histo cardio development

• blood cells initially develop
• aggregates of splanic mesodermal cells

formed from peripheral cells of blood islands joining together

• central cells of blood islands
• differentiate into blood cells

blood vessels from outgrowths that link up with neighboring islands

differentiates inot connective tissue and muscular layer of the blood vessels

left and right develop from splanic mesoderm adjacent to pericardial cavity

unite to form a hollow tube = cardiac tuble

vesicles in cardiac plates

• during head and lateral folding
• left and right cardiac tubes fuse together to become ventral to the foregut

mesoderm caudal to cardiac tube

diaphragm

developing heart tube bulges into the pericardial cavity and remain attached to the dorsal side of the pericardial cavity by a fold of mesodermal tissue (dorsal mesocardium)

• bulbous
• ventricle
• atrium

• truncus arteriosus
• sinus horn

• endocardium
• myocradium
• epicardium

in splanic mesoderm

• neural tube
• fore gut
• endocardial tube (pericardial cavity wraps around)

• 1. transverse arteriosus
• 2. bulbous cordis
• 3. ventricles
• 4. primitive atrium
• 5. sinuse venosus

• spirals
• bulbous and ventricle become U shaped

drops farther caudal and ventral

shift cranial direction until both lie dorsal and cranial to the rest

grow rapidly in lateral direction and forms a sacculation on each side which forshadow the future right and left atrium respectively

becomes incorporated into right side of common atrium

• increases in size
• makes sinlge chamber
• ventricle develops median longitudinal groove that indicates partitioning of the ventricle

• 2 endocardial cushions
• develop at common atrioventricular canal

• endocardial cushions meet and fuse creates -
• left and right atrioventricular orifices

• sickel shaped membrane grows down from the middorsal wall of the atrium
• expands ventrally towards the growing septum intermedium

• diminishing gap between septum primum and the septum intermedium
• will close when the 2 fuse together

numerus tiny perforations develop into septum primum to form this orifice

• develops on right side of septum primum
• thicker and more rigid
• does not grow completely = foramen ovale

permits blood to pass from the right atrium between 2 interatrial septum and into the left atrium via the foramen secundum

primitive atrium and sinus horns

becomes completely incorporated and open into the right atrium where cranial and caudal vena cava opens

in mature animal where cranial and caudal vena cava open

forms coronary sinus

pectinate mucsles of right auricle

develops left atrium mainly

• develops as an outgrowth of the left atrial wall
• later connects with veins of the developing lung buds

forming the large smooth walled part of the adult left atrium

pectinate muscles and left auricle

• 2 prominent longitudinal thickenings develop in endocardial lining of the bulbus and truncus
• these fuse to create a septum that dvide the truncus and bulbus into an aortic and pulmonary trunk

• partition between truncus arteriosus and bulbus cordis
• septum spirals so that base of pulmonary trunk opens off the right of the ventricle while the base of the aorta opens off the left ventricle

• distal part of bulbus in the right ventricle
• area around the origin of the pulmonary artery in the right ventricle

• develops with enlargement fo the halve of the ventricles
• median partition that grows as a crescent plate
• creates interventricular foramen

incomplete partition and the communication between the 2 ventricles b/c of the muscular interventricular septum

• from septum intermedium
• this outgrowth closes interventricular foramen
• grows toward muscular interventricular septum

• from ventral endocardial cushion
• fuses with muscular interventricular septum as well as the spiral septum to complete the partition

• develop around the margin of the artioventricular orifices as localized mesenchymal thickening
• become hollowed out to form endocardia cusps

• 3 on right
• 2 on left
• connect to papillary muscles by chorde tendinae

• develop as small tubercles at the pulmonary and aortic channel
• will hollow out at upper surface

• develops by differentiation of the myocardial tissue
• modified cardiac tissue
• no nerves in heart

• aorta
• pulmonary artery

• aorta
• pulmonary artery
• conus arerious
• and part of the right ventricle

left and right ventricle

left and right atrium

sinus venerum of right atrium

coronary sinus

• truncus arteriosus
• bulbus cordis

• truncus arteriosus
• bulbus cordis

bulbus cordis

primitive ventricle

• primitive ventricle
• bulbus cordis

primitive atrium

• primitve atrium
• sinus venosus

left horn of sinus venosus

right horn sinus venosus

• heart not in normal position
• common in cattle

• spiral does not spiral
• aorta on right venticle
• pulmonary trunk on left venticle

aorta opens from both ventricles

• 1. venticle septal defect
• 2. pulmonary stenosis
• 3. dextroaorta
• 4. ventricular hypertrophy

tetrology of fallot - pulmonary stenosis

• constrictions located at both valvualer and infundibular levels
• poststenotic dilations of pulmonary trunk
• right ventricle dilation and hypertropy

• due to formation of fibrous subaortic ring
• poststenotic dilation of the ascentding aorta
• left venticle dilatation and hypertropy
• left atrial dilation

• primary hypertropy of left ventricles
• right ventricle dialtion and hypertropy

• enlarged foramen secundum and foramen ovale
• dilation and hypertropy of right ventricle, right atrium and left atrium

• dextroaota
• pulmonary stenosis
• inverentricular septal defect
• dilation and hypertrophy of right ventricle

• dextroaorta
• interventricular septal defect
• right ventricle dilation and hypertrophy

• aorta from right, pulmonary trunk from left ventricle
• need shunts to survive
• interatrial septal defect
• PDA
• Interventricular septal defect

• both ventricles are the same size
• oxygen and deoxygenated blood mix b/c aorta and pulmonary trunk = 1

• tubular heart continuous with aortic artches
• vitelline arteries
• umbilical arteries
• umbilical and cardinal veins

continusous with aortic arch that empty into paired dorsal aortae

• pair
• from forsal aortae to the yold sac
• derived from the extra-embryonic mesoderm

• pair
• from dorsal aortae to allantois
• derived from the extraembryonic mesoderm

• drain into the sinus venosus
• vitelline(omphalomesenteric)
• umbilical and cardinal veins

• pharyngeal arches each receives its own cranial nerve and its own artery
• arrive from aortic sac (most cranial part of the truncus arteriosus
• arches join the right and left dorsal aortae
• six pairs of aortic arches develop but not all present at any one time

no derivatives

common and internal carotid artery

• right: right subclavian
• left: continues as desending aorta

• right and left pulmonary artery
• stays connected to aorta as ductuc arteriosus

• PDA - common in dogs "washing machine"
• persistant right aortic arch - vascular ring anomalies (ring around esophagus b/c of ductus (ligamentum) arteriosus)

• dorsal intersgmental arteries
• lateral aortic branches
• ventral aortic branches

• branch of the dorsal aorta
• arise bilaterally between the somites and form interocstal and lumbar arteries

• branch of dorsal aorta
• supply the derivatives of the intermediate mesoderm and form renal, testicular or ovarian arteries

• branches of dorsal aorta
• supply splanic mesodermal and endodermal tissues of the thoracic and abdominal cavities
• develop into broncho-esophageal and celiac and caudal mesenteric arteries

• left: regresses
• right: persists and form cranial mesenteric artery

• proximal part contributes to the external and internal iliac arteries
• distal part forms the round ligament of the urinary bladder

• proximal: left regresses
• right - hepatic segment of caudal vena cava
• middle: hepatic sinusoids and hepatic segment of caudal vena cavae
• distal segment: portal venosus system (blood intestine-liver-heart)

round ligament of liver

caudal and cranial join the common caridnal vein which enters the sinus venosus

• connect by a connecting channel which develops into brachiocephalic trunk
• caudal part - regresses
• cranial part and common cardinal develop into cranial vena cava

• regresses
• replaced by subcardinal and supracardinal veins

join to form subcardinal sinus which develops inot the mainsegment of caudal vena cava

develops into main segement of caudal vena cava

joins right vitelline vein which develops into the hepatic segment of caudal vena cava and opens into sinus venosus

• develops on both sides into left and right azygous vein
• horse and dog only right persists and in pig only left persist
• ruminants have both

• foramen ovale - fossa ovalis
• ductus venosus - ligamentum venosus
• ductus arteriosus - ligamentum arteriosus
• umbilical vein - round ligament of liver
• umblical artery:
• proximal part - external in internal iliac arteries
• distal part - round ligament of bladder

• O2 enters though umbilical vein
• most bypasses live by ductus venosus into the the caudal vena cava
• after pass liver O2 blood mixes with deoxygenated blood returning from the hind part of body
• enters right atrium
• most passes into left artium through foramen ovale some stays in right atrium
• blood enters left venticle and aorta and supplies O2 blood to cranial part of body
• deO2 retuning from cranial vena cava flows through right venticle into the pulomnary trunk (most passes through ductus arteriosus and mixes with O2 blood of aorta and supplies to the abdominal and lowers part of body
• after aorta blood flows toward the placent by the way of 2 umbilical arteries

• fibroblasts
• chondroblasts
• osteoblast
• myoblast
• adipocytes
• endothelial cells (vessels)
• mast cells

• paraxial mesoderm
• intermediate mesoderm
• lateral mesoderm (somatic and splanchnic)

• sclerotomes (vertebrae)
• mytomes (muscle)
• dermatomes (corium and subcutis of the skin)

• histogenesis od bone (intramembraneous and intrachondrial)
• appendicular skeleton
• vertbral column, ribs, sternum
• skull - desmocranium and viserocranium

• bone develops form several sites
• -sclerotome: vertebrae and ribs
• -somatic mesoderm: appendicular skeleton
• -pharyngeal arch mesoderm: several bones of the face
• - neural crest cells: contribute to several bones of face

• bone is first laid down in aggregagtes of mesenchymal cells from which bone is directly formed
• osteocyte - mature cells
• osteoid - secretion of matrix
• osteoclast - break down
• osteoblast - formed from mesenchymal
• mineralization

• bones are first formed as hyaline cartilage models later replaced by bone tissue
• 1st cartilage model (hyaline) - bone
• primary center of ossification (diaphyseal) starts in center of bone and moves outward and up to the epiphysis
• compact bone formed on periphery
• erosion of cartilage - primary site of ossification
• increased blood vessels and brings in more mesenchymal cells for differentiation into osteoblasts

primary center of ossification

• long bones
• epipyseal (secondary) centers of ossification appear in both epiphyses
• process of ossifcation is the same as in primary centers

cartilage plate located between the diaphyseal and epipyseal centers of ossification

when growth in length ceases in puberty, epiphyseal plate becomes ossified

• chondrodystrophy: abnormal inerstitial growth of cartilage
• premature cessation of growth plates leads to shortening of bones, especially limbs, base of skull and vertebral column
• joint and bone problems

• from paraxial mesoderm
• vertebrae develop from medial portion of somite
• sclerotome- proliferate and migrate medially to surround the neural tube and the notochord to form a condensed mesenchyme model of the vertebra

• somites and spinal nerves have a segmental arrangement
• arteries lie in an intermediate location (intersegmental)
• each sclerotome split into cranial and caudal portions
• caudal portion of one sclerotome unites with the cranial portion of the next

• primary centers of ossification:one in the body and one in each neural arch
• seconday centers of ossification: develop postnatally

28 days

42 days so that fetus is not damaged by the x-rays

arise from segmental sclerotome derived from condesation of mesenchymal cells lateral to the thoracic vertebrae, located between the developing myotomes

• develops independently from somatic mesoderm.
• 2 lateral sternal bands formed on either side of the midline
• later fuse to form cartilaginous model of sternabrae
• sternebrae ossify to form a common unpaired body of the sternum which joins the distal end of the ribs

• annulum fibrosus develops from the mesenchyme of the sclerotome
• nuclesus pulposus develops from the notochord

from mesenchyme of the sclerotome

from the notochord

• skeletal muscle - paraxial meosderm
• cardiac and smooth - splanic mesoderm
• *exception* muscles of iris - originate from optic cup ectoderm

from paraxial mesoderm

• from splanic mesoderm(gut and respiratory tract)
• from local mesoderm (blood vessels, arrector pili muscles)

sphincter and dilator pupillae originate from optic cup ectoderm

• derived from paraxial mesoderm (myotomes of somites and somitomeres)
• Somites: muscles of anial skeletaon, body wall and limbs
• somitomeres: muscles of the head
• mesodermal cels of the myotomes
• differentiate into single nucleated myoblasts that fuse to form multinucleated muscle cells

muscle of the axial skeletaon, body wall and limbs

muscles of the head

myogenic cells are separated into a smaller dorsal protion (epimere) and a larger ventral portion (hyopmere)

• smaller dorsal portion of myogenic cells
• innervated by dorsal rami of spinal nerves
• give rise to muscles dorsal of the transverse processes of the vertebrae (extensors of vertebral column)
• epaxial muscles

• innervated by ventral rami of spinal nerves
• lateral and ventral flexors of thoracic and abdominal musculature
• hypaxial muscles

• limb field: an area of somatopleure (somatic mesoderm and ectoderm) committed to forming a limb
• limb bud: localization of mesoderm covered by ectoder

area of somatopleure committed to forming a limb bud

• localized proliferation of mesoderm
• covered by ectoderm

• limbs grom outside from body wall somatopleure as limb buds
• bond cartilage and related connective tissue arise from somatic mesoderm of the limb bud
• dermis and skeletal muscles come from dermatome and myotome migrates into the lining

when they migrate they take their nerves also and as they travel to make the limb they also make the brachial plexus

• limb bud elongates, it becomes flattened in the dorsoventral plane of the embryo
• distal part is paddle shaped
• later - constriction divides the cylindrical proximal region into 2 segments
• forelimb - 2 segements represent the primordia of the arm and forearm, and in the hind limb the thigh and leg

• regions of the limb develop in proximo-distal order
• distal end of the limb (footplate) is flattened like a paddle
• along its outer margin ectoderm thickens to form an apical ridge (AER)

• outer margin of distal end
• ectoderm thickens

• Amelia
• meromelia
• micromelia
• bimelia
• polydactyly

complete absecence of a limb

abscense of one or more parts of a limb

• reduced size of limb
• all parts of the limb are present but it is significantly smaller in size

partial or complete duplication of one limb

• one or more extra digits
• genetic defect of cattle, sheep, pigs, horses, cats

• neurocranium: (enclose brain) chondrocranium and desmocranium
• viscerocranium: face and jaw bones

• base of cranium
• develops by endochondral ossfication
• derived from occipital somites(occipital bone) and neural crest cells (sphenoid, ethimoid, and temporal (petrous part)
• O S E T

• occipital bone in chondrocranium of neurocranium
• O

• sphenoid, ethmoid, and temporal (petrous part)
• S E T

strongest bone of the body

• vault of cranium
• develops by intramembraeous ossification
• derived from neural crest cells surrounding the developing brain to form meninges
• Bones: frontal, parietal, interparietal, temporal(sqaumous part)
• F P I T

• frontal, parietal, interparietal, temporal (squamous part)
• F Parietal I T

• face and jaw
• derived from the mesenchyme of the pharyngeal arches and develop by intramembraneous ossification
• Bones - lacrimal, nasal, incisive, maxilla, vomer, palatine, pterygoid, zygomatic, mandible and temporal(tympanic part)

• lacrimal, nasal, incisive, maxilla, vomer, palatine, pterygoid, zygomatic, mandible, and temporal (tympanic part)
• L N I M Pterygoid Palatine Z M T

suture joints - immovable

• chondrocranium - bones of base of skull
• Sphenoid, Ethmoid, Occipital, and Temporal

• Desmocranium: Frontal, parietal, interparietal, temporal (squamous part)
• Viscerocranium: Lacrimal, nasal, incisive, mailla, vomer, palatine, pterygoid, zygomaticc, mandible, temporal (tempanic part)