Recent experiments on the differentiation of the labyrinth in Amblystoma

Morphogenesis of the Inner Ear

“…If the otocysts were permitted to develop further, severe defects of dorsal (endolymphatic duct and vestibule) development were apparent. In addition, when the otic vesicle is transplanted to other rostrocaudal positions along the axis of the developing CNS, it fails to undergo normal morphogenesis (Detwiler and Van Dyke 1951). These results were extended by Herbrand et al (1998), who performed transplants of chick otic placode to abnormally rostral positions adjacent to the developing midbrain/hindbrain or to the wing bud.…”

“…Detwiler's original studies prompted the question, "What is it that the medulla possesses and gives off which so profoundly affects labyrinth differentiation and which is obviously lacking in any other of the primary segments of the embryonic brain?" (Detwiler and van Dyke 1951). Answers to this 50year-old question are only just beginning to emerge.…”

The Amphibian Eye: Development and Regeneration

“…Disturbances in the continued action of this inductor result in abnormalities in the paired nature of the eyes such as synophthalmia and cyclopia (ADELMANN, 1936;VON WOELL-WARTH, 1952. DRAGOMI-ROW (1936, IKEDA (1937IKEDA ( , 1938, and DETWILER and VAN DYKE (1951 transplanted optic vesicles or cups and ear vesicles next to each other Fig.7. The presence of the prechordal plate appeared to be the most important and the prechordal mesoderm the next most important element in ensuring the presence of paired eyes.…”

Developmental Physiology

“…The role of the prechordal mes oderm in induction of the forebrain in amphibians has been reinvestigated by Gallera (71). The role of the medulla in inducing and controlling normal ear development has been demonstrated by Detwiler & Van Dyke" (72,73,74) and Yntema (75).· The time at which the reacting system becomes "at tuned" to the inductor (i.e., becomes "competent") has been shown in the case of lens induction in A mblystoma to occur during the 'open neural fold stage [Liedke (76)J. The dependence of extrinsic eye muscle development upon the optic cup and the independence of the lids and lacrimal glands have been shown by Amprino (77,78).…”