An ACE project by Bryan Yan 2I102 Twins An ACE project by Bryan Yan 2I102

Agenda Fraternal Twins Identical Twins Semi-Identical Twins Siamese Twins

Fraternal Twins – What? Non-Identical Twins Small chance of having the same chromosome profile May be different sex

Fraternal – How? Two eggs are independently fertilized by two different sperm cells Two fertilized eggs are implanted in the uterus wall at the same time

Fraternal Twins – Who? More common for older mothers Twinning rates doubling in mothers over the age of 35

Fraternal Twins - Advances Advent of technologies and techniques to assist women in getting pregnant has cause the rate of fraternals to increase

Identical Twins – What? Nearly genetically identical Same sex, unless there are mutations during development

Identical Twins – How? Single egg is fertilized to form one zygote Then divides into two separate embryos

Identical Twins – When? Occurs approximately in every 3 out of 1000 births For IVF, it occurs approximately in every 21 out of 1000 births

Semi-Identical Twins – What? Genetically identical maternal genes Genetically dissimilar paternal genes

Semi-Identical Twins – How? (Type 1) Polar Twins A sperm fertilizes the ovum while the other fertilizes the polar body 25% genetic identity

Polar Body? Diploid cells in animals undergoing cytokinesis after meiosis to produce egg cells Sometimes divide unevenly

Polar Body? Most of the cytoplasm is segregated into one ovum Other smaller cells are called polar bodies

Semi-Identical Twins – How? (Type 2) Sesquizygotic twins Two sperms fertilize one ovum Form a triploid Triploid splits

Sesquizygotic twins Both cells from triploid splitting embeds on the endometrium Develop into identical twins

Siamese Twins – What? Conjoined twins Twins whose bodies are joined at a certain part e.g. upper chest

Siamese Twins – How? A fertilized egg completely separates But stem cells (which search for similar cells) find like-stem cells on the other twin Fuse the twins together

Siamese Twins – When? Ranges from 1:50000 births to 1:100000 births depending on country of birth

Siamese Twins – Where? Most common in Southwest Asia and Africa

Siamese Twins – Who? More common amongst females with a 3:1 ratio

References http://en.wikipedia.org/wiki/Twin http://www.vtaide.com/png/George/twins.htm http://pregnancy.about.com/od/pregnancy/a/Twin-Pregnancy.htm http://www.pennmedicine.org/encyclopedia/em_DisplayAnimation.aspx?gcid=000058&ptid=17 http://www3.telus.net/tyee/multiples/1formed.html http://answers.yahoo.com/question/index?qid=20080511034534AAUeVEH http://suite101.com/article/a-third-kind-of-twins-a183863 http://multiples.about.com/cs/glossary/g/polarbody_def.htm http://en.wikipedia.org/wiki/Polar_body http://en.wikipedia.org/wiki/File:Gray9.png http://en.wikipedia.org/wiki/File:Gray5.svg http://ars.sciencedirect.com/content/image/1-s2.0-S0165460897004718-gr2.jpg http://www.advancedfertility.com/images/ENDOCC1.JPG http://en.wikipedia.org/wiki/Conjoined_twins http://www.news.ku.edu/2007/may/11/images/07465_11.jpg http://www.sciencephoto.com/image/314150/530wm/P6800902-LM_of_human_ovum_at_the_two_cell_stage-SPL.jpg http://servinghimwithshakyhands.files.wordpress.com/2011/05/35-b-day-cake.jpg

References (Continued) http://vixstar1314.files.wordpress.com/2011/06/global-technology.jpg http://www.twinsrealm.com/othrpics/nicoleandjaqueline.jpg http://edu.glogster.com/media/3/12/25/45/12254586.jpg http://blogs.telegraph.co.uk/culture/files/2010/10/ivf-getty.jpg http://www.scientificamerican.com/media/inline/15DD5B0E-AB41-23B8-2B1E53E8573428C5_1.jpg http://blog.f1000.com/wp-content/uploads/2011/12/090709-sperm-egg-02.jpg http://upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Chang-eng-bunker-PD.gif/230px-Chang-eng-bunker-PD.gif http://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Mouse_embryonic_stem_cells.jpg/250px-Mouse_embryonic_stem_cells.jpg http://cwaboulder.files.wordpress.com/2010/05/numbers.jpg http://upload.wikimedia.org/wikipedia/commons/thumb/8/86/Africa_(orthographic_projection).svg/200px-Africa_(orthographic_projection).svg.png http://www.psdgraphics.com/wp-content/uploads/2009/06/female-sign.jpg

Thank You!