Experimentelle Analyse zur Entwicklung der chimärischen Vorniere beiTriturus undBombinaBosshard, Hans
doi: 10.1007/BF00582926pmid: 28304764
1.
The presumptive material of pronephros was exchanged betweenBombina variegata andTriturus alpestris in both gastrula and neurula stages. In further series the pronephros material was taken from the neurula stage of the two orders, dissociated mechanically and cultured in an ectodermal envelope (sandwich technique). This showed that the differentiation proceeds autonomously. No structures other than that corresponding to the prospective significance of the transplanted tissue have been found. Order-specific characters such as the rate of differentiation and the nuclear arrangement in the nephridial epithelial cells were maintained by both tissues. Chimeric nephridial tissues could not be observed.
2.
The pronephros tissue of a foreign order, when used as a donor, enters into the host's coelom and can be replaced reciprocally. This leads to the formation of a nephrostome. In this case the developmental-physiological factor is apparently common in both amphibian orders.
3.
The analysis and reconstruction of the pronephros inBombina andTriturus embryos of different ages showed that the formation of three nephrostomes in anurans and two in urodeles is only temporarily valid forBombina. Eight days after neurulation (PM24) only the two caudal nephrostomes persist inBombina.
4.
The interference to the pronephros function due to operation leads to hypertrophy of the intact kidney on the control side in older embryos.
Etude expérimentale de l'organogenèse de l'estomac chez le foetus de LapinDavid, Danielle
doi: 10.1007/BF00582927pmid: 28304765
1)
An ultrastructural and optical examination of the “in utero” development of the stomach in Rabbit embryos, demonstrates that the epithelium increases by“vacuolisation”. The intraepithelial vacuoles, formed by a secretory process, secondarily open into the gastric cavity, whence the constitution of primary villi. Then the mesenchyme buds chorionic evaginations under the epithelial crests and transforms the primary into secondary villi.
As the villi grow longer the epithelium loses its pseudostratified structure in order to become simply unistratified. At the same time, the four types of gastric cells progressively accomplish their differentiation into parietal, mucous, peptic cells and surface epithelium.
2)
The presumptive gastric area of a ten-day-old Rabbit embryo corresponds to the lower third of the entomesoblastic part of the embryonic pharynx, posteriorly amputated at the umbilical edge. This presumptive area, grafted in the Chick embryo, differentiates into characteristic gastric tissue.
Finally the stomach is explanted (“in vitro” and“in ovo”) at different stages of ontogenesis. Up to the thirteenth day it degenerates in culture but grows and accomplishes its morphogenesis as a graft. From the fifteenth day, the cultured and grafted stomach differentiates on both morphogenetic and cytochemical planes.
Erscheinungsbild und Entwicklung der Darmdottervene und ihre Beziehung zur Eingeweide-Asymmetrie bei UrodelenKraft, Arne
doi: 10.1007/BF00582929pmid: 28304767
1.
The shape of the embryonic blood island, the appearance of the vitelline vein under normal and experimental conditions as well as the relationship between the vitelline vein and the position of the asymmetrical viscera (heart, intestine) were investigated in larvae ofAmbystoma mexicanum andTriturus alpestris.
2.
The approximately symmetrical, Y-shaped blood island shows conspicous species and individual form differences. Larvae often show alterations of shape which indicate reorganization activities in the blood island. Remnants of the blood island can persist in the presence of a fully developed and functioning vitelline vein.
3.
Normally, the vitelline vein runs asymmetrically to the left (normal position), but even in controls and especially in experimental animals it shows great variation, ranging from normal to completely inverse position. The vitelline vein can be missing in developmentally damaged larvae. It is often originally paired and roughly symmetrical; furthermore, it can show abnormal local ramifications. The occasional position alterations of the vitelline vein, which in extreme cases can lead to inversion of the position, are especially remarkable and are without parallel in the evolution of the heart and the intestine. The caliber of the vein and the duration of its functional period are highly variable.
4.
In the greater number of cases, the course of the vitelline vein and the position of the intestine and the heart agree; only a small percentage of the larvae show a distinct discrepancy in this respect. According to this evidence, the intestinal vein is positionally and functionally not strictly dependant on the heart and the intestine.
5.
Defects on the left side of postneurulae have, on the average, a more pronounced effect on the course of the vitelline vein than defects on the right side. During the functional period of the vein alterations of its course occur more frequently toward the normal position (toward the left) than in the opposite direction.
6.
The phenomenon of the leftward tendency or “left-dominance” of the vitelline vein is discussed in connection with similar observations in the viscera. Apart from a general lateral determination of the asymmetrical organs in the gastrula and neurula stages, to which the vitelline vein is probably also subject, the effect of an unknown non-determinative factor on the vitelline vein must be assumed when one considers its occasional positional changes. The variability of the vitelline vein, considerable in every respect, becomes more readily understandable when one regards it as a component of a more comprehensive, dynamic functional system.
Der Einfluβ starker Lateraldefekte bei Triturus-Embryonen auf Darmvenenverlauf und EingeweidesitusKraft, Arne
doi: 10.1007/BF00582930pmid: 28304768
1.
Embryos ofTriturus alpestris in the tail-bud or post-tail-bud stage were severely damaged by removal of a large quantity of germinal tissue from either the left or the right side (Fig. 1a). The resulting extreme curvature of the torso and the tail toward the region of the defect sometimes remains more or less pronounced but is usually corrected in the course of regulative events (Figs. 1b–d, 2). These appear as intense right-left interactions of the embryonic and larval body which are aimed toward compensation of the primary defect.
2.
The lateral defects have a very strong influence on the course of the vitelline vein and there is sometimes a difference between the effects of left and right defects. Changes in the course of the vitelline vein, to the extent of complete situs inversus, occur relatively often; the transposition always takes place toward the defect or toward the restitutive tissue (Fig. 3).
3.
Neither left nor right lateral defects lead to fundamental alterations of the (already determinate) visceral position. Only the intestine often has abnormalities of form and position which can be considered as disturbance of the normal position (Fig. 4). These results directly contradict Spemann's hypothesis that lateral transposition of the viscera is due to the body curvature mechanically caused by loss of material on the left side.
Die Kopfregeneration vonLineus sanguineus Rathke(Nemertini) unter dem Einfluβ von Actinomycin-D. Chemomorphologische BefundeBecker, G.; Sasse, D.; Reutter, K.
doi: 10.1007/BF00582931pmid: 28304769
Fragments ofLineus sanguineus were incubated in seawater, which contained different concentrations of actinomycin-D (1.9 μg/ml, 0.95 μg/ml and 0.48 μg/ml). After 4, 5, 6 and 10 days the regenerates were studied by histological and histochemical methods (glycogen, glucose-6-phosphate-dehydrogenase and RNA). Corresponding to actinomycin-D concentration certain phases of regeneration are inhibited. The phases of proliferation are less sensitive to actinomycin-D than the phases of differentiation. If morphogenetic areas are inhibited, the normally demonstrable histochemical characteristics: accumulation of glycogen and later, the increase of G-6-P-DH activity and RNA concentration do not appear.
Autonome Determination für Pigmentbildung beimwhite-Positionseffekt vonDrosophila melanogasterJanning, Wilfried
doi: 10.1007/BF00582932pmid: 28304770
Inwhite position-effect ofDrosophila melanogaster, determination for the potential of pigment formation of eye cells takes place at the end of the first larval instar. Eye discs, prior to or after this developmental stage, were transplanted together with some larval tissue into the abdomens of adult females. After a cultivation period of 5 to 7 days, the implants were transplanted back into larvae. Imaginal differentiation occurred in these metamorphosing hosts. It could be shown that eye disc cells become autonomously determined during the cultivation period. An influence of the larval tissues transplanted together with the eye discs on determination could not be demonstrated. Therefore, this determinative event most likely is independent on the specific larval milieu.