bluuebunny/crossref_metadata_2025_split huggingface dataset:
The culture of mouse blastocysts in the presence of uterine flushings collected during normal pregnancy, delayed implantation and pro-oestrus
Authors: Aitken R. J. 
Published: April 2021

ABSTRACTWhen day-3 mouse embryos were cultured in a simple medium supplemented with uterine fluids of mice autopsied on day 4 of pregnancy, 48 h after administration of oestradiol, or during pro-oestrus, the percentage of blastocysts hatching from the zona pellucida was significantly greater than in unsupplemented medium. In the presence of uterine fluids recovered during delayed implantation this stimulation of blastocyst hatching was not observed. When the culture medium was supplemented with dialysed uterine flushings containing 20 or 30 μg protein/ml, both ‘day 4’ and ‘delay’ uterine proteins were equally effective in enhancing hatching frequency (P &lt; 0·05). The results suggested that ‘delay’ uterine fluids may contain a dialysable inhibitor of blastocyst activity. The putative inhibitor was not effective in the presence of serum, since uterine fluids recovered both on day 4 of pregnancy and during delayed implantation significantly increased the size attained by blastocyst outgrowths in the presence of foetal calf serum (P &lt; 0·001). The percentage of blastocysts exhibiting giant cell transformation and outgrowth was also increased (P &lt; 0·02) by these uterine fluids when the concentration of FCS in the medium was minimal (0·25 %).
Development of cytochalasin B-induced tetraploid and diploid/tetraploid mosaic mouse embryos
Authors: Tarkowski A. K. , Witkowska A. , Opas J. 
Published: April 2021

ABSTRACTBy subjecting F1 (CBA × C57/BL) × A eggs at the time of 2nd cleavage to 10 μg/ml of cytochalasin B (CB), tetraploidy was produced in 52 % of 2-cell eggs and 35 % of 3-cell eggs. 2n/4n mosaic embryos were produced from 2-, 3- and 4-cell eggs and amounted to 20 % of all treated eggs. 80 % of tetraploid embryos developed in vitro into regular blastocysts with half the cell number of control diploids. The effectiveness of CB in producing tetraploid embryos is limited by the asynchrony of 2nd cleavage, both between eggs and between sister blastomeres. Two-cell presumed tetraploids were transplanted to recipients and examined between the 6th and 11th day of pregnancy. Up to days development is normal and most embryos form egg-cylinders. At days the embryonic part of the cylinders is underdeveloped and in later development fails to form an embryo. Development of foetal membranes is much less affected and in the most successfully developing egg-cylinders their formation can be fully accomplished. Failure of embryonic development appears to be due to subnormal activity of the primitive streak, resulting in shortage of mesoderm. Postimplantation development of 2n/4n mosaics was normal. While in embryos tetraploid cells were either absent or in very low proportion (below 4 %), their contribution to the foetal membranes amounted in some cases to up to 50 °/o . Elimination of tetraploid cells from mosaic embryos suggests that they have a lower proliferation rate than diploid cells.
Effets de l’hybridation sur la population germinale embryonnaire et juvénile de canes issues du croisement Pékin ♂ × Barbarie ♀ (Anas platyrhynchos ×Cairina moschata)
Authors: Deray Armand 
Published: April 2021

ABSTRACTOvarian development has been studied in a hybrid duck (Anas platyrhynchos ♂ × Cairina moschata ♀) and in females of the parental Peking and Barbary species. In the hybrid, the gonadal ridge when it first forms is smaller than in either parental species, and after 16 days of incubation there is less cortical growth and less oogonial proliferation. At hatching, the left ovary of the hybrid contains fewer follicles, perhaps because the reduced size of the hybrid gonadal ridge limits germ cell colonization. However, the hybrid follicles develop very rapidly after hatching, and laying begins earlier in the hybrid than in Peking and Barbary ducks.
Localization of trophoblast-defined surface antigens during early mouse embryogenesis
Authors: Searle R. F. , Jenkinson E. J. 
Published: April 2021

ABSTRACTThe binding pattern of a rabbit antiserum raised against mouse ectoplacental-cone trophoblast on component cell populations in the pre-implantation and early post-implantation mouse embryo has been examined at the electron-microscope level using an immunoperoxi-dase-labelling technique. Binding was not detectable on the 1-cell stage, appeared at low levels at the 8-cell stage and was heavy on the trophectoderm and its trophoblast giant cell and extra-embryonic ectoderm descendants in the post-implantation embryo. In contrast, immunosurgically isolated day inner cell masses (ICM) showed only slight labelling, whilst ICM derivatives in the -day embryo were unlabelled.The results indicate that the antiserum may be identifying a trophoblast-specific surface determinant(s), which appears with the differentiation of the trophectoderm and is maintained on some of the cell populations derived from this tissue at least until the early postimplantation stages.
Parthenogenetic activation of mouse oocytes induced by inhibitors of protein synthesis
Authors: Siracusa G. , Whittingham D. G. , Molinaro M. , Vivarelli E. 
Published: April 2021

ABSTRACTRecently ovulated mouse oocytes at the Metaphase II stage undergo parthenogenetic activation (as indicated by the formation of pronuclei) when incubated for 6 h in the presence of cycloheximide or puromycin; the activation response increases progressively with the concentration of inhibitor. Activation is induced with concentrations of cycloheximide that depress protein synthesis by more than 70 %. Pronoculear formation occurs when protein synthesis is almost totally inhibited. Incubation of oocyte in Actinomycin D failed to initiate activation. The results show that the Metaphase II oocyte of the mouse synthesizes protein factor(s) which are necessary for the maintenance of the meiotic block. Other protein(s) having opposite effects and a different rate of turnover may also participate in activation since when the oocytes are treated with a high concentration of cycloheximide (10 μg ml-1) for varying periods of time, or with varying concentrations for a short period of time (1 h), a more complex activation response curve is obtained.Oocytes activated with cycloheximide are capable of further development, following transfer to the oviducts of pseudopregnant recipients, in a proportion similar to that of oocytes activated in other ways.
Ultrastructural localization of non-specific alkaline phosphatase during cleavage and blastocyst formation in the mouse
Authors: Mulnard Jacques , Huygens Roger 
Published: April 2021

ABSTRACT
The localization of non-specific alkaline phosphatase activity during cleavage and blastocyst formation has been investigated in the mouse by electron microscopy. The activity is detectable for the first time at the two-cell stage and is localized on the surface of the interblastomeric plasma membranes and on small cytoplasmic inclusions. It increases in the following stages, predominantly on the interblastomeric membranes, the outside membranes remaining devoid of reaction. From the four-cell stage on, small reactive grains are also observed in the crystalloid plates of the cytoplasm. At the morula stage, the plasma membranes of the inner mass cells are entirely marked by the reaction whereas the trophoblastic ceils are polarized, with their inner surfaces positive and outside surfaces negative. At the blastocyst stage the enzyme is gradually eliminated from the membranes bordering the blastocoel and from the interblastomeric furrows of the trophoblast and primary endoderm. The significance of the differential localization of the enzyme is discussed, especially in relation to the differentiation mechanisms of the trophoblast and inner cell mass.
The onset of osteogenesis in the developing chick limb
Authors: Holder Nigel 
Published: April 2021

ABSTRACTThe pattern of the onset of osteogenesis in each of the skeletal elements of the developing limbs of the chick embryo is described using Alizarin-red-stained whole mounts. Grafting experiments where 6-day unossified cartilage rudiments are placed into 4-day host wings show the initiation of ossification to be a programmed event. Truncation experiments show this to be the case not only for the initial onset of osteogenesis, but also for each region of each element. These results are discussed in terms of morphogenetic events occurring in the early wing bud.
Crystalline inclusion bodies in rabbit embryos
Authors: Daniel Joseph C. , Kennedy John R. 
Published: April 2021

ABSTRACTCrystalline inclusion bodies (CIB) may be found as prominent ultrastructural components of the trophoblast cells of rabbit blastocysts and of progestational uterine endometrium. In the work reported here we have sought to describe developmental steps in crystal formation, to correlate these events with embryonic age and to determine if the uterus is essential (either as a source or an environment) for crystal formation in the embryo.CIB, which are of a size and periodicity to make them appear to be clusters or packages of microtubules, are first detectable in embryos 4 days 6 h post coitum and by days are well established in significant numbers. Another structural component, granular vesicles, may be seen in embryos as early as days post coitum, and decrease in number during the same time the CIB are increasing. We believe that the CIB originate from the pre-existing granular vesicles and present electron micrograph evidence of crystal formation progressing from such vesicles.CIB formation does not occur in -to 5-day-old embryos which have been locked in the oviduct by a suture around the utero-tubal junction. However, when such tube-locked embryos are transplanted into the uterus, they develop crystals within 36 h thereafter. We conclude that the uterus is essential for CIB formation to occur in the rabbit embryo.
Neuronal adjustments in developing nuclear centers of the chick embryo following transplantation of an additional optic primordium
Authors: Narayanan C. H. , Narayanan Y. 
Published: April 2021

ABSTRACTFollowing transplantation of an additional optic primordium into the orbital mesenchyme of chick embryos of approximately 2 days of incubation age, the changes in cell number in the ciliary ganglion, accessory oculomotor and trochlear nuclei were studied at various stages of development. Cell counts were made at 1-day intervals from days 9 through 15 for ciliary ganglion, and from days 13 through 15 for the accessory oculomotor and trochlear nuclei. Cell counts for the ciliary ganglion on days 9 and 11 were similar on the operated and control sides which suggests that grafting of an additional optic primordium, and thus enlarging the periphery, is not involved in the control of proliferation. Comparison of the number of cells for the ciliary ganglia and the accessory oculomotor nuclei at days 13 and 15 showed an increase on the affected side ranging from 8 to 27 %, and 9 to 33 % respectively. We interpret this increase on the experimental side as a reduction in the number of degenerating cells that occur in normal development, as a result of an enlargement of the peripheral field of innervation. Three cases showed an increase in the number of cells in the trochlear nucleus ranging from 9 to 29 %. This increase was attributed to an increase in the size of the superior oblique muscle of the operated side as determined by volumetric measurements. On the basis of the evidence we conclude that an enlarged periphery acts by regulating the level of naturally occurring cell death by reducing the amount of cell loss, leading to a corresponding increase in final cell number.
Control of somite number in normal and amputated mutant mouse embryos: an experimental and a theoretical analysis
Authors: Flint O. P. , Ede D. A. , Wilby O. K. , Proctor J. 
Published: April 2021

ABSTRACT
A regulation is shown for size and number of serially repeated axial structures, the somites, in a mammalian embryo. The mammalian embryo is normally inaccessible to operation at post-implantation stages. This problem is resolved by the quantitative analysis of somite size, number and development in a recessive mutant of the mouse, amputated, whose axial length is greatly reduced. The effect of the gene simulates an experiment ablating part of the embryonic tissue available for somitic segmentation. Regulation occurs at the time when the somite is first formed, by control of the quantity of cells included in each new somite. A model is devised for the control of somitic segmentation which explains most of the features observed and which can be simulated on a computer.
Genetic analysis of vitellogenesis inDrosophila melanogaster: the identification of a temperature-sensitive mutation affecting one of the yolk proteins
Authors: Bownes M. , Hames B. D. 
Published: April 2021

ABSTRACTA number of female sterile mutations on the first and third chromosomes of Drosophila melanogaster have been screened for defects in the yolk proteins using polyacrylamide gel electrophoresis. Two new mutants were identified. 6m45 accumulates all three yolk proteins (YP1, YP2 and YP3) in the haemolymph but they are all absent from the ovaries suggesting it is a yolk-protein-uptake mutant. In contrast, 1163 is a temperature-sensitive mutation with a large reduction in the quantity of YP1 in the haemolymph and ovaries at 29 °C. Both mutants are autonomous in ovary transplant experiments.
On the origin of the ciliary ganglion in birds studied by the method of interspecific transplantation of embryonic brain regions between quail and chick
Authors: Narayanan C. H. , Narayanan Y. 
Published: April 2021

ABSTRACT
The development of the ciliary ganglion with reference to the site and cells of origin have been investigated by the method of quail-to-chick transplantation of embryonic fore-, mid- and hindbrain regions, and by the method of transplantation of cranial neural crest from specific brain levels. In chimaerical embryos, quail cells originating from the graft end up in the ciliary ganglion, only when the graft is from the midbrain level of quail embryo donors. In fore- and midbrain grafts the ciliary ganglia of chimaerical embryos are composed of chick cells only. The results indicate that the mesencephalon is the principal site for the pre-cursor cells of the ciliary ganglia and clearly rules out any contribution to the ganglia from either the forebrain or hindbrain levels.
In interspecific transplantation of cranial neural crest, quail cells originating from the graft are observed consistently in the ciliary ganglion of the operated side when the grafted neural crest mateiial is derived from the mesencephalon of quail embryo donors. On the basis of the evidence provided, it is concluded that the mesencephalon is the principal site and the cranial neural crest of this level the source from which the precursor neurons of the ciliary ganglia are derived.
Influence of embryonic stage on the transdifferentiation of chick neural retina cells in culture
Authors: De Pomerai D. I. , Clayton R. M. 
Published: April 2021

ABSTRACTNeural retina cells from chick embryos up to 15 days of incubation can transdifferentiate in culture into both lentoids and pigment cells. Some transdifferentiation into pigment cells but none into lentoids was found in cultures of 17-day embryonic neural retina. No trans-differentiation occurred in cultures of neural retina from embryos immediately before hatching. In general, lentoids and pigment cells develop more rapidly and in greater numbers in cultures of neural retina from the earlier embryonic stages, and lens-specific crystallins also appear earlier and accumulate in greater amounts in these cultures. Delta crystallin accumulation is much greater in transdifferentiating cultures of early embryonic neural retina, whereas α and β crystallins become proportionately more prominent in cultures of late embryonic neural retina. Traces of α and β but not δ crystallin are detectable in 60-day cultures of 17-day embryonic neural retina. Analogies between these results and the ontogeny of crystallin polypeptides in lens cells in vivo are discussed.
Induced segmental reorganization in sabellid worms
Authors: Berrill N. J. 
Published: April 2021

ABSTRACT
Processes of regeneration and reorganization are analyzed in two sabellid polychaetes. Abdominal pieces of Branchiomma nigromaculata, during head regeneration, ordinarily reorganize only a fraction of the number of segments typical of the thorax. In pieces transected in the vertical plane, but obliquely with regard to the main axis of the worm, the extent of reorganization is greatly enhanced. The same number of segments transform on the right and left sides, the surviving damaged segments transforming on one side and a corresponding number of more posterior, undamaged segments transforming on the other. Reorganization is shown, in abdominal pieces of Sabella melanostigma, to involve destruction and inversed dorso-ventral reconstitution of all parapodial structures in the segments affected, the conversion of intestine to thoracic stomach, and the invasion of previously abdominal segments by a pair of large nephridia which grow posteriorly after being formed in the basal portion of the head blastema. All three events exhibit a time-graded character, starting soonest at the anterior end and progressively later posteriorly, and apparently independently of one another. Abdominal type segments are formed only from the anterior region of the caudal, prepygidial zone of growth, successively, never by transformation. The dorso-ventrality of abdominal segments is the inverse of the thoracic, with the antero-posterior polarity unchanged, in all circumstances. Only during posterior regeneration from thoracic segments are thoracic segments produced from the posterior zone of growth, but only two or three are thus formed, the zone of growth then changing to the production of abdominal segments. It is concluded that the unique feature of sabellid-serpulid organization is the complete inversion of the dorso-ventrality of the posterior zone of growth as the result of emancipation from the generally dominating dorsal field emanating from the anterior end.
A trypsin-like oviducal proteinase involved in Bufo arenarum fertilization
Authors: Miceli Dora C. , Fernández Silvia N. , Raisman Jorge S. , Barbieri Francisco D. 
Published: April 2021

ABSTRACT
When the jelly-less eggs removed from the most cephalic region of the oviduct (pars recta) of the toad Bufo arenarum were inseminated at a high sperm concentration, high frequencies of fertilization were obtained. On the other hand, control eggs removed from the pleuroperitoneal cavity (coelomic eggs) were neither fertilized upon insemination under identical conditions, nor with the water extract of the jelly. Under these inseminating conditions, however, a high frequency of fertilization was obtained when coelomic eggs were pre-incubated in the presence of the fluid secreted by the epithelium of the pars recta or of an extract prepared from pars recta homogenate.
Experimental evidence is presented showing that the component responsible for this effect acts on the vitelline envelope of the egg, increasing its susceptibility to sperm lysin. It is probable, therefore, that it induces successful fertilization of coelomic eggs by making the vitelline envelope more easily penetrable by sperm.
The active factor was partially purified by Sephadex chromatography. The product obtained was of high activity and, as judged by its inhibition with soybean trypsin inhibitor and lima-bean trypsin inhibitor, it is likely to be a trypsin-like enzyme. The molecular weight of the factor was estimated to be 47000 by Sephadex chromatography. Secretion of the pars recta factor is hypophysis-dependent and its activity is not influenced by pH within the range tested (6·0–8·4).
Composition of the Foetal Fluids of the Rabbit
Authors: Davies J. , Routh J. I. 
Published: April 2021

ABSTRACTThe composition of the foetal fluids of the rabbit at different stages of gestation has been described with reference to nitrogenous materials, electrolytes, total reducing substance, and fructose.The composition of the amniotic and exocoelomic fluids resembles that of the foetal biood-serum except for the low total protein of the former. These findings are consistent with the origin of these fluids as a dialysate of the foetal blood. The allantoic fluid is characteristically opalescent largely due to the presence of colloidal fat. Its composition also differs from that of the foregoing fluids. Thus the total protein is lower while the level of urea nitrogen and creatinine is higher. Sodium, chlorides, and inorganic phosphates are lower; calcium and potassium are higher. Total reducing substances are about the same in all three fluids when allowance is made for the higher non-fermentable reducing substance of the allantoic fluid: all are lower than the foetal blood-levels. The fructose content is low and about the same in all fluids.The presence of allantoic fluid from about the 13 th to the 24th day of gestation coincides with the period of function of the foetal mesonephros as judged by embryological and histological criteria. The structure of the nephron of the mesonephros is briefly described and the presence of alkaline phosphatase, fat, and periodic acid Schiff-reacting substances in the proximal tubules is illustrated. The evidence is consistent with the origin of the allantoic fluid as wholly or in part a product of the foetal mesonephros.
The Composition and Origin of the Foetal Fluids of the Pig
Authors: McCance R. A. , Dickerson J. W. T. 
Published: April 2021

ABSTRACT
Many of the unicellular organisms have a greater concentration of osmotically active material within their body fluids than there is in the medium surrounding them, and the higher animals have glands like the kidney and sweat glands which are able to elaborate fluids with much lower concentrations of sodium and chloride than the body-fluids from which they were derived. The concentrations of sodium and chloride in hypotonic urine and sweat are much lower than those in the serum, and consequently the total osmolar concentrations are also lower, but the urea is characteristically higher. There is no proof that the process is one involving the secretion of water; and, indeed, the kidney is now thought to produce a hypotonic urine by the active reabsorption of sodium from the distal tubule, the walls of which are impermeable to water unless there is posterior pituitary hormone in the circulation.
Tracer Studies on Chick Embryosin vitro
Authors: Pantelouris E. M. , Mulherkar L. 
Published: April 2021

ABSTRACTChick blastoderms of the definite primitive streak stage were cultured in vitro for about 24 hours with radioactive DL-methionine-S35 added to the medium. It was shown by autoradiography that the neural tube and especially its roof and also adjacent areas of the ectoderm (neural crest) take up more activity than other structures. Mesodermal structures such as the notochord, somites, and myoepicardium also reach a high level of uptake, presumably correlated with their differentiation. Tissues of the host, the induced axis, and self-differentiating (non-labelled) grafts take up activity from the culture medium at the same rate. If a labelled organizer is grafted on to a host blastoderm, the induced neural tube takes up a substantial amount of labelled molecules but the host does not. Experiments involving dilution with unlabelled methionine or grafting of labelled peripheral organizer tissue, produced evidence for the view that the activity is carried to the induced tissues by diffusion or exchange of free aminoacid molecules; transfer of macromolecules does not occur on a scale detectable by the methods used but it cannot be excluded that it might occur on a smaller scale. In cases of induction caused by organizer graft the notochord, mesenchyme, and, occasionally, tissues lining the foregut associated with the induced axis are contributed by the graft.