on 22 August 2012
This book is about developmental biology of animal and plant where the coverage for plant is minimal. General readers need to have some knowledge of biology in order to have a fair understanding. Essentially, it covers how a fertilized egg develops into a baby, how organs and nervous system are formed as well as the growth, regeneration and ageing processes.
Early embryonic cells that will become different cell types differ only in their pattern of gene activity. Developmental proteins direct these development processes where thousands of genes are involved. Growth hormone is essential for the growth of humans and other mammals after birth. Organ development involves large number of genes. Organ size can be determined by both internal growth control and extracellular factors that stimulate or inhibit growth. Mutations to genes and environmental factors can lead to abnormal development.
During nervous system development, too many neurons are produced initially and only those that make appropriate connections survive. For many years, it was thought that no new neurons could be generated in the adult brian. However, neural stem cells have been identified that can generate neurons. The central nervous system of adult can not regenerate, but the peripheral nervous system involves regrowth of axons.
Ageing is essentially the result of wear and tear. However, the germ cells that are responsible for reproduction do not age. There is evidence that ageing is under genetic control and genetic variation within the FOX03A gene is strongly associated with human longevity!