1. Chapter 8 Embryology / Histology

2. Embryology Study of prenatal growth and development. Study of embryos
immature organism contained within the coverings of an egg or within the body of the mother

3. Conception Ovum Sperm This begins gestation Female cell
Fertilized by the
Sperm
Male cell
This begins gestation
The time from conception to birth
38 – 40 weeks average

4. Prenatal Phases Zygote (1st phase) Conception – 2 weeks
Cells are blank
‘Stem cells’
Proliferation occurs
Cells rapidly increasing in numbers
Causes cell growth
Multiply by dividing

5. Prenatal Phases Embryo (2nd phase) 5 weeks (ectopic pregnancy)
3 week – 8 week
Differentiation occurs
Development of individual characteristics
Cells
Tissues
Forms and shapes
5 weeks (ectopic pregnancy)
18-19 days→

6. Stages of differentiation
Cytodifferentiaton
Development of different cells
Histodifferentiation
Development of different tissues
Morphodifferentiation
Development of different forms / shapes

7. Primary embryonic layers
Ectoderm
Outside layer of the embryo
Forms
Skin
Hair
Nails
Brain
Enamel of the teeth

8. Primary embryonic layers
Mesoderm
Middle layer of the embryo
Forms
Lining of stomach
Bones
Muscles
Several body systems
Dentin, cementum, pulp of the teeth

9. Primary embryonic layers
Endoderm
Inside layer of the embryo
Forms
Glandular organs
Lining of respiratory system
Digestive tract

10. Prenatal Phases Fetus (3rd phase) 9th week – birth
Proliferation and differentiation continue
Growth and development continue

11. Stomodeum (primitive mouth) 1st sign of a developing mouth on an embryo
30-32 days →
28-29 days ↓

12. Developmental disturbances
Cause abnormal growth or development of the fetus.
Genetics
Medications
Trauma
Alcohol
Drugs

13. Developmental disturbances
Cleft
Improper fusion or joining of body structure.
Cleft lip
Improper fusion of the max. process w/ the nasal process.
Unilateral
Bilateral
Partial
Complete

14. Developmental disturbances
Cleft palate
Improper fusion of the palatal process w/ the max. process.
Unilateral
Bilateral
Partial
Complete

15. Developmental disturbances
FAS
Fetal alcohol syndrome
Consumption of alcohol during gestation.
Stunts growth / weight
Affects neurons / brain development
Causes Craniofacial deformities

16. Transition / conclusion
Understanding growth and development will lead you to understanding how different cells form different tissues.
This leads us to the next part of this chapter…..
Histology

17. Histology The study of tissue in thin slices. Aka microscopic anatomy
Essential part of understanding biology

18. Tissue types 4 basic types of tissue Epithelial Nervous Muscle
Connective

19. Tooth tissues Enamel Dentin Hardest tissue
Ameloblasts
Cells that form enamel
Covers the top of the tooth.
Anatomical crown
Translucent
Light passes through
No nerves/blood supply
No pain
Dentin
Harder than bone, harder than cementum.
Odontoblasts
Cells that form dentin
Bulk of the tooth
Comprised of dentinal tubules
Filled w/ dentinal fluid
Sends sensory info to the pulp.
Gives a tooth it’s ‘hue’
Underlying color

20. Tooth tissues Cementum Pulp Covers dentin on the roots
Cementoblasts
Cells that form cementum.
Softer than enamel or dentin.
Can be brushed away.
Pulp
Provides
Nourishment to the dentin.
Detects
Temperature and
Chemical changes
Transmits
Stimuli to the brain

21. Tooth pulp Pulp chamber Pulp horns Pulp canals
Bulk of the pulp located here!
Pulp horns
Upward projections at the top of the chamber
Pulp canals
Aka root canals
Small hollow tubes from apical foramen to the chamber.

22. Tooth tissue junctions
CEJ
Cementoenamel junction
DEJ
Dentinoenamel junction

23. Periodontal tissues Gingiva Bone Covers bone Alveolar bone Sulcus
Epithelial attachment
Bone
Alveolar bone
Lamina Dura
Compact bone that lines socket.

24. Periodontal tissues PDL Periodontal ligament Sharpey’s fibers
Attaches tooth to bone
“shock absorber”
Nourishment to cementum
Sharpey’s fibers
Attach PDL to tooth and bone.

25. Conclusion You are NOW the expert!
You should know the 4 different types of tooth tissues…
Their purpose/function
Where they are located on the tooth.
Please review this info for the quiz.
Any questions???????