Posterior Development of Pig Embryo

[DEVELOPMENT OF PIG EMBRYO: POSTERIOR] STRUCTURES DESCRIPTION LEVEL OF THE LUNG BUDS (STEM BROCHI) AND FORELEG BUDS Paired posterior cardinal  Most dorsal vein lying in the place occupied veins by the common cardinal veins. syn: postcardinal vein  Pair of bud-like tissue masses from the dorsolateral sides of the body  Level of the heart Foreleg bud  Outer layer – ectoderm  Apical ridge – at the apex of ectoderm  Core –mesoderm  interconnections of the ventral rami of the cervical & thoracic spinal nerves Brachial plexus  where the nerves of the forelimb branch out  innervates the limbs  small middle hole beneath the pair of dorsal Esophagus aorta  pair of vesicles that appear on both sides of Lung buds the trachea  thick partition of mesenchyme enclosing the Mediastinum trachea and the lung  pair of coelomic cavities on each side of Pleural cavity mediastinum where lung buds developed Parietal pleura  lining of the lateral wall of the pleural cavity  medial epithelial lining of the pleural cavity Visceral pleura which will cover the lungs  mesenchymal partition extending across Septum transversum the body  blood vessel embedded on the right sie of Posterior vena cava the septum transversum syn: inferior vena cava  occupies a dorsal position in the substance  thick-walled mass below septum Ventricle transversum LEVEL OF THE LIVER AND THE STOMACH Spinal nerve  arise from the spinal cord by the roots  contains spinal ganglion and sensory Dorsal root neurons that differentiate form the ganglion syn: afferent / sensory root cells Ventral root  made up of motor fibers from motor syn: efferent / motor root neurons of the basal plate of the spinal cord THREE (3) BRANCHES OF SPINAL NERVE TRUNK  carries fibers associated with the drsal parts of the body Dorsal ramus  skin, deep muscles of the back, spinal column  carries fibers associated with the ventral Ventral ramus and lateral body wall Ramus communicans  branch from ventral ramus  carries fibers to the viscera by means of

FATE

[DEVELOPMENT OF PIG EMBRYO: POSTERIOR]

  Dorsal root ganglion

Mammary ridges Descending aorta Sympathetic ganglion

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Mesonephric duct

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Glomerulus

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Mesonephros

Bowman’s capsule syn: glomerular capsule Malpigian corpuscle syn: renal corpuscle

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glomerulus + bowman’s capsule

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coiled tubules at the outer lateral portion of each mesonephros connected at the corpuscles horizontally enlarged segment of the foregut which replaces the esophagus (series) large mass with strands of cells hepatic cord and spaces between strands hepatic sinusoids divided into: dorsal and ventral lobes large blood vessels embedded in the liver drains blood from: subcardinal sinus  sinus venosus receives blood from: ductus venosus lies on the right side of the stomach supported by caval mesentery

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Liver    Posterior vena cava

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Ductus venosus

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Dorsal mesogaster Omental bursa Epiploic foramen

pair of ganglion immediately dorsal to the descending aorta functional kidney at this stage retroperitoneal & posterior to the liver large oval canal along the ventral margin of mesonephros knots of blood capillaries at the medial side of each kidney very flat epthelium which surrounds the glomerulus

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Mesonephric tubules Stomach

prevertebral sympathetic chain medioventral to sympathetic ganglion darkly nucleated body on both sides of the spinal cord fibers leads to the dorsolateral wall of spinal cord pair of elevations on the dorsolateral part of the body fused dorsal aorta paired in the branchial region

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Hepatogastric ligament 

embedded in the septum transversum holds the stomach in place mesenchymal cells within it will form the spleen closed cavity to the right of the stomach opens to peritoneal cavity opening at the omental bursa mesentery connecting the liver and stomach + + + + + hepatoduodenal ligament

metanephros Metanephric duct

Female: degenerate? Male: epididymis, vas deferens, seminal vesicle

Dorsal omentum

Lesser omentum

[DEVELOPMENT OF PIG EMBRYO: POSTERIOR] Falciform ligament

Somites

Common bile duct

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remnant of the ventral mesentery attaches the liver to the ventral body wall LEVEL OF THE COMMON BILE DUCT 44 paired somites lumen = myocoel myotome – dorsomedian part of the block dermatome – will migrate under epidermis sclerotome – surround spinal cord and notochord to form vertebral column

Skeletal muscles Connective tissue of dermis

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Duodenum  Posterior vena cava   Hepatic portal vein Gonad rudiment  Big left & small right  umbilical veins LEVEL THROUGH THE GALLBLADDER AND UMBILICAL CORD Hepatic portal vein   Dorsal pancreas Ventral pancreas   Gallbladder Pair of umbilical veins  Cranial and caudal limb  of the intestinal loop Superior mesenteric vein  and artery  Common vitelline vein Left and right umbilical  arteries allantois  Small right umbilical vein  & big left umbilical veins  tail LEVEL THROUGH THE UROGENITAL SINUS AND UMBILICAL CORD  Subcardinal veins Mesocolon   Mesonephric duct Urogenital sinus   Rectum Umbilical veins   Umbilical arteries Allantois   Umbilical cord Wharton’s jelly  LEVEL OF THE HINDLIMB BUD Hindleg bud 

[DEVELOPMENT OF PIG EMBRYO: POSTERIOR] Pair of mesonephric duct Mesocolon Ureter

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Spinal ganglia Ventral roots of the spinal nerves Sclerotome Myotome Dermatome Epidermis Intersegmental arteries

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LEVEL THROUGH THE SPINAL NERVE      