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The human face is invariably interesting, even as an object of
embryologic analysis. The early embryonic growth processes are
located around the developing sense organs, among which the nose
holds a key position. The first indication of the development of
the nose is the formation of the placodes, oval areas of thick ened
and condensed ectoderm, one on each side of the head. Each of these
placodes is transformed, via the nasal groove, into the nasal tube,
sometimes indicated as primitive nasal cavity. In the literature
this transformation has been described as an isolated process that
changes the superficial facial region. Some authors, including
Wolgensinger (1950), think that the active component of this trans
formation primarily is the ectoderm of the nasal placode. Others,
i. e. Hochstetter (1891), Kallius (1905) and Vermeij-Keers (1967),
assume this component be located in the mesenchyme. Peter (1913,
1949), Patten (1953, 1961), Warbrick (1960), and Andersen and
Matthiessen (1967) hold both these components to be active. In the
first and last of these three concepts the ectoderm of the nasal
placode and the nasal groove respectively, is thought to invade the
mesenchyme in the posterior direction. Invading ectoderm has also
been considered to form - independent of the transformation - the
organ of Jacobson and the naso lacrimal duct and to separate the
conchae (e. g. Born, 1876; Legal, 1883; Kallius, 1905; Peter, 1913,
1949; Streeter, 1948; Andersen and Matthiessen, 1967)."
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