Download PDF Langman's Medical Embryology Twelfth Edition by T.W. Salder

Sinopsis

The process of progressing from a single cell through the period of establishing organ primordia (the fi rst 8 weeks of human development) is called the period of embryogenesis (sometimes called the period of organogenesis); the period from that point on until birth is called the fetal period, a time when differentiation continues while the fetus grows and gains weight. Scientifi c approaches to study embryology have progressed over hundreds of years. Not surprisingly, anatomical approaches dominated early investigations. Observations were made, and these became more sophisticated with advances in optical equipment and dissection techniques. Comparative and evolutionary studies were part of this equation as scientists made comparisons among species and so began to understand the progression of developmental phenomena. Also investigated were offspring with birth defects, and these were compared to organisms with normal developmental patterns. The study of the embryological origins and causes for these birth defects was called teratology.

In the 20th century, the fi eld of experimental embryology blossomed. Numerous experiments were devised to trace cells during development to determine their cell lineages. These approaches included observations of transparent embryos from tunicates that contained pigmented cells that could be visualized through a microscope. Later, vital dyes were used to stain living cells to follow their fates. Still later in the 1960s, radioactive labels and autoradiographic techniques were employed. One of the fi rst genetic markers also arose about this time with the creation of chickquail chimeras. In this approach, quail cells, which have a unique pattern to their heterochromatin distribution around the nucleolus, were grafted into chick embryos at early stages of development. Later, host embryos were examined histologically, and the fates of the quail cells were determined. Permutations of this approach included development of antibodies specifi c to quail cell antigens that greatly assisted in the identifi cation of these cells. Monitoring cell fates with these and other

techniques provides valuable information aboutthe origins of different organs and tissues.

Content

1. General Embryology
2. Introduction to Molecular Regulation and Signaling
3. Gametogenesis: Conversion of Germ Cells into Male and Female Gametes 
4. First Week of Development: Ovulation to Implantation
5. Second Week of Development: Bilaminar Germ Disc
6. Third Week of Development: Trilaminar Germ Disc 
7. Third to Eighth Weeks: The Embryonic Period 
8. The Gut Tube and the Body Cavities
9. Third Month to Birth: The Fetus and Placenta 
10. Birth Defects and Prenatal Diagnosis  
11. Systems-Based Embryology
12. The Axial Skeleton
13. Muscular System
14. Limbs
15. Cardiovascular System
16. Respiratory System
17. Digestive System
18. Urogenital System
19. Head and Neck
20. Central Nervous System
21. Ear
22. Eye
23. Integumentary System

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