Introduction Development One must learn by doing the

Introduction & Development

“One must learn by doing the thing; for though you think you know it, you have no certainty, until you try” Sophocles “Memorization is what we resort to when what we are learning makes no sense. ” Anonymous FAQ: Will the lab get easier?

Lab Policies ● ● No food or drink allowed in the lab No shorts or open-toed shoes allowed in class.

Lab Resources ● ● ● Lab Manual Open Lab Blog Lab Presentations Lab Website pdbio 325. byu. edu pdbio 325 lab. blogspot. com

Lab Grade ● 11 quizzes – 10 pts. each ● ● Lowest score dropped (100 pts. Total) “Midterm” quiz (10 pts. ) – can be dropped Final – 100 pts. Extra Credit – Slide box inspection – 5 pts.

Quizzes ● ● Will end on the hour 10 slide questions (1/2 pt. each) ● ● ● Identify structure shown on projector You may have never seen the slide before, but you will have seen many that are similar 5 U-find questions (1 pt. each) ● Answer a question by finding a structure on your own slides

Slide Question Examples Q: Name this material. A: Colloid Matter

Q: Name this gland histologically. A: SMBT

U-Find Question Examples ● ● Q: Find and Name a simple multicellular coiled tubular exocrine gland. ● A: (Point to a sweat gland on your slides) ● A: (Point to enamel on your own slides) Q: Find and name the ectoderm derived secretion of ameloblasts.

How to be successful in Tissue Biology ● ● ● Have a firm grasp on the weekly material Identify landmarks (ask your TA’s if unsure) and be confident in identifying new slides Don’t fret over one bad quiz- identify the problem and don’t make the same mistake twice

Cheating: ● Absolutely NOT tolerated.

Missing Lab: ● Syllabus “Extreme circumstances” -contact your lab TA ASAP, as well as Dr. Reynolds.

What is Histology? ● Histology is the study of the microanatomy of tissues and their cellular structure

Anatomical vs. Histological Naming ● Anatomical ● Answers: What is this structure? ● Example: The subesophageal gland ● Histological ● Answers: What tissue is it made of? ● Example: CMTA (Compound multicellular tubular-alveolar exocrine gland)

Specimen Preparation 1. Obtain the tissue 2. Fixation & Processing 3. Sectioning 4. Staining

Planes of Section ● ● Longitudinal Cut – made on the long axis of the tissue Transverse Cut – opposite of the longitudinal, a. k. a. cross section cut

What type of section is this?

Common Stains

Hemotoxylin & Eosin (H&E) ● ● ● The most common stain we will see in our slide boxes Stains the nuclei blue/purple and cytoplasm pink or red Collagen and muscle stains pink

Wright’s Stain/Diff-Quik ● ● ● ● Used to stain Blood Smears Neutrophil nuclei stain dark blue, cytoplasm is unstained Eosinophil nuclei stain dark blue, cytoplasmic granules stain bright pink Basophil nuclei stain dark blue, ganules stain deep purple Lymphocyte nuclei stain purple-blue, cytoplasm pale blue Platelets stain light blue RBC’s stain pink

Verhoeff’s Stain/Orcein-Resorcein ● ● Used to stain elastic tissue Elastic fibers stain black Nuclei stain gray Remaining Structures stain pink

Silver/Argentaffin ● ● Used to stain Nerve fibers Myelinated and unmyelinatied fibers stain blue-black Background is colorless Astrocytes stain black

Supravital ● ● Used to stain Reticulocytes Stains chromatin dark

Less Common Stains

Masson’s Trichrome ● ● Used to distinguish collagen from smooth muscle Nuclei stain black Cytoplasm, muscle, and RBC’s stain red Collagen stain blue

Mallory’s Triple Stain ● ● Used to stain skin, connective tissue, and glands Connective tissue stains bright blue Red blood cells stain orange-red Muscle, epithelium and nuclei stain red

Microscopes Light Microscopes ● ● ● Gathers and reflects light through two magnifying lens. Magnification: 4 x, 10 x, 40 x, and 100 x. Replacement costs $3, 000, so be careful! Electron Microscopes ● Transmission EM (TEM) ● Scanning EM (SEM) ● We won’t be using these

Developmental Biology

Fertilization Cleavage 2 -Cell 4 -Cell 8 -Cell Morula Blastula

Gastrulation ● ● Cells migrate through the blastopore to form the primitive gut. Migrations forms the three primary germ layers are formed.

Germ Layers Ectoderm Mesoderm (Mesenchyme) Endoderm

Germ Layer Derivatives Ectoderm ● Retina ● Tooth enamel ● Lining of nose, mouth, & anus ● Inner ear ● Nervous system ● Epidermis Mesoderm ● Muscles ● Dermis ● Blood & vessels ● Reproductive organs ● Connective tissue ● Kidneys Endoderm ● Lining of GI ● Endocrine system ● Thyroid, parathyroid, & thymus ● Pancreas ● Urinary bladder ● Liver ● Lungs

Neurulation & the Neural Tube ● ● Migration of the ectoderm to the dorsal area of the embryo. Neural plate is formed and becomes the neural tube, which becomes the brain and spinal cord

Neural Crest Cells ● Neural Tube ● Neural Crest cells are migratory and derived from the ectoderm. They become pigment cells, neurons and Schwann cells.

Notochord ● ● Rod like structure formed from mesoderm that lies dorsal to the gut. Purposes: ● ● defines the dorsal/ventral axis of the embryo. Provides skeletal support for the early embryo, but degenerates in higher vertebrates (e. g. humans).

Chick Embryos

24 -hr chick whole-mount

24 -hr chick Cross Section Ectoderm Mesoderm Endoderm

Review: What are the derivatives of the endoderm?

Somites ● ● Somites are segmented blocks of mesoderm on either side of the developing spinal cord. Somites differentiate into: ● ● ● Part of the axial skeleton (sclerotome) Muscle (myotome) Dermal layer of the skin. (dermatome) S NT

48 -hr chick whole-mount head eye somite Neural tube

48 -hr chick whole-mount 1

Mesoderm Lineages Somatic Body wall Splanchnic Muscle lining of the G. I tract and circulatory system. Vertebrae Deep back, limb, tongue muscles Dermis

48 -hr chick Endoderm Notochord Neural tube Dermamyotome muscle, dermis, connective Paraxial mesoderm Sclerotome becomes axial vertebrae Intermediate mesoderm become kidney and internal reproductive tracts - Ectoderm Somatic mesoderm becomes muscles of the body wall Splanchnic mesoderm becomes muscles surrounding G. I. tract -

Practice: 2 1 7 6 5 4 3

72 -hr chick whole-mount

72 -hr chick Neural tube Notochord Dorsal aorta

72 -hr chick Dorsal aorta Gut endoderm

Clinical Connection

Neural Tube Defects Correct Neural Tube Closure Incorrect Neural Tube Closure

Epithelium

Epithelium Nomenclature • • Quantity of Layers – Simple, Pseudostratified, Stratified. – Squamous, Cuboidal, Columnar, Uroepithelium or Transitional Shape of The Cell

Epithelium Nomenclature • Free Surface Modifications – – – Microvilli Stereocilia Cilia Specialized Secreted Products* Glycocalyx*