Embryology
Dr. Scott Gilbert
Martin 302 sgilber1, x8049
"Glory to the science of Embryology!" This was the salutation of a letter sent me by embryologist Hans Holtfreter, shortly before his 90th birthday. And there is much glory here, for the developing organism is a remarkable phenomenon. It respires before it has lungs, digests before it has a mouth, and creates itself anew from ordinary matter. It is characterized by a species-specific pattern of orderly change, yet there is enormous variation within the permissible limits. Whereas the finished organism merely maintains its form, the embryo creates it. Developmental biology is the science studying the emergence of living order.
This developmental biology course is designed to introduce you to animal development, not so much as a discipline, but as a way of approaching nature. It will attempt to integrate the study of molecules, cells, tissues, organs, and organisms over time. This year, the course will attempt to integrate the study of animal development within the context of environmental disruptions. Therefore, our laboratory exercises will often compare normal development to the development of the same organism under some environmental condition that may alter its outcome. Don't expect any complete answers. We are just beginning to understand how certain developmental events occur. Moreover, we know very little about the development of most organisms. There is plenty of room for new work in this field! Welcome!
Student responsibilities:
1. Please be on time for all classes. They begin promptly. (Time is critical in embryology). Tuesdays and Thursday 9:55. Not 10:00.
2. Do well on your exams. There will be three exams during the semester. The first is a most un-Swarthmorean vocabulary quiz. The second test will review concepts. The third exam will be the final exam (during exam week.) There will also be a final ÒpaperÓ (more about that in a moment.)
3. Final paper. First, pick your favorite organ! Second, learn how it develops. Third, write a 10-12-page paper on itÑfor Wikipedia. (I find it strange that students are expected to write their papers for a single critical audient, me. I would rather you write something worthwhile for any educated person to read. IÕll be the only one giving you a grade, but the whole world may be your audience.) You can choose from the human organs that we have not yet covered in class, but don't be afraid to choose some unusual ones from the animal kingdom: Elephant tusks, bat wings, dolphin flippers, walrus penises, butterfly wing spots, zebra stripes, kangaroo pouches, and centipede legs are all fair game. (Warning: We know very little about the embryology of most animals, and you may have a rough time finding information on some of these topics). Use this paper to integrate development into some area that fascinates you. I will meet with you to go over parts of your paper to see if you have enough information. Papers can be turned in through Saturday, May 19.
4. Laboratories will meet Tuesday and Wednesday in the Temple of Development, Martin 307. Our laboratory TA is Aleia McCord, and the laboratories will be supplemented by the Vade Mecum CD in your textbooks. You should have fun with these. Each person is required to maintain an orderly, bound, laboratory notebook. These notebooks will not be collected. However, I expect that the drawings and observations recorded therein will be something of which you will be proud. Do all drawing in pencil (hard lead works best) and plan on spending time observing the embryos. (If time is the essence of embryonic development, patience is the essence of embryology). You can draw on unlined paper and then tape the drawing into your bound book. The basic principles of the laboratory notebook are: "Could another student repeat what I have done, using my notebook as a guide?" and "Could a person recognize the embryo and stage of development using my drawings as a guide?" Although "formal" laboratory periods are once a week, that's not the way nature works. So be prepared to come in throughout the week to check up on your embryos.
5. Outside lectures. We are very fortunate this year in that there will be at least five lectures in areas of developmental biology this semester. I expect that each of you will attend at least three of them. The first two are February 7 and 8 and will be presented by Dr. Trachette Jackson, the Dresden Memorial Lecturer, in Sci Center 101. They are sponsored by the Department of Mathematics, which should tell you something! They are both on the relationship between embryology and cancer. The first concerns a new model of cancer developmentÑwhere cancers originate from adult stem cells. The second concerns how growing cancers recruit blood vessels (just like developing tissues do.) The second set of lectures will be announced. These are from candidates for the one-year leave replacement developmental biology position.
Evaluations:
Final Grade= Test 1 (0.2) + Test 2 (0.2)+ Final paper (0.3) + Final Exam (0.3).
(Tests on laboratory material are done in these examinations).
Reading Assignments:
A tentative schedule of dates and text readings follows. There will be two texts for this course: The first is my Developmental Biology (2006; Sinauer Associates, Sunderland, MA) and the second is Bioethics and the New Embryology (written by me and two students who were graduated in 2003). It is strongly advised that you read each of the chapters of the textbook before the lectures, listen to the lectures, and then re-read the chapters in light of what you've heard. I've found that one never gets it the first time around. One learns from re-reading or doing. I'll be refunding my royalties into a party fund for the last week of class.
Tentative Schedule:
WEEK 1 (1/22): Introduction and Sea Urchin Fertilization
Text for class: Chapter 7
Text for laboratory: (In textbook) Chapters 1,2; Vade mecum
Amphibian life cycle
Laboratory exercise: Field trip to Linvilla orchards (bring money)
WEEK 2 (1/29): Sea Urchin and Mammalian Fertilization
Text for class: Chapter 7
Laboratory exercise: Fertilization in the sea urchin
http://www.swarthmore.edu/NatSci/sgilber1/DB_lab/Urchin/Urchin_fert.html
Vade mecum: Sea urchin fertilization; sea urchin UV fertilization
Bioethics Chapters 1 and 2.
WEEK 3 (2/5): Sea Urchin Development
Text for class: Chapter 8
Laboratory exercise: Normal sea urchin fertilization and development
http://www.swarthmore.edu/NatSci/sgilber1/DB_lab/Urchin/Polyspermy.html
http://www.swarthmore.edu/NatSci/sgilber1/DB_lab/Urchin/urchin_stage.html
Vade mecum: sea urchin development
Text for laboratory: Textbook Chapter 3, also for discussion:
Small, M. 1991. Sperm wars: The battle for conception. Discover(July,
1991), pp. 48 - 53.
Biology and Gender Study Group. 1988. The importance of feminist critique
for contemporary cell biology. Hypatia 3: 61 - 75.
WEEK 4 (2/12): Molecular techniques
Text for Class and Laboratory: Chapter 4-5.
Laboratory exercise: Localization of gene products in sea urchin embryos.
Laboratory CD: Differential enzyme expression inf sea urchin embryos.
http://www.swarthmore.edu/NatSci/sgilber1/DB_lab/Urchin/Urchin_AP.html
Laboratory reading: Bioethics Chapters 5,6.
WEEK 5 (2/19): Drosophila Development: The Anterior-Posterior Axis
Text for class: Chapter 9.
Vade Mecum: Drosophila
Text for laboratory: Bioethics Chapters 11, 12
Laboratory: Library meeting: How to research scientific articles
WEEK 6: (2/26): Amphibian development
Text for Class: Chapter 10
Vade Mecum: Amphibian
Laboratory: Review of class so far
Bioethics: Animal use chapter
WEEK 7 (3/5): Amphibian development and metamorphosis
Text for class: Chapter 18 on metamorphosis
Laboratory exercise: Chick development days 1-5; shell-less culture.
http://www.swarthmore.edu/NatSci/sgilber1/DB_lab/Chick/Chick_Observe.html
http://www.swarthmore.edu/NatSci/sgilber1/DB_lab/Chick/Shell-less.html
Vade Mecum: Chick development
THURSDAY: ÒVOCABULARYÓ TEST
WEEK 8 (9 Ð 18 March): Spring break week (You may want to start on the reading for next week. ItÕs a big week.)
WEEK 9 (3/19): Amniote Development 1: Cleavage, Gastrulation, Cloning, Stem Cells
Text for class: Chapter 11
Laboratory: Retinoic acid and teratogenesis
Dhouailly, D et al. 1980. Formation of feathers on foot appendages...J.
Embryol. Exp. Morphol. 58: 63 Ð 78. (In library.)
Laboratory reading: Chapter 21
WEEK 10 (3/26): Amniote Development 2: Ectoderm
Text for class: Chapter 12 and pp. 411 - 422.
Laboratory: Retinoic acid and teratogenesis (in situ hybridization)
http://www.springerlink.com/content/t60504v680t0u612/fulltext.pdf
Laboratory reading: Bioethics: Stem cells
WEEK 11 (4/2): Amniote Development 3: Somites
Text for class: Chapter 14
Laboratory: Retinoic acid and teratogenesis (in situ hybridization)
Laboratory readings: Lammer
http://www.ijdb.ehu.es/web/paper.php?doi=15272378
Lammer, EJ et al. 1986. Retinoic acid embryopathy. N. Engl. J. Med. 313:
837 Ð 841. (In library.)
WEEK 12 (4/9): Amniote Development 4: Heart and limb development
Text for class: Chapter 15 (heart) and 16
Laboratory: Field trip to the MŸtter Museum
Laboratory: Tissue sectioning and immunohistochemistry (chicks)
WEEK 13 (4/16): Sex Determination
Text for class: Chapter 17
Laboratory readings: Bioethics book on sex selection
Laboratory: Tissue sectioning and immunohistochemistry (chicks)
WEEK 14 (4/23): Evolutionary developmental biology
Text for class: Chapters 23
Laboratory: Immunohistochemistry (turtles and crocodiles)
Laboratory readings TBA
WEEK 15 (4/30) Ecological developmental biology
Text for class: Chapter 22
Laboratory: Immunohistochemistry (turtles and alligators)
Laboratory readings: TBA