Wilhelm Roux Archiv Fur Entwicklungsmechanik Der Organismen最新文献

The developmental properties of three neoplasms found in lethal mutants ofDrosophila melanogaster were studied and compared with the development of the corresponding wild-type organs. Two of these neoplasms are found in the late larval lethal mutant,lethal (2) giant larvae ⁴ (l(2)gl ⁴) and its allele,lethal (2) giant larvae (l(2)gl). The third neoplasm occurs in the hemizygous lethal male embryos of the mutantNotch ⁸ (Df(1)N ⁸).The mutantsl(2)gl ⁴ andl(2)gl were shown to possess defects involving imaginal primordia of ectodermal origin, such as the imaginal discs of the adult integument and the imaginal optic primordia in the larval brain. They also have enlarged lymph glands and abnormal gonads, salivary and ring glands. Thel(2)gl ⁴ andl(2)gl mutations transform the imaginal discs into noninvasive, lethal neoplasms and the imaginal optic primordia in the larval brain into an invasive and lethal neuroblastoma. Both neoplasms were serially subcultured in female adult hosts where they grew rapidly and killed their hosts in 7-14 days. The neoplastic development of thel(2)gl ⁴ imaginal discs and brain proved autonomous at all stages that were investigated from 10 hour old embryos to mature larvae. When exposed to the hormonal conditions of metamorphosis, the neoplastic tissues,in situ as well as those that had been culturedin vivo, ceased to grow but failed to metamorphose into parts of the adult integument or brain. Furthermore, in almost all cases they failed to resume their growth in the adult fly after metamorphosis.Thel(2)gl ⁴ brain neuroblastoma changed after prolonged subculturein vivo so that although the cells stopped dividing temporarily at the time of metamorphosis of the host, they resumed their growth shortly thereafter and continued to divide throughout adult development and in the emerged adult. Many of thel(2)gl ⁴ neuroblastoma cells showed abnormal karyotypes, shapes and sizes after prolonged culturein vivo.Thel(2)gl ⁴ imaginal disc tissue resembles, in both structure and behavior, certain atelotypic tissue sublines which arise from wild-type imaginal discs after prolonged culturein vivo: the ultrastructure of both types of cells are similar and both cease to grow when exposed to hormonal conditions of metamorphosis. Apparently the epigenetic processes which transform wild-type imaginal discs afterin vivo subculture into atelotypic neoplasms have the same phenotypic expression as the genetic processes at work inl(2)gl ⁴ imaginal discs.An analysis of several other late larval and larval-pupal mutants with defective imaginal discs, such asl(2)gd andl(1)d.lg.-1 revealed that they also had defects in parts of the brain destined to form adult structures. This observation indicates that mutations that affect imaginal discs of the adult integument also affect the imaginal primordia of the adult brain.The neoplasm in

Investigations are based on findings of Wolf and Krause (1971). Further advances in knowledge of ooplasm flows over the entire egg were obtained by slow time lapse micrographs. 1. We succeeded in filming the first reaction of eggs to fixation solution.Specific fixation reactions corresponding to the different phases at ooplasm motion indicate additional characteristics of dynamic potentialities in the egg. Osmium-bichromat solution does not cause fixation reactions. The microscopic-anatomical finding therefore correctly reproduces the situation in ooplasm in the moment of fixation. The movements, visible in time lapse micrographs taken before and after the beginning of fixation were recorded on micro-kymograms. The typical ooplasm flows coinciding to the different phases of mitosis and structural alterations in the ooplasm could be exactly determined by 77 individual lapses. 2. Each phase of mitosis is accompanied by typical movements in the ooplasm. As first maturation division in the anterior pole region nears completion, amixing motion begins in the posterior half of the egg and gradually spreads over the entire egg. As the mixing motion comes to an end, the egg is clearer and possesses a periplasm. During the first maturation division, the central and marginal plasm begin to flow weakly in opposite directions within the anterior third of the egg. 3. Thefirst unipolar flow begins with the end of the second maturation division. This and the following unipolar flow, running from the anterior to the posterior pole, are completing within a few minutes. The first unipolar flow and occasionally the second as well initiate not only in the maturation plasm but also in the posterior half of the egg. The strongersecond unipolar flow leads to cleavage, because the syncarion is shifted within it into the cleavage center. 4. The first cleavage divisions can be distinguished as pulses within thetransfer flow. This flow accompanies the energid group into the fontain flow initiation region, where the differentiation center for germ layers and segmentation is also localized. The pulsation point in the transfer flow indicates the position of the energid group, which reaches the fontain initiation region with 8-32 nuclei. 5. In this region, between 74-66%, the two fontain flows begin, moving in oppositely directed coincident flow pulsations towards both ends of the egg. These flows are correlated with the bipolar energid distribution to both egg poles. Thefront of the migrating energids is situated in the fontain flow front, which is recognizable by euplasmic streaks in sections. Within the energid group is a space containing vitellophags; the remaining contents of this space do not show a specific coloring and therefore are unknown. 6. The phases of the fontain flow are correlated in time with the phases of mitosis, between two pulses: pro- and metaphase, slow beginning phase: anaphase; quick mid-phase: telophase; slow ending phase: interphase. Eggs with

Thirteen enzymatic systems have been explored using electrophoretic techniques in eighteen permanentin vitro lines or clones ofDrosophila melanogaster embryonic cells. Significant differences have been observed and the isozymic patterns seem to constitute reliable markers for the characterization of the different lines. Moreover, interesting comparisons are possible with the data previously collected by several groups on the tissue-specific or stage-specific isozymic patterns inDrosophila. This study may give us some clues about the functional differentiation, underin vitro conditions, of the established lines ofDrosophila cells, and perhaps furnish some information on their tissue origin.

InO. notoglandulata, the most striking effect of either starvation or decapitation was a decrease in the number of gland-bearing segments, regardless of sex. In decapitated females, some oocytes grew to the unusual size of 180 μm in diameter. Both oogenesis and spermatogenesis continued in the absence of the prostomium. These results contrast with those obtained with the protandric hermaphrodite,O. puerilis, in which a cerebral hormone appears to be required for oogonial development.

Tissue maceration was used to determine the absolute number and the distribution of cell types in Hydra. It was shown that the total number of cells per animal as well as the distribution of cells vary depending on temperature, feeding conditions, and state of growth. During head and foot regeneration and during budding the first detectable change in the cell distribution is an increase in the number of nerve cells at the site of morphogenesis. These results and the finding that nerve cells are most concentrated in the head region, diminishing in density down the body column, are discussed in relation to tissue polarity.

Neoblasts of the posterior region of the body in the PlanarianD. lacteum have the same migratory and histogenetic properties as neoblasts of the prepharyngeal region. With transverse cuts at whatever level, neoblasts of the posterior fragment migrate forward to accumulate as a normal regeneration bud. But differentiation of these cells only occurs in ease of a section clearly anterior to the root of the pharynx (regeneration then follows). After a transection posterior to this level, the neoblasts degenerate.

Prospective diapause eggs ofBombyx mori become permeable to water in or after contact with paraffin, and they die before reaching diapause. If the eggs are hindered from drying up, their germ anlagen develop to diapausing germ bands. Prospective diapause eggs opened in paraffin, always develop without egg diapause, but their degree of organogenesis depends on the chorion: When eggs are completely dechorionized most of them develop to hatching or nearly hatching larvae; when eggs are completely dechorionized, but their chorion remains in the paraffin, the degree of organogenes is issignificantly lower; and when the opened eggs keep 1/2-3/4 of the chorion, their organogenesis is significantly lower than in the two previous experiments.It is discussed that nondormancy development ofprospective diapause eggs in vitro is not a specific effect of culture media containing water but is possible in paraffin oil too. It is not only possible to stop but also to prevent egg diapause. Nothing, as yet, can be said about the prospective significance of the chorion's reducing factor in organogenesis.

1. Dissociated neural retinal cells of 7-day-old chick embryos were reaggregated under rotation culture and the relation between the several kinetic changes in reaggregation and further histogenesis occurring in the reaggregates was analysed. 2. Aggregates formed by 72 hours' culturing consisted of many rosettes, each of which contained a receptor lumen in its center, and the ganglion lumen with many ganglionic cells. 3. Cell sorting occurred within a rosette, but not within an aggregate. 4. Retinal cells labeled with³H-thymidine and unlabeled cells were allowed to reaggregate separately. By mixing such labeled and unlabeled aggregates formed in the early phase of reaggregation, further fusion of aggregates was achieved. Through these experiments, the following facts were revealed. 4a. In 2 to 3 hours of culturing, primary aggregates of 35 to 70 μ diameter were formed. 4b. All cells within these primary aggregates were well oriented, and the orientation of cells persisted through the further process of fusion of aggregates. 4c. By the fusion of more than 10 primary aggregates, the H unit which contained a full set of structures of the reconstructed neural retina was formed. 4d. The final aggregate was formed by the fusion of aggregates of H units. The ganglion lumen was formed between the two cell groups of H units. 5. When a primary aggregate consisting of about 20 cells was transferred into stationary culture, a single rosette was formed in it. 6. On the basis of these results, the mechanism of the reconstruction of the histological architecture from dissociated retinal cells is discussed.

1. Some aspects of the influence of position on regeneration have been examined by comparing regeneration from two different levels along the newt forelimb. 2. We have defined a series of stages of forelimb regeneration in the newt,Notophthalmus viridescens, in order to facilitate this study. 3. Limbs amputated at either a proximal level (through the humerus) or a distal level (through the radius and ulna) pass through the same stages at the same times after amputation. 4. The histological sequence of events of digit regeneration was compared with that of limb regeneration from a proximal level of amputation and was found to be the same. 5. In limbs amputated at either proximal or distal levels, the rate of elongation of regenerates is the same during the phases of dedifferentiation, blastema accumulation, and blastema growth. 6. During the phase of differentiation and morphogenesis, the rate of elongation of regenerates from the proximal level is significantly greater than that of regenerates from the distal level. 7. The total length of regenerates from proximal and distal levels along the limb is significantly different. 8. The results indicate that positional information does not influence the developmental sequence of events of limb regeneration, but that it does influence the rate of growth of the regenerate and the specification of the structures to be replaced.

Investigations have been carried out on the long-term effect of a single whole body X-irradiation on radula, radula replacement rate, and radular gland ofLimax flavus L. 1. Damage in the radula. In the course of 8 weeks after irradiation with 50 000 R two separate damaged areas develop in the radula. Immediately after exposure 1-2 transverse rows of defect teeth arise. Posterior to an area with normal transverse rows an extensive zone of malformed teeth develops from the 2nd week on. Normal transverse rows are produced again after the 8th week. 2. Replacement rate. Adult snails replace 3-3,5 transverse rows/day during 5 weeks after a dose of 40250 R. The replacement rate decreases to 1,1 rows/day in the 6th week (Fig. 3, broken-lined graph). 3. Damage in the radular gland epithelia. After irradiation with 50 000 R the proliferation zones of thesuperior andinferior epithelium differ with respect to the extent of damage. In the first mentioned area numerous cells die; the cell proliferation is strongly reduced for weeks and reaches a normal level again at the beginning of the 10th week after exposure. The superior epithelium and its proliferation zone are temporary atrophied (Fig. 5a, b and 7a, b). They have recovered in the 10th week. The mitotic activity in theinferior epithelium is less reduced than in the proliferation zone of the superior epithelium. It has almost normalized in the 5th week after exposure. Only a few inferior epithelium cells die; atrophy of the inferior epithelium does not occur. From the 3rd week on after exposure the odontoblasts in numerous radular glands are deformed (Fig. 8). They assume their normal shape again in the beginning of the 10th week. No odontoblasts die after the irradiation. 4.

Controls: Head-shielded snails were irradiation with 50 000 R for controls. No effects of the body irradiation were found in the radula or in the radular gland epithelia. 5. Division of labour in the radular gland. The temporary elimination of the superior epithelium and the epithelial region above the odontoblasts-groups does not affect the tooth-formation and the radula transport into the oral cavity. Hence it follows: a) The odontoblasts-group is exclusively responsible for the definitive shape of the tooth (Fig. 8 and 9). b) The radula is transported into the oral cavity by the inferior epithelium (cf. Chap. E, II, b). On account of these results it is possible for the first time to described comprehensively the division of labour in the radular gland (cf. Chap. E, V). 6. Development of abnormal radular gland epithelia. After irradiation with 50 000 R an abnormal epithelial system develops from the 2nd week on in the tip of the radular gland (Fig. 10a, b;aEep). It encloses sphaeric or tube-like cavities. In many cases they communicate with the lumen of the radular gland. The light-microscopic appearence of the cells of this abnormal epithelium resembles those at the tip of a non-irradiated radular gla