|
Twelfth Week
|
Timing
|
Source |
The face has all the human characteristics.
|
12th week |
Sadler, p 116 |
| Movements begin, but are usually not
felt by the mother. |
12th week after fertilization |
Sadler, p 116 |
| Jaw openings were observed in 12 of
12 fetuses studied with a median rate of about 30
per hour. |
12th week after conception |
de Vries (1985), p 114 |
| The neck is well-defined. |
12th week after fertilization |
Moore, p 109; Williams, p 155 |
| The sex can be established by ultrasonic
measurement of the external genitalia. |
12th week after fertilization |
Sadler, p 113 |
| The sex can be determined from external
examination. |
12th week after fertilization |
Moore, p 109 |
| The fetus responds to stimulation
of the skin. |
12th week after fertilization |
England, p 206 |
| Red blood cells are forming in the
spleen. |
End of 12th week after fertilization |
Moore, p 112 |
| Primary ossification centers appear
in the skeleton, especially in the skull and long
bones. |
End of 12th week after fertilization |
Moore, p 110, Sadler, p 113 |
| Hair grows on the eyebrows and the
upper lip. |
End of 12th week after fertilization |
Moore, p 517 |
| Stroking the lips causes the fetus
to suck and stroking the eyelids results in a reflux
response. |
End of 12th week after fertilization |
Moore, 4th edition, p 91 |
| The sex is clearly distinguishable. |
End of 12th week after fertilization |
Williams, p 154 |
| The upper limbs have almost reached
their final relative lengths and are a bit better
developed than the lower limbs. |
End of the 12th week after fertilization |
Moore, p 111 |
| Respiration is evident. |
12th - 14th weeks after fertilization |
Williams, p 169 |
| Swallowing is evident. |
12th - 14th weeks after fertilization |
Williams, p 169 |
| Palm creases appear. |
3rd month |
Rugh, p 217 |
| The spinal cord extends the entire
length of the embryo. |
3rd month of development |
Sadler, p 422 |
| Taste buds are evident. |
3rd lunar month |
Williams, p 169 |
| The first hairs appear in the region
of the eyebrows and upper lip. |
End of 3rd month |
Sadler, p 407 |
| Reflex activity can be evoked in aborted
fetuses, indicating muscular activity. |
End of 3rd month after fertilization |
Sadler, p 114 |
| The penile urethra is forming. |
End of 3rd month |
Sadler, 7th edition p 298 |
