See folk all researches are important : ------ This Focus Report is extracted from the full-text Email publication SCIENCE-WEEK. ............................ Our current understanding of the differentiation and connectivity of human central nervous system neurons depends heavily on three decades of electron microscopy and histology of neural tissues of other mammals, particularly of the tissues of the rat and of various species of monkeys, and even of the tissues of several species of worms and of a giant snail. These are only some examples, and there are many others. This, therefore, is another principle: Nerve cell function, wherever it occurs, involves mechanisms that more often than not have been conserved by evolution, so that for the neurobiologist attempting to understand the human nervous system, every species provides experiments already performed by nature. All neuro- biologists are aware of this, but on occasion there are people in other disciplines, or in government offices or legislatures, who are unaware of it, and who think that research on single cockroach nerve fibers, for example, is unrelated to problems of human neurobiology. That idea is totally false: some species of cockroaches have relatively large diameter nerve fibers (for reasons indicated below), which makes it simple to do certain electrophysiological experiments, and since the basic mechanisms that are operating in cockroach nerve fibers are essentially identical to those operating in human nerve fibers, the use of the cockroach nervous system in experiments is completely relevant for human neurobiology -- as relevant as the continuing use of the nervous system of a mollusc called squid. And the same considerations hold true for investigations of other parts of the nerve cell. There are features that are unique to neurons, common to nearly all neurons no matter what the species, but not found in other cells. Neurons, for example, have special structures such as neurotubules that are not found in other cells, but which are found in neurons of many species. And the structures of synapses, the places where nerve cells are connected to each other, have a remarkable universality in nature, a boon for the neurobiologist. These and the other trans- species neurobiological identities provided by the laboratory of evolution, some of which will be discussed below, are important and precious advantages to the research worker, and they need to be fully utilized rather than constrained by misunderstandings of relevance for medical science. In summary, in the same way that molecular biology has depended so heavily on investigations of a few species of yeast and bacteria, investigations of mechanisms common to all living cells, so neurobiology has depended heavily on investigations of the nervous systems of lower forms, nervous systems which operate by mechanisms common to all forms that have nerve cells................(snipped).. -- Cheers, Joao Paulo - Salvador,BA,Brazil