[00:00.19] Unit 88 Siamese Twins Siamese twins are formed from a single egg which develops into two almost separate parts of cells. [00:12.22] Normally, each part becomes an identical twin. [00:15.59] However, cells in Siamese twins become confused about where they are in the body -- indeed which of the two Siamese twins they are actually in. [00:26.52] In normal fetus development every cell knows where it is in the body because the neighboring cells produce chemical messages. [00:35.04] So a skin cell knows not only it is skin, but that it is, say, nose skin, [00:41.02] rather than chin or ear or lip skin. [00:45.01] In Siamese twins these chemical messages do not work properly -- ho can they? [00:51.14] The end results can be very odd: a single organism with two heads, tow hearts, four legs and arms -- or is that single organism actually two people, [01:03.04] two individual Siamese twins? [01:06.10] Although at first sight each appeared to have a separate well formed body with some joining at the lower body, [01:13.02] detailed tests showed these Siamese twins were very unequal. [01:18.27] In some cases, one was providing the heart, lungs and many other basic functions. [01:24.48] The other Siamese twin was vey poorly equipped for separate life. [01:30.08] To make matters worse, these Siamese twins were to some extent dependent on each other. [01:36.09] If separated, the stronger and more capable Siamese twin would need huge amounts of surgery over the following years, [01:44.32] and was likely to suffer significant handicap. [01:48.38] It is a brave doctor indeed who is willing to take the knife to two Siamese twins, [01:54.25] both of which are at that point alive and growing, and see perhaps both Siamese twins die in the operating room or very shortly afterwards. [02:05.15] It is easier to go ahead if the parents want their Siamese twins separated and understand and accept the risks -- but what if you have had to force the whole thing on them in the first place? [02:17.40] A key Problem in Siamese twin decisions is that the parents themselves may no always agree on the separation, [02:25.37] and it is common for them to feel somehow that the birth of Siamese twins is their fault, [02:32.06] or to blame each other, doctors, society or God. [02:37.15] The natural joy of birth has been replaced by deep grief for the loss of one or two perfectly normal children. [02:45.50] And there is another issue. [02:47.54] The survivor of these Siamese twins would need huge care efforts. [02:52.53] This would be unlikely in some cultures and parents may feel very angry at medical interference. [03:00.23] On balance, doctors should tread with great care when it is a human right and the responsibility for parents to make decisions on behalf of their children to refuse certain medical treatment.

00:00

00:00

MP3下载 文本下载