On the formation of the myotomes in avian embryos. An experimental and scanning electron microscope study

Summary The formation of the myotomes to chick embryos was studied by using experimental and scanning electron microscope techniques. With the aid of the quail-chick marker system, it was demonstrated that the dermatome gives rise to the myotome plate. SEM studies support the conclusion that the myotome cells originate only from the edges of the dermatome.Supported by the Deutsche Forschungsgemeinschaft (Ch 44/2).     

Effects of 5-bromodeoxyuridine on in vitro development of mouse embryos in the early somitic stage

Summary The inhibitory effect of 5-bromodeoxyuridine on the early somitic stages of mouse embryos was largely prevented in the presence of excess thymidine but only partially prevented by deoxycytidine.     

Somatic and germinal chimerism after the intracoelomic graft of quail splanchnic mesoderm to chick embryos]

The splanchnic mesoderm of the genital area can develop in coelomic graftings as soon as it is colonized by the primordial germ cells (stage 15 of H. and H.). Heterospecific associations between Chick and Quail embryos lead to the differentiation of gonads showing more or less pronounced somatic and germinal chimerisms.     

Ultrastructural response of the neural plate cells of chick embryos to dithiodiglycol

Résumé La neurulation a été inhibée chez des embryons de poulet par des traitements au dithiodiglycol (10^–3 M). L'analyse ultrastructurale révèle que seuls les microtubules subissent des modifications.     

Electron microscopic study of the penetration and distribution of somitic cells in the mesoblast of the limb buds of reptiles (Anguis fragilis and Lacerta viridis)]

Based on characteristics of mitochondria and on the amount of lipid inclusions, a distinction between somitic cells and mesoblastic somatopleural cells is possible, at the early stages of the development of the limb bud in Reptiles (Anguis fragilis and Lacerta viridis). The dislocation of the ventral processes of the somites and the localisation of the somitic cells in the mesoblast of the anterior limb buds could be studied.     

A contribution to the study of lens regeneration capacity in chick embryos

Zusammenfassung Die Linsenregeneration beim Hühnchen tritt nur auf, wenn die Embryonen am 3. oder 4. Bebrütungstage operiert worden sind. Wenn die Operation später stattfindet, tritt keine Regeneration auf.     

An experimental approach to pH measurement in the intercellular free space of higher plant tissues

Summary An experimental approach to the measurement of pH in the free space of plant tissues was made, using both metal minielectrodes and H⁺-sensitive resin glass microelectrodes inserted in small environments artificially created inside the tissue. Experiments were carried out on the parenchyma of higher plants (corn, potato, squash,Senecio herraianus), monitoring pH changes in the free space as a function of the pH of the external medium. The pH in the free space has been found to be different from that of the surrounding solution and its variation in time much slower than would be predicted by assuming that simple diffusion of H⁺ ions took place. The results agree with the hypothesis that the free space behaves as a compartment distinct from both the cytosol and the surrounding medium.     

Comparative study on the ultrastructure of the primary mammary bud of male and female embryos at the stage of sexual differentiation]

The observation of embryonic mammary glands in male and female mice under the electron microscope has shown on one hand that the cellular ultrastructure of the buds is characterized by embryonic tissue only slightly differentiated, and on the other that, under the influence of testicular hormone, the detachment of the anlage from the epidermis in fourteen-day old embryos results in an important modification in the relationship between the ectoderm and the mesenchyme at the level of the neck of the gland rudiment. The basal membrane is destroyed and numerous centers of necrosis can be seen starting from the dense bodies in the ectodermic cells of the ruptured zone.     

An histochemical study of the nerve supply to the developing alimentary tract

Riassunto I neuroblasti dei plessi intramurali del canale alimentare mostrano attività acetilcolinesterasica istochimicamente dimostrabile sin dalle prime fasi di differenziazione. Essi sono riconoscibili nei differenti tratti del canale secondo una successione cronologica sovrapponibile a quella di comparsa di fibre estriseche con identici caratteri istochimici. Le tappe di penetrazione di queste fibre sono differenti nel polio, a confronto con quanto si osserva nel ratto e nel coniglio.