Download kidney and ureter

DEVELOPMENT OF
the Kidneys and Ureters
Dr Rania Gabr
Objectives
• 1- Describe the stages of development of
the kidneys and ureters
• 2-Discuss the congenital anomalies of the
kidneys and ureters
Stages of Development of the kidney:
• Human kidney is developed from the
intermediate mesoderm and passes through 3
stages :
1- Pronephros
2- Mesonephros
3- Metanephros
PRONEPHROS
• Appears at 4th week. In the cervical region, the
cranial part of the intermediate mesoderm is
segmented into 7 cell clusters called
“nephrotomes”.
• Those become cavitated to form 7 “pronephric
tubules”.
• Each tubule has 2 ends:
1- The lateral end: joins to form pronephric duct.
2- The medial end: joins the coelomic cavity.
• The lower end of the pronephric ducts join
the cloaca.
• Fate of the Pronephros:
1-“Pronephric tubules: and proximal
(cranial) part of its duct degenerate
2-The caudal part of the duct persists as the
“Mesonephric duct”.
MESONEPHROS
• It appears at the 6th week as 2 bulges on
posterior abdominal wall forming ovoid
mesonephric ridges.
• It develops in the middle part of the
(Intermediate mesoderm) that lies in the
thoracic and upper lumbar region.
• It is divided into segments which become
canalised to form the “mesonephric tubules”.
• The Medial ends form the ( internal
glomeruli ) while ,
• the lateral ends join the mesonephric duct
which opens in the primitive urogenital
sinus.
Fate of the Mesonephros
• 1- Tubules:
- In Males: form the “vasa efferentia”.
– Females: form epoophoron and paroophoron.
2- Duct:
- Males:
1-Epididymis,
2-vas deferens,
3-seminal vesicle,
4-ejaculatory duct,
5-ureter trigone of urinary bladder and
6- the upper part of the posterior wall of the urethra.
In Females:
1-Duct of epoophoron (Gartener`s duct),
2-ureter and
3- trigone of urinary bladder.
At the 8th week most of mesonephric tubules
degenerate.
KIDNEY AND URETER
• The human kidney develops from 2 main
parts:
1- The ureteric bud, and
2- The Metanephros
The ureteric bud
• The ureteric bud arises as an outgrowth of
the mesonephric duct close to the
entrance of the duct at the cloaca
• The ureteric bud is responsible for the
development of the collecting system
Ureter:
• The ureteric bud elongates dorso-cranially to be in
contact with the metanephros which will form the
metanephric cap.
• The upper end of the ureter divides to form 2 – 3
major calyces, which further divide into many minor
calyces which divide into collecting tubules.
• Each collecting tubule will be covered with
a piece of the metanephric cap which form
renal vesicles which form the rest of the
nephron except the collecting tubules
which is developed from dividing ureteric
bud.
• Collecting tubules communicate with the
rest of the nephron.(canalization)
KIDNEY
Metanephros:
• It is the caudal part of the intermediate
mesoderm in the pelvic cavity.
• It forms the metanephric cap (blastema) which
divides into small masses following divisions of
the ureteric bud.
• Each mass is called renal vesicles.
• Each vesicle will form:
1234-
Bowman’s capsule,
proximal convoluted tubule,
loop of Henle and
distal convoluted tubule.
Changes of the external features of the
developing kidney:
• 1- Ascent of the kidney:
It ascends from pelvic cavity to its adult site in
the lumbar region on the posterior abdominal
wall.
This is done by the dorso-cranial elongation of
the ureter pushing the kidney.
• 2- Change of the blood supply:
During its ascent, the arterial supply of the
kidney shifts to the nearest main artery .
1- First it is supplied by the Median sacral
artery, then 2- Internal iliac, 3- Common
Iliac, and finally 4- Abdominal aorta
• 3- Loss of fetal lobulation:
• The surface of the kidney becomes
smooth
• 4- Change of the direction of the
hilum:
from anterior to medial.
CONGENITAL ANOMALIES
A- KIDNEY
• 1- Renal agenesis: Unilateral or bilateral.
2- Congenital polycystic kidney:
due to failure of communication between the
collecting tubules and rest of the nephron.
3- Pelvic kidney: due to failure of ascent.
• 4- Horse shoe kidney: due to fusion
between lower ends of both kidneys.
Ascent is arrested at level of L3 vertebra.
• 5- Rosette kidney:
Due to fusion of the upper and lower poles
• 6- Persistence of fetal lobulation:
The surface of the kidney shows lobulations.
• 7- Ectopic kidney: abnormal site of the
kidney.
• 8- Abnormal rotation
Of the kidney:
Rarely, the kidney
shows lateral rotation
instead of medial
Rotation or faces anteriorly
• 9- Aberrant renal artery:
An additional artery that supply the kidney.
Might enter from the upper or lower poles.
It is usually a non degenerated
Artery during ascent.
CONGENITAL ANOMALIES
B- Ureter
• 1- Bifid ureter: Splitting of the upper
part of the ureter.
• 2- Double ureter and Ectopic ureter:
Two separate ureters due to formation of
2 ureteric buds.
• One will open normally in the bladder,
The other (Ectopic ureter):
Male: Opens in the urethra
Female: Opens either in :
a- the vestibule of the vagina, or
b- in the urethra