Session 10 A Embryology

Question 1

Describe the 3 sets of excretory organs

Answer 1

Pronephros
Mesonephros and duct
Metanephros

Question 2

Features of the development of the kidney system

Answer 2

Organisation of intermediate mesoderm

3 systems develop sequentially

Disappearance of one system marks the onset of development of the next developmental stage

Question 3

1st kidney system forms in the

Answer 3

Cervical region

The Pronephros

Question 4

What are these

Answer 4

Question 5

Intermediate mesoderm goes on to form

Answer 5

Pronephros

Mesonephros

Metanephros

Question 6

Answer 6

Question 7

What day does the intermediate mesoderm start to form the primitive kidney system

Answer 7

Day 28, pulls down

Question 8

Importance of Pronephros

Answer 8

First kidney system, never functions in humans

Pronephric duct extends from the cervical region to the cloaca, drives the development of the next stage (Mesonephros)

Question 9

Mesonephric ducts develop caudal to the

Answer 9

Pronephric region

Question 10

Embryonic kidney is made up of

Answer 10

Mesonephric tubules and duct

Question 11

What is lacking in the Mesonephros

Answer 11

No water conserving function

Question 12

Why do we need to know about the Mesonephros

Answer 12

Important in development of male reproductive system

Spouts the ureteric bud which induces development of the definitive kidney

Question 13

What forms Metanephros

Answer 13

Undifferentiated intermediate mesoderm, caudal to the Mesonephros

Ureteric bud induces development of the true kidney, Metanephros in this tissue

Question 14

What does this show

Answer 14

Question 15

What drives the development of the definitive kidney

Answer 15

Ureteric bud

Question 16

The collecting system is derived from the

Answer 16

Ureteric bud itself

Question 17

The excretory component is derived from the

Answer 17

Intermediate mesoderm under the influence of the ureteric bud

Question 18

Describe the ascent of the kidney

Answer 18

Metanephric kidney first appears in the pelvic region

Undergoes an apparent caudal to cranial shift, crossing the arterial fork formed by vessels returning blood from the fetus to the placenta

Question 19

What does this show

Answer 19

Question 20

Abnormalities in ureter development

Answer 20

Ureteric bud fails to interact with the intermediate mesoderm (renal agenesis)

Migration goes awry

Duplication defects

Ectopic ureter

Cystic disease

Question 21

Structural abnormalities related to migration

Answer 21

Question 22

Duplication defects and ectopic urethral orifices

Answer 22

Splitting of ureteric bud

Partial or complete

Symptomatic consequence is ectopic ureteral opening

Question 23

to begin with, the reproductive tract, urinary tract and GI tract share a common

Answer 23

Caudal opening

Question 24

hindgut ends in

Answer 24

A dilated structure- the cloaca

Closed to the outside by the cloacal membrane- no mesoderm

Question 25

Urogenital sinus is created from

Answer 25

Hindgut by urorectal septum

Question 26

Urogenital sinus is continuous with

Answer 26

Umbilicus

Question 27

Urachus closes to become the

Answer 27

Medial umbilical ligament

Question 28

What is this

Answer 28

Question 29

Features of urogenital sinus

Answer 29

Superior part connects to umbilicus Majority differentiates to form the urinary bladder Inferior part develops into the urethra (sex differences in structural development)

Question 30

Lower part of the urogenital sinus (urethra) forms what in men and women

Answer 30

Women: all urethra, clitoris Men: membranous and prostatic urethra, spongy tissue of penis

Question 31

Female development vs men

Answer 31

Female: MD reach UGS, UB sprouts from MD, UGS begins to expand, MD regresses Men: MD reach UGS, UB sprouts from MD, UGS begins to expand, smooth musculature begins to appear, UB and MDs make independent openings in UGS

Question 32

The nephrogenic cord gives rise to three sets of foundational renal structures

Answer 32

Pronephros- degrade at end of week 4 Mesonephros- form the trigone Metanephros- permanent kidney

Question 33

Metanephric blastema releases

Answer 33

growth factors, these cause uteric bud to form from Mesonephric duct

Question 34

Mesonephric duct releases growth factors which cause the

Answer 34

Metanephric blastema to grow Forms ureteric stalk- renal pelvis, minor and major calyx, millions of collecting tubes Metanephric blastema- nephron

Question 35

From 5-6 weeks the

Answer 35

Mesonephric duct absorbed into bladder to form trigone

Question 36

By week 10

Answer 36

The kidney is functional and the urinary system is developed enough to secrete urine