Answer the following question given this paragraph: organism's life cycle is as subject to the effects of evolutionary pressures as any other (although it is easy to concentrate our attentions on adult forms and behaviors). The study of these processes, known as embryology, is beyond our scope here, but we can outline a few common themes. If fertilized eggs develop outside of the body of the mother and without parental protection, these new organisms are highly vulnerable to predation. In such organisms, early embryonic development generally proceeds rapidly. The eggs are large and contain all of the nutrients required for development to proceed up to the point where the new organism can feed on its own. To facilitate such rapid development, the egg is essentially pre-organized, that is, it is highly asymmetric, with specific factors that can influence gene expression, either directly or indirectly, positioned in various regions of the egg (). Entry of the sperm (the male gamete), which itself is an inherently asymmetric process, can also lead to reorganization of the cytoplasm (SEP marks sperm entry point in the figure early frog development). Maternal and fertilization-driven asymmetries are stabilized by the rapid cycles of DNA replication and cell division, with growth being dependent upon the utilization of maternally supplied nutrients. As distinct cells are formed, they begin to become different from one another as i) they inherit different determinants, ii) the presence of these determinants leads to changes in gene expression, and iii) cells secrete and respond to different factors that drive their differentiation further into different cell types, with different behaviors based on differences in gene expression. On the other hand, in a number of organisms, and specifically mammals, embryonic development occurs within the mother, so there is no compelling need to stockpile nutrients within the egg and the rate of development is (generally) dramatically slower. In such developmental systems, it is not the asymmetries associated with the oocyte and... Q: In mammals, the cells on the exterior form the trophectoderm, which goes on to form what? Choices: - protoplanetary tissues - aeroponics tissues - cardiac tissues - extraembryonic tissues A:
extraembryonic tissues