Wilhelm Roux Archiv Fur Entwicklungsmechanik Der Organismen最新文献

In a study with the light microscope, we investigated the tissular localization of glycogen, R.N.A., and 4 phosphohydrolases in the pelvic fin bud of two species of Trout,Salmo fario andSalmo gairdneri, Pisces, Teleostei. In both, the epiderm bud, including the "pseudo-apical cap", is devoid of glycogen and the amount of R.N.A. histochemically demonstrable is not greater than in epidermal regions outside the bud. InSalmo gairdneri but not inSalmo fario, we observed four phosphatases, only in the inner layer of the epiderm of the fin bud: alkaline phosphomonoesterases, naphthol AS-BI acid phosphatase, nonspecific ATPase and AMPase. The "initial mesenchyme", from the somatopleura's proliferation, contains a great quantity of R.N.A. In both species we found there the four enzymes. The "secondary mesenchyme", obtained from the dispersion of four ventral somitic processes, has a metabolism that is similar inSalmo fario andSalmo gairdneri; alkaline phosphomonoesterase is found only inSalmo gairdneri.

The developmental changes in the pattern of chromatin nonhistone proteins have been investigated. The main feature of the observed changes was not the introduction of new or the disappearence of earlier existing species, but the stage-specific alterations in the rate of biosynthesis of the nonhistone protein constituents.

To analyse the main pathways of energy supplying metabolism, the following ratios of enzyme activities are measured in different developmental stages and in isolated embryos: GAPDH/CE, GAPDH/HOADH and HOADH/CE. The ratios show that the early stages are equally capable to metabolize carbohydrates and fat, but the enzyme activity pattern resembles more that of exclusively fat consuming insect tissues. Special features of the pattern are the very high ratio of HOADH/CE, as yet not observed in other tissues, and the ratio GAPDH/TIM of 1∶1 differing from the enzyme group of constant proportion. Generally the enzymes of intermediary metabolism exhibit low activities.The eggs contain a considerable supply of fat and a small one (0.1% of fresh weight) of glycogen, which begins to increase during the formation of the germlayer.The respiratory quotient of 0.6-0.7 mounts to 0.8, when the "Körpergrundgestalt" is formed.From the properties of the enzyme activity pattern, the early beginning gluconeogenesis and the height of the respiratory quotient it follows, that during early embryogenesis the break down of fat is realized as the main pathway of energy supplying metabolism.

1. During early embryogenesis (from blastula to late tailbud) ofTriturus vulgaris the DNA content of isolated nuclei from various regions was measured cytophotometrically. It became evident that the distribution of measurement data varies specifically with stage and region. 2. The nuclei were classified on the basis of their DNA content into the appropriate phases of the cell cycle (G₁ S_I, S_II, S_III, S_IV, and G₂). The relative lengths of the cell cycle phases were calculated from the frequencies of nuclei in the six classes. In all cases the S phase occupies the greatest part of the generation time. 3. In the neuroectoderm the proportionality of the cell cycle phases remains the same throughout the period studied. The relative lengths of S and G₁ + G₂ are 80 and 20%, respectively, of the interphase. The rate of DNA synthesis is approximately constant during S period. 4. In the presumptive epidermis there is a small increase in the length of the G₁ phase. The duration of the S period is 72.5% of that of interphase. 5. In the chordomesoderm a disproportionate increase of the cell cycle phases becomes visible during development. The G₁ phase increases from 7.9 to 25.8% of the length of the interphase. The G₂ period remains unchanged at approximately 12%. In early stages DNA replication rate is constant. With increasing age of the embryos, there is a slowing of the synthetic rate at the beginning of the S phase and an increase at the end. The proportion of late replicating DNA increases as development proceeds. 6. In the endoderm there is also a disproportionate change in the cell cycle phases. Up to the early tailbud stage the duration of G₂ and S_IV increases significantly. In these stages the rate of DNA synthesis is greatest at the beginning of the S period and slows down to the end. In late stages there is a lengthening of the G₁ and S_I phase and a decrease of the G₂. The DNA replication in these late stages is similar to that in the mesoderm. The proportion of late replicating DNA increases in the late stages.

The changes of histones related to the development of sea urchin embryos from blastula to pluteus stage were studied by an electrophoretic method. The observed alterations were found to be quantitative ones and related to the transition of embryos from blastula to gastrula stage. During this period an increase in the relative amount of the F-1 and F-3 histones on account of the F2b + F2a2 was observed. The patterns of gastrula and pluteus histones were found to be similar.

In the PlanarianDendrocoelum lacteum, the genital system degenerates after the egg laying season. It regenerates itself during autumn. The vitelline glands are the last to appear. They are exclusively reconstituted by neoblasts which migrate towards the oviducts, join themselves into cords, multiply by amitoses, enlarge and differentiate into vitelline cells. This differentiation characterizes itself essentially by a steady decrease of the nucleocytoplasmic ratio, an increase of the nuclear DNA amount, the appearance and accumulation of orthodiphenol granules in the cytoplasm.

The effect of uterine environment on lysis of the blastocyst coverings in the rabbit was studied in vivo and in vitro. After transplantation of 4, 5, and 6 days post coitum old blastocysts in foster does, the stage of pregnancy of which differed ± 2 days from the corresponding age of the blastocysts and after in vitro culture of 4 day old blastocysts, we investigated histologically the protease activity and the structure of the blastocyst coverings. The experiments revealed that only an exact synchronous in vivo medium is capable of initiating lysis or of support started lysis, although growth of the blastocysts seemed to be normal in foster uteri as well as in culture dishes. A series of figures on structural changes of the blastocyst between the 4 and the 8 day post coitum is compiled.

UnfertilizedCiona eggs were centrifuged, stratifying their mitochondria and some other cytoplasmic components. Each centrifuged egg had a mitochondria-free, centripetal clear layer that was contiguous with centrifugal layers containing mitochondria. By cutting centrifuged eggs in two at various levels along the centripetal-centrifugal axis, it was possible to obtain centripetal fragments including virtually no mitochondria, about one-tenth of the uncut egg's mitochondria or about one-fourth of the uncut egg's mitochondria. Most of these centripetal fragments, when fertilized, developed into larvae. However, only the centripetal fragments that included about one-fourth of the uncut egg's mitochondria developed into larvae giving the cytochemical reaction for cholinesterase, a convenient indicator of muscle cell differentiation inCiona. Therefore, the inclusion of a minimum number of mitochondria (more than one-tenth but less than one-fourth the number in the uncut egg) is correlated with muscle cell differentiation in larvae developing from the centripetal fragments. The possible influences of mitochondria and of other cytoplasmic components on muscle differentiation are discussed.

Experimental cyclopia and synophtalmia have been reproduced by the direct action of actinomycin D on the entire embryonic brain at an early stage of development. We excise the brain, treat it with solutions of different concentrations of actinomycin D and replace it in the embryo.We find that with increasing actinomycin concentration, there is a continous progression from the normal embryo to a type lacking a large part of the head. The fronto-nasal process, usually excised and treated, along with the brain, develops only at lower actinomycin concentrations. When it does not develop, fusion of the eyes and synophtalmia are favoured. The maxillary processes always develop, the position of the bones being dependent upon the fusion of the eyes and the development of the fronto-nasal process. It seems that actinomycin D has no effect on the development of the maxillary processes.