Embryology
Human embryology is the study of the formation, growth and development of the embryo. The human embryo undergoes rapid growth at the microscopic and macroscopic levels and many of these changes happen simultaneously. Use this website to learn more about each week of development.
Oocyte
Fertilization
Oocyte
The female gamete involved in reproduction. Without fertilization, the oocyte usually degenerates 24 hours after ovulation
Illustration of week one of development
Germ Layer Derivatives
Embryonic ectoderm
Primitive node
Primitive groove in primitive streak
Cut edge of amnion
Mesoderm
Embryonic endoderm
Migrating mesenchymal cells
Illustration of the cranial half of the embryonic disc during the third week. The disc has been cut transversly to show the migration of the mesenchymal cells from the primitive streak to form the mesoblast that will soon organize to form the intraembryonic mesoderm.
Ectoderm
-
Central nervous system
-
Epidermis and its appendages (hair and nails)
-
Neural crest cells
Mesoderm
-
Connective tissue
-
Cartilage
-
Bone
-
Striated and smooth muscles
-
Cardiovascular system
-
Reproductive system
-
Urinary system
Endoderm
-
Epithelial lining of the gastrointestinal and
respiratory tracts -
Epithelial lining of the urinary bladder and most of the urethra
Sadler, T. W., & Langman, J. (2004). Langman’s medical embryology. Philadelphia, Pa, Lippincott Williams & Wilkins.
Overview
Oocyte
2-cell stage
4-cell stage
8-cell stage
Morula
First cleavage
Early blastocyst
Meiosis
Fertilized egg
(zygote)
Fertilization
Late-stage blastocyst
(hatching blastocyst)
Implantation
Ovary
Uterus