Salamander Embryos Research Articles

Selective innervation and reciprocal functional suppression from grafted extra labyrinths in amphibians

After extra labyrinths along with portions of medulla were grafted in correct orientation into the neuraxes of frog and salamander embryos at early tailbud stages, the animals acted in every respect like normal individuals. If the grafts were placed in reversed anteroposterior orientation, however, the animals acted like controls with inner ears excised. Behavioral and histological evidence indicates that precise functional neural connections were made between the implanted labyrinths and appropriate centers within the brain of the host. The result of interaction between the two opposing sets of labyrinths in the animals with reversed grafts was an effective cancellation of responses to stimuli concerned with kinetic and static equilibrium.

Protein transfer in chimaeric Taricha-Rana explants

Cytological examination of chimaeric explants of salamander embryo gastrula ectoderm and frog embryo chorda mesoderm or larval brain (denuded of epidermis) did not reveal any passage of frog cells into the salamander tissue. The greater activity in precipitin reactions of test antigen preparations from salamander tissues that had been separated from the chimaeric explants, as compared to control cultures of salamander ectoderm, confirms previous results and tends to indicate that frog proteins are passing over into the salamander tissue. When Taricha tissues from the chimaeric explants are separated and cultured for a further period of time, the activity of extracts from these tissues against the anti- Rana gastrula serum decreases.

The influence of the nerve in regeneration of the amphibian extremity.

The influence of the nerve in regeneration of the amphibian extremity.

An analysis of induction of the ear from foreign ectoderm in the salamander embryo

An analysis of induction of the ear from foreign ectoderm in the salamander embryo

Correct Terminology in Salamander Myology II. Transverse Ventral Throat Musculature

The larvae of all salamanders have four superficial transverse ventral throat muscles. In the adults there may be either three or four, depending on the species. The prevailing terms-and those which are the only logical ones from the standpoint of comparative anatomy and embryology-are: intermandibularis anterior, intermandibularis posterior, interhyoideus, interhyoideus posterior, inter-ossaquadrata, quadrato-pectoralis, subhyoideus, and gularis. It remains only to demonstrate the proper allocation of these terms among the various urodele genera. In the larvae of all salamanders the most anterior, small, and occasionally indefinite muscle without a median raphe is the intermandibularis anterior. In the Proteidae, Necturidae, Amphiumidae, Cryptobranchidae, and Sirenidae this muscle persists throughout life. There may be occasional exceptions to this, but they are individual aberrancies and not differences between species. In the remaining families, Hynobiidae, Ambystomidae, Salamandridae, and Plethodontidae, the intermandibularis anterior disappears completely at metamorphosis. In these last four families, then, the most anterior muscle in the metamorphosed adult is the intermandibularis posterior. The fact that this latter muscle is very often subdivided into a number of separate slips has caused some confusion, and the entire muscle has very often been erroneously called the intermandibularis anterior by some writers, including the author (Piatt, 1935). According to Eaton (1936: 49) the accountgiven by Hoffmann (1873-1878: 95) is the best source of information concerning the presence of the intermandibularis anterior in urodeles. Hoffmann's brief account is inadequate and definitely wrong. A more detailed and very accurate paper on this subject is the one by Luther (1914). It has been shown (Edgeworth, 1911, 1935; Piatt, 1938) that the transverse throat muscles posterior to the intermandibularis posterior arise in the early salamander embryo as a single mass of mesoderm derived from the fusion of the ventral portions of the hyoid arches. Later the mass splits into an anterior interhyoideus and a posterior interhyoideus posterior. Both these muscles are maintained throughtout life in all salamanders, but with certain definite changes in different genera. Those species in which metamorphosis occurs normally and in which the interhyoideus and interhyoideus posterior remain unaltered are the Cryptobranchidae, Amphiumidae, and Ambystomidae. In these families the larval interhyoideus and interhyoideus posterior are carried over into the adult animal unchanged, save for a slight shifting of

Experiments upon the Segmentation of Spinal Nerves in Salamander Embryos

Experiments upon the Segmentation of Spinal Nerves in Salamander Embryos

Observations upon the growth, function, and nerve supply of limbs when grafted to the head of salamander embryos

Observations upon the growth, function, and nerve supply of limbs when grafted to the head of salamander embryos