Appendix 1
The Chronological Development of The Unborn Child

 

Fifth Week

 

Timing

Source
The esophagus is developing.
Early in the 5th week of development Larsen, p 249
The kidneys begin to develop. Early in 5th week after fertilization England, p 153

The trachea is developing.

Early in the 5th week of development Larsen, p 249
The forelimbs and hindlimbs appear as paddle-shaped buds. Beginning of 5th week Sadler, p 106
The face begins to look human. 5th week after conception Rugh, p 45
Pain pathways run from sensory receptors in the skin to those in the brain. Nerve endings that sense pain are at least as dense in the skin of a newborn as in an adult. Such receptors appear around the mouth in the 5th week after conception, and are present in the face, the palms, and the soles of the feet by the 9th week, spreading to the trunk, arms, and legs by the 13th week, and to all areas of the skin by the 18th week. The development of the neocortex, the largest part of the brain, begins at 6 weeks after conception, and by 18 weeks a full complement of nerve cells is present. The evidence thus suggests that by late in gestation the fetus has developed sufficiently to sense pain. from 5th week after conception Anand and Hickey, p 1322 & p 1326
The jaws are forming. 5th week after conception Rugh, p 45
The permanent kidneys appear. 5th week Sadler, p 305
The pharynx is present. 5th week after fertilization Rugh, p 45
Liver ducts are forming. 5th week after conception Rugh, p 46
The pituitary gland is developing. 5th week after ferilization Williams, p 178; Rugh, p 45
The spleen is forming. 5th week after conception Rugh, p 46
The spleen is formed. 5th week Larsen, p 159
The trachea is developing. 5th week after fertilization Moore, p 262
The thyroid is developing. Late in 5th week Larsen, p 249
The tongue is developing. Late in 5th week Larsen, p 249
The penis and scrotum form. 5th - 6th weeks Larsen, p 175
Limb development takes place. 5th - 8th weeks of development Larsen, p 209
Leg buds are present. Day 29 after fertilization Sadler, front pages
The three primary parts of the brain are present. Day 30 after conception Rugh, p 41
The ears have started to form. Day 30 after conception Rugh, p 41
The eyes have started to form. Day 30 after conception Rugh, p 41
The lens pits and optic cups are forming. Day 30 after fertilization Moore, p 5
The face is developing. Day 30 after fertilization Sadler, front pages
The gallbladder is developing. Day 30 of development Larsen, p 155
Nasal placodes are present. Day 30 after fertilization Sadler, front pages
The nasal pits, which are the primordia of the nostrils and the nasal cavaties, are forming. Day 30 after fertilization Moore, p 5 & p 239
The nasal organs have begun forming. Day 30 after conception Rugh, p 41
The stomach is forming. Day 30 Larsen, p 157
The trachea is developing. Approximately day 30 after fertilization Rugh, p 43
The intestines are defined. End of 1st month after conception Rugh, p 43
The pancreas is defined. End of 1st month after conception Rugh, p 43
The liver bud is present. End of 1st month Sadler, p 271
The thyroid gland, which plays a critical role in metabolism, begins developing. End of month 1 after conception Rugh, p 42
The nervous, muscular, vascular, digestive, and skeletal systems are in an incipient state. End of 1st month after conception Rugh, p 35
The ears are forming. During the 2nd month Sadler, p 106
The face is unmistakably human. 2nd month after conception Rugh, p 54
The nose is forming. During the 2nd month Sadler, p 106
The skeleton is developing. 2nd month after conception Rugh, p 52
The face is forming. During 2nd month Sadler, p 106
The limbs are forming. 2nd month 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 esophagus (the food tube leading to the stomach) begins to form. Day 31 after conception Rugh, p 43
Leg buds begin to form. Day 31 after conception Rugh, p 43
The primitive mouth is forming. Day 31 after fertilization Moore, p 5
Muscles appear in the pelvic region. Day 31 after conception Rugh, p 43
The stomach begins to form. Day 31 after conception Rugh, p 43
The nasal pits are visible. Days 31-32 after fertilization Moore p 91
Forelimbs are paddle-shaped. Days 31-35 of development Sadler, p 110
The nasal pits are formed. Days 31-35 of development Sadler, p 110
Coronary vessels appear. Day 32 after fertiliztaion Larsen, p xi
The primary intestinal loop forms. Day 32 after fertilization Larsen, p xi
The ventral pancreatic bud is present. Day 32 Larsen, p 157
Spinal nerves begin to sprout. Day 32 after fertiliztion Larsen, p xi
The primary intestinal loop is forming. Approximately day 32 Sadler, p 281
The larynx is developing. Approximately day 32 Sadler, p 281
The palate is developing. About day 32 after fertilization Moore, p 98
The pharynx is developing. About day 32 after fertilization Moore p 98
The cerebral cortex, the part of the brain that controls the intellect and motor activity, begins to differentiate. Day 33 after conception Rugh, p 44
Melanin first appears in the cells of the developing pigment retina. Day 33 Larsen, p 257
The forearm region can be distinguished. Day 33 of development Larsen, p 209
Hand plates are present. Day 33 after fertilization Moore, p 5
Hand plates are developing. Day 33 after fertilization Larsen, p xii
The shoulder region can be distinguished. Day 33 of development Larsen, p 209
Hand plates are formed and digital rays are present. Days 33-36 after fertilization Moore, p 91
The cerebral vesicles are distinct. Day 34 after fertilization Moore, p 5
The elbows are developing. Day 34 after fertilization Sadler, front pages
Foot plates are developing. Day 34 after fertilization Moore, p 5; Sadler, front pages
Hand plates are developing. Day 34 after fertilization Sadler, front pages
Echocardiography can detect heart movements. About day 34 after fertilization Williams, p 30
The ribs begin to form and lengthen. Day 35 of development Larsen, p 48
The olfactory lobe, which is related to the sense of smell, is present in the brain. Day 35 after conception Rugh, p 44
The nasal pits deepen to form the nasal cavity. Days 35-42 Larsen, p 230
The external ears are developing. Days 35-49 Larsen, p 261


 


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