For an explanation, see the main splats page
SPLATS about development and embryology
Development and embryology
- Multi-celled organisms begin as one cell that develops into a fetus which becomes a whole individual, under the control of genes that are switched on and off.
- Animals grow and develop from a single cell, under the control of genes that are switched on and off under the influence of interactions between the cells.
- Plants grow and develop from seeds which contain a small food store that provides the material for the initial growth, to the point where leaves form.
- Most animals develop further after birth, having been born with some parts of them less developed than others. The undeveloped parts vary between species.
- The development of a whole organism from a single cell is controlled by the genes found in every cell, but which are not necessarily active unless switched on.
- Most multi-celled plants and animals have tissues, and all advanced organisms are made up of different tissues, in which different genes are active.
- Plants use a variety of hormones as signals from one part of the plant to another. Gibberellin is an example of an important plant growth hormone.
- Tissues form organs, and they are most easily studied in thin sections. How tissues form is a fascinating aspect of biology, still not fully understood
- Specific genes are switched on in cells of a certain kind: in most cells, most of the genes do not operate at any given time. Many of them do not ever operate.
- Aging is a natural process. The telomeres on the chromosomes shorten as an organism gets older, and this seems to mark the age of cells in some readable way.
- The Eutheria, the placental mammals, go through a period of gestation after conception, when they are nurtured internally as their tissues develop.
- An insect larva becomes a pupa which becomes an imago, showing development and redevelopment over several stages, with tissues being resorbed and reconstructed.
- Gigantism and dwarfism occur when hormonal balances are uncontrolled in the developing body, so that the cells of the body receive confusing signals.
- Apoptosis helps to shape developing organisms This is a form of controlled cell suicide which serves to shape the individual, removing excess material.
- Development often involves recapitulation of some of the stages that were present in their distant ancestors. This leaves the way open for neoteny.
- Stem cells are unspecialized cells that can give rise to other types of cell. Some stem cells are more versatile than others, as the cells are less committed.
- The most versatile stem cells are embryonic stem cells, which are better referred to as totipotent stem cells, a less emotive and more accurate name.
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