Week 1 - Intro to Oral Histopathology of Oral Tissues Flashcards
What are the 3 stages of human development?
Proliferation period (0-3 weeks)
Embryonic period (3-8 weeks)
Fetal development period (9 weeks to term)
What is fertilized during the proliferation period and what does it yield?
Fertilization of ovum yields zygote
What does the mitotic cleavage of zygote form?
Blastomeres
> 32 blastomeres is called ______
morula
The 64 cell stage morula develops an internal blastocystic cavity referred to as ______
blastocyst
When the blastocyst develops an inner cell mass at days 6-7, what is this referred to?
Embryoblast
When does implantation of the embryoblast in the uterine wall begin and complete?
Day 4; Day 10
What does the inner cell mass of the embryoblast transition into?
The bilaminar embryonic disc (Two layers)
What do the outer cell masses become?
Cytotrophoblast and syntrophoblast layers which are precursor to the placenta
What are the layers of the bilaminar embryonic disc?
Epiblast layer
Hypoblast later
What makes up the epiblast layer?
Ectoderm
Mesoderm
What makes up the hypoblast layer?
Endoderm
What structures are associated with the bilaminar embryonic disc?
Epiblast layer
Hypoblast layer
Amniotic cavity
Blastocyst cavity
Syntrophoblasts
cytotrophoblasts
The enlargement of the amntiotic cavity and migration of cells out of the hypoblast form?
Heuser’s membrane
What does the Heuser’s membrane form?
Internal lining of the blastocyst cavity - now called the yolk sac
What are the three cell layers of the proliferation period?
Epiblast
Embryonic mesoderm
Hypoblast
What are embryonic cavities of the proliferation period?
Amniotic
Yolk sac
Chorionic
During the 3rd week of development, the bilaminar embryonic disc is characterized by formation of the:
Primitive streak
Notochord
Neural tube
During the 3rd week of development, the bilaminar embryonic disc is characterized by formation of what three distinct embryonic germ layers?
Ectoderm (formerly the epiblast layer)
Mesoderm
Endoderm (formerly the hypoblast layer)
What is a primitive streak? and what is visible during the time it is being formed?
Cells from the epiblast invaginating in forming the 3rd layer (mesoderm)
Pit
Node
Groove
Describe the steps of how the notochord is created
Primitive node -> notochordal process -> notochord
What invaginates within the primitive node?
Pre-notochordal cells
Cells invaginate until they reach the?
Prechordal plate “road block”
When the cells detach themselves from the ectodermal layer to line within the mesoderm, it forms the?
Notochord
What does the notochord function as?
A primitive skeletal sipport of the embryo around which the axial skeleton later forms
What does the notochord induce formation of?
Somites, the precursors of the vertebral column, ribs, associated back muscles and overlying dermis
What cells is the notochord made from and what is it derived from?
Ectodermal cells; primitive node
What does the notochord establish?
Symmetry and polarity of development
What does the notochord induce?
Somites
What two parts make up the lateral plate mesoderm?
Parietal
Visceral
What does the paraxial mesoderm form?
Somites
What does the intermediate mesoderm form?
Urogenital system
What does the parietal mesoderm form?
MEsothelial (serous) membranes that cover the perutoneal, pleural and pericardial cavities
What does the visceral mesoderm form?
The thin serous membranes that cover individual organs, stomach, pancreas, spleen
What are derivatives of ectoderm?
Epidermis, hair and nails
Epithelium of the oral and nasal cavities and paranasal sinuses
Salivary and endocrine glands
Nervous system
Tooth enamel
What are derivatives of endoderm?
GI tract epithelium and associated glands
What are neural tube related developmental defects?
Spina bifida
Meningocele
Meningomyelocele
Meningoencephalocele
Anencephaly
What is a spina bifida?
Folic acid deficiency
What is meningocele?
Extrusion of dura and arachnoid mater
What is meningomyelocele
Extrusion of neural tissue plus all three meninges
What is meningoencephalocele?
Extrusion of a ventricular cistern plus neural tissue
What is anencephaly?
Fetal defect characterized by lack of development of the cranium and brain
What are examples of minor neural tube defects?
Spina bifida
Meningocele
What are severe neural tube defects?
Meningomyelocele
Meningohydroencephalocele
What are fatal defects of the neural tube?
Anencephaly
What are different names for neural crest cells?
Ectomesencyme
Neuroectoderm
What are different names for neural crest cells?
Ectomesenchyme
Neuroectoderm
What does the 1st branchial groove develop into?
External auditory canal
What does the 1st branchial pouch develop into?
Eustachian tube
What does the 2nd branchial pouch develop into?
Palatine tonsils
What does the 3rd branchial pouch develop into?
Inferior parathyroids/thymus
What does the 4th branchial pouch develop into?
Superior parathyroids/ultimobranchial body
What are processes of the face?
mandibular process
maxillary process
lateral nasal process
median nasal process
When does development of the face and oral cavity occur?
Fetal development period - 9 weeks to term
Where is the development of the palate?
Hard palate and closes posteriorly
What results in a cleft lip?
Defective fusion of the medial nasal process with the maxillary process
When do the medial nasal process with the maxillary process fuse?
5-6 weeks of gestation
When does fusion of the palatine shelves begin and complete?
During 8th week of gestation and completed by the 12th week
Name the percents of frequency of combined cleft lip/palate and isolated cleft lip and palate
45% combined
30% isolated cleft palate
25% isolated cleft lip
What is the frequency of cleft lip/palate among populations?
1 in 500 chinese, japanese, native american
1 in 700 caucasian
1 in 500 afro-american
How prevalent is cleft palate?
1 in 2,500 births
If one child is born with cleft lip, there is a _____ change of a second child exhibiting the same
40%
What teratogens are involved in congenital malformations
Drugs-
Ethanol
Tetracyclcine
Dilantin
Lithium
Methotrexate
Warfarin
Thalidomide
Androgens
Progesterone
Retinoic Acid
Chemicals-
Methylmercury
Polychlorinated biphenyls
Radiation-
high levels of ionizing radiation
Where does the nasopalatine duct cyst develop at?
Line of fusion between palatine shelves and primary plate
When does the cervical sinus remain past and doing so what can it cause?
Remains past 7th week; can cause lateral cervical cyst aka branchial cleft cyst aka branchial fistula
What does the branchial arch #1 create?
Anterior 2/3 of the tongue
What does the branchial arch #2 create?
Overgrown by the hypobranchial eminence
What does the branchial arch #3 create?
posterior 1/3 of the tongue
What does the branchial arch #4 create?
Minor contributions
What cranial nerve and tongue structure is related to arch #1?
Trigeminal (C-V); sensory to the anterior 2/3
What cranial nerve and tongue structure is related to arch #2?
Facial (C-VII); taste to anterior 2/3
What cranial nerve and tongue structure is related to arch #3?
Glossopharyngeal (C-IX); sensory to the posterior 1/3
What cranial nerve and tongue structure is related to arch #4?
Vegas (C-X); sensory to the extreme posterior 1/3 via the superior laryngela branch
What cranial nerve and tongue structure is related to arch #6?
Hypoglossal (C-XII); motor to all tongue muscles
What is median rhomboid glossitis a result of?
Fungal infection
What is a failure of thyroglossal duct to involute?
Thyroglossal duct cyst
Where is the thyroglossal duct cyst located?
Midline of neck
What part of the face does the 1st arch make?
Mandible, maleus, incus
What part of the face does the 2nd arch make?
Stapes, stylodi process, stylohyoid ligament, lesser horn of hyoid
What part of the face does the 3rd arch make?
Greater horn of hyoid
What part of the face does the 4th arch make?
thyroid cartilage
How many auricular hilocks form the ear?
6
