Lab #1: The Cell and Nucleus

EGG (OVUM)

nucleolus

Heterochromatin (dark)

The egg (ovum) is a haploid cell in females that combines with sperm to form the zygote.

SPERM

flagellum

A sperm cell (spermatozoan) is a haploid cell in males that combines with egg to form the zygote. It has an organelle called a flagellum with a core axoneme of microtubules that is used for movement.

GOLGI APPARATUS (EPIDIDYMIS)

The golgi apparatus is similar to a warehouse that packages proteins for intracellular use in organelles or for secretion.

flagellum

VILLAE

Small microvillae at the surfaces

Villae and smaller microvillae are found in the intestines. They increase surface area for better absorption of nutrients.

flagellum

MITOCHONDRIA

Mitochondria are the powerhouses of the cell and produce ATP. Here they are seen in the liver, along with masses of pigment granules.

Liver

MAMMALIAN BLOOD

Mammalian blood has three cellular components: erythrocytes, leukocytes, and platelets. Erythrocytes have no nuclei, unlike reptilian blood.

STRIATED MUSCLE CELLS

Striated / Skeletal Muscle is made of giant mutinucleated cells that come from multiple myoblasts fusing together. It contains orderly, repeating contractile units of myosin and actin called sarcomeres.

MELANIN PIGMENTS

Structures at base with brown tint

Melanin pigments are produced by melanocytes in the epidermis. They protect chromosomes in the metabolically active basal cells against UV damage.

ZYMOGEN GRANULES (PANCREAS)

Zymogen granules are precursors of pancreatic enzymes. They appear at the apical ends of acinar gland cells, with nuclei at the base.

Nucleus

NERVE CELLS

Nerve cells have specialized organelles, axons and dendrites, to transmit electrical impulses for cell-to-cell communication.

Dendrites

Axon

Glial Cells

Nucleus

Nucleolus

Dendrites receive signals from other cells and convey them to the perikaryon. On their surfaces are small dendritic spines that are important in neural plasticity.

Perikaryon w/Nissl bodies

Axon Hilloc

k

DENDRITES

Axon

The axon conducts electrical impulses away from the perikaryon toward the synapse. Axons are often sheathed in myelin as a way of insulating and speeding up the signal.

AXON

AVIAN BLOOD

Mature red blood cells in avian blood contain nuclei, unlike mammalian erythrocytes which have no nuclei.

EXTRACELLULAR MATRIX

Extracellular matrix is composed of (1) fibers and (2) ground substance, including glycoproteins, proteoglycans, & glycosaminoglycans.

in: Loose (Areolar) Connective Tissue

WHITE ADIPOSE TISSUE

Nucleus

Plasma Membrane

White adipose tissue is also called unilocular due to its single large drop of stored lipid. Nuclei appear at the periphery of cells.

MICROTUBULES

Microtubules form the mitotic spindle during cell division. They are also found in cilia and flagella.

METAPHASE CHROMOSOMES

18

At metaphase, chromosomes are lined up at the center of the mitotic spindle. Homologous pairs are still connected at the centromere.

ANAPHASE CHROMOSOMES

19

At anaphase, homologous pairs separate and chromosomes move toward opposite poles aided by kinetochore microtubules.

Lab #2: Epithelium and Glands

SIMPLE SQUAMOUS EPITHELIUM

Simple squamous epithelium is a single layer of flattened cells. It is usually very permeable and allows molecules to pass through quickly.

Kidney glomerulus w/lining of simple squamous.

Lung alveoli with simple squamous lining.

MACERATED COLUMNAR EPITHELIUM

Macerated columnar epithelium has simply been separated from the epithelium to show individual cells.

KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM

Keratinized stratified squamous epithelium has many layers of flattened cells. The top layers lack nuclei entirely, are full of keratin, and form a waterproof barrier.

PSUEDOSTRATIFIED CILIATED COLUMNAR EPITHELIUM

Goblet Cell

Pseudostratified ciliated columnar epithelium has nuclei at different levels that makes it appear like several layers of cells. However, each cell contacts the basal lamina.

COMPOUND ACINAR GLAND

25

Compound acinar glands look like bunches of grapes. The secretory portion is enlarged, and when cut in cross-section, shows a rounded structure.

SIMPLE CUBOIDAL EPITHELIUM

Simple cuboidal epithelium is a single layer of cube-shaped cells with very round nuclei. The specialize in secretion and absorption and are commonly found at the surface of the ovaries, lining nephrons & renal tubules, and in parts of the eye and thyroid.

SIMPLE TUBULAR GLAND

27

Simple tubular glands retain their shape as a tube throughout and do not have branching or division.

Large Intestine

Uterine Gland

BASEMENT MEMBRANE OF SIMPLE COLUMNAR EPITHELIUM

28

The basement membrane is a thin sheet of fibers that underlies epithelia. It is composed of both the basal lamina and underlying reticular lamina.

GOBLET CELL

29

Goblet cells

Intestinal Villi

Conjunctiva (Eye)

Goblet cells are simple glands with the sole function of secreting mucin, which becomes mucus when mixed with water. They are found in the epithelial lining of organs such as in the digestive and respiratory tracts.

LUMEN

30

A lumen is the clear space in a tubular organ/gland/structure.

LUMENS FOUND IN BONE

31

Two different kinds of lumens are found in bone. Haversian canals run up the center of osteons. Volkmann’s canals run perpendicular to Haversian canals and connect them to one another. At the center of the canal are nerves, blood vessels, and lymph vessels, to supply things like nutrients and immunological protection.

VILLI OF INTESTINE SHOWING SIMPLE COLUMNAR EPITHELIUM WITH GOBLET CELLS

32

TRANSITIONAL EPITHELIUM

33

Also known as “urothelium,” transitional epithelium has umbrella-shaped epithelial cells that can expand and contract.

ENDOTHELIUM OF ARTERY / Endothelial Cells

34

The endothelium is a single layer of squamous epithelium that lines the interior of blood and lymphatic vessels. It forms a selective barrier for passage of materials in capillaries. It also secretes nitric oxide causing vasodilation.

SIMPLE COLUMNAR EPITHELIUM

Simple columnar epithelium has one layer of tall rectangular cells. It is commonly found the stomach, small intestine, large intestine, and uterus.

Lab #3: Connective Tissue

LOOSE CONNECTIVE TISSUE (areolar tissue)

37

Loose connective tissue is composed of fibroblast cells that produce an extracellular matrix with ground substance, as well as collagen and elastic fibers. It appears in serous membranes of the digestive tract, as well as in the skin and mucous membranes.

Fibroblasts

Elastic Fibers

Collagen Fibers

DENSE IRREGULAR CONNECTIVE TISSUE (DERMIS)

38

Dense irregular connective tissue has tightly-packed fibers that are not organized in parallel bundles like dense regular. It is found in the dermis, submucosa of the GI tract, periosteum, and perichondrium.

Perichondrium

DENSE REGULAR CONNECTIVE TISSUE

39

Dense regular connective tissue has tightly-packed fibers that are aligned in orderly, parallel bundles. It is commonly found in tendons (regularly arranged collagen fibers) and ligaments. Note that in the tendon nuclei of fibroblasts can be seen throughout, whereas in muscle the nuclei of the multinucleated fibers appear towards the periphery.

Tunica Albuginea (Testis)

Muscle-Tendon Junction

Fibroblast

Skeletal Muscle

VEINS

40

Veins carry blood toward the heart, with most carrying deoxygenated blood. Compared to arteries, veins have less muscle and also contain valves. The have the same three layers as arteries: tunica intima, tunica media, and tunica adventitia, but the layers are usually thinner.

Large Vein

Dense Irregular Connective Tissue

MESENCHYMAL CELLS

Mesenchyme is an embryonic connective tissue derived from mesoderm and contains ground substance, reticular fibrils, and unspecialized cells that can develop into connective tissue, bone, cartilage, the lymphatic system, and the circulatory system.

Mesenchymal Cells

Reticular FibersGround Substance

MESENCHYMAL CELLS (Developing Bone)

This mesenchyme is visible in developing bone (lighter pink). Appearing also, in dark pink areas, are the trabeculae of woven bone, with rounded osteocytes inside, and osteoblasts lining the edges.

Mesenchymal Cells

Reticular Fibers

Ground Substance

ERYTHROCYTE

43

What is the name of the cell at the tip of the red pointer?Erythrocytes, or “red blood cells” are created by hemopoietic stem cells in the bone marrow and loose their nuclei before entering the blood stream. They have no organelles but contain abundant hemoglobin which is an allosteric protein that can bind oxygen and carbon dioxide.

RETICULOCYTES

Reticulocytes are a stage of RBC formation right after the nucleus has been ejected but before all the polyribosomes have disappeared. These can be seen sometimes in circulating blood with a special dye that shows ribosomal RNA.

PLATELET

Platelets are small fragments of cells produced by megakaryocytes that extend long projections from the bone marrow into the blood stream. They contain growth factors and are also involved in the formation of clots.

LYMPHOCYTE

46

Lymphocytes are white blood cells important in the immune system system. The three types are the smaller B and T lymphocytes and large, granular natural killer cells. B and T can only be differentiated by immunocytochemical methods.

Natural Killer Cell

MONOCYTE

Monocytes circulate in the blood and in response to inflammation, will move into tissues and differentiate into macrophages, dendritic cells, and other cells of the mononuclear phagocyte system.

NEUTROPHILS

48

Neutrophils are the most common leukocyte in blood. They help protect the body against bacterial pathogens as part of the innate immune system. They are granulocytes, but their granules stain a neutral pink. Nucleus is polymorphonuclear, divided into 3-5 lobes.

EOSINOPHIL

Eosinophils have basic granules (i.e. major basic protein) that stain with acid dyes. They are part of the innate immune response and protect against helminth worms and parasites. They are also mediators of immune reactions.

BASOPHILS

50

Basophils are the least common of the granulocytes. They contain dark-staining acid granules. They are very similar to mast cells and can secrete histamine (vasodilator) and heparin (anticoagulant) in response to antigens that they recognize through IgE surface receptors.

MAST CELLS

Mast cells, similar to basophils, contain granules of histamine (vasodilation) and heparin (anticoagulant), and are active in allergic actions as well as wound healing. Mast cells release granules in response to direct injury, cross-linking of IgE receptors, or activated complement proteins.

BONE MARROW

52

Bone marrow is where blood cells are formed. It contains hemopoietic cells (red bone marrow) as well as adipocytes (yellow bone marrow). As people mature, most bone marrow becomes yellow, but if large amounts of blood are lost, yellow bone marrow can turn back into red bone marrow.

ADIPOSE TISSUE

53

White adipose tissue is also called unilocular due to its single large drop of stored lipid. Nuclei appear at the periphery of cells.

COLLAGEN FIBERS (Silver Stain, Decalcified Bone)

54

Collagen fibers are produced by fibroblasts. They are made of a triple helix of two identical chains (α1) and one slightly different (α2). Collagen is the most abundant protein in mammals.

ELASTIC FIBERS

55

Elastic fibers appear in both the ECM of connective tissue (produced by fibroblasts) and in the elastic lamina of arteries. When arties have large amounts of elastin in the tunica media, they are called elastic arteries. Here the elastin helps maintain a constant pressure despite the pulsing of blood from the heart.

ELASTIC FIBERS OF ARTERY

56

Elastic fibers appear in both the ECM of connective tissue (produced by fibroblasts) and in the elastic lamina of arteries. When arties have large amounts of elastin in the tunica media, they are called elastic arteries. Here the elastin helps maintain a constant pressure despite the pulsing of blood from the heart.

RETICULAR FIBERS

Reticular fibers are produced by reticular cells (similar to fibroblasts) and are made of collagen type III. They crosslink to form a mesh network that can support the cells of organs like in liver, bone marrow, and the lymphatic system.

RETICULAR FIBERS (SPLEEN)

Reticular fibers form the framework of the spleen and support spleen cells.

RETICULAR FIBERS (LIVER)

These reticular fibers form the framework of the liver and support the hepatocytes.

Lab #4: Adipose & Cartilage

FETAL HYALINE CARTILAGE

Hyaline cartilage is blue-white in color with lots of collagen. The tissue is avascular but has a surrounding perichondrium (dense irregular conn. tissue) with blood vessels. All the bones of the fetus are originally made of cartilage and gradually turned into bone through endochondral ossification.

RESPIRATORY EPITHELIUM & CARTILAGE

Chondrocytes are the cells of cartilage. They produce the collagen and ground substance of the matrix and also maintain it. Chondroblasts are found at the periphery of cartilage, and chondrocytes are found in the center surrounded by matrix.

CHONDROCYTES

lacunae

territorial matrix

interterritorial matrix

nucleus of chondrocyte

cartilage capsule

CHONDROCYTECHONDROCYTE

EPITHELIUM (Ciliated Pseudostratified Columnar)

Respiratory epithelium is found lining the upper airways, where it moisturizes and protects. Below it are layers including the submucous layer, the fibrous membrane, hyaline cartilage, and fibrous membrane.

CHONDROCYTES, ISOGENOUS GROUPS

Chondrocytes

Hyaline cartilage Fibrocartilage

Elastic cartilage

Isogenous Groups

ELASTIC CARTILAGE

Elastic Cartilage

Elastic cartilage appears in the outer ear, larynx, and epiglottis. It is similar to cartilage but also has many yellow elastic fibers in the matrix. The elastin makes the tissues very flexible.

ELASTIC FIBERS

Elastic Fibers

Elastic fibers stain dark blue/purple with Verhoeff stain.

FIBROUS CARTILAGE

Fibrous Cartilage

Fibrous cartilage is found

COLLAGENOUS FIBERS

Collagenous Fibers

Fibrocartilage – Rows of Chondrocytes

FIBROCARTILAGE

CONNECTIVE TISSUE

Connective Tissue

FIBROBLASTS

Fibroblasts

Lab #5: Bone

FETAL HYALINE CARTILAGE

Hyaline cartilage is blue-white in color with lots of collagen. The tissue is avascular but has a surrounding perichondrium (dense irregular conn. tissue) with blood vessels. All the bones of the fetus are originally made of cartilage and gradually turned into bone through endochondral ossification.

OUTER CIRCUMFERENTIAL LAMELLAE

Outer circumferential lamellae are thin sheets of lamellar bone that wrap around the groups of osteons collectively.

OSTEON

Haversian canal

Osteons are cylindrical structures that are the functional units of compact bone. They are made of many concentric layers of bone, called lamellae, around a central canal called the Haversian canal.

OSTEOBLASTS

Osteoblasts are responsible for the formation of bone. Once they become surrounded by bone, they turn into osteocytes. Upon simulation by growth factors, osteoblasts arise from osteoprogenitor cells in the deeper layer of periosteum and bone marrow.

OSTEOBLASTS

Osteoblasts are responsible for the formation of bone. Once they become surrounded by bone, they turn into osteocytes. Upon simulation by growth factors, osteoblasts arise from osteoprogenitor cells in the deeper layer of periosteum and bone marrow.

PERIOSTEUM

LACUNAE

CANALCULI

MATURE HYALINE CARTILAGE

Interterritorial matrix

PERICHONDRIUM

LAMELLAE

CEMENT LINE

DECALCIFIED BONEWhat is the tissue type based on the preparation?

DECALCIFIED BONEWhat is the tissue type based on the preparation?

GROUND BONE

What is the tissue type based on the preparation?

(2) To study the lamellar and canalicular pattern of the calcified matrix, it is necessary to grind dried bone that has not been decalcified to a thickness that permits the microscope light to be transmitted ("ground bone").

GROUND BONE

What is the tissue type based on the preparation?

GROUND BONE

What is the tissue type based on the preparation?

DENSE REGULAR CONNECTIVE TISSUE

What is the tissue type based on the arrangement of cells and fibers?

INTERTERRITORIAL MATRIX / INTERSTITIAL LAMELLAE

Interstitial lamellae are remnants of osteons that have been mostly destroyed.

Lab #6: Nervous Tissue

MOTOR NEURON

“Motor neuron” refers to neurons that control muscle movements.

What type of cell is at the black pointer?

NISSL BODIES

Most of the neuron’s organelles and ribosomes are located in the perikaryon and form a visible granular substance called Nissl bodies.What is the granular material located inside the cell?

NUCLEOLUS

What is the small dark purple structure indicated by the black pointer?

The nucleolus contains densely concentrated rRNA which is transcribed, processed, and complexed into ribosomal subunits in that area.

AXON HILLOCK

The axon hillock is a pyramid-shaped region right next to the perikaryon. It is somewhat clear due to the absence of organelles.

What is the name of the clear area at the end of the black arrows?

DENDRITES

What is the name of the organelle at the end of the black arrows?

Dendrites receive external stimuli and convey them to the perikaryon. One neuron can have many dendrites.

AXON

What is the name of the organelle at the end of the black arrows?

The axon conducts nerve impulses to other nerve cells or effector organs (e.g. muscle, gland). A neuron will have only ONE axon.

CEREBELLUMGray matter is on the surface.

White is in the interior.

The cerebellar CORTEX coordinates muscle activity and has three layers.

GRAY MATTER

Gray matter occurs at the surface/cortex of the cerebellum and cerebrum.

It is made of:(1)Neuronal cell

bodies(2)Dendrites(3)Initial

unmyelinated portions of axons

(4)Astrocytes(5)Microglial cells

*Syapses occur here

Of what type is the cell layer with the black bracket?

MOLECULAR GRAY MATTER

Molecular gray matter is the layer closest to the surface of the cerebellum.

Dendrites from the Purkinje cells branch profusely here, but the axons extend back toward the white matter (medullary layer)

What is the name of the cell layer circled?

MOLECULAR GRAY MATTER (silver stain)

What is the name of the cell layer at the black bracket?

MOLECULAR GRAY MATTER (silver stain)

What is the name of the cell layer at the tip of the arrow?

GRANULAR GRAY MATTER

Granular gray matter shows:(1) Numerous granule cells – small neurons whose axons terminate in the molecular layer. They have nuclei about the size and shape of lymphocytes (purple). (2) Glomeruli – islands of synapses within the granular layer.

(3) Axons and dendrites

What is the name of the cell layer circled?

WHITE MATTER (Cerebral Medulla)

What is the name of the cell layer at the tip of the arrow?

White matter contains primarily:

(1)myelinated axons

(2)microglial cells(3)myelin-producing

oligodendrocytes

The WHITE color comes from the myelinated axons.

PURKINJE CELL

What is the name of the structure at the tip of the arrow?

Purkinje cells are especially large nerve cells located between the granular and molecular layers of gray matter.

The dendrites extend down into the molecular layer and have many branches.

The axons go up through the granular layer to join tracts in the medulla.

CEREBRAL CORTEXThe cerebral cortex is the outermost layer of neural tissue in the cerebrum of the brain (purple). This image comes from a macaque brain.

GRAY MATTER is present here at the cerbral cortex, and WHITE MATTER makes up other layers farther inside.

What is the name of outer dark purple layer?

CEREBRAL CORTEX (made of Gray Matter)

What is the name for this tissue layer?

WHITE MATTER (below Cerebral Cortex)

What is the name for this tissue layer based on its myelination?

PYRAMIDAL CELLS

What is the name for the structures at the tips of the arrows?

Pyramidal neurons look like small triangles. They have long dendrites that extend toward the cortical surface.

NEUROGLIAL CELLS

What is the name for the structures at the tips of the arrows?

DENDRITES

What is the name for the structures at the tips of the arrows?

PACINIAN CORPUSCLES

What is the name for the circular structures at the tips of the arrows?

SKIN CORPUSCLE

What is the name for the structure at the tip of the pointer?

SPINAL CHORD

GANGLION (Dorsal Root Ganglion)

GANGLION (Dorsal Root Ganglion)

MENINGESThe meninges is composed of three layers of connective tissue that surround the spinal cord. This slide shows only a small portion.

Layers (from inside out) include:

(1)Pia mater(2)Arachnoid(3)Dura mater

MENINGES

CENTRAL CANAL

POSTERIOR HORN

ANTERIOR MEDIAN FISSURE

ASTROCYTES

Astrocytes are star-shaped glial cells in the CNS. This image comes from the gray matter of the spinal cord.

ASTROCYTES

PERINEURIUM

PERINEURIUM

Lab #7: Muscle Tissue

NUCLEI (Small Intestine)

What is the name of the structure at the tip of the black arrows?

Connective tissue nuclei are typically more oval in shape than those of fibroblasts.

villi

Dense irregular connective tissue

smooth muscle

DENSE REGULAR CONNECTIVE TISSUE (Tendon)

What type of tissue is shown based on the arrangement of cells and fibers?

Tendons hold together parts of the musculoskeletal system. Due to richness in collagen fibers, they are white and inextensible. They also contain fibroblasts with nuclei parallel to the fibers.

collagen fibers

ENDOMYSIUM

What is the name of the tissue at the tips of the black arrows? (small lines)

Endomysium is a delicate connective tissue that surrounds individual muscle fibers. It is made of reticular fibers and fibroblasts and also has a basal lamina. This and other surrounding connective tissues help transmit the mechanical forces generated by the contracting muscles.

individual muscle fiber

PERIMYSIUM

What is the name of the white tissue outlined in yellow? (small lines)

Perimysium is a connective tissue that surrounds a single “fascicle,” or a bundle of fibers within a muscle.

nerve fibers

fascicle

NERVE FIBERS

What are the structures at the tips of the arrows?

Myelinated motor nerves branch through the perimysim. Each nerve branches into terminal twigs, which become “motor end-plates” or the neuromuscular junction.

RETICULAR TISSUE (Immune/Lymphatic)

What type of tissue is shown here based on its fibers?

Germinal center -- houses immune cells and enlarges during infection.

Trabeculae – form baffles which direct lymph over germinal centers

Medullary fiber chambers – collect filtered lymph

RETICULAR FIBERS (Immune/Lymphatic)

What are the black structures at the tips of the arrows?

Reticular fibers provide structure and anchor macrophages.

Lymphocytes (round purple)

A BAND and H ZONE

What is the name for the dark lines?

The A Band is darker and contains both actin and myosin. A narrow region called the H Zone is in the middle of the A band and contains only myosin.

PURPLE SPACES

I BAND

A

PINK SPACES

The I Band contains only actin.

Z LINE

What is the name for the structure down the center of the light bands?

The Z line bisects the lighter I band. Protein actin attaches to the Z line. The Z line also attaches to the sarcolemma to give stability to the muscle. One “sarcomere” is the distance from one Z line to the next.

one “sarcomere” RED

LINES

INTERCALATED DISC

What is the structure at the black pointer?

Cardiac muscles fuse together with gap junctions that work as “electrical synapses” to allow the cells to contract together in a wave. These areas are visible in the microscope as thin lines, called intercalated discs.

SMOOTH MUSCLE (of stomach)

What type of tissue is at the black pointer?

Dense irregular connective tissue

Smooth muscle

CARDIAC MUSCLE

What type of tissue is shown?

SKELETAL MUSCLE

What type of tissue is shown?

A

SMOOTH MUSCLE FIBERS

What type of tissue is at the black arrow?

Smooth muscle fibers are made of individual cells that are long but nonstriated. Each cell has only one nucleus.

CAPILLARY

What is the structure at the black pointer?

Capillaries are extremely small, only large enough for one red blood cell to pass at a time.

BRANCHING OF CARDIAC MUSCLE

What is the structure called at the tip of the arrow?

Cells within one fiber will connect to cells of another fiber forming a branching pattern.

TUNICA MEDIA (of artery)

What is the structure at the arrow tip?

The tunica media around the artery is made of smooth muscle cells and elastic fibers.

MUSCLE/TENDON JUNCTION

What type of tissue is at the black pointer to the left?

Tendons attach skeletal muscles to bone allowing for contraction and movement.

skeletal muscletend

on

SKELETAL MUSCLE FIBERS (Cross Section)

What type of fibers are shown?

In cross section, skeletal muscle fibers show as round bundles. Cells are mutinucleated, and nuclei are pushed to the outer edges.

Lab #8: Circulatory System

ARTERY

Arteries carry blood away from the heart. They often have lots of elastic fibers with a pronounced elastic lamina, as well as a thick layer of smooth muscle for the tunica media.

VEIN

Veins carry blood to the heart, usually deoxygenated blood. Veins contain valves that help prevent backflow. The thickest layer is the tunica adventitia, made of connective tissue. Veins do have smooth muscle usually, but the layers are thin because veins do not have contractile function like arteries.

CAPILLARYCapillaries are extremely small blood vessels, the diameter of a single blood cell. They have a wall with a single thin layer of epithelial cells that allows for passage of materials. The three types are continuous, fenestrated, and sinusoid capillaries.

ENDOTHELIUM

Endothelium is a single layer of simple squamous epithelium. It acts as a non-thrombogenic surface to prevent blood clotting unless the endothelium is damaged/missing. Upon stimulation by acetylcholine, endothelium secretes nitric oxide, which quickly diffuses into smooth muscle cells and signals smooth muscle relaxation, causing vasodilation.

INTERNAL ELASTIC LAMINA

The internal elastic lamina is the outermost layer of the tunica intima. It makes the vessels resilient to moderate the high pressure of blood coming from the heart. In large muscular arteries, elastic lamellae will be regularly distributed between muscle layers.

SMOOTH MUSCLE

Smooth muscle is made of single cells connected by gap junctions that help spread chemicals (calcium) or action potentials between cells. The contractions are

TUNICA MEDIA

TUNICA ADVENTITIA

ARTERIOLES

VENULES

Lab #9: Blood and Bone Marrow

WHOLE BLOOD

Whole mammalian blood contains formed elements (erythrocytes, leukocytes, platelets) and plasma.

BLOOD (FISH)

Unlike mammalian blood, fish erythrocytes contain nuclei.

BLOOD (FROG)

Unlike mammalian blood, frog erythrocytes contain nuclei.

BLOOD (SNAKE)

Unlike mammalian blood, snake erythrocytes contain nuclei.

BLOOD (BIRD)

Unlike mammalian blood, bird erythrocytes contain nuclei.

ERYTHROCYTE

Erythrocytes, or “red blood cells” are created by hemopoietic stem cells in the bone marrow and loose their nuclei before entering the blood stream. They have no organelles but contain abundant hemoglobin which is an allosteric protein that can bind oxygen and carbon dioxide.

NEUTROPHILS

Neutrophils are the most common leukocyte in blood. They help protect the body against bacterial pathogens as part of the innate immune system. They are granulocytes, but their granules stain a neutral pink. Nucleus is polymorphonuclear., divided into 3-5 lobes.

EOSINOPHIL

Eosinophils have basic granules (i.e. major basic protein) that stain with acid dyes. They are part of the innate immune response and protect against helminth worms and parasites. They are also mediators of immune reactions.

BASOPHIL

Basophils are the least common of the granulocytes. They contain dark-staining acid granules. They are very similar to mast cells and can secrete histamine (vasodilator) and heparin (anticoagulant) in response to certain antigens that they recognize through IgE surface receptors.

MONOCYTES

Monocytes circulate in the blood and in response to inflammation, will move into tissues and differentiate into macrophages, dendritic cells, and other cells of the mononuclear phagocyte system.

LYMPHOCYTES

ADIPOCYTES

ERYTHROBLAST

MEGAKARYOCYTE

MYELOCYTE

NEUTROPHILIC METAMYELOCYTE

Lab #9: Lymphatic System

LYMPHOCYTES

Lymphocytes are white blood cells important in the immune system system. The three types are the smaller B and T lymphocytes and large, granular natural killer cells. B and T can only be differentiated by immunocytochemical methods.

PEYER’S PATCHES

Peyer’s patches, aka “aggregated lymphoid nodules,” are small groups of lymph follicles located in the ileum of the small intestine. They are what differentiate the ileum from the jejunum and duodenum. Their epithelium has specialized M cells (microfold cells) that sample antigens from the lumen and take them to the base. B cells, macrophages, or other cells may respond to the antigens by stimulating an immune response.

LYMPH NODE

Lymph nodes are small round/oval organs in the immune system. They act as filters/traps for foreign particles and are packed with lymphocytes. They are common, e.g., in the stomach, armpits, head and neck, etc.

LYMPH NODE

COREX (LN)

The cortex is the outermost region of the lymph node. It is directly underneath the connective tissue capsule and contains primarily B lymphocytes.

GERMINAL CENTERS

Germinal centers are areas of proliferating B lymphocytes within a lymph node, found in the cortex.

PARACORTEX (LN)

The paracortex is the part of the lymph node between the cortex and medulla. It has a mix of both mature and immature T cells, and lymphocytes will enter the lymph nodes through special endothelial venules here in the paracortex.

MEDULLA (LN)

The medulla is at the center of the lymph node. It is composed of (1) cords and (2) sinuses.

MEDULLARY SINUSES (LN)

Medullary sinuses are vessel-like spaces that allow for the flow of lymph fluid. Lymph flows in through the cortex, to the paracortex and medulla, and out at the hilum (very center) into efferent lymph vessels.

Direction of Lymph Flow

MEDULLARY CORDS (LN)

Medullary cords are the parts of the medulla that contain most of the cells, primarily B cells and plasma cells.

RETICULAR FIBERS (LN)

Reticular fibers form a supporting “reticular network” that allows for adhesion of dendritic cells, macrophages, and lymphocytes.

Lab #11: Digestive System

SALIVARY GLAND

Salivary glands are exocrine glands with ducts that produce saliva (mucous) and amylase (serous, breaks down starch).

Mucous Secretory Cells

Serous Secretory Cells

Duct

ESOPHAGUS

The esophagus is a muscular tube that moves food from the pharynx to the stomach. It has several layers:(1) Non-keratinized

stratified squamous epithelium

(2) Submucosa (3) Muscle - The type

varies depending on whether it is the early esophagus (swallowing) or later esophagus (peristalsis, smooth muscle).

STOMACH

The stomach releases mucous, proteases (to digest protein) and hydrochloric acid (to lower the pH to kill bacteria and to provide the acid pH for enzymes to work).

Tubular gastric glands

PARIETAL CELLS

Parietal cells are larger than chief cells, with more rounded central nuclei. They secrete HCl.

CHIEF CELLS

Chief cells have nuclei closer to the periphery and produce pepsinogen, a precursor of the proteolytic enzyme pepsin.

GASTRIC PIT

Gastric pits are indentations in the stomach that are the openings to gastric glands.

Simple Columnar Epithelium

SMALL INTESTINE

This is the jejunum of the small intestine. The small intestine is where most chemical digestion takes place.

Muscularis Mucosa (Smooth Muscle)

Simple Tubular Gland

Connective Tissue

Villi

DUODENUM

The duodenum is the first section of the small intestine where most chemical digestion takes place. It can be distinguished from other parts of the intestine due to the presence of Brunner’s glands which secrete mucus.

Bruner’s Glands

VILLI

Intestinal villi are fingerlike projections that increase the surface area for absorption of materials from the lumen. Many nutrients pass through via diffusion, which is only effective over short distances. On the surface of villi are even smaller microvilli which are not visible here.

MUCOSA

The mucosa is made up of:

(1) An epithial lining(2) Lamina propria of loose

connective tissue rich in blood, lymph vessels, and smooth muscle

(3) Muscularis mucosae that separates muscosa from submucosa

SUBMUCOSA

The submucosa has denser connective tissue with blood and lymph vessels, as well as autonomic nerves.

MUSCULARISThe muscularis has smooth muscle cells divided into two layers. The first layer closer to the lumen has a circular orientation. The second layer has fibers arranged longitudinally. Some connective tissue exists between the layers with blood, lymph vessels, and more autonomic nerves.

SEROSA

The serosa is a thin layer of connective tissue with a simple squamous epithelium covering (mesothelium). In the abdominal cavity, it is continuous with the mesenteries (thin membranes covered by mesothelium on both sides).

LYMPHATIC NODULE

Lymphatic nodules are smaller groups of lymphoid tissue located in the digestive and respiratory systems and urinary bladder (wet epithelial membranes).

CAPILLARY

Capillaries are extremely small blood vessels, about the diameter for only one blood cell to pass through. Capillaries have only a thin wall of epithelial tissue and allow for exchange of gasses, nutrients, and other particles.

LARGE INTESTINE

The large intestine the third-to-last part of the digestive system. Its primary function is to help absorb water from waste.

LIVER

The liver is important in detoxification, glycogen storage, plasma protein synthesis, hormone production, production of bile, and more.

CENTRAL VEIN

The liver is made up of polygonal lobules, and each lobule is centered on a central vein, which is a branch of the hepatic vein. It takes deoxygenated blood from liver sinusoids and returns it to the inferior vena cava to go to the heart.

CENTRAL VEIN

PANCREAS

The pancreas is both a digestive organ and endocrine gland. It secretes hormones like insulin and glucagon to regulate blood sugar and also digestive enzymes into the duodenum to help break down chyme from the stomach.

PANCREATIC ISLET

Pancreatic islets, aka “Islets of Langerhans” contain the hormone-producing endocrine cells.

Lab #12: Reproductive Systems

TESTIS

The testis are the male gonads, and their primary function is to produce sperm and androgens, esp. testosterone.

EPIDIDYMIS

The epididymis is a narrow, tightly-coiled tube that connects the testis to the vas deferens. Sperm are stored and mature here.

SEMINIFEROUS TUBULES

Seminiferous tubules are located in the testis. Meiosis occurs here and results in the formation of spermatoza.

TUNICA ALBUGINEA

The tunica albuginea is a layer of dense regular connective tissue that surrounds the testis.

SPERM

Sperm are male reproductive cells. They combine with haploid eggs to make a diploid zygote. A spermatozoon is a motile sperm cell.

Testis

Epididymis

SERTOLI CELLS

Sertoli cells are “nurse” cells in the testes. They are a permanent population and nourish the sperm as they develop. The shape of the cytoplasm is somewhat like a tree, where early cells in sperm development are a the base, and move toward the branches as they mature. They have a dark-staining nucleus with a prominent nucleolus.

SPERMATOGONIA

Spermatogonia are stem cells located near the basement membrane which undergo meiosis. Some divide to make more spermatogonia and others differentiate to eventually produce sperm.

Spermatogonia

PRIMARY SPERMATOCYTES

Primary spermatocytes are in the cell layer luminal to the spermatogonia (first cells of spermatogenesis). They are somewhat larger. Cell divisions are incomplete, and the cells remain connected by thin bridges of cytoplasm.

Primary Spermatocytes

SPERMATIDS Early Spermatids

Spermatids are products of the second meiotic division. They are transitioning into spermatoza so are visible in early through late forms.

Late Spermatids

Sertoli Cell Nucleus

ARTERIES

Arteries carry blood away from the heart. They often have lots of elastic fibers with a pronounced elastic lamina, as well as a thick layer of smooth muscle for the tunica media.

VEIN

Veins carry blood to the heart, usually deoxygenated blood. Veins contain valves that help prevent backflow. The thickest layer is the tunica adventitia, made of connective tissue. Veins do have smooth muscle, but the layers are thin because veins do not have contractile function like arteries.

OVARY

The ovaries produce ovum in females, and they are both gonads and endocrine glands.

PRIMARY OOCYTE

Primary oocytes are cells arrested meiosis. Oogonia will begin to enter prophase of the first meiotic division but stop after synapsis and recombination.

OVARIAN STROMA

Ovarian stroma is the surrounding tissue with a rich supply of blood vessels. Mostly it contains spindle-shaped cells with connective tissue. At the surface, the tissue is more condensed and is called the tunica albuginea.

Tunica Albuginea

Ovarian Stroma

ZONA PELLUCIDA

The zona pellucida is a layer of four secreted glycoproteins that lies between the oocyte and granulosa cells. ZP components bind proteins on sperm and induce acrosomal activation.

GRANULOSA CELLS

Granulosa cells are cuboidal cells arranged in a stratified epithelium surrounding the oocyte. They produce sex steroids (e.g. follicle stimulating hormone) and growth factors that aid in development of the oocyte.

ANTRUM

The antrum is filled with a fluid called liquor folliculi. Filling of the antrum causes the follicle to swell and rupture, releasing the egg.

Follicular Antrum

CORPUS LUTEUM

After ovulation occurs, the follicle develops into a corpus luteum. Inside are granulosa cells and thecal cells. They accumulate lutein a few hours after ovulation, and become lutein cells that produce progesterone and estrogens. If fertilization does not occur, the corpus luteum degenerates and becomes a corpus albicans.

CORPUS ALBICANS

A corpus albicans develops from the follicle if the oocyte is not fertilized. It is composed of whitish scar tissue, with collagen laid down by fibroblasts as the corpus luteum is broken down by macrophages.

GERMINAL EPITHELIUM

Germinal epithelium is a single layer of cuboidal cells that covers the outside of the ovary.

CUMULUS OOPHORUS

The cumulus oophorus is a group of cells that forms a small pedestal for the egg. It also surrounds the oocyte and helps coordinate folicular and egg development.

GRAAFIAN FOLLICLE

A graafian follicle is a mature follicle where the egg has reached its full size and includes one or more fluid-filled cavities.