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).


 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 “paper” (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 it—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; if you choose a medical topic, you should budget time to go to the UPenn medical school library.) 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 the last day of final exams.


4. Laboratories will meet Tuesday and Wednesday in the Temple of Development, Martin 307. Our laboratory instructor is Jocelyne Noveral (!), 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: Please note that you are expected to attend a lecture by Dr. Kathleen Sulik on December 4. Dr. Sulik is a world authority on fetal alcohol syndrome, the condition that results in the fetus when pregnant women drink ethanol. It is a major cause of mental retardation in the USA. Her website is at




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). The second is a series of papers from several sources, including 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. The Bioethics book will be on reserve in the library. I'll be refunding my royalties into a party fund for the last week of class.


TENTATIVE SYLLABUS (And I do mean tentative):


WEEK 1 (9/1 PLUS LABORATORY PERIODS): Introduction to development: Developmental Anatomy and Genetics

Text for class: Chapters 1, 2, 4, and 5.

There will not be class on Thursday, and there will not be any laboratories this week; so that should give you plenty of time to read these .


 WEEK 2 (9/8,10 ): Fertilization: Sea Urchin and Mammalian

Text for class: Chapter 7

 Laboratory exercise: Fertilization in the sea urchin

         Go to see the Virtual Urchin at

         Vade mecum: Sea urchin fertilization; sea urchin UV fertilization

         Bioethics Chapters 1 and 2. These can be accessed at



The lecture that would have been given last Thusday will be given during the  90 or so minutes between fertilization and first cleavage of the sea urchin. Developmentmulti-tasks, andso shall we.


WEEK 3 (9/15, 17): Sea Urchin Development

 Text for class: Chapter 8

 Laboratory exercise: Normal sea urchin fertilization and development

         Vade mecum: sea urchin development

 Texts for laboratory:   

         (1) Small, M. 1991. Sperm wars: The battle for conception.

         Discover (July,

       1991), pp. 48 - 53.

         (2) Biology and Gender Study Group. 1988. The importance of feminist

         critique for contemporary cell biology. Hypatia 3: 61 - 75.

Note: This laboratory exercise will require daily visits throughout the week.


WEEK 4 (9/22,24): Cells and Development: Adhesion and Signaling

Text for Class and Laboratory: Chapter 3, 6.

Laboratory exercise: Normal chick development. Observations.

Laboratory CD: Vade Mecum on Chick Development


WEEK 5 (9/29, 10/1): Drosophila Development: The Anterior-Posterior Axis

Text for class: Chapter 9.  

Laboratory exercise:  Sectioning and immunostaining of chick embryos I.

         Plus library exercises on doing research papers.

Vade Mecum: Later chick development

Text for laboratory: Bioethics Chapters 11, 12



WEEK 6: (10/6,8): Amphibian development

Text for Class: Chapter 10

Vade Mecum: Amphibian development

Laboratory: Sectioning and immunostaining of chick embryos II.

Bioethics: Animal use chapter




WEEK 8 (10/20,22): Amphibian development and metamorphosis

 Text for class: Chapter 18 on metamorphosis

 Laboratory exercise:  Sectioning and Immunostaining of chick embryos.


WEEK 9 (10.27,29): Amniote Development 1: Cleavage, Gastrulation, Cloning, Stem  Cells 

Text for class: Chapter 11

 Laboratory: Anaysis of chick data and introduction to zebrafish

 Vade mecum: Zebrafish

 Laboratory reading:  Chapter 21


 WEEK 10 (11/3, 5): Amniote Development 2: Ectoderm

Text for class: Chapter 12 and pp. 411 - 422.

Laboratory:  Zebrafish development and developmental mutations

         Laboratory reading: Bioethics: Stem cells


 WEEK 11 (11/10, 12): Amniote Development 3: Somites

Text for class: Chapter 14

Laboratory: Zebrafish development and mutations

Laboratory readings:  

Green ML et al. 2007. Reprogramming of genetic networks during initiation of the Fetal Alcohol Syndrome. Dev Dyn. 2007 Feb;236(2):613-31.


Loucks, E. and Ahlgren, SC. 2009. Deciphering the role of Shh signaling in axial defects produced by ethanol exposure. Birth Def. Part A. 85: 556 – 567.


WEEK 12 (11/17,19): Amniote Development 4: Heart and limb development

Text for class: Chapter 15 (heart) and 16

Laboratory: Field trip to the Mütter Museum

Have ideas for final papers


WEEK 13 (11/24,26): Sex Determination

Text for class: Chapter 17

Laboratory readings: Bioethics book on sex selection

Laboratory: zebrafish.


WEEK 14 (12/1,3): Evolutionary developmental biology

Text for class: Chapters 22, 23

Laboratory:  Review of everything you’ll ever need to know

Dr. Kathleen Sulik lecture


Royalty Lunch on to be scheduled