development of liver

1. LIVER :ORIGIN AND
DEVELOPMENT
By :-
Zafar Mahmood

2. LIVER :AN INTRODUCTION
• Liver is largest gland of the body which is primarly
situated in right hypochondrium and epigastric region.
• It weighs about 1600 gms in males and 1300 gms in
females.
• It is reddish brown in appearance with soft consistency
• It performs various vital functions like
metabolism,storage,synthesis and excreation of
subustances

3. • The Liver primodium appears in 3rd week as an outgrowth
of endodermal epithelium at the distal end of the fore
gut.
• This outgrowth(Hepatic derticulum) consists of rapidly
proliferating cells that penetrate Septum transversum.
• The diverticulum divides into 2 parts pars
hepatica(cranial) and pars cystica(caudal bud)

4. PARS HEPATICA
• It is the larger cranial part of the hepatic diverticulum.
• Gives rise to:
1. Hepatocytes
2. Hepatic sinusoids
3. Kupffer cells and hematopoietic tissue
• The liver grows rapidly to fill a large part of the abdominal cavity.
• At first, the 2 lobes are of the same size but soon the right become larger.

6. PARS CYSTICA
• Pars cystica becomes the gall bladder and the stem of the diverticulum
forms the cystic duct.
• The stalk connecting the hepatic and the cystic ducts to the duodenum
becomes the common bile duct.
• The right and the left branches of the pars hepatica canalized to form the
right and the left hepatic ducts.
• Bile begins to flow at about the 12th week.

7. • The cells form cords(line of cells) which interact with vitelline and umbilical
veins in the septum transversum form Hepatic sinusoids
• Epithelial liver cord deffernciate to form lining of parenchyma.
• Hematopoietic cells, Kupffer cells and connective tissue are derived from
septum transversum

8. • Due to rotation, Bile duct
opens dorsally

9. • Mesoderm on ventral surface of the liver differentiates into
ventral peritoneum except on cranial surface.
• At this point, the liver remains in contact of original septum
transversum,which is packed densely with mesodermal cells
that will form central tendon of the diaphragm
• This part of liver which is never covered with peritoneum is bare
area of liver.

11. FUNCTIONS IN THE FETUS
• Hematopoiesis
Begins during 6th week
subsides during the last 2 months only
• Bile production
Starts at 12th week
gives dark green color to the meconium

12. ANOMALIES OF LIVER DEVELOPMENT
• Extrahepatic billiary atresia:-Failure of recanilzation of Extrahepaticducts.It
occurs in 1 of 15,000 live births.
• intrahepatic billiary atresia:-Failure of recanilzation of intrahepatic ducts.It
occurs in 1 of 100,000 live births.Usually lethal
• Duplication of Parts of extra billiary tracts like the Gall bladder and ducts
• The Hartmann's Pouch:-The wall of infundibulum projects downwards as a
pouch which may be adherent to cystic or bile duct.