Histology Lecture 1- Intro, Epithelium, Connective tissues

Hematoxylin

basic dye and attracted to net negative charge, stains nuclei blue/purple

Structures are basophilic

Eosin

acidic dye, positive charge

stains Amino Acids and proteins

pink/red

Structures are eosinophilic

Periodic acid-Schiff (PAS)

stains carbohydrates magenta

What are the components of epithelium tissue

covers surfaces, lines cavities, forms glands

Has a free surface, basal lamina, and specialized cell-to-cell junctions

Connective tissue has what function and components

supports tissue, structurally and functionally

characterized by its extra-cellular matrix

blood, cartilage, bone, and adipose

Components of muscle tissues

composed of contractile cells, produces movement

Skeletal, cardiac, smooth

nerve tissues function and components

composed of neurons and support cells

receives, transmits, and integrates information

CNS and PNS

what are the germ layers of the epithelium?

ectoderm, mesoderm, endoderm

Epithelium mesoderm

vascular endothelium

which germ layer has -angiomas and -sarcomas

mesoderm

Benign tumor of mesoderm epithelium

-angiomas

malignant tumor of mesoderm epithelium

-sarcomas

What is the mesoderm

vascular epithelium

what is the endoderm

epithelium of structures derived from yolk sac (gut, airway)

What are the benign tumors of the endoderm?

papilloma/adenomas

what is the malignant tumor of the ectoderm?

-carcinomas

What parts of the body have the ectoderm layer?

epidermis, ependyma

What are the benign tumors of the ectoderm

papilloma, adenomas

what is the malignant tumor of the ectoderm

-carcinomas

Connective tissue contains which germ layers

mesoderm and neuroectoderm (neural crest) for head

Mesoderm in connective tissue have which types of body parts

torso and limbs

Mesoderm benign tissues in connective tissues

fibroma (connective tissue proper), lipoma, chondroma, osteoma

mesoderm malignant tumors in connective tissues

-sarcomas

Benign tumors of the muscle mesoderm

-myomas

malignant tumors of the muscle mesoderm

-myosarcomas

What is a tumor called that is made up of more than one germ layer?

teratoma

What does it mean when epithelial tissues are avascular

they do not have blood vessels

epithelial tissue is absent from which types?

arterial cartilage, anterior surface of iris, enamel of teeth

What are the functions of epithelial tissue

protection (skin), absorption (intestines, kidneys), transport of nutrients/waste (along or across an epithelium), excretion (kidneys), secretion (glands), selective barrier, sensory receptors for special senses (olfactory epithelium, hair cells, taste buds, retina)

What are the three main features of epithelial tissue

1. Basement membrane

2. Cell polarity

- Free surface (apical)

- Lateral domain

- Basal domain

3. Closely apposed and adhered to each other

apical

lumen of external environment (for skin)

Which tissues do not have free surface

epithelioid tissues (pancreas, adrenal gland, ovary, testis, anterior pituitary gland)

What are the apical modifications of epithelial cells

Keratinized/ non-keratinized

Ciliated

tissues with simple squamous and the functions

endothelium, mesothelium

Exchange and barrier

tissues with simple cuboidal and their functions

gland ducts, ovary, kidney, thyroid

Absorption, secretion, barrier, conduit

tissues with simple columnar and their functions

GI tract and gallbladder

Absorption and secretion

tissues with stratified squamous and their functions

epidermis, oral cavity, vagina

Barrier and protection

tissues with stratified cuboidal and their functions

gland ducts, anorectal junction

Barrier, conduit

tissues with stratified columnar and their functions

gland ducts, anorectal junction

barrier, conduit

Pseudostratified epithelium are located where?

trachea, bronchi, ductus deferens, epididymis

Simple epithelium

transitional epithelium are located where

lower urinary tract (minor calyces, ureter, bladder, proximal urethra)

what are transitional epithelium cells specialized for

distension- cells flatten and unfold

apical modifications: Microvilli contain what features

brush border or striated border

short cytoplasmic processes

Microvilli apical modifications are the core of what and are located where?

Core of actin filaments, anchored to terminal web

located on epithelial cells of intestine, kidney, etc

microvilli are specialized for

absorption and secretion (increase surface area)

Stereocilia apical modifications have what features

long, immotile microvilli (Actin core)

limited to epididymis (absorptive) and hair cells on inner ear (mechanoreceptors)

mechanoreceptors have what function

move and open up ion channels for fluid movement in inner ear, which is influenced by sound waves

cilia apical modification has what features

long cytoplasmic processes (crew cut), core of microtubules (axoneme), anchored to basal bodies

Motile cilia are located where and specialized for?

located on respiratory epithelium, olfactory epithelium, uterine tubes, etc.

Transport specialization

primary cilia

Acts as a receptor and one per cell

nodal cilia

present during embryonic developement

Kartagener's syndrome

ciliary dyskinesia (cilia cant move)

Symptoms: increased upper respiratory infections, infertility, organs on opp. side

Lateral domain of epithelial cells

junctional complexes between epithelial cells

what are the 3 types of lateral domains

1. Occluding junctions (Zonula Occludens/Tight junctions)

2. Anchoring Junction (Zonula Adherens and Macula Adherens/Desmosomes)

3. Communicating Junctions (Gap Junctions)

occluding junctions (Zonula occludens/Tight junctions) function

allows epithelium to act as selectively permeable diffusion barrier

Anchoring junctions (Zonula Adherens and Macula Adherens/Desmosomes) functions

serve to anchor cytoskeleton of adjacent epithelial cells and provide structural and mechanical integrity

which type of anchoring junction interacts with actin

Zonula Adherens

which type of anchoring domain are associated with intermediate filaments

Macula Adherens/Desmosomes

communicating junctions (gap junctions)

allow adjacent epithelial cells to communicate directly via passage of small molecules

permits coordinated cell activity (ex: cardiac muscle, smooth muscle)

Terminal bar of lateral domains

Junctional complex at the junction between the apical and lateral surfaces.

lateral folds

increase SA between adjacent cells

Basal domain of epithelial cells

cells adhered to basement membrane (basal lamina + underlying reticular connective tissue)

functions of basal lamina

cell attachment, compartmentalization, filtration, tissue scaffolding, regulation + signaling

How are cells anchored to underlying connective tissue

junctions (hemidesmosomes, focal adhesions)

What increases surface area in the basal domain

basal infoldings

exocrine glands may be:

unicellular or multicellular

What is a unicellular exocrine gland

goblet cell

Multicellular exocrine glands

duct (simple, compound- opens to epithelial surface) and secretory unit (tubular, acinar, alveolar, tubuloacinar)

Simple Multicellular gland

no duct, or single unbranched duct, leads to epithelial surface

(ADD PICTURE)

Simple tubular look and location

Large intestine (intestinal glands of the colon)

(ADD PICTURE to term)

Simple coiled tubular look and location

skin: eccrine sweat gland

(ADD PICTURE)

simple branched tubular

location: stomach: mucus-secreting glands of pylorus

Uterus: endometrial glands

What is the location of simple acinar (alveolar)?

Urethra: paraurethral and periurethral glands

(ADD PICTURE)

Simple branched acinar

Location: Stomach: mucus-secreting glands of cardia

Skin: sebaceous glands

Where is compound tubular glands found?

Duodenum- submucosal glands of Brunner

(ADD PICTURE)

compound acinar

Location: Pancreas- exocrine portion

(ADD PICTURE)

Compound tubuloacinar

Location: submandibular salivary gland

Compound multicellular glands

branching duct system, one duct per secretory unit

Multicellular gland secretions: Mucous classification

Viscous and slimy; extensive glycosylation of proteins (PAS +)

Cells stain pale with H and E

Ex: Sub-lingual and stomach gland

Goblet cells

Multicellular gland secretions: Serous classification

Ex: Parotid gland and pancreas

Secretions are watery; little to no glycosylation on proteins

apical cytoplasm is eosinophilic; perinuclear cytoplasm is basophilic

Multicellular gland secretions: Mixed classification

ex: submandibular gland

Contains both mucous and serous cells

processing artifact- serous demilune

characteristics and function of connective tissue

composed of cells and extra-cellular matrix (ECM)

Function- reflection of composition of ECM

Where is connective tissue located?

fascia (connects diff. organs and tissues), tendons, ligaments, supportive layers of vessels/nerves/muscles/organs

Composition of connective tissues: Cells

fibroblasts and immune cells

composition of connective tissue: ECM

fibers (collagen, elastic fibers, reticular fibers) and ground substance (proteoglycans, glycoproteins, glycosaminoglycans)

embryonic connective tissue

mesenchyme (undifferentiated CT) and mucous connective tissue (umbilical cord)

connective tissue proper

loose connective tissue and dense connective tissue (regular, irregular)

Specialized connective tissue

bone, cartilage, blood, adipose, lymphatic, hemopoietic (produces RBCs)

Embryonic CT: Mesenchyme

undifferentiated CT, very circular with sparse collagen and reticular fibers

viscous ground substance

Embryonic CTL Mucous CT

found only in umbilical cord

gelatin-like ECM (Wharton's jelly)

Connective Tissue Proper: Loose CT

Areolar tissue, relatively cellular with thin, sparse fibers

Abundant ground substance- site of inflammatory/immune response ideal for diffusion

location of loose CT

under epithelium and mucous membranes, around vessels

Connective tissue proper: Dense CT

relatively few cells (mainly fibroblasts) and abundant fibers (mainly collagen)

dense irregular CT

bundles oriented in various directions

function: strength and support

dense regular CT

densely packed fibers arranged in parallel

Function: comprise ligaments, tendons, aponeuroses

Collagen is produced by?

fibroblasts

collagen characteristics and function

appear eosinophilic and of variable size

function: provide flexibility and tensile strength

Collagen formation

three alpha-chain polypeptides -> collagen fibrils -> collagen fiber

Type I collagen

bone, CT proper (loose CT, tendon, ligaments, etc.)

Type II collagen

cartilage