AFM121 Lecture Notes - Lecture 7: Hypoblast, Blastocoel, Blastocyst
Document Summary
The process of progressive and continuous change that generates a complex multicellular organism from a single cell. Holoblastic: refers to a cell division (cleavage) pattern in the embryo in which the entire egg is divided into smaller cells, as it is in frogs and mammals. Meroblastic: refers to the cell divisions pattern in zygotes containing large amounts of yolk, wherein only a portion of the cytoplasm is cleaved. The laws argue against the flawed view of recapitulation. Homologous structures: are similar because they are derived from a common ancestral structure - out arms and bat"s wing are homologous structures. Disruption: abnormality or congenital defect caused by exogenous agents (teratogens) such as plants, chemicals, viruses, radiation, or hyperthermia. Malformation: abnormalities caused by genetic events such as gene mutations, chromosomal aneuploidies, and translocations. The agents associated with such disruptions are called teratogens.