EMBRYOLOGY

Pediatric GU Review

UCSD Pediatric UrologyGeorge Chiang MD

Sara Marietti MD

Outlined from The Kelalis-King-Belman Textbook of Clinical Pediatric Urology 2007

(not for reproduction, distribution, or sale without consent)

Timeline Quiz I0 4 8 12 16 20 24 28 32 36

Anterior Abdominal Wall

Renal Vasculature

Pronephros

Mesonephros

Kidney

Ureter

Calices

• What is Pronephros?

Transitory, nonfunctional kidney, analogous to that of primitive fish. First evidence seen in the 3rd week and completely degenerates by the 5th week

• What is Mesonephros?

Second kidney. Transient but serves as the excretory organ for the embryo while the definitive kidney the metanephros begins its development

Timeline Quiz II0 4 8 12 16 20 24 28 32 36

Cloaca

UG Sinus

Bladder

Primitive Gonads

Gonadal Ridge

Ovary/Testes

• What is cloaca?clo·a·ca (klō-ā'kə) pronunciationn., pl. -cae (-sē').

1. A sewer or latrine. 2. Zoology. 1. The common cavity into which the intestinal, genital, and urinary tracts open in vertebrates such as fish, reptiles, birds, and some primitive mammals. 2. The posterior part of the intestinal tract in various invertebrates.

Timeline Quiz III0 4 8 12 16 20 24 28 32 36

Phallus

Vagina/Uterus/Fallopian tubes

Prostate, SVs, Vas Deferens

Match the Teratogen

Rubella Virus

Cocaine

Oral Contraceptives

ACE Inhibitors

Anticonvulsants

Maternal Hyperthermia

Ethanol

Progestational Agents

Eagle-Barrett Syndrome,hypospadias, hydronephrosis

Micropenis

Hypospadias, cryptorchidism

Hypospadias,hydronephrosis

Renal Dysplasia

Hypospadias, ambiguous genitalia, cryptorchidism

Ambiguous genitalia

Hypospadias

Adrenal Development

Adrenal Medulla or Adrenal Cortex

Derived from migrating ectodermal neural crest cells

• Where is adrenal cortex derived from?

Primitive mesoderm medial to the urogenital ridge; 4th gestational week

• Cortex develops 2 distinct areas by 8th week– Central area(fetal zone)– Outer Rind (adult cortex) GFR

• Adrenal glands increase in size from 2nd/3rd month from 5 mg-->80 mg but lose 1/3 weight in first 2 weeks of life secondary to fetal zone involution

Adrenal Development

Adrenal Medulla or Adrenal Cortex

Cells may migrate to celiac plexus, broad ligament, ovarian/spermatic vessels or around kidneys/ueterus

Hypothalamic-pituitary-adrenal axis

Placental Estrogens

Fetal Cortisol

Inactive Cortisone POMC

mRNA

ACTH

Adrenal Cortisol

Fetal HPA Axis??

Hypothalamic-pituitary-adrenalAxis

• Hypothalamus releases CRH 8-12 weeks

• Fetal glucocorticoid stimulates release of placental CRH

• Overall upregulation of fetal cortisol is essential for survival

Adrenal Development

Adrenal Medulla or Adrenal Cortex

In fetus produces large amounts of DHEA after 1st trimester

• Adrenal medulla– Chromaffin cells can be found throughout

medulla and sympathetic chain– Organ of Zuckerkandl– Go over pg 238 of adrenal handout

• Who is Zuckerkandl?

Emil Zuckerkandl (September 1, 1849 in Raab, Hungary – May 28, 1910 in Vienna) was a Hungarian-Austrian anatomist. Educated at the University of Vienna (M.D. 1874). In 1875 he became privat-docent of anatomy at the University of Utrecht, and he was appointed assistant professor at the University of Vienna in 1879, being made professor at Graz in 1882. Since 1888 he has been professor of descriptive and topographical anatomy at the University of Vienna.

Zuckerkandl has contributed many monographs to medical journals. Among his works the following may be mentioned: "Zur Morphologie des Gesichtschädels" (Stuttgart, 1877); "Über eine Bisher noch Nicht Beschriebene Drüse der Regio Suprahyoidea" (ib. 1879); "Über das Riechcentrum" (ib. 1887); and "Normale und Pathologische Anatomie der Nasenhöhle und Ihrer Pneumatischen Anhänge" (Vienna, 1892).

Match the Condition

Retrocaval ureter

Renal Agenesis

ADPKD

ARPKD

Multicystic dysplastic kidneys

Pelvic Ectopia

Horeshoe Kidney

Supernumerary Kidney

Pronephros fails to develop and mesonephros fails to develop

Failure of renal ascent

Persistence of R subcardinal vein as IVC

Ascent arrested by IMA

Enlargement of collecting ducts with “sunburst pattern”

Early ureteral obstruction or faulty ureteral bud 1 in 3000 pregnancies

Division of ipsilateral ureteral bud

Cysts form thru abnormal collecting duct branching

Renal Vasculature and Kidney

Anterior wall/Bladder/Urethra

• Exstrophy– Failure of secondary mesoderm to cover

infraumbilical abdominal wall– Premature rupture of the cloacal

membrane

Cloacal Exstrophy week

Classic Exstrophy week

5th

7th

• When does the cloaca develop?

First 3 weeks

Notch is filled with mesenchyme to form urorectal septum

This pushes caudally and divides cloaca into primitive rectum and UG sinus

5th week

• 7th week ureters empty into bladder

• Mesonephric ducts shift caudad in UG sinus and lie close to each other

• Ureters shift cephalad and laterally into bladder

• 8th week bladder muscle begins to appear• 9th week bladder expands into sac • 12th week bladder epithelium becomes transitional• Urachal anaomalies can occur from mesodermal

failure• Bladder duplications are usually caudal duplication

• What is Eagle Barrett Syndrome?– A) Triad syndrome– B) Prune Belly Syndrome– C) Deficient abdominal musculature, UDT,

urinary tract anomalies– D) All of the above

• What are the theories behind Prune Belly?

1) Faulty mesodermal development during the 6th to 12th week

2) Deformation of abdominal wall by distended viscera or increased pressure

3) Primary abdominal wall defect resulting in decreased pressure

Ureteral Development

• How does ureteral atresia develop?

• How does duplication occur?

• Where does the ureteral bud develop?

Relative or total ischemia during kidney migration

Multiple ureteral buds develop

Distal end of mesonphric duct or Wolffian duct

Ureteral Development

• How does the trigone develop?

Formed by integrating the upper portions of the common excretory ducts and a small portion of the mesonphric ducts

Gonads, genital ducts,genitalia

Week Male Female

6th Indifferent Gonad Indifferent Gonad

10th Ext genitalia are becoming more visible

11th Prostate arises Urethral Glands

12th Littre’s glands Secondary ovarian cortex

Gonads, genital ducts,genitalia

Week Male Female

13th SVs start to develop

Mesonephric ducts regress

14th Penile shaft elongates

16th Uterus forms

20th Prepuce completely formed

Vaginal lumen completely formed

Gonads, genital ducts,genitalia

Week Male Female

24th Efferent ductules of epididymis

Tunical albuginea of ovary forms

28th PV has herniated thru abdomen

Gub fuses with lateral uterus

Embryological Remnants

• Male Mullerian Remnants?

Appendix Testes, Prostatic Utricle

•Female Wolffian Remnants?

Epoophoron, Paraoophoron, Gartner’s cyst

• What is a utricle?

sau·tri·cle 1 (ytr-kl)n.1. A membranous sac contained within the labyrinth of the inner ear and connected with the semicircular canals.2. Botany A small bladderlike one-seeded indehiscent fruit, as in the amaranth.

Embryological Homologues

UG Sinus

Genital Tubercle

Genital Folds

Genital Swellings

Clitoris

Labia Minora

Urethra/Upper Vagina

Labia Majora

Glans Penis

Scrotum

Urethra/Penile Shaft

Prostatic Urethra/Prostate

MORE QUESTIONS

Classic features of prune-belly syndrome include dilated tortuous ureters, atretic anterior abdominal wall musculature, and undescended testes. In addition, there is usually hypoplasia of the:

a) Radius

b) Tibia

c) Prostate

d) Vas deferens

e) epididymis

In a patient with an absent right kidney and a left pelvic kidney, the right adrenal is:

a) Absent and the left is adjacent to the upper pole of the kidney

b) Absent and the left is in the normal anatomic position

c) In the normal anatomic position and the left is adjacent to the upper pole of the kidney

d) In the normal anatomic position and the left is in the normal anatomic position

e) In the normal anatomic position and the left is absent

During embryologic development, the duct that passes through the umbilicus is the:

a) Mullerian

b) Wolffian

c) Gartner’s

d) Luschka

e) Omphalomesenteric (vitelline)