oral histology exam 1

fertilization, cleavage, morula, blastocyst, implantation

order of events in week 1

bilaminar disc, syncytiotrophoblast formation, prochordal plate formation

order of key developments during week 2 of embryonic development.

primitive node/streak/pit, gastrulation (endoderm and mesoderm), notochord, neurulation, neural plate

order of key processes during week 3 of embryonic development

neural tube, head folding, stomodeum, mandibular process, branchial archs/grooves/pouches, mand process join, buccopharyngeal mem rupture, nasal placodes form

order of major developments during week 4 of embryonic development.

nasal pit

key development during week 5

end of week 4

when does odontogenic epithelium form

meging and fusion of facial processes, naso-optic and bucconasal groove, nasal fin, oronasal membrane

key development during week 6

nasal fin, week 6

what is this structure and when does it form

oronasal membrane, week 6 after nasal fin

what is this structure, when does it form

end of week 6

when does the odontogenic epithelia merge to form primary epithelial bands

week 7-8

when does formation of secondary palate begin

nasal septum, frontonasal process, palatine shelves

what three structures merge together during weeks 7-9

1st arch/mandibular process

what structure is represented by the star

weeks 5-8

when does pouch/neck development occur

week 5

when do auricular hillocks form

weeks 4-9

when does tongue development occur

artery, vein,nerve, branchial cartilage (NCC)

what ar the common structures within each brachial arch

cervical sinus

A temporary structure formed during embryonic development from branchial grooves 2-4

branchial pouches

Structures that develop internally leading to the formation of various organs and tissues, including the thymus and parathyroid glands.

branchial grooves

The external depressions between the branchial arches during embryonic development, which contribute to the formation of the neck and structures of the head.

rhombomeres 3-8

where is the hox gene family expreessed

Msx gene family

which genes are responsible for midbrain and rhomobomeres 1 and 2

neural crest cells

a population of cells that arise from the ectoderm and migrate to form various structures in the embryo, including craniofacial elements and peripheral nervous system.

paraxial mesoderm

the region of mesoderm located on either side of the notochord that gives rise to SOMITES, which contribute to the development of the vertebral column and associated musculature.

Hox

what gene controls branchial/pharyngeal development (branchial arches 2-6)

1

branchial arches controlled by NCCs from rhombomeres 1, 2 and midbrain

2

branchial arches controlled by NCCs from rhombomere 4

3

branchial arches controlled by NCCs from rhombomere 6

4-6

branchial arches controlled by NCCs from rhombomere 7

foramen cecum

what is C

branchial mesenchyme

mix of NCC ectomesenchyme and paraxial mesoderm mesenchyme

NCC ectomesenchyme

forms branchial cartilages and associated bone

face and neck muscles, blood vessels (branchial arteries and veins)

structures derived from paraxial mesoderm

1st branchial pouch

what forms auditory tube, middle ear cavity (with contributions from 2nd), inner layer of tympanic membrane

1st branchial groove

forms external auditory meatus

palatine tonsil (CN VII), supra-tonsillar fossa

formed from 2nd branchial pouch

inferior parathyroid (dorsal wings) and thymus gland (ventral wing) (CN IX)

formed from 3rd branchial pouch

superior parathyroid and ultimobranchial body (parafollicular cells of thyroid gland)

formed from 4th branchial pouch

thyroid C cells

formed from 5th branchial pouch

cranial nerve ganglia

formed from neural crest cells from ectodermal placodes

CN V

formed from ectodermal placode in 1st branchial arch

CN VII

formed from ectodermal placode in the 2nd branchial arch

CN IX

formed from ectodermal placode in the 3rd branchial arch

CN X

formed from ectodermal placode in the 4th-6th branchial arch

meckel’s cartilage: incus,malleus, sphenomalleolar, sphenomandibular ligaments

ectomesenchyme from NCCs gives rise to what structures in 1st branchial arch

stapes, styloid process, stylohyoid ligament, lesser horns and upper rim of hyoid

formed from ectomesenchyme in the 2nd branchial arch

lower rim and greater horns of hyoid

formed from the 3rd branchial arch ectomesenchyme.

laryngeal cartilages (thyroid, crycoid, aryteenoid)

develop from the fourth and sixth branchial arches ectomesenchyme.

lingual swelling

develops into body of tongue

primarily 1st arch

what branchial arch does the tongue develop from

inner ear

what does otic placode develop into

auricular hillocks of the 1st and 2nd branchial arches

what structures give rise to external ear

week 5

when do auricular hillocks form

auricular hillocks

what structures are shown here labeled 1-6

complete branchial fistula

A congenital abnormality resulting from incomplete closure brachial grooves 2-4 leading to a connection between the pharynx and the skin.

maxillary

artery of 1st branchial arch

hyoid, stapedia

artery of 2nd branchial arch

internal carotid

artery of 3rd branchial arch

right subclavian, aorta

artery of 4th branchial arch

muscles of mastication

muscle of 1st branchial arch

muscles of facial expression

muscles derived from the 2nd branchial arch

stylopharyngeus

muscle derived from the 3rd branchial arch

pharyngeal and laryngeal musculature

muscles derived from the 4th and 6th branchial arches

NCC migration to ventral pharynx

provides ectomesenchyme for formation of branchial/pharyngeal structures

mid week 3-end week 4

when does anteerio-posterior folding begin

neurocranium

surrounds brain composed of cartilages and placodes

dermocranium

the part of the skull that forms a protective shell around the chondrocranium

chondrocranium

the cartilaginous part of the skull that supports the brain and forms the base of the skull.

viscerocranium

the portion of the skull that forms the facial skeleton, including the jaw and other structures.

ectomesenchyme

derived from NCCs, develops into dental and skeletal tissues of oral cavity, responsible for early development of face

mesenchyme

a type of embryonic connective tissue that develops into various types of tissues including bones and cartilage.

cranial NCCs fron MB (midbrain) and rhombomeres (Rhb) 1 and 2

provide material for bone and cartilage of the face and 1st branchial arch

NCCs from Rhbs 4,6,and 8

provide material for 2nd-4th branchial arches

FGF, BMP

growth factors that influencee anterior head development

frontal,maxillary,stomodeum, mandibular, heart

processes that define the embryonic mouth

odontogenic epithelium

the epithelial tissue involved in tooth development, originating from the ectoderm.

week 4

when does odontogenic epithelium develop

week 4

when does the buccopharyngeal membrane rupture

frontal process

(A)

maxillary process

(B)

mandibular arch (1st)

(C)

mandibular process

(D)

hyoid arch (2nd)

(E)

branchial arch (3rd)

(F)

stomadeum

(X)

end of week 4 (28 days)

olfactory placodes (nasal placodes) begin to develop

placodes

thickening of ectoderm that forms sensory organs

nasal pit formation

sign of week 5 development

medial nasal process

give rise to mid-portion of both nose and upper lip and premaxilla and primary palatee

primary choanae (interenal nasal opening)

what is a sign of week 6 development

trabecular cartilages (NCC)

responsible fot development of ethmoid bone

fusing of trabecular cartilage to midline of ethmoid

essential for fusion of facial processes in the midline

week 4

what week of development?

maxillary process

identify region marked by X

X:lateral nasal process, Y:medial nasal process

label X and Y

odontogenic epithelium

on the margins of processes surrounding the stomodeum develops into teeth

medial nasal process

forms into primary palate and premaxilla

maxillary process

forma secondary palate

7.5 weeks

tongue lowers to allow the fusion of the palatal shelves

week 8

palatal shelves begin to merge