Histology Quiz 3

connective tissue

Collagen Type 1 or 2

What fiber is seen here in H&E?

Collagen type 3

What fiber is seen here in silver stain?

Elastic

What fiber is seen here in Verhoeff’s stain?

Dense irregular, dermis of skin or digestive system walls

What type of CT proper? Where could it be found?

dense regular, tendons and ligaments

What type of CT proper? Where could it be found?

loose, under epithelia and in glands

What type of CT proper? Where could it be found?

dermis of skin, lining of organs, tendons and ligaments

Which tissues do you think might be most affected by mutations in the Collagen I gene?

support and protect other tissues and organs

What is the function of connective tissue?

extracellular matrix

mix of proteins secreted by cells into extracellular environment that can form meshes, gels or hard crystals

ECM, cells

In many connective tissues, the ____ becomes more abundant than the _____ themselves

protein ground substance and fibers

what is ecm composed of?

ground substance

• More heavily glycosylated

• Variety of carbs and glycosylated proteins

• Structure with more flexibility

• Hydrated and gel like-> important for nutrient/waste exchange

• Mediates movement of molecules and cells as well as cellular adhesion

collagens and elastins

what are the 2 types of fibers

fibers

Component of ecm that provides strength, structure, support, and sometimes flexibility

collagen

-most abundant protein in body at 30% of dry weight

• Very strong-> resistant to tearing

• Self assemble outside of cell to form bundles of fibers or mesh like sheets

types I and II

 large collagen fibers, very acidophilic in H&E

type III

very delicate collagen fibers (supports highly cellular environments), not visible w/ H&E use silver stain

elastic

• Flexible, found in tissues that need to stretch

  • Musculature, arteries ect

• Don’t stain well w/ H&E (Verhoeff’s often used)

  • Usually squiggly bc tissue is relaxed

connective tissue proper

* Primarily composed of cells called fibroblasts
* Embedded in surrounding ECM
* Produce and secrete the extensive ECM

Embryonic Fibroblasts

actively producing ECM and have enlarges nuclei w/ well developed RER and golgi

inactive, nuclei, cytoplasm

\n Fibroblasts of mature CT are typically _____ and thus have condensed ___ and minimal ________

loose CT

highly cellular; abundant ground substance in ECM; ECM fibers less abundant and scattered (no bundles, may include both collagen and elastin)

dense irregular CT

less cellular; abundant fibers in ECM (mostly collagen I/II), often bundled but not well organized

dense regular CT

ECM is abundant and packed densely with parallel arrays of protein fibers (collagen I/II); cells are sparse and squeezed in between fibers of the ECM

1 and 3

What types of collagen are found in loose CT?

1

What types of collagen are found in dense irregular CT?

adhesion beneath epithelia and in glands, permeable for diffusion

function of loose ct

directly under epithelia and in glands

Where is loose CT found in the body?

not very active or permeable, tough and supportive with some flexibility

function of dense irregular CT

dermis of skin, walls of organs

Where is dense irregular CT found in the body?

extremely tough but lacks activity for repair

function of dense regular CT

tendons and ligaments

Where is dense regular CT found in the body?

brown

What type of adipose tissue?

white

What type of adipose tissue?

white (embedded in other tissue)

What type of adipose tissue?

fibrocartilage

What type of cartilage?

elastic

What type of cartilage?

hyaline

What type of cartilage?

Hyaline, perichondrium, nose or respiratory system

demineralization

how was this bone prepared?

ground bone

how was this bone prepared?

demineralized, osteocytes, osteoblasts osteoclasts osteoprogenitor

adipose tissue

•“Fat” \n •Distributed throughout body, both in specific deposits and embedded within other tissues

energy storage, cushioning and protection, temp regulation, metabolic signaling

functions of adipose tissue

adipocytes

name of adipose tissue cells

lipid

Adipocytes are dominated by internal ______ deposits

no

does adipose tissue have a lot of ecm?

yes

is adipose tissue highly vascularized

white and brown

2 types of adipose tissue

thermoregulation

function of brown adipose tissue

energy storage, metabolic and endocrine signaling, insulation, cushioning

functions of white adipose tissue

single large fat droplet

in white adipose tissue, cytoplasm is dominated by ______

hormones, insulin, pancreas, glucagon, norepinephrine, adrenal medula

Fatty acid storage and release is regulated by ________

–____ from ____ stimulates uptake/storage \n __–_______ from pancreas and _____ from ________ stimulate release

adipokines

White adipose tissue secretes hormones called _____ that help to regulate body weight and energy homeostasis

leptin

best studied adipokine known to act on hypothalamus and regulate satiety and energy expenditure

cytokines

White adipose tissue also releases signals called ______ that stimulate the immune system

multiple small fat droplets

brown adipose tissue structure consists of…

mitochondria, acidophillic

brown adipose tissue has abundant ____ resulting in ______ cytoplasm

thermogenesis

\n process that generates heat in response to norepinephrine from sympathetic nervous system

ATP production

thermogenesis triggers hydrolysis of triglycerides and activation of _______ in mitochondria

heat

BAT mitochondrial enzymes generate ___ during atp production

infants

in who is BAT more abundant

higher

Individuals with higher proportions of BAT have _____ \n metabolic rates

cells called chondrocytes and abundant ecm

what is cartilage made of?

lacunae

Chondrocytes produce and secrete abundant ECM, then become trapped in that ECM in cavities called _______

extensive, vasculature

cartilage ECM is _____ and lacks ______

ground substance

Cartilage ECM has lots of ground substance that forms a gel that is good at absorbing shock

perichondrium

Some types of cartilage are surrounded by a fibrous sheath called the ________ that holds vasculature

hyaline cartilage

\-smooth, faintly staining appearance in H&E staining

\-ECM is strong and supportive, but more flexible than bone \n •EMC also has a gelatinous texture that makes it good for \n absorbing shock, and also good at reducing friction surfaces

respiratory system, nose, ribcage

where can hyaline cartilage be found?

elastic cartilage

\-chondrocytes are located in lacunae, and separated from one another by extensive ECM

\-in that it contains more fibers than hyaline– specifically, more elastic fibers \n •“streakier” in H&E; elastic fibers are even more prominent \n when using specialized stains such as Verhoeff’s

hyaline and elastic

which cartilage types can have perichondrium?

ear and epiglottis

where is elastic cartilage found

fibrocartilage

\-mixture of cartilage and dense CT

\-ECM is enriched with collagen fibers, often in parallel arrays

\-identifiable by the presence of collagen rich ECM, \n chondrocytes AND fibroblasts, and distinctive rows of chondrocyte isogenous groups packed in between collagen fibers

intervertebral discs and pubic symphysis

where is fibrocartilage found?

less

Types of cartilage w/ no perichondrium _____ capable of regeneration

rare and slow growing

Cancers within cartilage are ______ because cells are not effective at growth or division

bone

Provides structure and support, Protection for vital organs, site of hematophatosis

osteocytes

bone cells within lacunae

bone matrix

what is bone ecm called?

osteoblasts

Cells called _______ secrete type 1 collagen and ground substance in bone

periosteum

Fibrous sheaths lining external surfaces of bone matrix

endosteum

Fibrous sheaths lining internal surfaces of bone matrix

osteoblasts

• Cells that can produce new bone matrix

• Tend to have basophilic cytoplasm

  • Lots of rough ER for collagen synthesis

osteoclasts

• Can break down existing bone matrix

• Large, multinucletate cells

• Often slightly acidophillic cytoplsm

demineralization

* place in solution to dissolve minerals, soften tissue, and re-expose original collagen foundation of bone ecm
* Then stain/section
* Keeps living cells alive

ground sectioning

* grind down bone, typically unstained or treated w/ black ink that settles into cracks
* No living cells

long bones

humerus, femur, etc

flat bones

\n scapula, bones of the skull, ect

compact and spongy

bones can contain what 2 regions?

lamellar

layered bone

alternate direction perpendicularly

Within each layer of bone collagen fibers are organized in parallel bundles

\-Bundles ________ to increase strength

ostens

\n In compact bone, cylindrical structures called ______ are apparent

concentric layers, central canal

Within osteons, lamellae are organized into _____ surrounding a central open space called the ________ holding blood vessels and nerves

volkmann canals

Blood vessels also found in perforating canals which are called…

canaliculi

Osteocytes access volkmann canals via cytoplasmic projections which they extend through tiny tunnels in the matrix called ______

resting zone, proliferation zone, hypertrophic zone, calcification zone, ossification zone

name each zone in an epiphyseal growth plate

body will take calcium out of bones, osteoclasts will be activated

If your diet is low in calcium, you may experience a decrease in bone density – why? Which cell type will be activated in response to low blood calcium concentration?

embryonic development

when does most bone development occur?

\n Intramembranous and endochondral ossification

2 mechanisms to produce new bone