KIDNEY DEVELOPMENT
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Mesoderm ist appear arround the notochord called
paraxial mesoderm.
• Paraxial mesoderm spread out between ectoderm&
endoderm forming lateral plate mesoderm.
• Lateral plate mesoderm splitt around coelom into
Somatic & splanchnic mesoderm.
• Mesoderm lies the somite and coelom is called
intermediate mesoderm and form the kidney.
• Three types of kidneys are developed :
• Pronephros.
• Mesonephros.
• Metanephros.
Pronephros Kidney
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Head of kidney.
Paired of pronephric tubules, one
end in coelom and other in the
pronephric duct.
Dorsal aorta idented into the coelom
,one called internal glomeruli and
other called external glomeruli.
Glomeruli is civered by thin
epithelium for filtration between
glomeruli and coelom.
Wastes passed to the internal
glomerulus, then to the expanded
portion of the nephrocoele
(expanded portion of the pronephric
tubule, then to the nephrostome.
Pronephros &
Mesonephros
Kidney
Mesonephric
Kidney
• Formed of 3to 4 per
segment.
•35-49 tubules.
•Each tubule connect
laterally to the mesonephric
or wollfian duct.
•The median end is
invaginated by ba
glomerulus, arrouind which
a thin double-walled
Bowmans capsule is formed.
•Both capsule and
glomerulus form the renal
corpuscle.
•The embryonic kidney in reptiles, birds,
& mammals. The functional adult kidney
in fish & amphibians .
Metanephric Kidney
• The adult amniote kidney
• The number of corpuscles is large; up to about 4.5 million
is some species
• Drained by a duct called the metanephric duct or ureter
• Mammalian kidneys are divided into
• Cortex - contains renal corpuscles & lots of capillaries
• Medulla - contains collecting ducts and loops of Henle;
divided into pyramids & columns .
• Pelvis - hollow; receives the urine (which exits the kidney
via the ureter).
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Ureter bud begin to originate from the dorsal wall of the
mesonephric duct.
The diverticulum grow dorsal and then cranial forming the ureter.
The distal blind end of this duct expand to form the renal pelvis.
Differentiation of nephrons:
Condensation, in which groups of about 100 cells condense tightly
together to form a distinct mass .
Epithelialisation, in which condensed cells lose their mesenchymal
characteristics and gain epithelial ones; at the end of this period
they have formed a small epithelial cyst complete with a
basemement membrane, cell-cell junctions and a defined cellular
apico-basal polarity .
Early morphogenesis, in which the cyst invaginates twice to form a
comma and then a S-shaped body, one of these invagination sites
later becoming the glomerular cleft. At about this time, blood vessel
progenitors invade the cleft to begin construction of the vascular
component of the glomerulus.
Tubule maturation, in which the sepcialised transporting segments
of the nephron differentiate, and the complex morphogenesis of
convoluted tubules is created