Ureteric bud develops to form:

Answer 14

calyces, pelvis, ureter

all the parts that drain urine!

Question 15

Doubling of ureteric bud results in:

Answer 15

doubling of ureters

Question 16

What is an ectopic ureter?

Answer 16

ureter develops abnormally and misdirects urine to area other than bladder, causes incontinence
(Female commonly = vagina, urethra, vestibule; Male commonly = bladder neck, prostatic urethra)

Question 17

What structure forms the nephron?

Answer 17

metanephric blastema (mass)
**forms cortex/medullary

Question 18

Metanephric blastema develops from:

Answer 18

metanephric caps on ureteric buds

Question 19

3 conditions related to abn renal development?

Answer 19

unilateral renal agenesis (most commonly M + L side)

unilateral hypoplastic kidney

supernumerary kidney

Question 20

What condition results from bil renal agenesis, and why is it so bad?

Answer 20

Potter’s sequence
Most common cause of oligohydroaminos (fetus takes in amniotic fluid, but can’t send it back out)

**also causes facial abn, clubbing of hand, hypoplastic lungs

Question 21

What causes the movement of kidneys during development?

Answer 21

“body grows out from under them”

some upward pull PLUS they do not descend along with pelvis + trunk, which grow downward and disproportionately (relative to upper trunk)

Question 22

What causes a “pelvic kidney?”

Why would this be a problem?

Answer 22

kidney is “caught” and descends with the pelvis abnormally

if it were to rotate, ureter may become obstructed

Question 23

What is a horseshoe kidney?

Answer 23

renal poles fuse, causing grossly abn but functionally normal kidney; get stuck at inferior mesenteric artery

Question 24

What divides UG sinus from anorectal canal?

Answer 24

urorectal septum

Question 25

What was the original space which is divided into the UG sinus + anorectal canal?

Answer 25

cloaca (hindgut)

Question 26

The urogenital sinus forms:

Answer 26

bladder, urethra, prostate, lower vagina

Question 27

What layer is distal urethra originally derived from?

Answer 27

ectoderm

Question 28

How does the positioning of the ureter and vas deferens develop?

Answer 28

- -mesonephric duct and ureteric bud eventually separate - -the ureteric duct connects directly/independently to the posterior bladder - -mesonephric duct descends downward, but remains hooked over the ureter

Question 29

What path do primordial germ cells talk to reach gonad?

Answer 29

1. originate in yolk sac 2. migrate through connecting stalk 3. pass through dorsal body wall 2. populate gonads (bilaterally at urogenital ridge)

Question 30

What does the yolk sac originate from?

Answer 30

extra-embryonic tissue

Question 31

When do germ cells migrate?

Answer 31

4th-6th week

Question 32

What occurs once the germ cells reach the gonads (male vs female)?

Answer 32

males: remain dormant until puberty, then meiosis female: immediate meiosis I

Question 33

What occurs to the gonad following primordial germ cell migration?

Answer 33

remains in "indifferent" stage, does not have M or F characteristics

Question 34

What are the 3 components of an indifferent gonad?

Answer 34

1. primordial germ cells present 2. primary sex cords (grow from surface epith) 3. 2 duct system (mesonephric + paramesonephric)

Question 35

What effect does the absence of testerone have on sex cords?

Answer 35

primordial follicles = regress, break into segments

Question 36

What effect does testosterone have on sex cords?

Answer 36

Become semeniferous tubules = length, coil, form lumen

Question 37

Each follicle in an ovary contains:

Answer 37

one primordial germ cell

Question 38

Wolffian ducts form... | Mullerian ducts form...

Answer 38

M genital tract F genital tract **only keep 1 duct

Question 39

4 classic proteins/hormones in 7,8,9th week, which drive male development:

Answer 39

1. Testes determining factor 2. T (Leydig cells) 3. MIF (Sertoli cells) 4. DHT (requires 5aR)

Question 40

Early production of ___ drives male development.

Answer 40

T

Question 41

Where does testes determining factor develop?

Answer 41

short arm of Y chromosome | SRY gene codes for TDF

Question 42

Why is it easier to develop an ovary?

Answer 42

develop by the ABSENCE of Y chromosome, which = absence of TDF

Question 43

What is the function of MIH?

Answer 43

secreted by testes to drive suppression fo paramesonephric ducts

Question 44

What drives female duct development?

Answer 44

E

Question 45

Paramesonephric ducts ultimately become:

Answer 45

uterine tubes uterus upper part of vagina (two portions fuse) (all from mesoderm)

Question 46

What layer does the lower part of the vagina develop from?

Answer 46

ectoderm

Question 47

Remnant of mesonephric duct which may become infected?

Answer 47

Gertner's cyst

Question 48

Congenital abn are usually resultant from:

Answer 48

abn fusion of paramesonephric ducts

Question 49

How does male external genitalia develop from the indifferent stage?

Answer 49

1. genital swellings fuse into midline = scrotum 2. genital tubercle forms glans 3. UG fold fuses along ventral shaft

Question 50

How does female external genitalia develop from the indifferent stage?

Answer 50

1. genital tubercle forms clitoris 2. genital swelling becomes labia majora 3. UG folds form labia minora

Question 51

Hypospadias is caused by... | Epispadias is caused by...

Answer 51

failure of UG folds to fuse: ventrally = hypo dorsally = epi (can extend along abd)

Question 52

How/when do testis/ovary migrate?

Answer 52

in last trimester, ovary/testes departs from UG ridge in lateral body wall

Question 53

What is processus vaginalis?

Answer 53

piece of peritoneum captured during descent, remains in scrotum with testis (later called tunica vaginalis, reduces ball friction)

Question 54

What is the gubernaculum?

Answer 54

CT that = pathway of testis into scrotum

Question 55

What does a patent processus vaginalis cause?

Answer 55

congenital indirect inguinal hernia

Question 56

What does excess fluid of tunica vaginalis cause?

Answer 56

hydrocele

Question 57

Ovarian tissue with masculinization of female ext genitalia =

Answer 57

female intersexuality due to congenital adrenal hyperplasia

Question 58

Testicular tissue with stunted male ext genitalia =

Answer 58

female intersexuality caused by inadequate T/MIH by testes

Question 59

XY but develops testes located within labia majora, has female ext genitalia =

Answer 59

androgen R mutation