ABSTRACT
One property of invertebrate nervous systems used to great experimental advantage is the ‘identifiability’ of individual neurones. A principal tenet of the ‘identified neurone’ concept is that a certain degree of structural regularity can be expected when investigating an identified cell in individual members of a single species. Yet in organisms that reproduce sexually some degree of structural variability should be expected over and above that attributed to developmental noise. Genotypic lineage appears to be a strong determinant of neurone structure. Recent studies using controlled lineages through selective and parthenogenetic breeding have indicated a fairly strong genetic influence on neurone number, structure and interconnections (Macagno, Lopresti & Levinthal, 1973; Goodman, 1977, 1978; Steeves & Pearson, 1983). In wild populations, however, some genetic variability may be selectively eliminated through environmental factors as well as intra-and interspecific biological interactions.
