PSYCH 2AA3 Lecture Notes - Vanishing Twin, Prenatal Development, Miscarriage
12 Jun 2013
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Document Summary
When the two sets of instructions are the same at any given locus. When the two sets of instructions are different at any given locus. All of the information regardless if it is expressed. Both recessive genes must be present to express their characteristics. Single egg that has been fertilized and split. Sharing of the placenta depends on how early or late the split has occurred. Identical set of genes (100% of shared genes) Two separate eggs released within 24 hours. No more similar than siblings (50% of shared genes) Blood supply to one twin is inhibited killing the second foetus. Between weeks 4 and 8, males begin to secrete testosterone from primitive testes. Males are more likely to result in miscarriage. Males have more disease, earlier death, and shorter lifespans in most of the world. Lack of testosterone will demasculinize the male embryo. The amount of testosterone influences the direction the embryo will take.
