Embryology of urogenital system Flashcards
1
Q
From what tissue layer does the urinary and genital tracts arise?
A
- intermediate mesoderm
2
Q
True/ False
The intermediate mesoderm separates the lateral and paraxial mesoderm, and will form to give rise to the urogenital ridge.
A
true
3
Q
What are the three phases of kidney development?
A
- pronephros
- mesonephros
- metanephros
4
Q
What features best characterize the pronephros time frame?
A
- regress at 5 weeks
- begins development in cervical region of embryo
- fully contained in embryo; essentially useless for secretion of waste out of embryo
5
Q
Which features characterize the mesonephros development from 6-10 weeks?
A
- time functional glomeruli form
- mesonephric tubes form off the mesonephric duct
- mesonephric duct opens into cloaca
- ureteric bud begins formation
6
Q
What structures are derived from the ureteric bud?
A
- collecting ducts
- major/minor calyces
- major calyces
- renal pelvis
- ureters
7
Q
What structures does the mesonephric duct system give rise to?
A
- ductus deferens
2. vestigial female structures
8
Q
What features characterize the metanephros phase of development?
A
- ureteric bud forms the metanephric duct which developems into ureter
- metanephrogenic blastema forms the renal tubules
- glomerulus forms
9
Q
What is the primary purpose of the metanephros (in utero)?
A
- provides supplementation to amniotic fluid
2. no filtering; performed by placenta
10
Q
What is one way that oligohydramnios can occur?
A
- obstruction to emrbyo urethra
2. kidney agenesis
11
Q
Renal agenesis can result in both oligohydramnios and fetal compression, what are further effects of both of these symptoms?
A
- pulmonary hypoplasia
- altered face (deformity)
- club foot, from compression; lack of space
- breech presentation
12
Q
What is an accessory renal vessel and is it problematic?
A
- extra vessel that supplies the kidney.
2. only problematic if it enters at upper/lower pole of kidney. Entrance at hilum has no negative effects
13
Q
What is an aberrant accessory renal vessel?
A
- vessel that enters kidney at upper/lower poles
14
Q
What negative side effects can an aberrant renal vessel have?
A
- obstruct portions of the ureters
- reduce glomerular pressures–> systemic effects
- all vessels arise from abd aorta
15
Q
What is renal fusion?
A
- when the kidneys develop, they fuse together preventing their rotation of hilum to midline.
- generally unnoticed
16
Q
Horseshoe kidneys are best described as what?
A
- kidneys that fuse into shape of horsehoe.
- generally catch on IMA while rising from the pelvic caivty
- then can receive blood supply from iliac or middle sacral artery
17
Q
What are commone types of ectopic kidneys?
A
- horseshoe
2. pelvic kidney
18
Q
Where will most ectopic kidneys receive blood supply?
A
- potentially abd aorta, unless trapped in the pelvis.. Then from common iliac artery or middle sacral artery
19
Q
What is a Wilmer’s Tumor? (this does not refer to the pig in Charlotte’s web; that’s Wilber)
A
- benign kidney cancer in newborn
2. caused by mutation to WT1 gene
20
Q
The cloaca separates to form what during urinary bladder development?
A
- anteriorly: forms bladder and urogenital sinus
2. posteriorly: forms rectum and anal canal
21
Q
The anterior section of the cloaca further develops to form what structures?
A
- lower urogenital tract
- prostate and penile urethra
- lower vaginal urethra
22
Q
What are the borders of the trigone?
A
- ureters entrance mark the top border
- mesonephric ducts (form ductus deferens in males) mark the inferior most point
- mesonephric migration inferiorly expands the bladder and moves the vas deferens out of the bladder into the urethra for ejaculation
23
Q
How does the body correct the small size of the bladder, and prevent semen from entering into the urinary bladder?
A
- the mesonephric ducts migrate inferiorly to the ureters causing the bladder to expand
- mesonephric ducts then insert into the urethra just inferior to the internal urethral sphincter
24
Q
What must the bladder be continuous with in order to remove urine into the umbilical cord?
A
- continuous with the allantois which becomes the urachus
25
What is a urachal fistula?
1. malformation where the urachus does not close and urine is able to leak from the bladder out of umbilicus
26
What is a urachal sinus?
1. urachus is patent to the umbilicus, but has closed some portion that reaches to the bladder. Small amount of urine able to leak, but will not continue to leak
27
What is a urachal cyst?
1. small pockets of urine that are trapped, when the urachus began to close.
2. these become infectious and painful.
3. Present as hard "pockets" from umbilicus inferiorly
28
How much of the genital system has developed at week 1-6?
1. none, still undifferentiated embryo
29
What genital features are present at week 7?
1. phenotypic genital differentiation begins to take place
30
What genital features are occurring during week 12?
1. external genitalia can begin to become recognized
31
At what time is sex determined for the fetus?
1. week 20, phenotypic differentiation is complete
32
If SRY is present, it will act on the gonads to produce what structures?
1. sertoli cells which produce MIS which will degrade the Mullerian duct formation
33
If SRY is present, it will act on the testis to produce what?
1. leydig cells-->testosterone**--> wolffian ducts--> epididymis, vas deferens, seminal vesicles, ejaculatory ducts
** 5 alpha reductase is required to convert testosterone into dihydrotestosterone (DHT) more active form for phenotype differentiation
34
No SRY present will have what effect on the gonads?
1. no sertoli cells, mean no MIS secretion
2. Mullerian duct will form and give rise to:
- - uterine tube (fallopian), uterus, vagina
35
No SRY present will have what effect on the ovary?
1. no leydig cells produced
| 2. minimal amounts of testosterone produced "none"
36
What will the mesonephric duct later develop into?
1. vas deferens
37
What will the paramesonephric duct later develop into?
1. uterine tubes
2. uterus
3. cervix
4. upper 1/3 of vagina
38
What tissues are required for development of gonads?
1. intraembyronic coelom epithelium
2. intermediate mesoderm
3. primoridal germ cells
39
What will the intraembryonic coleom epithelium ultimately rise to form?
1. cells that line the coelomic cavity and gonadal primordium.
2. originate from region overlaying the ventral-medial surface of mesonephros
40
What does the intermediate mesoderm give rise to in terms of development?
1. gives rise to pro-, meso-, metanephros development
| 2. develops the kidneys, gonads and associated tracts
41
What do the primordial germ cells give rise to?
1. sex determination of the embryo
| 2. migrate to the genital ridge via the hindgut and dorsal mesentery
42
What will the phallus develop into?
1. penis or clitoris
43
What will the urogenital fold develop into?
1. labis minora, or penile shaft
44
What will the labioscrotal fold develop into?
1. labis majora, or the scrotum
45
What does the presence of AMH or MIF do for development?
1. cause degeneration of the paramesonephric ducts (vagina)
| 2. promote formation of testosterone and DHT
46
What does the presence of DHT lead to?
1. paramesonephric ducts regress
2. urogenital sinus closes--> urethra, prostate
3. genital tubercle--> penis
4. labioscrotal closes--> scrotum
47
What does lack of DHT lead to ?
1. regression of mesonephric duct
2. urogenital sinus remains open--> lower vagina, vestibule
3. genital tubercle--> clitoris
4. labioscrotal remain open--> vulva
5. paramesonephric duct open--> uterus, upper vagina, oviductus
48
What leads to the formation of the ductus deferens and epididymis?
1. expression of AMF, or MIF
| 2. testosterone converts the mesonephric ducts into these structures
49
What is Mullerian Agenesis?
1. a failure of paramesonephric duct development
| 2. no uterus, uterine tube, upper vagina formation
50
What is MRKH. Mayer-Rokitansky-Kuster-Hauser Syndrome?
Mullerian Agenesis
51
Hypospadias?
1. incomplete fusion of urethral folds
2. urethra opens on ventral aspect of penis
3. inadequate androgen production or inadequate recptor sites for DHT
52
Epispadias?
1. incomplete fusion of urethral folds
| 2. urethra opens on dorsal aspect of penis
53
What are the types of hypospadias and how are they named?
1. named for region that urethra opens on the penis
2. names
- glandular ( most normal)
- penile
- penoscrotal
- perineal (more vaginal like)
54
What is female intersex?
1. female (XX, 46) genotype
2. has adrenal hyperplasia leading to ambiguous external genitalia formation
3. contain normal ovary, uterine tubes, uterus
4. clitoromegaly or labioscrotal fold fusion
55
What is the phenotypic presentation of female intersex (XX, 46)?
1. clitoromegaly (minor)
| 2. labioscrotal fold fusion (major)
56
What is the best way to characterize Androgen Insensitivity Syndrome (AIS)
1. male genotype with female external genitalia
| 2. testis develop but are non-functioning leading to default genitalia development
57
What genitalia are common to form is Androgen Insensitivity Syndrome (AIS)?
1. female external
| 2. breasts later with estradiol production
58
What is the role of 5-alpha reductase?
converts testosterone to dihydrotestosterone (DHT) the more active form to promote growth or male external genitalia.
59
What can occur with 5-alpha reductase deficiency?
1. underdeveloped male genitalia, depends on amount of reductase that was or was not formed.
60
Are the ductus deferens or epididymis, derivatives of the mesonephric ducts, affected with a 5-alpha reductase deficiency?
1. no, mesonephric duct development is based on presence of testosterone, not DHT
