Histo embryo - quiz 2 info

• wall is composed of three layers
• endocardium (inner) (3 layers)
• Myocardium (middle)
• epicardium (outermost)

• lines atria and ventricels (3 layers)
• endothelium
• inner subendothelia layer
• outer subendothelial layer

• endothelium
• simple squamous epithelium

• inner subendothelial layer
• dense irrgular CT w/ collagen and elsatic fibers and occasional smooth muscle cells

• outer subenthelial layer
• loosely arranged collagen and elastic fibers
• may contain purkinji fibers

• cardiac valves
• endocardial folds that consist of a central layer of dense CT coverd by enothelium

• most common heart disease in vet med
• an infection travels to heart endocardium

• thickest layer
• bundles and groups of cardiac muscle cells (caps, lymph, nerves, intersitial CT)
• SA and AV nodes (impulse generation)
• Purkinje fibers (impulse conducting, below endocardium)
• Cardiac skeleton

• in myocardium
• network of small, branching nodal cells that are modified cardiac muscle cells w/ fewer myofibrils

• 3 layers
• fibrous rings
• fibrous triangle
• fibrous part of the interventricular septum

• collagen and elastic fibers
• surrounds AV openings and aorta and pulmonary trunk

• CT that fills space betreen AV opening and base of aorta
• between RV and LV
• predominantly dense irregular CT (pigs and cats)
• fibrocatilage (dog)
• bone (large ruminants, mainly cow) hyalin hores and cow

collagen fiber bundles

loose CT containing blood vessels, nerves and ganglia and adipose tissue

• visceral pericardium
• simple squamous epithelium

• parietal pericardium
• mesothelial layer
• collagen layer and elastic fibers

• pericardial cavity
• contains serous fluid lubricating the surfaces for frictionless cardiac movement

high fluid in pericardial cavity

• elastic or large
• muscular of medium
• arteriole or small sized

small, medium and large sizes

comprised of arteriole, capillaries and venules

• inner most layer of vessels
• simple squamous endotheilum
• subendothelial layer w/ collagen and elastic fibers(orcin stain, blk)
• smooth muscles

internal elastic membrane

• middle layer of vessels
• smooth muscles cells, layered in a helical arrarangement with elastic and collagen fibers

external elastic membrane

• outer most layer of vessels
• collagen and elastic fibers predominate, smooth muscles may be present,
• contains vasa vasorum and nervi vasorum

• tunica intima - thicker, subendothelial layer has numerous fine elastic fibers
• internal elastic membrane - indictinct
• tunica media - thickest layer, concentrically arranged fenestrated elastic laminae w/ smooth muscle in between laminae, ground substance is basophilic b/c of sulphated GAGs
• external elastic membrane - distinct
• tunica externa - longitudinally arranged bundles of collagen fibers intermixed with few elastic fibers, vasa vasorum and nervi vasovorum

• tunica intima - usual
• internal elastic membrane - distinct
• tunica media - thick, soomth muscle in a helical pattern, elastic and collagen fibers between smooth muscle layers for strenght
• external elastic membrane - not always clearly defined
• tunica externa - usual

• tunica intima - usual
• internal elastic membrane - fenestrated and eventually disappears in smaller arterioles
• tunica media - 1-3 layers of smooth muscle and may contain collagen fibers
• external elastic membrane - absent
• tunica externa - loose CT and usual

through pre-cap sphincter of smooth m. or into metarterioles, which have isolated bundles of smooth m.

• 5 10um diameter
• endotheial cells and associated basal lamina. pericytes and a thin adeventitial CT layer(lacks in brain)
• form networks - cap beds for exchange of circulating blood and intersititial fluid
• pericytes form CT

• continuous
• fenestrated
• sinusoidal, sinusoids
• porous

• in muscles, endothelial cells are held together by tight junctionc
• transcytotic vesicles are common

• visceral caps,
• GIT - for exchange

fenestrated caps in endocrine glands

• present in the kidney glomerulus
• filtration barries

• liver parenchyma
• larger than caps
• shape changes with the surrounding parenchyma
• large openings and pores in the endothelial cells provide a max exchange

• post-capillary venules
• pericytic or collecting venules
• muscular venules

• similar in structure to capilaries, but larger in diameter (10-30um) and have continuous or fenestrated enothelial cells
• lymphoid organs - simple cuboidal epithelium

pericytes form the continuous layer plus collagen fibers form a thin tunica externa

pericyte layer is replaced by one or 2 smooth layers plus the tunica externa becomes more prominent

• larger lumen, thiner walls, all similar to arteries except
• tunica media- thinner
• tunica externa - thicker
• semilunar valves - folds of tunica interna with a core of collagen fibers

• lymph caps
• small and medium
• large lymph vessels
• valves in small medium and large lymph vessels

• are endotheilium- lined tubes that are usually larger than blood cap
• basal lamina is either absent or discontinuous

• continuous basement membrane, increasing with diameter
• firsst small amount of CT and then on or two layers of smooth muscle and elastic fibers are added
• tunica externa is not distinct

• three distinct layers
• internal elastic membran is usually absent
• similar to veins

• direct connections between arterioles and venules w/o an intervening capillary bed are called arteriovenous anastomoses
• thick muscular layer that receives a dense vasomotro nerve supply(sympathetic and para)
• ANS regualtes BP and temp, erection
• are present in skin, lip, nasal mucosa, male and female repro tract

• transport - most important (regulation and protection)
• type of connective tissue
• blood cells and plasma - Wright's stain
• erythrocytes, thrombocytes (platelets), leucocytes
• 7% of body weight

• 45% packed cell volume or hemocrit (erythrocytes) in lowest layer
• 1% buffy coat (thrombocytes and leucocytes) middle layer
• plasma top layer

fluid part of blood w/o cells and fibrinogen

• granules in cytoplasm
• neutophils - neutral stain (most)
• eosinophils - granules pink
• basophils granules purple (rare)

• lymphocytes (most)
• monosytes

• non-nucleated biconcave disc
• surrounded by plasma lemma - 33% hemoglobin
• mature - don't have mito, ribo, and cytoplasmic enzymes

• 120 days dogs
• 75 days cats
• 160 cow
• 85 pig
• 150 horse and sheep
• blood transfer shorter life span

• RBC adhere to form long chains
• prominent in horses and cats
• b/c inflammation, shows disease

• from kidney = RBC production in bone marrow
• kidney problems cause decrease in RBC

• more that 1/2 of RBC
• Fe deficiency less than 1/2

• flattened disc
• smallest RBC
• poikilocytosis (variation in size of RBC)

• llama, camel
• reptiles and amphibians - have nucleus

• variation in size of erythrocyte
• normal in ruminants
• if other animals have it then there is a problem

• variation in shape of the erythrocytes
• only normal in goats

decreased number of RBC in blood

• crenated cells could be b/c of storage and glucose is used up
• pigs are prone too

• immature RBC
• in dogs and cats

• DNA fragments
• normal in dogs and cats

• oxidized hemoglobin, can't carry o2
• Felines - onion and acetaminophen

• multilobe 3-5 joind by thin bands
• 12-15um diameter, heterochromatic segmented nuclei
• barr body (extra chromatin lobe) Females
• cytoplasm is greyish blue: cytoplasmic granules (bactericidal compound)
• azurophilic granules ( hydrolytic enzymes)
• go to chemotoxins
• 10-14 hr in circulation

heterophils

• 10-15 diameter, bilobed nucleus
• pink eosinophilic granules (large in horses)
• allergic and anaphylactic reaction
• parasitic infestation
• matures in bone marrow

• 10-15 um, segmented of irregularly shaped heterochromatic nuclei
• metachromatic granules - reddish violet (h2o soluble), hard to see nucleus
• inflammatory response - histamine and heparin
• mature in bone marrow

• mononuclear, no granules
• small round w/ spherical nucleus (thin rim of cytoplasm
• 7-15um

eosinophils

in tissue, secret histamine and heparin

• aus shep,
• genetice
• nuclear morphologic changes to granulocytes and moncytes
• does not cause disease

• from bone marrow
• cloacal bursa in birds
• produces antibodies (plasma cells) some develop into memory cells
• non speceific immunity
• 10 % of circulating lymphocytes

• B and T lymphocytes
• NK cells

• dervied from thymus
• cell mediated immunity - some memory cells formed
• 75% of circulating lymphocytes
• non - specific immunity

• helper cells - receptors or chemical signals, ID anitgens
• cytotoxic cells - destroy body cells that are infected

• from bone marrow
• mainly protect against cancer cells
• nonspecific immunity
• 10 - 15 % of WBC

• largest WBC
• phagocytic - vacuoles
• nucleus - kidney shape, oval or horse - shoe shape
• cytoplasm - abundant, greyish blue, fine azurophilic granules (blue)
• precursors of tissue macrophages (different names depending on where at in the body)
• cytokines

• many types of different effects
• Fever

• intimate contact of lymphocytes and monocytes
• cause cell signaling

• 1-4 um, discoid, spherical or elongated, individual or clusters
• external membrane is covered by an amorphous material forming the external coat that is responsible for platelet adhesive property
• microfilament and mictotubules are present beneath the plasmalemma and are responsible for platelet shape change and clot reduction

blood cell formation in bone marrow

• early - occur in yolk sac
• later - hematopoitic cells migrate from yolk sac to fetal liver
• cells from liver migrate to the bone marrow, spleen, lymph nodes and thymus

• nutrients from arteries that enter midshaft and provide blood supply, terminate on periphery of marrow and join veins by periphery sinouses
• venous or vascular siouses that anastomose and drain blood to the central vein (mature cells of to sinuses then circulation)

• red - actively involved in hematopoisis
• yellow - inactive and fatty
• can be interconveted

• totipotent - differentiat to any cell
• lymphoid stem cell
• myeloid stem cell

T B and NK cells

protects the body from foreign particles (antigens) and cancer cells

immune cells from parenchyma (immunocytes)

• reticular cells
• epithelial reticular cells
• dendritic cells

• form reticulum in lymphatic organs (except tymus and cloacal bursa)
• fomation of reticular fibers

• endoderm
• long processes
• thymus and cloacal bursa have stellate epithelical reticular cells which form the stroma
• DO NOT PRODUCE RETICULAR FIBERS

• anitgen capture and presenting to lymphocytes
• develop in bone marrow
• stellate-shaped cells present in nearly all tissues

• filter lymph before going back too blood stream
• affertn vessels to node
• effernt vessels away from node (mostly)
• capsule of dense irregular CT with a few elastic fibers
• trabeculae exten from the capsule in to the parnchyma = irregular septa

• primary or central lymphoid organ (produce lymphoid percursors)
• Ebryonic yolk sac
• Thymus
• GALT (pyers patches)(galt associated lymph tissue)
• Cloacal Bursa
• Bone marrow

• secondary or peripheral lymphoid organs
• house mature immunocytes and site of immune responsiveness
• lymph nodes - antigen presenting
• spleen
• MALT - mucosa associated lymph tissue

• subscapular, trabecular and medullary sinus
• endothelium like reticular cells (stroma) lines
• lymphocytes and macrophages are "free"
• some perculates through cortex and medulary cords to reach the medulary sinus

• outer - primary and seconday lymphatic nodules separated by diffuse lymphatic tissue
• Primary - reticular CT with tightly packed lymphocytes
• Seconday - germinal centers w/ dark zone (large lymphocytes w/ intense mitotic activity)
• light zone (small lymphocytes w/ few mitotic cells)
• deep cortex - diffuse lymphatic tissue

• medullary cords that branch and anastomose throughout the medula - composed of lymphocytes, plasma cells and macrophages
• separated by a network of endothelial-lined sinuses and CT
• (reversed in oigs)

• artery enters at hilus
• post cap venules - deep in cortex, cuboidal epithelium, join veins in the medullary trabeculae, return and empty into large veins that leave the hilus

• capsule - CT prenetrates the parenchyma and divides it into lobules
• lobes - dark (cortex) and light zone (medulla)
• cortex - epithelial reticulum ( stellate shape, light staining oval nuclei, processes are connected by desmosomes)
• active in young - involutes after puberty (degenerates and b/c CT and fat)

• same cell population as the cortex with larger number of epithelial reticular cells
• contains Hassal's or thymic corpuscles - keratinized, flattened and concentrically arranged cells

• marcophages - abundant in vicinity of medulla
• lymphoblasts and medium sized lymphocytes predoinated the meshes of the peripheral reticulum, for mitotic division producing small lymphocytes that mainly occupy the deep cortex

• no afferent lymh vessels
• cap network drain into post capillary venules in the medulla to join veins in CT septa
• arteries penetrate the parnechyma at the corticomedullary junction by way of the CT septa and form a capillary network in the cortex
• Blood thymic barrier- cap endothelium, perivascular space and a sheath of epith cell process (prevents circulating antigen from reaching thymic cortex where T - cytes form for protection)

• filter blood by removing abonormal or worn out RBC
• store erythrocytes, platelets, Fe for hemoglobin syn
• Erythropoiesis in Fetus
• involved in immune response against blood-borne antigens

• Surround by capsule - CT and smooth muscle
• - sends out trabeculae (contain arteries, veins, lymph vessels and nerves)
• Splenic parenchyma - red and white pulp (capsule trabeculae and reticular fibers support)

• Splenic cords - 3D network of reticular fiber w/ reticular cells, enmeshed w/ erythrocytes, macs, lymphocytes, plasma cells and other leucocyter
• Splenic sinuses - wide vascular channels between the splenic cords, lined w/ enodthelial cells containing contractile microfilaments which on contraction create gaps allowing erythrocytes to pass between the splenic cords and sinuses

• lymphatic nodules - PeriArterial Lymphatic Sheaths (PALS): T-cells concentrated adjacent to the tunica media of the artery of the white pulp, peripheral region has mixture of T - cells, B - cells and macs
• reticular cells form a 3D network containing lymphocytes and macs
• germinal centers - in nodules present depending on functional state

• between white and red pulp, filters blood
• white pulp - periphery is bounded by circumferential reticular network w/ B-cell and macs
• reticular network - receives capillaries from the white pulp and red that empty into marginal sinuses, blood then drained towardsvenous sinuses or venules of red pulp

• Splenis artery - enters capsule goes to trabecular arteries, leaves trabecula now called artery of white pulp w/ lots of lymphotcytes (PALS)
• Branches of white pulp - continue to feed cap beds in nodule and terminate in the marginal zone or enter the red pulp as pulp arterioles
• pulp arterioles - make sheathed caps or ellipsoids (surrounded by a sheath of mac sequesteres in a network of reticular cells and fibers

• CLosed theory - terminal caps open directly into the splenic sinuses or venules
• Open theory - terminal caps open into the spaces between the reticular cells of the red pulp and then enter the venous sinuses through the slit in walls
• Third theory - existnece of both, depending on physiological state: distended open predominates, contracted closed predoninates

• no Afferent lymph vessels
• efferent capsular and trabecular lymph vessels originate in the white pulp and drain into splenic lymph nodes

• Dog - sinusual spleen: abundant venous sinuses
• Cat, horse, pig, ruminant - nonsinusual spleen: poorly developed sinuses

• Mucosa Associated Lymphoid Tissue
• lymphoid aggregation present in submucosa of digestive and respiratory system organs
• RALT and BALT

• Gut Associated Lymphoid Tissue
• large aggregates of single lymphatic nodules: peyers patches (ileum) present in distal jejunum/ileum in young ruminants and carnivores
• solitary lymph nodules are present in colon and rectum and cecum in birds
• SI ileum peyers patches - Submucosa
• primary lymphoid organ

• BIRDS - sac like diverticulum or proctodeum
• Plicae - tall mucosal folds, many lymphoid follicles
• lined by pseudostratified columnar epithelium
• B - lymphocytes differentiate here

• small brown-dark red ONLY IN RUMINANTS
• "acessory spleen" no internal partitions , enlarge after spleenectomy
• cortex and medula not distinct
• NO lymph vessels - get everything from blood
• Young - diffuse lymphatic tissue and few lymph nodes present
• Adults - fills w/ RBC b/c of antigenic stimulation, many nodules may form, sinuses are wide with few mac and lymphocytes

• Surrounded by CT capsule (stratified squamousm oropharynx, psuedostratified nasopharynx)
• beneath epithelium, diffuse lymphatic tissue w/ plasma cells surrounded by lymphatic nodules w/ germinal centers (lighter)
• epithelium infiltrated w/ lymphocytes, neutrophils and macs