Chapter 1- “The anatomical tradition”

1. Chapter 1- “The anatomical tradition” • ______________- progressive change in multicellular organisms • ___________- study of animal development • _________________ = development + embryology

2. Big questions • What dictates _________________? • How can cells form ordered ___________? • How are _________ cells set apart? • How do cells know when to stop _____________? • How do cells know where to ___________?

3. 1. ___________ theory- All organs prefigured, but very small Backed by science, religion, philosophy 2. ______________ All organs made de novo (from scratch) Historical settingPre-1800s - Two theories • Early 1800s- staining techniques/microscopy • disprove preformation theory- • The birth of “_______________” • Late 1800s- _______ (instead of goo) theory • recognized

4. Fate mapping- the mapping of cell lineage Strange terminology

5. _____________- Organisms with three primary germ layers • _______________- lack a true mesoderm • Hydra, jellyfish, sponges • ________________- Cells receiving cues from other cells

6. Four Principles-“Von Baer’s laws” 1. ___________features appear prior to ______________ ones • All vertebrates have gill arches, notochords, primitive kidneys 2. Less general characters are developed from _______ general (i.e. specialized from non-specialized) • Scales vs. feathers • Legs vs. wings • Nails vs. claws 3. An embryo does not pass through the ___________________ of other, lower creatures 4. Thus, the early embryo of a higher animal in never like a lower animal, but only like it’s ___________________. • Humans never look like ____________

7. Fate mapping • Major layers- • _____________- • Outer embryo layer • Skin • Nerves • ______________- • Inner embryo layer • Digestive tract • Respiratory system • _____________- • Middle layer • Blood • Heart • Kidney • Gonads • Bones • Connective tissue • Muscle Commit these to memory

8. “________________”- Similarity arising from a common ancestral structure e.g. bird wing and human arm “_______________”- Similar function, but not common ancestor e.g. bird wing and insect wing Bat wing “Homologous” vs “Analogous” Human arm Seal limb Bird wing

9. Teratology • Environmental agents causing disruption of development -called “________________” • Example- __________________ (1961)

10. Chapter 2- Life cycles • All animals follow similar life cycle • __________________- mixing of genetic material between sperm and egg • ___________________- events between fertilization and hatching (or birth)

11. General Animal Development 2. _________________- Extensive cell rearrangement to form endo-, ecto- and meso-derm • __________- One cell is subdivided into many cells to form a blastula 4. _________________- produce germ cells (sperm/egg) Note: Somatic cells denote all non-germ cells 3. ____________________- Cells rearranged to produce organs and tissue

12. The Frog Life cycle Single egg, early blastula Animal pole 100’s of fertilized eggs Unfertilized egg (Stained) Vegetal pole Note: Cells get smaller, but egg ___________ remains the same!

13. The Frog Life cycle- gastrulation through neurula 1. _______________________________ forms at “belly” 2. Dorsal blastopore lip becomes the ____________ (a circle) 3. Ectoderm cells encase 4. Mesoderm cells migrate inside along blastopore edges 5. Neural folds and groove appear Fig. 2.3

14. The Frog Life cycle- metamorphosis

15. Species 1 Species 2 A single cell 3 cm long! Nucleus (in Rhizoid) A unicellular protistThe “goo” theory can work! What happens if we swap nuclei??

16. Sexual reproduction • Sex and reproduction are two distinct processes • Sex- mixing of genetic material from two individuals • Reproduction- creation of new individuals • Bacteria, amoeba- Reproduction without sex • _________________- Sex without reproduction Swap “micronuclei” then separate • ________________- Sex with reproduction

17. “Plus” “Minus” Asexual reproduction Sexual reproduction “Plus” “Minus” Chlamydomonas (A eukaryote) Chromosome mixing Fig. 2.8

18. Unicellular eukaryotes have basic developmental • processes observed in higher organisms • - • Mitosis and meiosis is accomplished • Sexual reproduction • Chromosomal structure is stable and similar But, multicellular organisms are a whole new ball game These require cell-cell communication and distinct cell functions “_________________________________” Example – Volvox

19. Example – Volvox Principle 1 : One cell ______________ into 4-64 cells Single cell Gonium Chlamydomonas Panadorina 2000 cells Somatic cells (appear as dots) Germ cells Eudorina Pleodorina Volvox Fig. 2.11 Principle 2 : ___________________ of cell types- somatic vs reproductive

20. Multicellular aggregation to from a slug- Dictystelium Individual cells Start here Principle 3 : _______ cells instructed to perform specific functions Travel to new food source This cycle requires adhesion, _____________ and ______________. A _______ is formed (2-4 mm ) Differentiate into _______ and spore case Fig 2.17 >10,000 cell _____________ Stalk dies, spores released

22. General Animal Development (From chapter 2) 2. __________- Extensive cell rearrangement to form endo-, ecto- and meso-derm • ________- One cell is subdivided into many cells to form a blastula 4. _______________- produce germ cells (sperm/egg) Note: Somatic cells denote all non-germ cells 3. _____________- Cells rearranged to produce organs and tissue

23. Fig. 3.1 Summer Spring Chapter 3- Experimental Embryology • Three major approaches • External forces - ____________________ • Internal forces- ____________________ • Organ development (Morphogenesis) 1. External forces • a. Sex determination • Boellia- depends on where larva lands • Alligator egg temperature - <30C = _________ development • b. Embryo ______________ • Butterflies- colors depend in season • Frogs and UV light

24. Chapter 3- Experimental Embryology 2. Internal forces • A few definitions • ____________________- development of specialized cell types • ____________________- developmental fate is restricted • Two stages- • 1. ___________________- capable of becoming specific • cell types, but decision is reversible • 2. __________________- non-reversible cell fate decision a. __________________specification- blastomere cell fate is determined at blastula stage (e.g. isolated blastomere will become same type if removed from blastula) Most ________________ do this

25. Normal development Chapter 3- Experimental Embryology 2. Internal forces (continued) b. ______________specification- cell fate is determined on where a cell finds itself (e.g. isolated blastomere will become what surrounding cells dictate) Transplant cells All ___________ do this Cell fate dictated by location c. Note- insects display __________ Specification- cell fate is determined in egg cytoplasm Removed cells are compensated Fig. 3.11

26. Chapter 3- Experimental Embryology 2. Internal forces (continued) More definitions- __________- soluble molecule that instructs cells to differentiate Concentration ___________- A morphogen at different concentrations depending on location of cell Example of concentration gradient- the flatworm (Hydra) The French flag analogy to understand gradients It grows back!

27. 2. Internal forces (continued) A lot makes blue French Flag Analogy A modest amount makes white A little makes red Transplanted tissue retain it’s _____________, but differentiates according to new _______________ Fig. 3.19

28. 2. Internal forces (continued) An example of a concentration gradient- Activin levels dictate cell fate in Xenopus Activin levels Fig. 3.20

29. 2. Internal forces (continued) Tree frog Salamander If remove limb bud, surrounding cells will form the limb A _________________ field- a group of cells whose position and fate are specified with respect to the same set of boundaries. • The general fate of a cell group (e.g. tissue) is determined, • but individual cells within that tissue can respond to • new positional cues Example- a “_______ field” -Transplantation of cells specified for limb development results in limb formation in new place -But nearby cells will form a limb Nematode infection disrupts normal limb field Fig. 3.22

30. 3. Morphogensis Morphogenesis is the bigger question of how cells within a given organ are in a precise place and have a precise function. • How are _________formed from populations of cells? • How are __________ constructed from tissues? • How do organs form in particular ____________, and how do migrating cells reach their destinations? • How do organs and their cells grow, and how is growth ____________________ throughout development? • How do organs achieve ____________? Compare leg and finger cross-sections- the same yet different.

31. 3. Morphogensis (continued) Observations- Mix cells from different cell types in a culture dish, they migrate to pre-instructed location. Mesoderm + endoderm +epidermis Mesoderm + epidermis Mesoderm + endoderm How do the cells “know” where to go? One model- The ____________ model Malcolm Steinberg 1964

32. Surface tension 3. Morphogensis (continued) The _____________ model 20.1 Cells interact so as to form an aggregate with the smallest _________________free energy 12.6 In other words, those with stronger _________ properties move to the _________ of a cell mass 8.5 4.6 • Adhesion is dictated by • Number of cell adhesion molecules • Type of cell adhesion molecules 1.6 Fig. 3.30

33. 3. Morphogensis (continued) • _____________ – Calcium-dependent adhesion proteins • - a major class of proteins that mediate cell adhesion • Establish intercellular connections • Required for _____________ segregation • Required for organization of animal formation Cadherin Cadherins bind to __________in cells, which bind to actin cytoskeleton Catenins Fig. 3.31

34. 3. Morphogensis (continued) Cadherin types ___-cadherin- in all mammalian embryos, then restricted in epithial tissues of embryos and adults ___-cadherin- primarily in placenta ___-cadherin- in mesoderm and developing central nervous system ____-cadherin-required for blastomere adhesion Cadherins are responsible for cell sorting Cells with different cadherin _____sort Cells with different ___________ sort Fig. 3.31