bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of high temperature incubation upon the myocardial glycogen in the chick embryo
Authors: Delphia John M. , Elliott John
Published: April 2021

Glycogen accumulation in the myocardium during incubation at 40 ·0°C. has been investigated. Normal temperature incubation (37 · 5° C.) was used for the Control Group. Specimens in Experimental Group I were incubated at 40 ·0°C. during the 3rd through the 6th day of incubation while the specimens in Experimental Group II were incubated continuously at a temperature of 40 ·0°C. The Anthrone method of glycogen determination was employed. The glycogen from the heart was studied in three to thirteen embryos from the Control Group and each Experimental Group for each of the following days of incubation : 6, 8, 10, 11 and 12. The mean per cent, glycogen, standard error and standard deviation from the mean per cent glycogen was determined for each group studied on the days of incubation indicated above. The ‘t’ test for the comparison of two groups was applied. The following results were obtained : There was no significant difference in the per cent, myocardial glycogen in the embryos from the groups at 6 days incubation. The Experimental Group I showed a significant decrease (1 per cent, level of significance) in myocardial glycogen from the Control Group at 11 and 12 days incubation. The myocardial glycogen in Experimental Group II was significantly lower (1 per cent, level of significance) than that of Experimental Group I at 10 days incubation. The application of elevated temperature (40 ·0° C.) sufficient to cause visceral enlargement and coelosomia, whether it is applied during the 3rd through the 6th day of incubation or continuously in the incubation of the chick embryo, results in a significant decrease in the accumulation of myocardial glycogen.
Mesodermal alterations induced by hypervitaminosis A
Authors: Marin-Padilla Miguel
Published: April 2021

The administration of a single dose (20000 u) of vitamin A by gavage to the pregnant hamster is followed almost immediately by changes in the mesoderm of the embryos. These changes appear 6 h after the administration and after 10 h they have reached their maximum severity. The alterations appear first in the cephalic mesoderm, later in the axial non-segmented mesoderm of the body of the embryo and finally in the somitic mesoderm. They consist of shrinkage of the cell cytoplasm, enlargement of the intercellular spaces (fluid accumulation) and reduction of the mitotic rate of mesodermal cells. These alterations precede the cellular necrosis which appeared later in the somites and is considered a secondary change. An analysis of the embryogenesis of the vitamin A induced skeletal malformation based on the changes described is discussed.
Early changes in limb buds of chick embryos after thalidomide treatment
Authors: Jurand A.
Published: April 2021

Since the first observations of hypoplastic and aplastic thalidomide deformities in infants (McBride, 1961; Lenz, 1962), the literature on this subject has grown to many hundreds of communications. Experimental investigations in almost all cases have been undertaken to show whether thalidomide and its metabolites have any teratogenic effects in experimental animals. Numerous review papers are available on this subject, e.g. Giroud, Tuchmann-Duplessis & Mercier-Parot (1962), Somers (1963), and Salzgeber & Wolff (1964).
Les corps multivésiculaires de l’œuf de Barnea candida (Mollusque Bivalve) étudiés au microscope électronique
Authors: Pasteels par Jean J.
Published: April 2021

Multivesicular bodies of the egg o/Barnea candida studied with the electron microscope Fertilized eggs, stained for 5 min with 1/5000 neutral red solution, when examined an hour later (at the stage of the pronuclei) show all the stain con-centrated in vacuoles having a diameter from 4 to 5 μ, crowded around the pronuclei (cf. Pasteels & Mulnard, 1963). After examination with the electron microscope, it appears that these vacuoles are the result of an enlargement of the multivesicular bodies (m.v.b) deriving from the transformation of the yolk platelets. Acid phosphatase activity (after an incubation of 1 h) has been detected in e.m. sections; this activity appears selectively in very limited areas of some yolk platelets, on the m.v.b. and at the top of the cortical microvilli. These observations allow us to confirm the previous hypothesis of Pasteels & Mulnard (1963) : that the a meta-granules are some of the yolk platelets while the β meta-granules are the m.v.b. deriving from those platelets. The pictures of the accumulation of neutral red into the m.v.b. are identical with those which have been published by Robbins, Marcus & Gonatas (1964), who stained Hela cells with acridine orange under the same experimental conditions. The m.v.b. of the egg, although being a transitory phase of the transformation of the yolk, have thus the same properties as the m.v.b. of some non-embryonic cells. It might be concluded that the ‘vacuome’ of Parat (1928) is constituted by the m.v.b. The existence of an acid phosphatase activity on top of the cortical micro-villi permits one to presume that this activity is preliminary to an excretion of some substances from the egg into sea-water.
Les mouvements corticaux de l’œuf de Barnea candida (Mollusque Bivalve) étudiés au microscope électronique
Authors: Pasteels par Jean J.
Published: April 2021

Cortical movements in the egg o/Barnea candida (Mollusca, Lamellibranchiatd) studied with the electron microscope The crenulations of the egg-chorion (‘vitelline membrane’), previously described in Chaetopterus, have been observed occasionally in certain batches of Barnea’, they may be provoked with greater intensity by cold treatment. In both cases the electron microscope demonstrates that these undulating movements are the result of an elongation of the microvilli, occurring in suc-cessive waves. This elongation of the microvilli is autonomous and occurs independently of any undulation of the basal plasmalemma. The tips of the microvilli are firmly embedded in the dense peripheral layer of the chorion, which is, as a result, lifted up and folded by the elongation of the villi. In eggs which have been cold treated before the expulsion of the first polar body, this expulsion is considerably delayed; under these conditions the undula-tions of the chorion may be observed before and during the formation of the polar body, progressing from the animal towards the vegetative pole. Those undulations progressing towards the vegetative pole provoke a translation movement of the chorion which accumulates at the vegetative pole. Through this translation there occurs a tangential disrupture at the base of the microvilli; also, the microvilli-chorion complex is thus lifted from the basal plasmolemma resulting in an ‘elevation of the membrane’, a condition which is pathological for the species (Barnea and Chaetopterus) considered in the present work. The meaning of this cortical activity is discussed. It appears in correlation with physico-chemical changes affecting the entire surface of the egg immediately before the formation of furrows and furrow-like deformations (i.e. polar lobe). In all cases in which the formation of furrows is either abortive (monasters) or considerably delayed (cold shock), this cortical activity is enhanced.
Cell division and morphogenesis of Limnaea eggs after treatment with heat pulses at successive stages in early division cycles
Authors: Geilenkirchen W. L. M.
Published: April 2021

Cellular reproduction is related to a number of apparently independent processes of which the integrated results are bound to produce cell division. In eggs with determinate cleavage the results of division are daughter cells of a different prospective significance.
Developmental behaviour of fragments of symmetrical and asymmetrical imaginal discs of Drosophila melanogaster (Diptera)
Authors: Nöthiger Rolf , Schubiger Gerold
Published: April 2021

The developmental behaviour of imaginal discs of Drosophila melanogaster was investigated. The discs were medially halved and transplanted into 55 h old larval hosts to allow a sufficient time for cell proliferation. The different anlagen for the male first leg are asymmetrically distributed on the leg disc. Its median and lateral halves did not differentiate any structures of the complementary half even after intensive growth. The proliferation resulted only in an enlargement or duplication of the already present anlagen. In the symmetrical male genital disc certain anlagen could be eliminated by unilateral local irradiation with UV. This technique allowed the production of asymmetrical discs. After cutting, the non-irradiated half formed a complete and symmetrical genital apparatus. The irradiated half differentiated into a symmetrical apparatus which lacked, however, single elements on both sides. A schematic illustration is given. The results are interpreted to mean that the cell divisions initiated by the fragmentation of the disc always repeat the same state of determination. During a culture period of 3-4 days before metamorphosis a replacement of missing anlagen does not occur. The two terms ‘regeneration’ and ‘regulation’ are discussed with respect to imaginal discs. We have proposed the modified term ‘proliferative regulation’ to describe the special behaviour of imaginal disc fragments. This phenomenon consists of two processes : (1) an intensive cell proliferation whereby the state of determination is conserved; (2) a division of the overgrown blastema into areas of a fixed size (homonomous arealization).
A comparative study of the mechanisms by which X-irradiation and genetic mutation cause loss of vibrissae in embryo mice
Authors: Jacobson C. M.
Published: April 2021

Both X-irradiation and certain genetic mutations can produce loss of vibrissae in mice. The aim of this investigation was to determine whether disruption occurred at the same point in development and in the same manner. Histological investigation was made of vibrissae during early stages of development. It was found that two periods of epigenetic crisis exist in vibrissa develop-ment, one at the time of site determination and the other at the time of follicle-papilla interaction when development has just been initiated. Irradiation damage acts by disrupting this follicle-papilla interaction. If the contact is broken in the very early stage, the vibrissa will degenerate. If irradia-tion acts a little later, when the cells are less sensitive, the contact is not broken, and the vibrissa follicle cells will recover from the damage and continue to develop. In one mutation studied, the same interaction was destroyed because there was a genetic abnormality in the papilla. This produced the same ultimate effect as did irradiation. In other cases, the mutation acted on the first crisis, affecting the site determination. Here, although the apparent effect was the same as in irradiation, the mechanism differed.
Experimental studies on the role of ‘polar granules’ in the segregation of pole cells in Drosophila melanogaster
Authors: Jazdowska-Zagrodzińska Bożenna
Published: April 2021

When Drosophila eggs are centrifuged at 4250 g posteriorly, anteriorly and laterally, the highest mortality rate was found among the eggs centrifuged posteriorly (46 %) and the smallest among those centrifuged laterally (20 %). The pole plasm is not displaced by centrifugation at 4250 g. Polar granules begin to move when centrifuged at 2700 g for 30 min; complete removal of granules takes place at 4250 g for 10 min. When polar granules are removed from the pole plasm no pole cells are detached from the egg. Polar granules shifted from the pole plasm to other regions do not induce the detachment of any cells similar to pole cells. Both pole plasm and polar granules, in association, are indispensable for pole cell formation in Drosophila melanogaster.
A reinvestigation of some of the tissue movements involved in the formation of the neural tube and the eye/lens system of Triturus alpestris and Xenopus laevis
Authors: Lowery R. S.
Published: April 2021

A scheme of eye/lens development suggested by Chanturishvili is described and compared with the ‘classical’ scheme of Spemann. A cine-micrographic examination of the ectodermal movements involved in neural tube formation in Triturus alpestris and an experimental embryological investigation of the process in Xenopus laevis provided data consistent with the classical scheme and irreconcilable with Chanturishvili’s suggestion that the whole eye/lens system originates as a single continuous anlage within the flat neural plate of Amphibia.
Effects of temperature on reptilian and other cells
Authors: Stephenson N. G.
Published: April 2021

Reptilian cells, whether from adult organs or from entire embryos, may be cultured satisfactorily in Medium 199, to which is added 20 % foetal-calf serum. This medium, used at normal strength, is adequate even for the maintenance and proliferation of kidney and liver cells from an amphibian tadpole, but the performance of cells of lower vertebrates in the medium is inferior to that of mammalian and avian cells. When cultured for periods of at least 2 days, avian cells survive in an apparently normal fashion at higher temperatures (maximal, 45 °C) than reptilian; reptilian cells at higher temperatures than mammalian; and mammalian cells at higher temperatures than amphibian. There is a close correspondence between the lethal high temperatures of embryonic cells of diurnal lizards in culture (42-43 °C) and the known heatdeath temperatures of adult animals. Although inactive and contracted in culture at 3 °C, reptilian, avian and mammalian cells remain viable, often for prolonged periods without change of medium. The optimal temperature for cell culture is in the vicinity of 37·5 °C for reptilian, avian and mammalian cells, and about 31·5 °C for the amphibian cells used. Different types of cells from the same animal may have different temperature ranges. Epithelioid cells, for example, function better at higher temperatures than fibroblasts and in some cases may be shown to have a slightly higher maximal temperature. Dissociated epithelioid cells in culture may adopt a fibroblast-type of morphology, wandering on the glass surface with extended processes, or they may come together with other similar cells to form epithelial sheets. Fibroblasttype cells may contribute to monolayer formation, but do not join with epithelioid cells to form epithelial sheets.
Experimental evidence for the nuclear control of differentiation in Micrasterias
Authors: Selman G. G.
Published: April 2021

After individual cytoplasmic lobes of growing hemicells of Micrasterias were irradiated for 30 or 60 s with a microbeam of ultraviolet light 20 in diameter, the corresponding parts of the fully developed wings were stunted. Tn subsequent divisions the new hemicells were normal. In one case a hemicell, grossly malformed as a result of a 5 min dose of ultraviolet light to the cytoplasm, did not give a completely normal hemicell in the first seven divisions after treatment, although it did so in subsequent divisions. Abnormal development was induced with dinitrophenol. The ultraviolet microbeam irreversibly inactivated the nucleus when applied to it for longer than 5 s. Growth continued after nuclear inactivation but neither thickening of the cell walls nor differentiation took place. After applying the microbeam to the nucleus for 3-4 s, an anuclear type of development was followed by cell-wall thickening without differentiation. Subsequent divisions took place normally. After applying the microbeam to the nucleus for 2 s, partial differentiation took place and subsequent divisions were normal. By allowing hemicells to develop in the presence of actinomycin D at high concentrations for short periods, exactly the same patterns of abnormal development followed by cell recovery were observed as after ultraviolet irradiation of the nucleus. From the experiments, estimates were made of the times of nuclear determinations of lobe-splitting, cell-wall thickening and differentiation. Nuclear determination appeared to take place between 30 and 155 min before the developmental event was observed under the light microscope.
Thyroid growth and its relationship to metamorphosis in Rana temporaria
Authors: Fox Harold
Published: April 2021

Thyroid growth of larvae of Rana temporaria was investigated in relation to specific stages (29-54 inclusive; see Cambar & Marrot, 1954) and events in the metamorphic cycle. Growth is by cellular multiplication and vesicular enlargement, and from stage 41 (16 mm larva) to almost the end of metamorphosis cell volume is constant. Maximum rate of growth in vesicular, tissue and overall volumes occurs between stages 41 and 45 (16 and 28 mm) respectively.
The release of soluble H-2 alloantigens during disaggregation of mouse embryo tissue by a chelating agent
Authors: Edidin Michael
Published: April 2021

Treatment with chelating agents binding divalent cations has been found to effect the dissociation of a variety of tissues of both embryo and adult animals (reviewed in Steinberg, 1958). In the course of dissociation it appears that materials are released from cell surfaces which play a part in their specific adhesion, and which may be shown experimentally to promote selectively the re-aggregation of dissociated cells (Humphreys, 1963; Moscona, 1963). The extracted materials appear to be glycoprotein complexes (Humphreys, 1965), made up of fairly small subunits, estimated to be of 13000-20000 molecular weight (Margoliash et al. 1965). Units of about the same size appear to be the antigenic sites involved in the blocking of sponge cell aggregation by rabbit anti-sponge serum, specific for a given sponge species (MacLennan, 1963). I shall here present evidence that materials of similar molecular weight bearing immunological specificities of the H-2 alloantigen system are released from the tissues of certain mouse embryos during the course of their dissociation by the chelating agent Versene (ethylenediaminetetraacetic acid).
More about the. tabby mouse and about the Lyon hypothesis
Authors: Grüneberg Hans
Published: April 2021

The Lyon hypothesis (L.H.) of dosage compensation of sex-linked genes in mammals postulates that in the female, during embryonic development and at the cellular level, either the paternal or the maternal X-chromosome is inactivated; that this inactivation happens at random; and that it persists in the descendants of the cell in which it has taken place. The genetic evidence hitherto adduced as favouring the L.H. has mainly involved complex situations such as the simultaneous segregation of two sex-linked genes and/or the behaviour of genes in structurally abnormal chromosomes.

By contrast, this paper examines the behaviour of sex-linked genes in mammals (other than man) taken one at a time and in structurally normal X-chromosomes. Criteria are discussed by means of which the validity of the L.H. in such genetically simple situations can be tested. These tests reveal that the behaviour of heterozygotes for three sex-linked genes in the mouse (tabby, striated, brindled) is decisively at variance with the L.H., and the same is probably true for a fourth gene, bent-tail. The remaining sex-linked genes in the mouse give no evidence for or against the L.H. As there is thus clear evidence that in three, and probably in all four instances, both alleles are active as in ordinary autosomal heterozygotes, it is evident that in the mouse there is no inactivation of a whole Jf-chromosome. Indeed, the facts discussed in this paper (including those of one instance each in hamster, cattle and cat) do not suggest that there is any inactivation at all.

Nonetheless there is a suspicion that heterozygotes for sex-linked genes, taken as a group, may include more cases of semi-dominance than occur in autosomal heterozygotes. If this should be substantiated, it would require an explanation.
Limited axial structures in nodeless chick blastoderms
Authors: Butros Joseph
Published: April 2021

Definitive streak to head-fold blastoderms were given two lateral cuts parallel to the streak and a third transverse cut at 0·35 mm posterior to the pit, thus removing a rectangular piece around the node 0·8 × 0·35 mm in area. Upon explantation many of these U-blastoderms developed somites and neural tubes, but notochords were absent. Two types of controls were used: posterior segments of blastoderms produced by transection at 0·35 mm posterior to the pit, and lateral regions of blastoderms explanted from outside the central 0·8 mm zone. These controls did not develop true somites or neural tubes but did form ectodermal invaginations and mesodermal aggregations in the midline. The results are interpreted as manifestations of an increase in the amount of mesoderm and of the space available for morphogenetic movements.
Inductive influence of testosterone upon central sexual maturation in the rat
Authors: Smith W. N. Adams , Peng M. T.
Published: April 2021

The influence of testosterone propionate upon the central sexual maturation of the male rat has been investigated. Male rats castrated on the day of birth and injected with testosterone propionate at 5, 10 or 20 days of age had immature ovarian tissue transplanted to the anterior chamber of one eye when 3 months old. Ovarian grafts in castrate males injected with testosterone at 5 or 10 days of age did not show cyclical activity. Grafts in non-injected castrates or hosts injected with testosterone at 20 days of age showed cyclical activity. The site of action of testosterone is discussed, and it is suggested that it may have an inductive influence upon the sexual maturation of the rat brain.
Induction of the trophoblastic giant-cell transformation after ovariectomy in the mouse
Authors: Dickson A. D.
Published: April 2021

Mice were ovariectomized on the fourth day of gestation and the trophoblastic giant-cell transformation sought in blastocysts recovered from them after progesterone or corn oil had been injected or no treatment given. The giant-cell transformation does not occur in blastocysts of untreated mice. It does take place after progesterone but not after corn oil injection on the fourth day. The transformation does not occur after progesterone on the sixth, seventh and eighth days. Progesterone injection on the fourth day is associated with growth of the blastocyst as a whole and also of its inner cell mass.
A quantitative assessment of mesenchymal contribution to epithelial growth rate in mouse embryonic lung developing in vitro
Authors: Alescio Tommaso , Piperno Emilia Colombo
Published: April 2021

The growth rate of the epithelial tree of mouse embryonic lung cultured in vitro was studied after removal of the right or left part of the rudiment, or after modification of the epithelium/mesenchyme ratio to about one-half of the normal. The epithelial growth rate is enhanced in both experimental conditions well above that of the controls. No satisfactory explanation can be put forward, so far, for the fact that when the total mass of the rudiment is reduced without any change in the ratio of the tissues, the growth rate of the epithelium is enhanced. From the results of the experiments in which the ratio of the two tissues was experimentally changed the conclusion may be suggested that, under the reported conditions of growth in vitro, lung mesenchyme exerts some stimulating influence on the total growth of the epithelium, expressed as total amount of branching, and that this influence is to some extent proportional to the amount of mesenchyme as compared with epithelium.
Etude sur la différenciation in vitro de l’épithélium œsophagien embryonnaire de Souris. Action de la vitamine A et de l’hydrocortisone
Authors: Soriano Luis
Published: April 2021

A study of the differentiation in vitro of the mouse embryonic oesophageal epithelium. The effects of vitamin A and of hydrocortisone

Fragments of embryonic (18 days) oesophagus cultured in standard medium for 8 days achieved a minimum degree of keratinization. Appropriate doses of absolute alcohol administered over the same period enhanced normal keratinization. Vitamin A inhibited keratinization, and differentiation into multistratified epithelium or into a minimally keratinized epithelium took place. The effect of vitamin A depends upon the duration of its administration. Hydrocortisone in concentrations of between 1·1 μg/ml and 10 μg/cc inhibits keratinization in a similar way but with the difference that vacuolated and degenerating cells are found in some of the epithelial cultures. Low concentrations of hydrocortisone (0·5 μg/ml) stimulate keratinization after 9 days of culture. Vitamin A and hydrocortisone in combination appear to be toxic in some cases though they usually together inhibit keratinization in a manner similar to their separate effects. However, there is some evidence of synergistic activity. When explants are treated first with hydrocortisone (0·5 μ g/ml) and later with vitamin A (6·6 i.u./ml) they show predominantly the influence of the vitamin, i.e. inhibition of keratinization. When the reverse treatment occurs, i.e. vitamin A followed by hydrocortisone, most explants show full keratinization.

These results show that it is the last-acting of two opposing influences that is effective in controlling the differentiation of cultured mouse oesophageal epithelium.
Inducing activity in extracts from Xenopus embryos and from isolated dorsal lips
Authors: Deuchar E. M.
Published: April 2021

Tiedemann and his collaborators (Tiedemann, Becker & Tiedemann, 1961) have demonstrated both neural- and mesodermal-inducing activity in extracts from whole gastrulae and neurulae and from ventral gastrula ectoderm of Triturus alpestris. They have also obtained a wide range of inductions from subcellular fractions of 9-day chick embryos (Tiedemann, Kesslring, Becker & Tiedemann, 1962). Microsomal and ribosomal fractions were particularly active. A further finding was that the inducing activity of gastrula ectoderm could be enhanced by phenol treatment (see Tiedemann, 1963, for review). Latterly most of the work has been pursued with chick extracts, and no systematic study of the inducing ability of extracts from different embryonic stages of an amphibian has so far been reported.
Studies on the cell degeneration rate during the differentiation of the epithelium in the uterine cervix and Müllerian vagina of mouse
Authors: Forsberg John-Gunnar
Published: April 2021

Glücksmann (1951) has summarized the results of earlier investigations on cell degeneration processes during normal vertebrate development. To the few investigations on the degeneration in the urogenital region made before the publication of Glücksmann’s paper (1951) can be added Bengmark’s study (1958) on degeneration processes during the separation between the Wolffian duct and the ureteral anlage and Forsberg’s study (1961) on the mechanism of the division of the cloaca. Finally, Forsberg (1963) has given a description of those regions where degeneration can be seen during the development of the vaginal anlage in several species, including man.
Effects of position in the uterus on fetal mortality and on response to trypan blue
Authors: Beck Sidney L.
Published: April 2021

In three strains of mice and an outcross of each to ZRDCT-An, the fetuses occupying the implantation site nearest the common uterus are less likely to survive than the ones nearest the ovary. When dams are treated with trypan blue, mortality in excess of the spontaneous frequency seems greater in the ovarian than in the cervical position. Both the heterogeneity of distribution of spontaneous mortality and the suggestion of treatment-position interaction show the importance of intra-uterine selection upon survival of a developing organism. None of the data are inconsistent with the hypothesis that one mechanism of selection is through variations in blood supply in different regions of the uterus.
Regeneration and growth control inNereis
Authors: Golding D. W.
Published: April 2021

The annelid body, as typified by that of Nereis, consists of a presegmental prostomium, a number of segments, and a postsegmental pygidium. The larval trochosphere is unsegmented. Once proliferation of segments has started, their number increases steadily throughout most of the life of the adrenal, though the rate of proliferation declines (Clark & Clark, 1962). New segments are added posteriorly by proliferation and differentiation of tissue comprising the growth zone, which forms the anterior border of the pygidium. After loss of the pygidium and posterior segments, wound healing is followed by the formation of a new growth zone. Amoebocyte migration (Stephan-Dubois, 1955,1956,1958) and dedifferentiation of cells adjacent to the level of transection (Herlant-Meewis & Nokin, 1962) are important in the early stages of regeneration. Proliferation of segments recommences and they are produced more rapidly than they are in the intact animal, as will be shown later.
Studies on pattern regulation in Hydra
Authors: Webster Gerald
Published: April 2021

The effect of colcemide and puromycin on polarity and regulation in hydra has been investigated at the biological level using isolation and transplantation techniques. Colcemide treatment of hydra from which the hypostome has been removed can bring about an alteration of polarity so that multiple distal structures (hypostome and tentacles) can form on a single animal. Such forms do not arise if the original hypostome is not removed. Treatment with puromycin is much less effective in altering polarity. Transplantation experiments indicate that hypostome formation is inhibited by colcemide treatment but that this substance does not irreversibly affect the determined hypostome or the ‘adult’ hypostome which retain their organizing properties. Puromycin treatment does not inhibit hypostome formation completely since some animals reconstitute tentacles while in puromycin. However, the hypostome which is formed does not possess the normal resistance to absorption following transplantation. This result may indicate that the factors responsible for the organizing properties of the hypostome (i.e. tentacle induction) are distinct from those which control resistance to absorption. Both colcemide and puromycin change certain important properties of the subhypostomal region to those characteristic of more proximal regions. These properties are believed to ‘control’ polarity. The effects of colcemide and puromycin on polarity and regulation are discussed in terms of their effects on a control system which has been previously postulated to account for polarised regulation in hydra. This system involves axial gradients in time for hypostome determination, inhibition of hypostome formation and threshold for inhibition. The experimental results can be explained as a consequence of the direct or indirect action of these substances on the axial gradients.
Etude cytologique des premiers stades du développement de quelques hybrides létaux d’Amphibiens Urodèles
Authors: Ferrier Par Vincent
Published: April 2021

A cytological study of the first stages of development of some lethal hybrids of urodele amphibians
The correlation of the processes of proliferation and determination in the morphogenesis of iris and ciliary body in rats
Authors: Stroeva O. G.
Published: April 2021

In spite of the fact that causal embryology dealt extensively with the development of the eye in vertebrates, the iris attracted the attention of investigators only as a source of lens restitution in the course of Wolffian regeneration (Reyer, 1954, 1962; Goss, 1965; Scheib, 1965; Yamada, 1966). This is shown by the absence of sections on iris development in recent reviews devoted to the experimental analysis of eye development (Twitty, 1955; Lopashov & Stroeva, 1961 ; Coulombre, 1961, 1965a, b). The present communication reports a study of the development of the neural layers of iris and ciliary body in rat embryos.
Premeiosis and premeiotic DNA synthesis in the left ovary of the female chick embryo
Authors: Callebaut M.
Published: April 2021

Cytological changes occurring during premeiosis in the germ cells of the ovarian cortex of the chick embryo were studied by means of Feulgen staining (specific for DNA).

The evolution of the preleptotene stages of the germ cells after 3H-thymidine pulses was investigated by the combination of pre- and post-autoradiographic observations and photographs.

The germ cells in premeiotic S phase present a particular structure, different from the structure found in germ cells during premitotic S phase. They are the direct precursors of the meiocytes in leptotene stage.
Restauration de la régénération de membres irradiés d’Axolotl par des greffes hétérotopiques d’origines diverses
Authors: Lazard Par L.
Published: April 2021

Un membre d’Urodèle, irradié à une dose convenable de rayons X, ne régénère plus spontanément (Butler, 1931, 1933; Umanski, 1937; Butler & Puckett, 1940; Brunst, 1944). Toutefois, la régénération des membres irradiés peut à nouveau être obtenue, si on transplante dans le membre irradié des tissus frais. Si les tissus transplantés proviennent d’un autre membre non irradié, le régénérât est un membre (Trampusch, 1951, 1958; Polejaev, 1959; Stinson, 1960, 1963, 1964 a, b et c). Dans ce cas, la peau semble constituer le matériel le plus favorable à la restauration de la régénération. Si les tissus transplantés proviennent d’un autre territoire de régénération, tels que la crête ou la queue, l’appendice qui se développe reconstitue de façon plus ou moins parfaite l’organe dans lequel le transplant a été prélevé (Efimow, 1933, 1943; Liosner & Worontsowa, 1936, 1937; Glade, 1957, 1963; Lazard, 1959a). La morphogenèse du régénérât ainsi obtenu est plus ou moins accomplie selon la qualité des tissus implantés, peau ou éléments squelettiques musculaires, cartilagineux ou osseux.
Marquage nucléaire par la thymidine tritiée des dérivés de la crête neurale chez l’Amphibien Urodèle Pleurodeles waltlii Michah
Authors: Chibon Par P.
Published: April 2021

Nuclear labelling by tritiated thymidine of neural crest derivatives in the amphibian Pleurodeles waltlii

Nuclear labelling of the neural crest by 3H-thymidine was used to trace the migration of neural crest cells, and to study the total range of their derivatives. The main findings are:

The posterior part of the neurocranium is partially derived from the cephalic neural crest. In the teeth, only the dental papilla cells and the odontoblasts are derived from the cephalic crest, but they control the formation of the adamantin organ. Cranial ganglia do not arise from the cephalic crest, but from ectodermal placodes. The anterior part of the brain and the olfactory epithelium are derived from the cephalic crest. The trunk crest is absolutely unable to produce cartilage. Schwann cells first arise from the neural crest, and later from the neural tube. Sympathetic ganglia and chromaffin cells are derived from the crest. Spinal ganglia, Rohon-Beard cells, pigment cells, mesenchyme, and part of the meninges originate from the neural crest.
Analyse des facteurs de la différenciation spécifique de la plume néoptile chez le Canard et le Poulet
Authors: Dhouailly Par Danielle
Published: April 2021

An analysis of the factors in the differentiation of the neoptile feathers of chicken and duck

In the spinal pteryla, the neoptile feather (prepenna) of the chicken differs from that of the duckling by its umbelliform structure, by having few barbs (11 to 14), by its nodose barbules, and by the almost total absence of spines. The prepenna of the duckling is characterized by its well-developed rachis, its numerous barbs (14 to 30), whose barbules are adorned with a double row of spiny barbicels. The xenoplastic association of dermis and epidermis of 7-to 8-day chick embryo and 8- to 9-day duck embryo results, after 11 days on the chorioallantoic membrane, in the formation of chimaeric feathers, the general macroscopic morphology of which is in conformity with the specific origin of the dermis. The xenoplastic skin expiants containing duck dermis and chick epidermis develop feathers with a large number of barbs (17 to 21) and a duck-type rachis; the ones that contain chick dermis and duck epidermis grow umbelliform chicktype feathers with a small number of barbs (11 to 14). The fine structure of the barbules of these chimaerical feathers always differentiates according to the specific origin of the epidermis, as regards the number, distribution and shape of the spiny barbicels.
Rôle du tapetum dans la différenciation de la sclérotique chez l’embryon de poulet
Authors: Reinbold Par Rene
Published: April 2021

On sait que la sclérotique apparaît chez l’embryon de poulet après 7 jours d’incubation sous forme d’une enveloppe de cartilage. Elle se différencie autour de la cupule optique constituée elle-même par le double feuillet de la rétine (feuillet interne, nerveux, ou rétine proprement dite et feuillet externe pigmenté, ou tapetum). Entre le tapetum et la sclérotique apparaît l’ébauche de la choroïde.
Etude au microscope électronique de l'évolution des structures embryonnaires de Planaires après irradiation aux rayons x
Authors: Moigne Par A. Le
Published: April 2021

A la suite d'études sur le développement des embryons de Polycelis nigra, après irradiation aux rayons X, j'ai pu constater deux séries de faits (Le Moigne, 1966).

Les embryons jeunes sont détruits même par de faibles doses de rayons X (1.000 r); mais à partir d'un stade donné (stade 4), ils résistent, même à des doses plus fortes de rayonnement (3.000 r), continuent à se différencier et peuvent éclore.

Les embryons qui se sont ainsi développés, après l'irradiation, ne régénèrent pas si on les sectionne Ils peuvent cicatriser mais ne forment pas de blastème, alors que les témoins normaux de même âge régénerènt toujours. J'étudierai ici l'ultrastructure des tissus d'embryons irradiés, pour déterminer quelles sont les cellules détruites par les rayons X, et comment des irradiations précoces pendant l'embryogenèse peuvent empêcher la régénération à l'éclosion. Je rappellerai auparavant les caractéristiquesde chaque stade étudié (Le Moigne, 1966, 1967b):

Stade 4A: Ebauche du pharynx transitoire. Pharynx embryonnaire toujours visible.
Muscle proteins in the chick myotome examined by the immunofluorescent method
Authors: Ikeda Akira , Abbott Rana L. , Langman Jan
Published: April 2021

This work was undertaken to examine by the immunofluorescent antibody technique at which stage of development of the chick embryo the first muscle proteins are formed. In addition the spatial interrelationship of presumptive myoblasts, myoblasts and myotubes was studied. Chick embryos ranging in age from 52 h to 5 days were fixed in Carnoy and transverse sections cut at 3 – 4 μ .The indirect fluorescent method (sandwich technique) was applied using fluor-scent goat gamma-globulin and myosin antiserum.

When the specificity of the myosin antiserum was tested by the immuno-electrophoretic technique, antibodies against myosin as well as against actin, adenylic acid deaminase and some other fractions were detected. Consequently, the fluorescent reactions found in the embryo do not specifically indicate the prescence of myosin, but rather that of muscle proteins. The first fluorescent reaction over the myotome was found at stages 17–18, and was restricted to a few cells on the lateral side of the central myotome region. From here the reaction spread rapidly to other cells on the lateral side in a ventral and dorsal direction. Simultaneously with the increase in thickness of the myotome, the fluorescent reaction spread in a medial direction. The cells of the myotome, particularly those in the most dorsal portion, did not begin to show fluorescense until the adjacent dermatome cells had lost their epithelial structure. At stages 24 – 26 the lateral side of the myotome is formed by myotubes with fluorescent myofibrils. In a medial direction are found subsequently heavily fluorescent spindle cells, either in bundles or as individual cells, which in turn are followed by irregular cells either slightly or not at all fluorescent. The latter cells sometimes showed DNA synthesis. Hence, the differentiation from presumptive myoblast to myoblast and from myoblast to myotube proceeds from lateral to medial.
Relationship of epithelial growth to mitotic rate in mouse embryonic lung developing in vitro
Authors: Alescio T. , Michele M. DI
Published: April 2021

The rate of cell division was studied as a function of over-all growth of the epithelial tree of the 11-day mouse embryonic lung developing in vitro, under conditions of: (1) normal growth in vitro of intact rudiments; (2) mass reduction; (3) increase of the relative amount of mesenchyme. The over-all rate of epithelial growth under experimental situations (2) and (3) is significantly higher than that of intact rudiments. The epithelial cell proliferation rate is highly correlated with the over-all size of epithelial growth in all cases. It was concluded that the over-all growth and budding activity of the epithelial tree depends on cell division. Reduction in mass and an increased amount of mesenchyme increase the rate of epithelial growth by stimulating the mitotic activity of the epithelial cells.
The development of bovine syndactylism
Authors: Grüneberg Hans , Huston Keith
Published: April 2021

In homozygous condition, the gene for syndactylism (symbol sy) in Holstein-Friesian cattle has a variable manifestation. Affected limbs typically have a single digit with a single hoof. This happens more often on the fore than on the hind limbs, and some sy/sy animals show no syndactylism at all. Whereas normally the blastemata for digits III and IV at first diverge widely from each other, those of sy/sy embryos arise close to and approximately parallel to each other and have a tendency to coalesce distally. If coalescence is complete, a single but rather massive digit is formed; incomplete fusion may give rise to limbs with incomplete syndactylism, and if coalescence fails to happen the digits remain separate and have separate hooves. The limb buds of sy/sy embryos are thicker but correspondingly narrower from side to side, and it is probable (but not certain) that the atypical shape of the limb buds is the cause of the close juxtaposition in which the digital blastemata are laid down in the first instance.
Fine structure and early fertilization changes of the animal pole in eggs of the river lamprey, Lampetra fluviatilis
Authors: Nicander Lennart , Afzelius Björn A. , Sjödén Inger
Published: April 2021

Fertilization is accompanied by changes in the structure of the egg cytoplasm (cf. Rothschild, 1958; Raven, 1961). At the level of fine structure such changes have mainly been studied in some marine invertebrates with small eggs that can easily be fertilized in vitro (Pasteels & de Harven, 1963; Schäfer, 1966). Vertebrate eggs are less favourable in this respect, but electron microscope studies have been made on eggs of mammals (Fléchon, 1966; Zamboni & Mastroianni, 1966; Zamboni, Mishell, Bell & Baca, 1966) and Xenopus (van Gansen, 1966). Changes generally observed soon after fertilization include the formation of polysomes or an increase in their number, a hyper-trophy of the Golgi complexes, and the appearance of granulated endoplasmic reticulum and annulate lamellae. Afzelius (1957) observed the dispersal of mito-chondria in fertilized sea-urchin eggs. Pasteels & de Harven (1963) reported that the structure and distribution of cytoplasmic organelles in eggs of the bivalve mollusc, Barnea candida, are not altered by fertilization. The structural changes produced by fertilization in the small, telolecithal eggs of lampreys were re-peatedly studied during the late nineteenth century (cf. Herfort, 1901) and later by Kille (1960). Vivid cortical activity and complicated cytoplasmic movements were observed at the animal pole. Electron-microscope studies of lamprey eggs have apparently been restricted to the yolk platelets (Karasaki, 1967). During a study of sperm penetration in lampreys, the eggs were found to be very favourable for electron microscopy, and some observations of early changes in the thin layer of pole plasm will be reported below. The structure of the egg envelopes, the emptying of cortical vacuoles, and sperm penetration are des-cribed in separate papers (Afzelius, Nicander & Sjödén, 1968; Nicander & Sjödén, 1968).
Abnormalities in bone and cartilage development in the talpid3 mutant of the fowl
Authors: Hinchliffe J. R. , Ede D. A.
Published: April 2021

The complex pleiotropic pattern of damage caused in chick embryos by the talpid3 gene has been described previously by Ede & Kelly (1964b, b) and Hinchliffe & Ede (1967). The pattern of segregation of the mesenchyme in forming the precartilaginous or membranous skeleton is abnormal, and the resulting cartilaginous skeleton shows characteristic fusions of the vertebrae and of the limb elements. By 11 days of development there is a complete failure of cartilage-replacement bone to appear, even in the more normally formed cartilage rudiments (e.g. ribs, scapula, coracoid, ilium). By contrast, ossification to give the membrane bones (the clavicle and bones of the skull and jaws), which are formed directly from condensations in the mesenchyme, proceeds normally. This paper describes the attempts made by experimental and histochemical means to account for the failure of cartilage-replacement bone formation.
Development of embryonic rat eyes in organ culture
Authors: Armstrong R. Christy , Elias Joel J.
Published: April 2021

Previous studies on the differentiation of whole embryonic eyes in culture have been carried out mainly in the chick (Strangeways & Fell, 1926; Dorris, 1938; Harrison & Berry, 1959) and in one case in the rat (Tansley, 1933). Early post-natal intact eyes of rats and mice were cultured by Lucas & Trowell (1958), while more recently intact and trypsinized early eye rudiments (9 and 10 days) of mouse embryos have been grown in various modified organ culture systems (Muthukkaruppan, 1965). In all these experiments the media employed were either entirely biological or chemically defined media supplemented with biolo-gical media. Also, with the exception of the work done by Muthukkaruppan (1965), eye differentiation was well advanced at the start of the culture period.
The evolution of vertebrate gastrulation
Authors: De Robertis E. M. , Fainsod A. , Gont L. K. , Steinbeisser H.
Published: April 2021

The availability of molecular markers now permits the analysis of the common elements of vertebrate gastrulation. While gastrulation appears to be very diverse in the verte brates, by analyzing a head-organizer marker, goosecoid, and a marker common to all forming mesoderm, Brachyury, we attempt to identify homologous structures and equivalent stages in Xenopus, zebrafish, chick and mouse gastrulation. Using a tail-organizer marker, Xnot-2, we also discuss how the late stages of gastrulation lead to the formation of the postanal tail, a structure characteris tic of the chordates.