OSS Quiz 1

Steps of Long bone formation in Endochondral bone formation

*** Comes from mesenchymal Progenitor (cartilage to bone) Outside to inside: 1. Proliferating chondrocytes 2. prehypertrophic chondrocytes (at which point switch to synthesize collagen X) 3. Hypertrophic (recruit cartilaginous skeletal elements and drives longitudinal bone growth. Recruits mineralization of surrounding matrix and production of VEGF. Under go apoptosis whcih leaves behind matrix for osteoblasts to invade) and lay down primary spongiosa) 4. Terminal hypertrophic

Stages of tooth development

*requires interaction between epithelium and mesenchyme 1. Thickening 2. Bud 3. Cap 4. Bell 5. Erupted Tooth

Runx2

- Affect on osteoblast to osteocyte lineage

FGF signaling in bone

- Chondrocyte proliferation and differentiation

Cartilage / Chondrocyte features

- Has larger vacuole - Lacunae = The pocket that the chondrocyte sits in

Proliferative zone cells

- High o2 content and glycogen content - increased mitochondrial ATP production - separated via aggrecan and type II collagen

Functions of Epithelia

- Protection - Absorption -Secretion -Sensory

Cellular components of the skeleton - Defect in Runx2 or SOX9

- Runx2 = formation of osteoblast precursor - Sox9 = chondrocyte formation

Treacher Collins Syndrome

- abnormal arch 1 produces facial anomalies -

Synchondrosis: Located where?

-- Union between two bones (due to formation of hyaline cartilage or fibro-cartilage) -- 3 in midline of cranial base - --- Spheno-ethmoidal ---intersphenoid --- spheno-occipital (can grow bidirectionally as opposed to others)

What pharyngeal arch gives rise to teeth?

1

What is derived from Ectoderm?

1. Brain, Skin, Teeth, hair

1. Epithelial Neoplasm 2. Mesenchymal neoplasm

1. Carcinoma 2 Sarcoma

1. Pinocytosis 2. Receptor-mediated endocytosis 3. Phagocytosis

1. Cell "sipping" extracellular fluid into vesicles 2. Solid particles 3. Clathrin coated pits

1, Pluripotent 2. Totipotent 3. Multi

1. Cells that are capable of developing into any embrylogical origin 2. Can become anything in embryo and extra embryological cells 3. Can develop within specific lineages

1. Jansen Metaphyseal chondrodyslplasia 2, Bloomstrand lethal osteochondrodysplasia

1. Constitutively active PPR or High PTHrP = PTHrP inhibits hypertrophy so osteochondrocytes never mature and bones are short 2. Inactive PPR mutation = No PTHrP to stop hypertrophy so have decreased proliferation = increased hypertrophy and differentiation (causing decreased bone growth)

How to treat aggressive periodontal inflammation

1. Control inflammation 2. Bone 3. Microbial community colonization

Periodontal ligamnet is derived from the?

1. Dental Sac

Morphogen Transport models 1. Restricted Diffusion 2. Planar Transcytosis model 3. Lipoprotein Transfer model 4. Cytoneme model

1. Dependent on number binding induces certain gene expression 2. Transport through the cells 3. 4. Pseudopods help transfer morphogen

1. Surface Ectoderm 2. Neural Crest 3. Neural Tube

1. Epidermis, hair, nails, sebaceous glands, oral epithelium, teeth (enamel) 2. PNS, dentin, facial cartilage, 3. CNS, brain, spinal cord

Mechanisms of Bone formation

1. Intramembranous (frontal, parietal, temporal bones) 2. Endochondral Bone Formation (appendicular, vertebrae, base of the skull

hereditary ectodermal dysplasia

1. Most commonly x-linked - Thin hair - discolored skin - Peg incisors - Hypohidrotic = less sweat - Hypotrichosis = less hair - Caries b/c no PDL, missing teeth Have over 150 types b/c can have anywhere within the pathway (EDA, EDAR, EDA-RAAD)

Order of growth:

1. Neural 2. Lymphoid 3. General body 4. Genitals

Functions of ECM

1. Supportive, mechanical 2. Substrate for adhesion/ migration 3. permissive and instructive for cell differentiation 4. Factor for cell survival

Smooth ER functions

1. Synthesis of lipids, phospholipids + steroids 2. Detoxifies via Cytochrome P450 3. Sequestration of Ca2+

Tongue Development 1. Begins at and formed from

1. Week 4 - Anterior 2/3 = lingual swellings - Posterior 2/3 = copula and hypobranchial eminence

Bell Stage

11 weeks Tooth shaped bud occurs - enamel organ is defined - composed of stratum intermedium and reticulum

Week 4 -10

4 = mand/ max 5 = nasal pits 6 = front nasal pits fuse/ secondary and primary palate form 7. Palate shelves elevate 10. Fusion of secondary and primary palates and nasal septum (defect results in cleft palate)

Initiation stage

6 weeks - ectomesenchymal cells induce overlying ectoderm to proliferate into dental laminal

Bone is Composed of

60% inorganc material 30% organic material 10% water

Bud Stage

8 weeks Form: 1. Dental Lamina 2. Condensing Mesenchyme - ectoderm and mesenchyme proliferate around bud - Localized thickening at site of each tooth (can see condensing mesenchyme)

Cap Stage

9 weeks: - Dental papilla forms from condensed mesenchyme (indentation starts to make pulp) Form: - Outer enamel epithelium - Inner enamel epithelium - Lose Stellate Reticulum Later dental sac/ follicle forms

Why Mouse Models

>99% are the same

Accessory Root canals can be formed by

A break in the root sheath before formation of dentin

PPR

Active PRP (in prehypertrophic) = stops hypertrophy increase proliferation Hypertrophic chondrocytes = secrete IHH which cuases increase in PTHrP secretion PTH and PTHrP receptor = expressed in low level in Proliferative Chondrocytes = Expressed in high levels in Prehypertrophic and hypertrophic chondrocytes

Adnexal Appendages derived from?

All have placode and bud stage Ectoderm (i.e. epithelial bud) - Therefore hair follicle and mammary glands / teeth/ salivary glands would be affected if epithelial bud stage affected

After EMT neural crest cells can migrate how? Somites

Along Dermomyotome (limb/;body, skeletal muscles, dermis or Sclerotome (vertebrae / ribs) SOmite = lateral to neural crest mesoderm

Apoptosis vs. Necrosis

Apoptosis doesn't cause inflammation

Arch I forms frontonasal prominence and meckel's cartilage

Arch

Where do neural crest cells form?

At the boundary of the neural and non-neural ectoderm

Tooth type determined by?

BMP (incisor) and FGF (molar) signaling

Mucinocele

Blue nodule, well demarkated, excisional biopsy (

Mandibular and Maxillary formed from

Both undergo intramembranous ossification

Sutures are assisted by

Brain comes forward and induces the cranial vault (top) to grow because don't have synchondrosis which have cartilage to assist in the growth of the bone.

Accessory root canals can be formed via?

Break in root sheath before formation of dentin

5 Signs of acute inflammation

Calor, dalor, redness, tumor, loss of function

IHH deletion

Causes no Ihh secretion leading to No PTHrP production causing early differentiation. Does not grow in the length, the bone.

Cillia vs. Microvilli

Cillia = motile Microvilli = increased surface area for absorption

Rough ER composed of

Cisternae (flattened membrane disck,) and ribosomes

Example of a collagen that is also a proteoglycan

Collagen 18

Articular Cartilage is composed of

Collagen that has: Proteoglycans = bind water Hyaluronic acid - binds water (made of di-saccharide repeat) Collagen fibrils - Aggregan - bottle-brush molecule (core protein that binds water molecules)

Cre-Lox mouse

Cre targets a specific sequence of DNA =

OPG

Decoy receptor for RANKL to block osteoclast activity (produced by osteoblasts)

ACH achondroplasia

Defect in FGFR3 normally inhibits proliferation (mutation = an activating mutation) and prevents proliferation causing => early differenitation and short extremities

Cleidocranial Dysplasia

Defect in Runx2 - Osteoblast lineage mesenchymal stem cells to osteocytes --- often born without clavicles or open fontanels

Dental Papilla vs Dental Follicle Dental lamina

Dental papilla = ectomesenchyme Dental sac= forms cementoblasts (cementum) Lamina = epithelial

Area at which calcification of a tooth begins

Dentinenamel junction

Derivation of epidermal Tissue from ectoderm

Derivation of epidermal tissue = BMP produced from ectoderm induced epidermal tissue

Morphogens

Diffusible biochemical molecule that forms a gradient (ex. placode induction)

Lysosome

Digests organelles, with several 40-50 hydrolytic enzymes - Low pH environment (optimal activity for enzymes)

Early vs. Late migrating cells

Early = form dorsal root ganglion and heart/ adrenal gland Late = melanocytes after dermis invasion

Bone Arises from?

Ectoderm and mesoderm

Multiple root formation in a tooth follows unequal proliferation of the?

Epithelial diaphgragm (turning of the apical root sheath)

Multiple root formation in a tooth follows proliferation of

Epithelial diaphragm

Tissue Recombination experiments

Epithelial induces it but Mesenchymal determines (the fate) .Kidney = invovled in EMT ; liver is not involved in EMT

What closes the growth plate

Estrogen

Trophectoderm cells

Extraembryonic cells (on outside) with inner cell mass on inside

Neural Crest cells are pluripotent

FALSE (I THINK) = Pluripotent stem cells: Can make all three layers

Neural Crest found in other non vertebrates

False

Periosteum - Layers

Fibrous layer covers bone (plays role in bone strength and tissue regeneration 1. Endomesial layer (mesenchyme) -- involved in regeneration 2. Outer layer = fibroblastic (plays structural layer)

Apposition

Formation of crown - First = odontoblasts (secrete dentin matrix) - 2nd = ameloblasts secrete enamel matrix

Which branchial arch gives rise to thyroid cartilage?

Fourth

What causes the mesoderm to form?

From Nodal and Wnt Signaling from epiblast cells

What is derived from endoderm?

GI tract, liver, pancreas, gallbladder, resp tract lining

PAS stain stains

Glycoproteins in wall ("periodic acid shift stain")

Synchondroses bone growth

Growth = similar to long bone growth (but Bipolar) and used via endochondrial

HED symptoms

Hereditary Ectodysplasin

Derivatives of the branchial arches

I = maxillary artery, trigeminal V, muscles mastication, II = hyoid, stapedial , facial VII, muscles of facial expression , stapes III = internal carotid, glossopharyngeal IX ,

What collagens are invovled in interarticular cartilage

II, XI, and XIV

Stem cells for endochondrium are located where?

In the resting zone

Role of 4-hydroxyproline

Increases melting temperature of collagen

Sclerostin

Inhibits Wnt --> decreased bone formation

Endosteum

Inner layer (lines bone cavity) Skeletal homeostasis role i.e. consists of osteoprogenitor cells -

Overall Signaling Pathway

Intermediate BMP + FGF + Wnt => Pax3 and Zic 3 which then induce Snail and FOXD3 forming the neural crest

Neural plate border genes (i.e. cells that will form neural crest cells) formed via what signaling?

Intermediate levels of BMP and Wnt and Fgf induce Neural Place border genes i.e. Pax3 and Zic3) which induce Via induction of Snail Gene ( ( which then causes development of the Epithelial-mesenchymal transition High BMP would be ectoderm Low BMP would be neural tube

Cytoskeleton

Intracellular scaffolding -

Maxilla grows via

Intramembranous

Gingivitis Periodotitis

Irreversible = periodontitis (progresses past the CEJ) Reversible = gingivitis

Collagen V role

Lots of collagen V = small diameter fiber

4th week of embryonic development the first branchial arch divides to form

Maxillary and mandibular processes - Meckels cartilage dissolves as the mandible forms (5th week nasal pits form)

Failure of fusion of which embryonic processes cause cleft lip and palate

Medial nasal and maxillary and maxillary

What determines type of tooth

Mesenchyme

Week 6 Brachial arch I End of week 6

Mesial nasal porcesses merge with each other AND maxillary process Mandibular processes fuse End of week 6 -- Primary palate forms becomes part of premaxillary

Derivation of Neural Tissue from ectoderm

Mesoderm produces noggin which inhibits BMP (produced from ectoderm) This causes formation of neural tissue **Works with Chordin as well ****This induces the Neural Plate to form Neural tube/ (CNS) with the neural crest cells coming off of it (PNS)

Osteoclasts come from -important differentiator for macrophages?

Monocytes (same as macrophages) Come from hematopoietic stem cells -Know cathespin K

What is derived from Mesoderm?

Muscle, bone = forms cranial vault bone -- Formed from cells from primitive streak -- Formed from Wnt and Nodal signaling from epiblasts in the ectoderm layer

4-5 week development

Nasal/ olfactory placodes from nasal pit - FORM lateral and medial nasal placodes

Skull derived from

Neural Crest (from ectoderm) = Frontal, maxilla, mandible Mesoderm = Fronal, parietal, occipital

Dentin Formed from

Neural Crest (via odontoblasts)

• When the definitive mandible forms and meckel's cartilage dissolves, what structure remains as a remnant?

No remnant remians in the adult

Wnt and BMP signaling in tooth

Oral ectoderm induces odontogenic mesenchyme and vice versa

Mucopolysaccharidoisis

Oral manifestations - Micrognathia (MPS I) - Macroglossia - Gingival hyperplasia

Osteocytes formed form

Osteoblasts

Week 7 Development

Palatal shelved

Peripheral Nerve Bundle

Perineurium/ axon/ myelin

Osteoclasts form what on bone

Pits (and can their see multinucleated cells

Primary versus Secondary Ossification

Primary = below growth plate Secondary = above growth plate

WEEK 6 continued... Cleft lip palate can occur due to failure of

Primary palate (from medial nasal processes after merge with maxillary process on each side) and secondary palatal shelves (form maxillary process)

Initial epithelial attachment joining gingiva to tooth

Reduced enamel epithelium

The epithelial attachment joining the gingiva to the tooth arises directly from?

Reduced enamel epithelium

Ihh regulation invovled in

Regulates the onset of hypertrophic differentiation - expressed in more mature cells of the growth plate (prehypertrophic and hypertrophic) induce PTHrP expression in Resting round chondrocytes which then acts back on prehypertrophic chondrocytes on their PPR receptor to stop hypertrophy (keeping more cells in proliferative phase) - Increases condrocyte proliferation (but PTHrP negatively feeds back inhibiting IHH)

Bone modeling vs remodeling

Remodeling = formation and reabsorption on both sides (occurs on endosteal surface) Modeling = reabsorption on one side, formation on the other (early on in life

The growth plate is

Responsible for bone length growth -- and it involves the formation and differentiation of chondrocytes - located between epiphyseal and metaphyseal one

Which branchial pouch gives rise to the palatine tonsils

Second

Increase in BMP causes medial expression of ____along neural plate

Snail gene (Snail gene = neural crest when it is a part of the ectoderm) **Snail = induced by intermediate levels of BMP High BMP = ectoderm Low BMP = neural Noggin + Chordin (from mesoderm) = inhibit BMP

Bones that form via Intramembranous

Squamous part of temporal bone, ethmoid, sphenoid parietal, Maxilla and mandible

Root Formation =

Starts at 14 weeks in utero - HERS (Hertwig's epithelial root sheath) at epithelial diaphragm angles inward - HERS disintegrates leaving epithelial rests of malassez -- Follicle cells migrate and differentiate into cementoblasts, osteoblasts and fibroblasts

Prehypertrophic zone

Synthesize (collagen Type X) - Secrete Ca, hydroxyapatit, phosphatases, and metalloproteinases (MMPs)

Gastrulation

The process by which a blastula develops into a gastrula with the formation of three embryonic layers - specifically with the mesoderm inbetween the ecto- and endoderm

Bell Formation

Tooth shaped bud occurs "morphodifferentiation" Histodifferentiation occurs"

Vertebrates are ____blastic

Triploblastic

Common structural property that defines the proteins in the collagen super family?

Tripple helix

Pharyngeal arches developed from?

Ventrally migrating (cranial neural crest cells)

Vitamin required for fibril formation

Vitamin C

Tooth Stage Initiation

Week 6 Dental Lamina is induced and formed from underlying mesenchymea

nucleolus

Where ribosomes are synthesized

Neural Crest fox domestication example

Whiter foxes = more domesticated (b/c lack neural crest cells that don't populate the adrenals i.e. don't migrate as far along with adrenal glands) - have white tips, etc.

Neural Crest in addition to Intermediate level of BMP requires what signal to form

Wnt and FGF Signaling (inducing Pax3 and Zic1)

Which nerve is associated with 2nd pharyngeal arch

facial

What are major functions of proteoglycans

hydrated sturdy proteoglycans

CathespinK

produced by osteoclasts after NFATc1 pathway activiated through RANKL == leads to functional osteoclasts

Fibroblasts

synthesize extracellular fibers - Have spindle shaped extracellular matrix / collagen

Resting zone of growth plate houses

unique stem cells (can differentiate into bone cells for growth, repair and maintenance

Zones of periosteum

zone 3 = outer fibrous layer Zone 2 = Cambium layer Zone 1 = Osteoblasts