Appendix 2
The Development of the Unborn Child's Body


Prenatal Development



The beginnings of the various organs and systems are established, especially in the third week when certain key organs start to develop.
1st - 3rd weeks of development O'Rahilly, p 23
The nervous, muscular, vascular, digestive, and skeletal systems are in an incipient state. End of 1st month after conception Rugh, p 35
The beginnings of many of the organ systems, including the cardiovascular system, are established. End of 4th week after fertilization Moore, p 91
The embryo grows in length from 5 millimeters to approximately 16 to 17 millimeters. Day 27 to day 37 of development Sadler, p 220
It is believed that the majority of women do not realize they are pregnant during the first six weeks after conception. 6th week after conception. Rugh, p 54
Although the embryo begins developing immediately after conception, the most visible advances occur during the third to eighth weeks. 3rd - 8th weeks after fertilization Moore, p 2
The most important features of the body's form are determined because of the formation of organs that occurs during this time. 3rd - 8th weeks Sadler, p 108
Most major organs and organ systems are formed during the embryonic period. The mother may not be aware of her pregnancy during this critical period, especially in the third and fourth weeks when the embryo is quite vulnerable. During 3rd - 8th weeks Sadler, p 106
Great changes occur in appearance because of the emergence of a disproportionately large head and the formation of the limbs, face, ears, nose, and eyes. During the 2nd month Sadler, p 106
The embryo has a distinct human appearance. About day 56 after fertilization Moore, p 100
The term embryo refers to the developing human being during the first eight weeks after conception. At the end of this period, all major structures have started to form. End of 8th week after fertilization Moore, p 3
The embryonic period concludes at the end of the 8th week after fertilization and the fetal period begins. Few, if any, new structures are formed after this time. Development during the fetal period involves growth and maturation of structures that are already present. End of 8th week after fertilization Williams, p 153
The beginning of all essential structures are present. 8th week after fertilization Williams, p 154
The organs and systems of the body are formed. From late in the 3rd week through the 8th week Larsen, p 319
The embryonic period consists of the first eight weeks after the last ovulation. During this time, the overwhelming majority ( several thousand) of the named human structures appear, and the embryo is about 30 millimeters in length. End of 8th week O'Rahilly, p 55
Scientists have examined the embryonic period in far greater detail than the fetal period, which begins in the ninth week and continues until birth. Few new features appear during the fetal period. Instead, the structures that are already present continue to develop. End of 8th week O'Rahilly, p 55
The initial formation and development of nearly all of the organs is complete and they can be identified in a grossly recognizable state. End of 8th week of pregnancy Carlson, p 407
The head is disproportionately large compared with the rest of the body. End of 8th week of pregnancy Carlson, p 407
The embryo has human characteristics. The neck area is established and the eyelids are obvious and are closing. The auricles of the external ears begin to take their final shape. End of 8th week after fertilization Moore, p 99
Squinting, incomplete closing of the fingers, and opening the mouth can be induced by local stimuli. 8th week after fertilization Williamsn, p 169

The face is broad, the eyes are widely separated, the ears are low-set, and the eyelids ares fused.

9th week after fertilization Moore, p 110
Humans develop continuously, starting at conception, but the changes don't stop at birth. Obvious examples of further growth are the development of teeth and female breasts. In addition, the brain triples in weight between birth and age 16 years. By age 25, most developmental changes are finished.   Moore p 2
Physicians can now measure how the fetus is growing and what its state of health is with a very high degree of accuracy. Through advanced surgical procedures, doctors can operate on the fetus without leaving a scar.   Carlson, p 407
Ultrasonic imaging is used to measure the stages of development of the embryo.   Moore, p 3


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