1. Histology Lecture 4

2. Key Points: Tissues Development of Epithelial Tissues
Embryonic Development
Epithelial Tissues
Types
Characteristics
Classification
Glandular Epithelia

3. Tissues Tissue = woven fabric Histology – Study of Tissues
Microscopy
Staining of Samples
Cells of similar in structure and perform common or related functions
Types of Tissues:
Epithelial
Connective
Muscle
Nervous

4. Primary Embryonic Germ Layers
The 3 germ layers - the ectoderm, the mesoderm, and the entoderm (endoderm)

5. Primary Embryonic Germ Layers
THE ECTODERM gives rise to the central nervous system; the peripheral nervous system; the sensory epithelia of the eye, ear, and nose; the epidermis and its appendages (the nails and hair); the mammary glands; the hypophysis; the subcutaneous glands; and the enamel of the teeth

6. Primary Embryonic Germ Layers
THE MESODERM gives rise to connective tissue, cartilage, and bone; striated and smooth muscles; the heart walls, blood and lymph vessels and cells; the kidneys; the gonads (ovaries and testes) and genital ducts; the serous membranes lining the body cavities; the spleen; and the suprarenal (adrenal) cortices

7. Primary Embryonic Germ Layers
THE ENTODERM gives rise to the epithelial lining of the gastrointestinal and respiratory tracts; the parenchyma of the tonsils, the liver, the thymus, the thyroid, the parathyroids, and the pancreas; the epithelial lining of the urinary bladder and urethra; and the epithelial lining of the tympanic cavity, tympanic antrum, and auditory tube

8. Sheet (or fabric) of cells that covers a body surface or lines a cavity.
Two Types of Epithelium
Covering and Lining
Glandular
Functions
Form Boundaries
Protection
Absorption
Filtration
Excretion
Secretion
Sensory Reception
Epithelium Tissue

9. Epithelium Tissue 5 Characteristics Polarity Specialized Contacts
Two surfaces with different functions
Apical Surface – Free upper surface
Basal Surface – Lower Attached Surface
Examples
Microvilli – fingerlike projections of the plasma membrane increasing surface area
Basal lamina – made of glycoproteins secreted by epithelial cells. It is a selective filter.
Specialized Contacts
Cells fit closely together to form specialized sheets with special contacts between the cells.
Lateral Contacts – Tight Junctions/Desmosomes bind adjacent cells.

10. Epithelium Tissue 5 Characteristics 3. Supported by Connective Tissue
All epithelial sheets rest on and are supported by connective tissue.
Avascular but Innervated
No blood vessels
Receive nutrients from the blood vessels of the underlying tissue
Regeneration
Has a high regenerative capacity

11. Classification of Epithelial Tissue
Simple Epithelia – consist of a single layer.
Function – Absorption, secretion, and filtration
Stratified Epithelia – composed of two or more single layers staked upon each other.
Function – Protection. Examples skin and lining of the mouth.
Squamous Cells – Flattened Cells
Cuboidal Cells – Boxlike
Columnar – Tall and Column Shape

12. Glandular Epithelia
Gland – Consists of one or more cells that secrete a particular product.
Secretion – An aqueous solution usually of proteins but may vary.

13. Glandular Epithelia Endocrine Glands Exocrine Glands
They are ductless and secrete hormones.
Exocrine Glands
Secrete their productions onto a surface or body cavity.

14. Summary: Write a summary of your notes.
List the things/items you feel are important.
Paraphrase key topics
Minimum of 10 Sentences
Then exchange your summary with a neighbor.
Read your neighbor’s summary.
Return the summary.
Compare your summary to your neighbor’s and update yours.
Turn it in before you leave.