Lab Practical 3

3 basic layers of veins, arteries, and capillaries

Tunica Intima: inner most layer of simple squamous epit. supported by basal lamina and CT

Tunica Media: varying amounts of smooth muscle + elastic tissues. nonexistent -millimeters thick

Tunica adventitia: Outer layer composed of CT and varies in thickness.

Veins

• Carry blood away from the heart

• thicker walls than veins

• Composed of elastic tissue and smooth muscle tissue

  • Elastic arteries and muscular arteries

Veins:

• Passive component, carrying blood back to the heart

• thinner walls (tend to collapse

Blood composition

• CT

• plasma made of albumin, globulin, and fibrinogen

Erythrocytes vs Platelets

RBCs most vertebrates have no nuclei

Platelets disk-like cell fragments circulating in blood

Leukocytes

White blood cells = leukocyte

• nucleated cells

• can move from blood to tissue

Classification 1:

• Multi-lobed nucleus and granules (granulocytes)

  • neutrophils, eosinophils, basophils

Classification 2:

• lack specific granules and contain a round or indented nucleus

  • agranulocytes (lymphocytes and monocytes)

Elastic Arteries

Notable features:

• found in areas of high blood flow (aorta, pulmonary artery)

• In the aorta, tunica media is thick and has lots of elastic fibers

• Vaso Vasorum: special group BV that provide nutrition to walls of arteries (small BV in tunica adventitia)

Elastic artery

Vasa Vasorum (large elastic arteries) : 

• Tiny branches of the artery/BV that provide nutrients to elastic arteries

• Also visible as small BV in tunica adventitia  

Pointer at Vaso Vasorum in tunica media left, and tunica adventitia right

Aorta, elastic artery

3 Layers: 

1. Tunica intima (inner layer) SS endo lining

1. Tunica Media (eosinophilic) 

   

• Elastic lamellae (diffusion can work through them) 

• Nuclei in between lamellae (modified smooth muscle cells, secrete ECM) 

3. Tunica adventitia (mostly CT)

Aorta, elastic artery

IEL = internal elastic lamellae

mucsular artery

WAVY TUNICA INTIMA 

• Less elastic lamellae more smooth muscle cells 

Muscular Arteries: 

• Thick walls, tunica media are concentrated in smooth muscle 

• Tunica intima has internal elastic membrane (elastic fibers), separating from tunica media 

• External elastic membrane separating tunica media from tunica adventitia, more diffused than internal elastic membrane  

WAVY TUNICA INTIMA 

• Less elastic lamellae more smooth muscle cells

WAVY TUNICA INTIMA 

• Less elastic lamellae more smooth muscle cells 

Muscular artery:

Well developed internal elastic lamellae, causing waviness of tunica intima 

Well developed internal elastic lamellae, causing waviness of tunica intima 

Muscular artery

Darker brown = internal elastic lamellae 

muscular artery on left, Vein on right

muscular artery and medium vein

vein

medium vein

Arteroilles:   Small arteries  Tunica media is 1-2 cell layers thick  Larger arteroilles have elastic lamina in tunica intima  NO external elastic lamina

arteriole and venule (arteriole bottom)

arteriole and venule

arteriole and venule

Capillaries are?

• Smallest element of circulatory system

• Wide enough for 1 RBC (nearly impossible to see in cross section) 

• Form beds that connect between the arterial and venous systems 

• SS epithelial layer 

3 types of capillaries: 

1. Continuous: 

   1. Continuous epithelium and basal lamina 

   2. Less permeable

   3. CT, muscles, and CNS

2. Fenestrated: 

   1. Continuous epithelium and basal lamina 

   2. Gaps between endothelial cells 

   3. Intestine, endocrine glands, glomerulus

3. Discontinuous (sinusoids): 

   1. Gaps in basement membrane and epithelium 

   2. High permeability for water + water sol mlcls + proteins 

   3. Larger and more irregular lumen 

   4. Appear as small irregular spaces within tissue 

   5. Liver, spleen, bone marrow 

capillary network

Venules are?

Venules: 

• Smallest veins 

• Postcapillary venules 

  • Formed when capillaries join together, appear like continuous capillaries 

  • Receive blood from capillaries 

  • Only have tunica intima 

• Muscular venules 

  • 1-3 layers of smooth muscle cells in tunica media 

Veins and venules often travel together 

Medium veins have?

• Thin layer of smooth muscle.

•  tunica adventitia (may have vaso vasorum)

• Many have flap valves to prevent back flow

Medium veins

Thin tunica intima and media but thick tunica adventitia 

medium vein with valve

Medium Vein with valve

Irregularly dispersed smooth muscle 

• No internal elastic lamellae 

• Valves are the extensions of tunica intima to break into small compartments for movement (skinny extensions in photo)

Large veins are:

• Tunica adventitia is thickest layer 

  • Bundles of collagen and smooth muscle 

  • May have vasa vasorum 

• Vena Cava, Portal vein

Large vein

• vena cava

• Thin tunica intima = ss. Tunic media = dispersed smooth muscle + CT 

Granulocyte are:

1. Granulocytes

   1.  Neutrophils 

      1. Leukocyte

      2. nucleus has small lobes 3-5 connected by filaments 

      3. Darkly stained nucleus light stained cytogranules 

      4. Smallest granulocyte 

   2. Eosinophils 

      1. rare 

      2. Larger than neutrophils

      3. Bi-lobed nucleus visible among cyto granules  

      4. Prominent bright/orange granules, spectacle shape 

   3. Basophils 

      1. Least common 

      2. Violet or purple granules (Giemsa stain) 

      3. Nucleus often obscured by granules

Agranulocytes are

1. Agranulocytes

   1. Lymphocytes 

      1. Smallest leukocyte

      2. Round darkly stained round nucleus filling almost entire cell 

      3. Thin wall of cytoplasm visible as thin crescent 

   2. Monocytes

      1. Largest leukocyte 

      2. Kidney shape nucleus, pale grey/light cytoplasm

      3. Fairly large amount of cyto around nucleus 
         

Other: 

• Platelets are the smallest, with no nucleus and blue cyto granules

• Erythrocytes are medium small with no nucleus and no granules

neutrophil eosinophil b asophil

1. Neutrophils 

   1. Leukocyte

   2. nucleus has small lobes 3-5 connected by filaments 

   3. Darkly stained nucleus light stained cytogranules 

   4. Smallest granulocyte 

2. Eosinophils 

   1. rare 

   2. Larger than neutrophils

   3. Bi-lobed nucleus visible among cyto granules  

   4. Prominent bright/orange granules, spectacle shape 

3. Basophils 

   1. Least common 

   2. Violet or purple granules (Giemsa stain) 

   3. Nucleus often obscured by granules 

lymphocytes and monocytes

1. Lymphocytes 

   1. Smallest leukocyte

   2. Round darkly stained round nucleus filling almost entire cell 

   3. Thin wall of cytoplasm visible as thin crescent 

2. Monocytes

   1. Largest leukocyte 

   2. Kidney shape nucleus, pale grey/light cytoplasm

   3. Fairly large amount of cyto around nucleus 

neutrophils

eosinophils

basophils

lymphocytes

monocytes

blood key

Kidney

Kidney: 

• Remove metabolic waste, foreign chemicals, regulate salt concentrations, and maintain blood volume and acid-base balance 

• Proximal convoluted tubule and thick descending limb have cuboidal epithelium with a brush border (microvilli)

• Thin segments have either low cuboidal or simple squamous epithelium (look similar to capillaries or small veins) 

• Thick ascending limb and distal convoluted tubules are lined with cuboidal epithelium without a brush border 

Renal medulla contains segments of medullary pyramids. The apex points to the hilum. 

• Medullary rays extend from base of pyramid to cortex 

Renal corpuscle consisting of glomerulus surrounding bowmans capsule.

Kidney 

• Outer cortex 

• And inner medullary region 

• Renal pyramid, point/peak at renal papillae where urine drips out

kidney:

Cortical tissue 

• Proximal distal convoluted tubules 

• Medullary rays and renal corpuscles 

Outer renal cortex contains:

• Renal corpuscle (macula densa)

• Distal and proximal convoluted tubules 

• Medullary rays

kidney

• Stripes are medullary rays (extensions of medullary projecting towards edge) 

  • Collecting ducts and loop of henle

• In between are cortical tissue 

kidney;

• Renal corpuscles are the onion shapes 

• Tubules surround it 

• Distal convoluted tubules clearer lumen (cuboidal)

• Proximal convoluted tubules have brush border (cuboidal epi)

Distal convuluted vs proximal convuluted tubules in kidney

• Distal convoluted tubules clearer lumen (cuboidal)

  • thin ascending to thick ascending

• Proximal convoluted tubules have brush border (cuboidal epi)

  • thick descending to thin descending

• Thin segments have either low cuboidal or simple squamous epithelium (look similar to capillaries or small veins) 

• Thick ascending limb and distal convoluted tubules are lined with cuboidal epithelium without a brush border

kdieny renal corpuscle

• Outer parietal layer of bowmans capsule of ss 

Ureter

• Urine from kidney to urinary bladder 

• Folded lumen (star shape) 

• Inner mucosa composed of transitional epithelium on lamina propria 

• Muscularis layer contains 2-3 layers of smooth muscle 

  • Thin inner longitudinal 

  • Large circular muscle fibers ringing ureter 

• Adventitia lies outside muscularis layer and is coated with a serosa 

Ureter

star shaped lumen, well developed muscularis layer

Ureter

star shaped lumen, well developed muscularis layer

• Transitional epithelium 

  • Surface cells (umbrella cells)

  Underlying layer of LCT and muscularis layer 

  
  

Ureter

star shaped lumen, well developed muscularis layer

Muscularis layer: 

• Thin inner band of longitudinal parallel to ureter 

• Large layer of circular muscle fibers 

• Longitudinal layer of smooth muscle 

outer layer of serosa surruonding adipose tissue

Urinary bladder

• Lumen is larger and muscularis is thicker than ureter 

  • Three distinct layers 

  • Inner and outer longitudinal layer 

  • Separated by a middle circular muscle layer

Urinary bladder

• Mucosa, muscularis, serosa 

Urinary Bladder, Transitional epithelium on upper surface 

urinary bladder

• Three distinct layers 

• Inner and outer longitudinal layer 

• Separated by a middle circular muscle layer

Endocrine glands

Endocrine Glands (lack ducts, hormones are released into the blood or lymphatic circulation) 

pituitary, thyroid, parathyroid

Pituitary gland (anterior pituitary ais lower end)

1. Hypophysis (PITUITARY GLAND) 

   1. Part of the brain composed of: 

   2. Anterior pituitary (adenohypophysis)

      1. Pars distalis (anterior) 

      2. Pars tuberalis 

      3. Pars intermedia 

      4. Cells: 

         1. Large round acidophils (orange)

         2. Basophils blue to purple general larger

         3. Chromophobes weakly stained

3. Pars Intemedia 

   1. Between anterior and posterior pituitary 

   2. Fluid filled vesicles

3. Posterior Pituitary 

   1. Unmyelinated nerve axons and endings originating in hypo 

   2. Near capillary beds 

   3. Oxytocin and vasopressin is released and appear as pink masses called herring bodies

1. Hypophysis (PITUITARY GLAND) 

   1. Part of the brain composed of: 

   2. Anterior pituitary (adenohypophysis)

      1. Pars distalis (anterior) 

      2. Pars tuberalis 

      3. Pars intermedia 

      4. Cells: 

         1. Large round acidophils (orange)

         2. Basophils blue to purple general larger

         3. Chromophobes weakly stained

3. Pars Intemedia 

   1. Between anterior and posterior pituitary 

   2. Fluid filled vesicles

4. Posterior Pituitary 

   1. Unmyelinated nerve axons and endings originating in hypo 

   2. Near capillary beds 

   3. Oxytocin and vasopressin is released and appear as pink masses called herring bodies

Pituitary 

Thyroid

• Produces, stores, and releases thyroid hormone 

• Sphericle follicesl lined with cuboidal follicular cells 

Contains parafollicular cells (C-cells) in CT secreting calcitonin and don’t extend into the follicular lumen

Thyroid

Para follicular cells - secrete calcitonin (don’t extend into lumen), exist between follicular cells  

• Produces, stores, and releases thyroid hormone 

• Sphericle follicesl lined with cuboidal follicular cells 

Contains parafollicular cells (C-cells) in CT secreting calcitonin and don’t extend into the follicular lumen

thyroid follicular and parafollicular cells

• Produces, stores, and releases thyroid hormone 

• Sphericle follicesl lined with cuboidal follicular cells 

Contains parafollicular cells (C-cells) in CT secreting calcitonin and don’t extend into the follicular lumen

Parathryroid: 

Composed of glandular cells:

Chief Cells: 

• Most common, small dark nuclei, pale cytoplasm 

• Secrete parathyroid hormone (PTH)

Oxyphil cells:  

• Larger, fewer, eosinophilic cytoplasm.  

• Unkown function 

Parathryroid: 

Composed of glandular cells:

Chief Cells top: 

• Most common, small dark nuclei, pale cytoplasm 

• Secrete parathyroid hormone (PTH)

Oxyphil cells bottom:  

• Larger, fewer, eosinophilic cytoplasm.  

• Unkown function 

Adrenal: 

• Two endocrine glands 

• Outer Cortex- secretes corticoids 

• Inner medulla - secretes catecholamines under NS control 

• Surrounded by CT capsule contain BV and nerve fibers 

Secretory cells form cords divided into 3 layers

1. Outer glomerulosa (zona glomerulosa) secreting mineral corticoids 

2. Middle fasciculate (zona fasciculate) 

3. Deep reticularis (zona reticularis) produce cortisol 

Composed of large round chomaffin cells arranged in short cords or clumps. Many capillaries viens and nerve fibers ‘

Adrenal: 

• Two endocrine glands 

• Outer Cortex- secretes corticoids 

• Inner medulla - secretes catecholamines under NS control 

• Surrounded by CT capsule contain BV and nerve fibers 

Secretory cells form cords divided into 3 layers

1. Outer glomerulosa (zona glomerulosa) secreting mineral corticoids 

2. Middle fasciculate (zona fasciculate) 

3. Deep reticularis (zona reticularis) produce cortisol 

3 zones of the:

Adrenal: 

• Two endocrine glands 

• Outer Cortex- secretes corticoids 

• Inner medulla - secretes catecholamines under NS control 

• Surrounded by CT capsule contain BV and nerve fibers 

Secretory cells form cords divided into 3 layers

1. Outer glomerulosa (zona glomerulosa) secreting mineral corticoids 

2. Middle fasciculate (zona fasciculate) 

3. Deep reticularis (zona reticularis) produce cortisol 

Exocrine Glands 

Secretions by duct systems opening at surface of body. Glands are buried deeper, but excrete on the outside

Salivary glands 

• all have DIRC, all have septa dividing glands into lobules

Salivary:

Salivary:

Three major glands: 

1. Parotid 

2. Submandibular 

3. Sublingual 

Surrounded by a capsule, divded by septa (lobesa dn lobules) 

Basic secretory unit: Salivon 

• Acinus 

  • Serous (prot secreting). Pyramid shape 

  • or mucous secreting cells 

• intercalated duct

  • Simple cuboidal 

  • Becoming simple columnar when joined with excretory duct 

  • Central nuclei and basal infoldings 

• excretory duct 

  • Carry salivary products from stirated ducts to oral cavity 

  • Epithelium depends on diameter 

  • Small duct: 

    • Simple cuboidal → pseudostratified columnar or stratified columnar 

  • Large duct: 

    • Stratifed columnar or stratified squamous are present 

Parotid Salivary gland: 

• ALL Serous 

• Round basaly located nuclei 

Striated duct visible below 

Duct with stirations, representing basal infoldings 

Submamdibular - mostly Serous salivary gland

• Mucous acini are pale staining (cursor)   salivary gland

Sublingual mostly mucous salivary gland

Mammary Gland: 

Mammary Gland: 

• Ducts with cuboidal or columnar epitelia 

• Embedded in CT 

• Lymphocytes and myoeptihelial cells

mammary gland

Sweat Gland:

• Tubular coiled glands 

• Salivons = secretory units

• Clear cells - contain glyocgen 

• Dark cells 

• Myoepithelila cells 

• Ducts in cross ection have stratified cuboidal and no myoepithelial cells 

Apocrine glands appear near follicles in the skin 

And have largel umens 

Simple cuboidal or columnar epithelial

Lymph nodes 

• Small bean shaped lymphati organs found along lymphatic vessels 

• Contain lymphocytes aiding in fighting infection 

• Near blood stream

Lymph nodes 

• Small bean shaped lymphati organs found along lymphatic vessels 

• Contain lymphocytes aiding in fighting infection 

• Near blood stream

Lymph node

Palatine tonsil 

• Guard the opening to the gastrointestinal and respiratory systems 

• Luminal surface = SS projecting deep into tonsil forming crypts 

• Crypts lined with lymphoid tissue and lympoid nodules 

Palatine tonsil 

• Guard the opening to the gastrointestinal and respiratory systems 

• Luminal surface = SS projecting deep into tonsil forming crypts 

• Crypts lined with lymphoid tissue and lympoid nodules 

Thymus 

• Maturation and proliferation of lymphocytes 

• Surrounded by CT capsule 

• Several lobes separated by CT septa 

  • Each lobe has dense cortex and inner paler medulla 

Hassalls or thymic corpuscles 

• Flattened epithelial reticular cells in concentric layers 

Thymus 

• Maturation and proliferation of lymphocytes 

• Surrounded by CT capsule 

• Several lobes separated by CT septa 

  • Each lobe has dense cortex and inner paler medulla 

Hassalls or thymic corpuscles 

• Flattened epithelial reticular cells in concentric layers

Spleen 

• Filters blood 

• Surrounded by dense CT capsule with trabeculae penetrating the itssue (network of reticular cells and fibers) 

White pulp (DARKER)

• Lymphoid tissue (central artery) 

• Periarterial lymphatic sheaths (PALS) surround it 

red pulp (LIGHTER) 

• Contains splenic sinuses and splenic cords. Containing blood cells, macrophages, and reticular cells.

Spleen WHITE PULP

• Filters blood 

• Surrounded by dense CT capsule with trabeculae penetrating the itssue (network of reticular cells and fibers) 

White pulp (DARKER)

• Lymphoid tissue (central artery) 

• Periarterial lymphatic sheaths (PALS) surround it 

red pulp (LIGHTER) 

• Contains splenic sinuses and splenic cords. Containing blood cells, macrophages, and reticular cells.

Spleen PALS

• Filters blood 

• Surrounded by dense CT capsule with trabeculae penetrating the itssue (network of reticular cells and fibers) 

White pulp (DARKER)

• Lymphoid tissue (central artery) 

• Periarterial lymphatic sheaths (PALS) surround it 

red pulp (LIGHTER) 

• Contains splenic sinuses and splenic cords. Containing blood cells, macrophages, and reticular cells.

Spleen RED PULP

• Filters blood 

• Surrounded by dense CT capsule with trabeculae penetrating the itssue (network of reticular cells and fibers) 

White pulp (DARKER)

• Lymphoid tissue (central artery) 

• Periarterial lymphatic sheaths (PALS) surround it 

red pulp (LIGHTER) 

• Contains splenic sinuses and splenic cords. Containing blood cells, macrophages, and reticular cells.

Spleen SPLENIC SINUSES

White pulp (DARKER)

• Lymphoid tissue (central artery) 

• Periarterial lymphatic sheaths (PALS) surround it 

red pulp (LIGHTER) 

• Contains splenic sinuses and splenic cords. Containing blood cells, macrophages, and reticular cells.

• Filters blood 

• Surrounded by dense CT capsule with trabeculae penetrating the itssue (network of reticular cells and fibers) 

Spleen 

White pulp (DARKER)

• Lymphoid tissue (central artery) 

• Periarterial lymphatic sheaths (PALS) surround it 

red pulp (LIGHTER) 

• Contains splenic sinuses and splenic cords. Containing blood cells, macrophages, and reticular cells.

• Filters blood 

• Surrounded by dense CT capsule with trabeculae penetrating the itssue (network of reticular cells and fibers) 

Lymphatic tissue and nodules 

PEYES PATCH IN ILEUM

• Distributed along respiratory and gastrointestinal tract as lymphocytes or lymphatic nodules 

• Peyers patches in ileum of small intestine

OVARY: Outer cortex, containing follicles at varying stages 

Inner medullary region, ovarian artery and veins

simple cuboidal on ovarian surface epithelium in outer cortex 

• Has basement membrane and DIRCT below as tunica albuginea 

• Corcles are follicles at varying stages of development 

• Cortex contains follicles