History of Medicine Home > From 'Monsters' to Modern Medical Miracles Home > Embryology and Classification of Conjoined Twins Embryology of Conjoined Twins Identical twins develop when a single fertilized egg, also known as a monozygote, splits during the first two weeks of conception. Conjoined twins form when this split occurs after the first two weeks of conception. The monozygote does not fully separate and eventually develops into a conjoined fetus that shares one placenta, one amniotic sac, and one chorionic sac. Because the twins develop from a single egg, they will also be the same sex. The extent of separation and the stage at which it occurs determine the type of conjoined twin, i.e., where and how the twins will be joined.
The Ronald G. Becker Collection of Charles Eisenmann Photographs Using the Collection The collection of 1412 images can be accessed via the Library's CONTENTdm server and is fully searchable by keyword, subject, and image number. The item level inventory of the collection (in Excel) can help with formulating searches and sorting. About the Photographs The most common method of photography during the 1870s and 1880s was the wet plate albumen process. Albumen prints are characterized by a warm sepia tone that distinguish them from later silver gelatin prints. Eisenmann's images are noted for particularly being sharp, clear, and well-posed. The most common formats were cartes de visite and and cabinet cards.