bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hormone control in regeneration:effects of somatostatin on appendage regeneration,blood glucose and liver glycogen in Diemictylus viridescens
Authors: Vethamany-Globus S. , Globus M. , Hartford J. A. , Fraser I. , Weber D. 
Published: April 2021

ABSTRACT
In the present communication, synthetic somatostatin, a hypothalamic factor which has a known inhibitory effect on the release of growth hormone, thyroid-stimulating hormone, prolactin, insulin and glucagon in man and other mammals, was found to have an inhibitory effect on limb and tail regeneration in adult Diemictylus viridescens, when the newts were treated with a daily dose of 3·5 or 15 μg/animal for a period of 34 days post-amputation. At the higher dose, the animals exhibited total inhibition of appendage regeneration in a few cases and the remainder showed a considerable delay compared to the controls; none of the experimental animals reached the advanced four-digit stage achieved by the controls. Furthermore, the blood glucose and liver glycogen values in the somatostatin-treated animals were significantly lower than the control values. Mechanisms in the storage, mobilization and utilization of glucose (involving hormones) are discussed in relation to appendage regeneration in the newt and possible controls of regeneration at the level of the hypothalamus are suggested.
Retinal growth in double dorsal and double ventral eyes in Xenopus
Authors: Straznicky K. , Tay D. 
Published: April 2021

ABSTRACT
The growth of normal and surgically produced compound dorsal and ventral retinae in Xenopus laevis has been studied autoradiographically following injections of [3H]thymidine at stages 50 and 58. The animals were sacrificed 3 weeks after metamorphosis. The histogenetic pattern of the dorsal and ventral retinal halves was different at the three time points investigated, i.e. up to stage 50, between stages 50 and 58 and between stage 58 and 3 weeks after metamorphosis. Asymmetrical dorsal retinal growth occurred up to stage 50. From stage 50 onwards the retinal growth tendency reversed so that more ganglion cells were produced along the ventral than the dorsal ciliary margins. The overall preponderance of ventral retinal growth was 32·4% in cell number and 12·4% in retinal length from early embryogenesis to 3 weeks after metamorphosis. The characteristic histogenetic pattern of the dorsal and ventral retinal halves was maintained in an ectopic position in the compound eye, indicating that this particular property of the retinal halves is intrinsically determined.
Variation in Habrobracon juglandis ovariole number: I. Ovariole number increase induced by extended cold shock of fourth-instar larvae
Authors: Grosch Daniel S. , Kratsas Robert G. , Petters Robert M. 
Published: April 2021

ABSTRACT
Variation from zero to five ovarioles in the braconid wasp, Habrobracon juglandis, is reported for dissections of females from laboratory stocks. Four ovarioles (two per ovary) is the standard phenotype for the species. Storage of fourth-instar larvae in a refrigerator resulted in a large proportion of females with an increased number of ovarioles (5–11). A
1-to 2-week cold exposure during the period of ovarian differentiation is required for the maximum effect.
Weight differences in rat embryos prior to sexual differentiation
Authors: Scott William J. , Holson Joseph F. 
Published: April 2021

ABSTRACT
Sex of day-.12 rat embryos was determined using Barr body counts made on spreads of amniotic membranes examined histologically. Embryonic weight, protein content and rate of thymidine incorporation were compared in male and female embryos. Male embryos were found to be heavier and accordingly to contain more protein on absolute but not on per unit weight basis. The rate of thymidine incorporation did not differ in the two sexes. Since gonadogenesis in day-12 rat embryos is rudimentary, with gonadal differentiation of sex not yet apparent, the increased weight suggests that sex-linked genes exist which influence body growth prior to gonadal endocrine activity.
Viability and metabolic activity of homozygous Brachyury (T) embryos
Authors: Yanagisawa K. O. , Fujimoto H. 
Published: April 2021

ABSTRACT
Some features of metabolic activity of homozygous mutants for the Brachyury (T) mutation were studied. The embryos incorporated tritium-labelled thymidine up to about the ‘32-36 somite’ stage. The total amount of protein per embryo increased until the same stage. T/T cells proved viable in vitro over the in utero lethal period. Several cell lines were established from +/+ and T/T embryonic cells.
The effects of thalidomide and two analogues on the regenerating forelimb of the newt
Authors: Bazzoli Allan S. , Manson Jeanne , Scott William J. , Wilson James G. 
Published: April 2021

ABSTRACT
Oral administration (3 mg/day) of thalidomide during the dedifferentiation and early limb-bud stages of newt forelimb regeneration produced a variety of specific limb deformities. Proximal and preaxial skeletal elements were the most severely malformed, e.g., preaxial hemimelia, severe proximal deformities, and preaxial polydactyly.
Likewise, oral, daily doses (3 mg) of the teratogenic analogue, EM12, on days 7 and 8 following bilateral amputation caused the same incidence and type of forelimb abnormalities as did thalidomide. Conversely, the non-teratogenic analogue, EM87, when orally administered (3 mg/day) on days 7 and 8 post-amputation resulted in a low rate of limb deformities, similar in type to those seen in control regenerates.
The type of limb deformities observed in the regenerating newt forelimb following thalidomide treatment nearly mimic those seen in the human and monkey syndromes. Therefore, the newt represents a possible model for investigating some of the problems associated with thalidomide teratogenesis.
Cytological and cytochemical studies of the necrotic area of the bulbus of the chick embryo heart: phagocytosis by developing myocardial cells
Authors: Hurle J. M. , Lafarga M. , Ojeda J. L. 
Published: April 2021

ABSTRACTThe muscular wall of the bulbus cordis of the chick embryo was studied by electron microscopy during H. H. stages 27–31. Results show that the muscle cells of the bulbus undergo necrosis during these stages. The morphology of dead cells in this area is similar to that described in other embryonic myogenic tissues. Although dead myocytes appear acid-phosphatase-negative, lysosomes may well be involved in this necrotic process as there is a significant number of cells with autolytic lesions among the neighbouring healthy muscle cells. The phagocytosis of the cell detritus resulting from the degenerative process appears to be carried out by neighbouring myocytes and by macrophages. The significance of these results is discussed both from the cytological and from the morphogenetic point of view.
Tooth development in the ‘crooked’ mouse
Authors: Sofaer J. A. 
Published: April 2021

ABSTRACTThe semidominant gene ‘crooked’ (Cd) in the mouse produces anomalies of the axial skeleton (resulting in a crooked tail), microphthalmia and dental abnormalities, including small molars with simplified cusp patterns that are equivalent to patterns passed through during normal morphodifferentiation. A series of embryonic litters from Cd/+×Cd/+ matings was used to investigate the embryological basis for the dental abnormalities. Micro-phthalmic embryos were classed as Cd/Cd, and their most normal litter mates were selected as controls (+ /+ or Cd/+). An additional set of control embryos came from the inbred strain CBA/Cam (+/ + ). Serial sagittal sections of the heads of these embryos were examined microscopically, and the maximum anteroposterior diameters of the developing upper and lower first molars were measured. Reduction in the rates of growth and morphodifferentiation of Cd/Cd first molars, relative to those of litter mate controls, was associated with the appearance of an adjacent abnormal proliferation of the dental lamina. Some proliferations in older embryos showed signs of early tooth germ formation, but many were seen to have regressed and no examples of supernumerary teeth have been found in Cd/Cd adults. Small size of Cd/Cd molars may therefore result from competitive inhibition of molar growth by a transient abnormal laminal proliferation, and Cd/Cd cusp patterns from the relatively premature onset of hard tissue formation during normal but retarded sequences of morphodifferentiation.
Changes of organelles associated with the differentiation of epidermal melanocytes in the mouse
Authors: Hirobe Tomohisa , Takeuchi Takuji 
Published: April 2021

ABSTRACT
Electron microscopic observations on normally differentiating and a-MSH (melanocytestimulating hormone)-treated epidermal melanocytes of newborn mouse skin were carried out. The process of melanocyte differentiation from premelanosome-containing melanoblasts was investigated in detail with respect to melanosomes as markers.
Melanoblasts containing unmelanized premelanosomes gradually decreased in number after birth, while the number of melanocytes rapidly increased. The epidermis of a-MSH-treated 3-day-old mice and normal 6-day-old mice contained melanocytes with numerous fully melanized melanosomes, and with no or only a few melanoblasts.
Changes in other organelles in differentiating melanocytes were also noticeable. Golgi apparatus and RER (rough endoplasmic reticulum) decreased in number during the normal or a-MSH-induced differentiation of the epidermal melanocytes, though the number of mitochondria showed no notable change. The number of SER (smooth endoplasmic reticulum) per cell did not change in the cells of newborn mice, while in a-MSH-treated cells the number increased significantly. These results led us to an assumption that Golgi apparatus or RER transforms into other forms of organelles including melanosomes and SER during the differentiation of melanocytes.
Le développement de l’appareil uro-génital après la greffe hétérotopique du mésoblaste latéral chez la neurula du crapaud commun Bufo bufo L. (Amphibien Anoure)
Authors: Gipouloux J.-D. , Hakim J. 
Published: April 2021

ABSTRACT

The development of urogenital organs after lateral mesoblast heterotopic graft in the toad (Bufo bufo) neurula

I.
Distinct inversions of anteroposterior and dorsoventral axis of the lateral plate
Anteroposterior inversion of lateral mesoblast of early toad neurula is followed by differentiation of diverse urogenital blastema, according to the transplant position before the graft. Anteroposterior polarity of lateral mesoderm is thus perfectly determined in young neurula. On the contrary, dorsoventral inversion of lateral mesoblast leads to mesodermic blastema formation according to the transplant position after the graft. Particularly, the dorsal region of the lateral plates displaced to ventral position does not form blastema. On the other hand, the ventral region which shows a dorsal position after the graft develops and produces a typical blastema. Thus, in the young neurula, the dorsoventral polarity is not yet determined in the lateral plate of the mesoblast. Such a result shows also that the ventral and posterior regions of the lateral mesoblast are competent to form blastema. Moreover, factors from dorsal origin and external to lateral mesoblast take part in urogenital organ anlagen formation.
Le devéloppement de l’appareil urogénital après la greffe hétérotopique du mésoblaste latéral chez la neurula du crapaud commun Bufo bufo L. (Amphibien Anoure): IL Inversion simultanée des axes antéro-postérieur et dorso-ventral de la lame latérale
Authors: Hakim Par J. , Gipouloux J.-D. 
Published: April 2021

ABSTRACT

The development of urogenital organs after lateral mesoblast heterotopic graft in the toad (Bufo bufo) neurula. II. Simultaneous inversion of anteroposterior and dorsoventral axis of the lateral plate
Simultaneous inversion of the anteroposterior and dorsoventral axes of the lateral meso-blast in the early toad neurula leads to the total agenesis of the urogenital organs. The experimental results show that the lateral mesoblast is unable to undergo self-differentiation, and that three factors at least are required for the formation of the urogenital blastemata.
The mesoblast must be competent: only the posterior (dorsal, but also ventral) part of the lateral mesoderm is endowed with this competence. It must receive two stimulating influences, from the cordomesoblast on the one hand, and from the dorsocaudal endoblast on the other hand.
Permissive and directive interactions in lens induction
Authors: Karkinen-Jääskeläinen Marketta 
Published: April 2021

ABSTRACTThe interactive events leading to lens formation and the developmental potentialities of the presumptive lens ectoderm were examined in vitro. The presumptive lens ectoderm of both mouse and chick embryos was capable of forming a lens even when isolated from the optic vesicle before the two tissues reach the stage of close association. This lens-forming bias can be released with favourable culture conditions and by various heterotypic mesenchymes. The same permissive, unspecific conditions or heterotypic tissues failed to trigger lens formation in trunk ectoderm. The directive effect of the optic vesicle was demonstrated in experiments where it was grown in contact with the trunk ectoderm. The latter developed distinct lentoid bodies synthesizing lens proteins. The origin of the lentoid was confirmed in interspecies combination of chick and quail tissues. It is concluded that lens formation is governed by a series of interactive events consisting of both directive and permissive influences.
Tissue specificity for incorporation of [3H]thymidine by the 10- to 12-somite mouse embryo: alteration by acute exposure to hydroxyurea
Authors: Miller Sue Ann , Runner Meredith N. 
Published: April 2021

ABSTRACT
Radioautograms from 10- to 12-somite mouse embryos labeled for 30 min in vitro with [3H]thymidine were examined for frequency and intensity of incorporation. Results from ten tissues showed that values ranged from 82% of nuclei with a mean of 16·6 grains for visceral yolk sac to .17% of nuclei labeled with a mean of 4·4 grains for epithelium of the anterior gut tube. Labeling in the ten tissues indicated (1) a tissue-specific spectrum of incorporation of [3H]thymidine, (2) close correlation between frequency and intensity of labeling within a tissue and (3) asymmetrical quantities of incorporation between right and left somatopleure.
Treatment with hydroxyurea in vitro reduced the frequency of labeled nuclei by 85% to 12 % of control values. Mean numbers of grains over treated nuclei, 3·3–4·6 grains, were well above background but were clustered below the low end of the control range. Tissues exposed to hydroxyurea showed (1) labeling of significant numbers of nuclei, (2) inhibition of labeling in selected tissues and (3) equalization of bilateral asymmetry in quantity (frequency and intensity) of incorporation in somatopleure. The selective reduction of thymidine incorporation and equalization of asymmetrical rates of proliferation may constitute mechanisms by which hydroxyurea causes abnormal morphogenesis.
Developmental analysis of the tumorous head mutation in Drosophila melanogaster
Authors: Bournias-Vardiabasis N. , Bownes M. 
Published: April 2021

ABSTRACT
The extent and type of adult transformations in the tumorous head (tuh) mutation of Drosophila melanogaster were studied. The observations indicate homeotic transformations, duplications and deficiencies of eye antennal disc derivatives. Contrary to previous observations there is no transformation of eye to abdomen and the only homeotic transformations identifiable are antenna to leg and rostralhaut to genitalia. Embryonic and post-embryonic lethality was also examined. Specific anterior abnormalities were found in embryos leading to early death. The amount of embryonic lethality was not affected by increased temperature during oogenesis. When analysing the adult phenotype, however, the whole period of oogenesis was sensitive to pulses of increased temperature; the pulses however did not have to be restricted to any particular stage of oogenesis to be effective in increasing tuh penetrance. The increase in the penetrance of the adult transformations is also exhibited when eggs are moved from 25 °C to 29 °C from the 8th to the 12th hour of embryonic development. Experiments indicate that the tuh-3 gene is active before the 8th hour of embryogenesis.
A comparative study of spermiogenesis in wild-type and T:t-bearing mice
Authors: Hillman Nina , Nadijcka Mary 
Published: April 2021

ABSTRACT
The results of a comparative ultrastructural study of spermiogenesis in T/tx, + /tx, +/T, C57BL/6J, BALB/c and randomly breeding Swiss Albino mice are reported. The observations show that aberrant spermiogenesis occurs in males of all strains and genotypes and that the same specific types of abnormal spermatids are found in all of the males examined. No unique morphological defect which could be correlated with the increased transmission frequency of tx-bearing gametes can be found in males heterozygous for the tx allele.
The effects of high hydrostatic pressure on microfilaments and microtubules in Xenopus laevis
Authors: Messier Paul-Emil , Seguin C. 
Published: April 2021

ABSTRACT
Xenopus laevis embryos of stages 14–20 were subjected, for periods of 5–330 min, to hydrostatic pressures ranging from 500 to 10000 psi. The specimens were fixed under corresponding pressures and their neuroepithelium was studied under light and electron microscopy. A pressure of 3000 psi, maintained for as long as 180 min, did not inhibit neurulation though it induced slight deformities of the neuroepithelium. A pressure of 4000 psi, applied for 180 min, disrupted the apical ring of microfilaments and blocked neurulation. The cells lost their dissymmetry. The effect was reversible. Lengthening the duration of treatment to 330 min caused the neuroepithelial cells to loose their microtubules and to become round. This situation was not reversible. Our results indicated that microfilaments are more sensitive than microtubules, that both organelles became increasingly sensitive as the exerted pressure was increased and that microtubules of older embryos exhibited a better resistance. Finally, we showed a correlation between the presence of microfilaments and the constricted state of the cellular apices and a relationship between the presence of microtubules and cell elongation.
The stabilization of morphological field size during slime mold morphogenesis
Authors: Peacock Michael , Soll David R. 
Published: April 2021

ABSTRACT
The relationship between aggregate size and morphological field size has been investigated in the cellular slime mold Dictyostelium discoideum. Evidence is presented that aggregate size and field size exhibit different temperature sensitivities and that an aggregate can be induced to separate into several morphological fields by a decrease in temperature. In addition, evidence is presented that field size is stabilized at a point in time just prior to tip formation.
Enteroendocrine APUD cells in the digestive tract of larval Barbus conchonius (Teleostei, Cyprinidae)
Authors: Rombout J. H. W. M. , Lamers C. H. J. , Hanstede J. G. 
Published: April 2021

ABSTRACT
The development of Barbus conchonius is described with special attention to the differentiation of the gut.
Amine precursor uptake and decarboxylation (APUD)* are present in enteroendocrine cells during development, whereas these processes are lacking in adult specimens. The first APUD cells originate on the fourth day of development in the anterior part of the gut and on the fifth day in the caudal areas. The APUD facility of the cells disappears within 2 days, and after the 6th day APUD cells can no longer be distinguished in the intestinal epithelium.
The first APUD cells were observed when four types of enteroendocrine cells were recognized with the electron microscope. These enteroendocrine cells contain granules of different electron densities, and microtubules and cilia can be observed. Some enteroendocrine-like cells are found below the basement membrane of the intestinal epithelium, indicating a possible extra-endodermal origin.
APUD cells, except melanoblasts, have not been found migrating from the neural crest in ventral direction. The origin of the enteroendocrine cells of B. conchonius is discussed.
* Abbreviations: APUD, amine precursor uptake and decarboxylation; F1F, formalin-induced fluorescence; L-DOPA, L-dihydroxyphenylalanine; 5-HTP, 5-hydroxytryptophan.
Metabolic behaviour and cleavage capacity in the amphibian egg
Authors: Legname Arnaldo H. , Buhler Marta I. 
Published: April 2021

ABSTRACT
During the winter season the full grown Bufo arenarum oocyte shows the metabolic behaviour characteristic of differentiated tissues of the same species. Due to seasonal variations, during the amplexus period, it acquires the metabolic behaviour of the segmenting egg.
Short-time-induced ovulations (5–6 h) determine germinal vesicle breakdown immediately before the expulsion of the oocyte, without modifying the ovarian metabolism of the same. The incidence of the operative type of metabolism upon their capacity to cleave after insemination and needle pricking, has been studied in coelomic oocytes, which have attained nuclear maturation and have not experienced oviducal secretion effects.
The results obtained indicate that the segmenting capacity of the egg is attained only when, through biochemical modifications, the oocyte acquires the metabolic behaviour characterizing embryonic cells.
It is postulated that the metabolic changes observed in the oocyte constitute a fundamental aspect of cytoplasmic maturation.
Allophenic mice in cleft-palate investigations
Authors: Sulik K. Miller , Ainip R. L. 
Published: April 2021

ABSTRACT
TlWh (Rb (5; 19)lWh), an albino strain of mice not previously used in the investigation of cleft palate (CP), is homozygous for a (5; 19) Robertsonian translocation which provides conspicuous chromosomal markers. Preliminary studies in this laboratory revealed that CP is induced in all the offspring of TlWh females treated with 2 · 5 mg of cortisone acetate on days 11–14 of pregnancy and that palatal closure is accomplished at a later morphological and chronological age than in C57BL/6J strain mice. The latter strain had a CP frequency of 42 % under similar experimental conditions.
Eight- to 16-cell embryos were aggregated in the following combinations: TlWh ↔ TlWh, C57BL/6J ↔ C57BL/6J and TlWh ↔ C57BL/6J. The resulting allophenic blastocysts were transferred to pseudopregnant C57BL/6J recipients which were given the above cortisone treatment and killed on the 18th day of pregnancy. CP was found in all of the 48 TlWh ↔ TlWhfetuses, 4 (20 %) of 20 C57BL/6J ↔ C57BL/6J fetuses and in 17 (26-2 %) of 65 TlWh ↔ C57BL/6J fetuses. Analysis of chromosome preparations from the palates of the TlWh ↔ C57BL/6J fetuses demonstrated that there is a positive correlation between the presence of CP and the percentage of susceptible cells in the palate (P &lt; 0·02). Other data suggest a possible growth advantage in favor of C57BL/6J cells in the palates of TlWh ↔ C57BL/6J allophenic mice.
Neurotrophic control of the cell cycle during amphibian limb regeneration
Authors: Maden M. 
Published: April 2021

ABSTRACTIt is shown here that amputated and denervated limbs of larval axolotls dedifferentiate and a proportion of the cells released undergo DNA synthesis and mitosis. When the limb is denervated prior to amputation fewer cells go through the cell cycle, implying the existence of a pool of trophic factor in the limb. Recent work has demonstrated that denervated blastemal cells accumulate in the G1 phase of the cycle. These results strongly argue against the theory that the trophic factor controls the G2 phase. Rather, it is proposed that this factor regulates either the total number of cells cycling or the rate at which they cycle by varying the length of the G1 phase.