Result of Your Query

A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Z

phylotypic stagephylotypisches Stadium (ger.)

  • Those developmental stages that are most characteristic for a phylum.

    All insects during ontogenesis pass a stage known as the germ band. […] This stage represents a generalization called ‘Körpergrundgestalt’ by Seidel (1960), which term may be translated as ‘basic body pattern’ (Sander, 1976a). A comparable stage has long been recognized in somer other phyla. It can be defined as the first stage that reveals the general characters shared by all members of that phylum, and therefore was called the ‘phyletic’ stage by Cohen (1977). I suggest the term ‘phylotypic’ instead, because phyletic refers to phylogenesis rather than to characters typical of individual phyla. Incidentally is is the stage separating ‘primitive development’ from ‘definitive development’ in the terminology of the classical embryologist (e.g. Schleip, 1929). Different members of a phylum embark on ontogenesis from very different starting conditions – compare for example the egg cells and early developmenta of trout, frog, chick and mouse – and thence converge on the phylotpyic stage (marked for instance in vertebrates by chorda, neural tube, somites, gill clefts, tubular heart, etc.).

    Sander, K. (1983). The evolution of patterning mechanisms: gleanings from insect embryogenesis and spermatogenesis. In: Goodwin, B.C., Holder, N. & Wylie, C.C. (eds.). Development and Evolution, 137-159: 140.


    The postulated existence of common embryonic stages within taxa prompted a search for stages so conserved that they typify phyla. Seidel called such a stage in insects Körpergrundgestalt (form-building stage), Sander identified it with the germ-band stage. Such stages were termed phyletic by Cohen, phylotypic by Sander, and phylotypes by Slack et al. The explicit presumption is that the basic body plan or bauplan of a phylum is reflected in such a stage; hence its evolutionary conservation and conservatism. […] The phylotypic stage is the physical embodiment of the link between ontogeny and phylogeny.

    Hall, B.K. (1997). Phylotypic stage or phantom: is there a highly conserved embryonic stage in vertebrates? Trends Ecol. Evol. 12, 461-463: 461.