Xenoplastic ear induction between Rana pipiens and Amblystoma punctatum

The Induction of the Otic Placode

“…A role for mesoderm in the induction of the otic placode was first suggested in the early 1930s (Dalcq 1933;Holtfreter 1933) and confirmed by others (Harrison 1936(Harrison , 1938(Harrison , 1945Albaum and Nestler 1937;Kohan 1944), but once again, a lack of host and donor markers in these experiments should be noted. Several studies in different species of Rana, chick, and Discoglossus conclude that the ear is committed before the hindbrain is morphologically visible, and interpret this as evidence for an exclusive action of mesoderm, rather than the hindbrain, in the induction of the otic placode (Szepsenwol 1933;Pasteels 1939;Zwilling 1941;Ginsburg 1995).…”

“…A variety of early studies attempted to demonstrate that the hindbrain can induce the otic placode when grafted to ectopic locations, but in the absence of clear markers to distinguish host from donor tissue, these studies should be interpreted with caution (Stone 1931;Harrison 1936;Albaum and Nestler 1937;Waddington 1937;Kohan 1944;Harrison 1945). Other experiments attempted to examine the role of the hindbrain in placode induction by replacing the hindbrain with other neural tissue (Detwiler 1948;Detwiler and van Dyke 1950).…”