pedi gu review embryology i
TRANSCRIPT
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)