Salient. Victoria University Student Newspaper. Volume 39, Number 18, July 26, 1976.

Aspects of Intrauterine Life

Aspects of Intrauterine Life

We each began life as a single cell. Forty-five generations of cell growth divisions were needed to reach the 30 million million cells of an adult. Of these 45 generations of division, eight, or nearly one-fifth, have occurred by the time we were implanted in the uterus, 30, or two-thirds, by the time we were eight weeks old, 39 by 28 weeks' gestation, and 41 by the time we were born. The remaining tedious four occupied the whole of childhood and adolescence, and then there were no more.

This dramatic and rapid sequence of cell replications in early intrauterine life is matched by an equally dramatic and rapid differentiation and morphogensis.

He promptly [ unclear: journey down the home for] capsule of fluid for himself.

By 25 days from conception, the developing heart starts beating, although two or three weeks must elapse before we can reliably detect heart beats with current technology. These first strokes of the pump are not associated with a circulation, but with an ebb and flow system as envisaged by physiologists before Harveian, for the cardiovascular system is initially valveless. But soon valves develop and, with a pump to provide a pressure gradient and valves to give direction, we have a circulation.

By 30 days, just two weeks past mother's first missed period, the baby - one quarter of an inch long - has a brain of unmistakable human proportions, eyes, ears, mouth, kidneys, liver an umbilical cord and a heart pumping blood he has made himself.

By 45 days, about the time of the mother's second missed period, the baby's skeleton is complete - in cartilege, not bone, at first; the buds of the milk teeth appear and he makes the first movements of his body and new-grown limbs, although it will be another 12 weeks before his movements are strong enough to be transmitted through the insensitive uterus to be detected by mother's sensitive abdominal wall. By 63 days he will grasp an object stroking his palm and can make a fist.

These structural changes, of course, are not mediated by any external agency, but internally, directed by the zygote and embryo. In this regard the zygote with his cargo of genetic information is much more than a mere blueprint of a new human.

A blueprint is simply a plan, and does not include the machinery to fulfil that plan - but a zygote does. He even has the power to phenocopy himself, to reproduce a sexually as about one in 400 zyogtes or embryos does in identical twinning - and there is no known external agency which affects the incident? of identical twins.

However our new human has in hand even greater designs and undertakings than simply his own internal organisation and development. He also develops his own life-support system, his placenta, and his own confines, for it is the embryo and fetus who develops his membranes, forms his amniotic fluid and regulates its composition and volume.

Women speak of their waters breaking and their membranes rupturing, but such expressions are so much nonsense - these structures [ unclear: belong to the baby This reality]. Tests on the amniotic fluid are tests on [ unclear: the not ex other. His own] anything to the chance co-operation or others, and therefore he must organise his mother to make her body a suitable home.