1. 组织胚胎学课件
中国医科大学
基础医学院
组胚—英文教学组

2. HUMAN EMBRYOLOGY Department of Histology and Embryology
China Medical University

3. Chapter 1
Introduction to
Human Embryology

4. 1. What is Embryology？ Zygote Fertilization Nine months
(266 days or 38 weeks to be exact)
in the uterus
Prenatal period
Gestational period
Infant

6. 1. What is Embryology？ Zygote Fertilization Nine months
(266 days or 38 weeks to be exact)
in the uterus
Prenatal period
Gestational period
Infant

7. 1. What is Embryology？
Embryonic period
Prenatal
period
Fetal period

8. 1. What is Embryology？ Embryonic period
1. It extends from fertilization
through 8 weeks
2. The developing individual is
called an embryo.
Prenatal
period
Fetal period

9. 1. What is Embryology？ Embryonic period
1. It extends from fertilization
through 8 weeks.
2. The developing individual is
called an embryo.
Prenatal
period
Fetal period
1. It extends from week 9 until
birth.
2. The developing individual is
called a fetus.

10. 1. What is Embryology？
Embryology is the study of the formation and development of the embryo (or fetus) from the moment of its inception up to the time when it is born as an infant.

11. Embryonic period
Fertilization through 8 weeks
Each of the first 3 weeks is characterized by specific developments.
Week 1 starts with fertilization and extends through the
first cell divisions that produce an embryo with one
germ layer.

12. 2-cell stage
8-cell stage
4-cell stage
morula
Early blastocyst
Late blastocyst

13. Embryonic period
Fertilization through 8 weeks
Each of the first 3 weeks is characterized by specific developments.
Week 1 starts with fertilization and extends through the
first cell divisions that produce an embryo with one
germ layer.
Week 2 produces two germ layers.

14. Embryonic period
Fertilization through 8 weeks
Each of the first 3 weeks is characterized by specific developments.
Week 3 produces three germ layers and folds those layers
into a recognizable three dimensional body.

15. Embryonic period
Fertilization through 8 weeks
Each of the first 3 weeks is characterized by specific developments.
Weeks 4 through 8 (month 2) are the period of organogenesis.
All the major events of organ formation and formation of body regions occur during the period of organogenesis, which is completed in the embryonic period.

16. Embryonic period
Fertilization through 8 weeks
Week 1 an embryo with one germ layer
Week two germ layers
Week three germ layers
Weeks 4 through 8 (month 2)
organogenesis

17. Fetal period Month 3 to birth
The major events that occur during the fetal period involve growth in size (hypertrophy) of organs by rapid increase in cell number (hyperplasia), as well as biochemical and functional maturation.
Mature functional status is not achieved in most organ systems until after birth.
Most organ systems begin a rudimentary form of functioning during the fetal period, but this usually is important only for the development of the organ itself.
The most important exception is the cardiovascular system. The heart begins pumping blood to all organs as they are first forming. Without this circulation, organs would not be able to develop.
Mature functional status is not achieved in most organ systems until after birth.
This explains why you will find so little discussion of physiologic maturation in any embryology book, and so much discussion of physiology in pediatrics and neonatology books.

18. 2. Why a medical student should study Embryology？
1. This subject tells us how the organs of the body develop.
1. This subject tells us how the organs of the body develop.
2. This knowledge helps us to understand many complicated facts of adult anatomy.
Give an example: You have already learned Human Anatomy. You know the position of caecum and appendix, they are on the right side of the abdominal cavity. But do you know why they are on the right side of the abdominal cavity, not on the left side? Embryology can give you the answer.
rotation of midgut loop, location of caecum and appendix.
3. Embryology helps us understand why some children are born with organs that are abnormal. Appreciation of the factors responsible for maldevelopment assists us in preventing, or treating, such abnormalities.

19. 2. Why a medical student should study Embryology？
1. This subject tells us how the organs of the body develop.
2. This knowledge helps us to understand many complicated
facts of adult anatomy.
1. This subject tells us how the organs of the body develop.
2. This knowledge helps us to understand many complicated facts of adult anatomy.
Give an example: You have already learned Human Anatomy. You know the position of caecum and appendix, they are on the right side of the abdominal cavity. But do you know why they are on the right side of the abdominal cavity, not on the left side? Embryology can give you the answer.
rotation of midgut loop, location of caecum and appendix.
3. Embryology helps us understand why some children are born with organs that are abnormal. Appreciation of the factors responsible for maldevelopment assists us in preventing, or treating, such abnormalities.

20. Midgut loop Caudal limb Cephalic limb
1. This subject tells us how the organs of the body develop.
2. This knowledge helps us to understand many complicated facts of adult anatomy.
Give an example: You have already learned Human Anatomy. You know the position of caecum and appendix, they are on the right side of the abdominal cavity. But do you know why they are on the right side of the abdominal cavity, not on the left side? Embryology can give you the answer.
rotation of midgut loop, location of caecum and appendix.
3. Embryology helps us understand why some children are born with organs that are abnormal. Appreciation of the factors responsible for maldevelopment assists us in preventing, or treating, such abnormalities.
Cephalic limb

21. Midgut loop Cephalic limb Caudal limb
1. This subject tells us how the organs of the body develop.
2. This knowledge helps us to understand many complicated facts of adult anatomy.
Give an example: You have already learned Human Anatomy. You know the position of caecum and appendix, they are on the right side of the abdominal cavity. But do you know why they are on the right side of the abdominal cavity, not on the left side? Embryology can give you the answer.
rotation of midgut loop, location of caecum and appendix.
3. Embryology helps us understand why some children are born with organs that are abnormal. Appreciation of the factors responsible for maldevelopment assists us in preventing, or treating, such abnormalities.

22. Midgut loop Cephalic limb Caudal limb Superior mensenteric artery
1. This subject tells us how the organs of the body develop.
2. This knowledge helps us to understand many complicated facts of adult anatomy.
Give an example: You have already learned Human Anatomy. You know the position of caecum and appendix, they are on the right side of the abdominal cavity. But do you know why they are on the right side of the abdominal cavity, not on the left side? Embryology can give you the answer.
rotation of midgut loop, location of caecum and appendix.
3. Embryology helps us understand why some children are born with organs that are abnormal. Appreciation of the factors responsible for maldevelopment assists us in preventing, or treating, such abnormalities.

23. 2. Why a medical student should study Embryology？
1. This subject tells us how the organs of the body develop.
2. This knowledge helps us to understand many complicated
facts of adult anatomy.
3. Embryology helps us understand why some children are
born with organs that are abnormal. Appreciation of the
factors responsible for maldevelopment assists us in
preventing, or treating, such abnormalities.
1. This subject tells us how the organs of the body develop.
2. This knowledge helps us to understand many complicated facts of adult anatomy.
Give an example: You have already learned Human Anatomy. You know the position of caecum and appendix, they are on the right side of the abdominal cavity. But do you know why they are on the right side of the abdominal cavity, not on the left side? Embryology can give you the answer.
rotation of midgut loop, location of caecum and appendix.
3. Embryology helps us understand why some children are born with organs that are abnormal. Appreciation of the factors responsible for maldevelopment assists us in preventing, or treating, such abnormalities.

24. some main branches of Embryology
Descriptive Embryology
Comparative Embryology
Experimental Embryology
Chemical Embryology
Molecular Embryology
Reproductive Engineering
Teratology

25. Questions 1.What is Embryology？ 2.What is the prenatal period?
3.How many periods is the prenatal period
divided？Point out their names and duration.
Preview Chromosome , Cell division
Gametogenesis, Fertilization