Wednesday, November 02, 2005

The Visible Embryo

The Visible Embryo is a great site I refer folks to frequently. Today I was perusing it. Here's some cool bits:

Stage 10, 21-23 days post-ovulation, "The cells which become the eyes appear as thickened circles just off of the neural folds. The cells of the ears are also present." "The two endocardial tubes formed in Stage 9 fuse in Stage 10 to form one single tube derived from the roof of the nueral tube, which becomes S-shaped and makes the primitive heart asymmetric. As the S-shape forms, cardiac muscle contraction begins."

Stage 11, 23-25 days post-ovulation, "A primitive S-shaped tubal heart is beating and peristalsis, the rhythmic flow propelling fluids throughout the body, begins."

Stage 13, 27-29 days post-ovulation, "The brain differentiates into the three main parts: the forebrain, midbrain and hindbrain." "Primitive mouth with a tongue is recognizable." "Gall bladder, stomach, intestines, pancreas continue to form and the metanephric bud appears in the chest cavity."

Stage 17, c. 41 days post-ovulation, "The nasofrontal groove becomes distinct and an olfactory bulb (sense of smell) forms in the brain." "The dental laminae or teeth buds begin to form."

Stage 18, c. 7 weeks post-ovulation, "Nipples appear on the chest." "Kidneys begin to produce urine for the first time."

Stage 19, 47-48 days post-ovulation. "Brain has the first detectable brain waves."

Stage 20, c. 8 weeks post-ovulation. "Brain is connected to tiny muscles and nerves and enables the embryo to make spontaneous movements." "Testes or ovaries are distinguishable."

Stage 21, c. 52 days post-ovulation. "Over the next few days, tongue development finishes."

Stage 22, c. 9 weeks post-ovulation. "In female embryos, the clitoris is beginning to form."

Stage 23, 56-57 days post-ovulation. "By the last stage of embryonic development, all essential external and internal structures are present." "Taste buds begin to form on the surface of the tongue."

Week 10, "Brain structure of the fetus is complete and the brain mass increases rapidly." "Early facial hair follicles begin to develop." "Vocal cords form in larynx and fetus can make sounds." "Fingernails begin to grow from nail beds." "Fetus develops reflexes and the skin is very sensitive."

Week 12, "Sucking muscles of mouth fill out cheeks, tooth buds continue to develop and salivary glands begin to function."

Week 16, "Growth continues, but no new structures form after this point." "Fingertips and toes develop the unique swirls and creases of fingerprints and toe prints."

Week 18, "Fetus has phases of sleep and waking and may prefer a favorite sleep position." "Ovaries of female fetuses contain primitive egg cells, all of the eggs a woman will have for her entire life. The uterus of female fetuses is also fully formed."

Week 20, "Testes of male fetuses begin descending from the pelvis into the scrotum."

Week 22, "Bones of the ear - hammer, anvil and stirrup - harden, making sound conduction possible. Fetus recognizes maternal sounds such as breathing, heartbeat, voice, and digestion." NB: This is the earliest any state in the US restricts abortion. Up until this point it's on-demand throughout the US.

Week 24, "Fetal brain waves begin to activate auditory and visual systems, both mouth and lips show more sensitivity. Eyes respond to light, while ears respond to sounds originating outside uterus. Permanent teeth buds appear high in gums." NB: This is the most common point at which those states with restrictions no longer allow abortion on demand.

Week 26, "Brain wave patterns resemble those of a full term baby at birth."

Week 30, "The iris is colored and the pupil reflexes responding to light."

Week 36, "Fetus turns toward light sources in what is known as the orienting response."

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