bluuebunny/crossref_metadata_2025_split huggingface dataset:
The relationship between the anterior pituitary gland and the pancreas in tail regeneration of the adult newt
Authors: Vethamany-Globus Swani , Liversage Richard A. 
Published: April 2021

ABSTRACTHistological examination of the amputated tails of 17 hypophysectomized newts revealed abnormal and extremely retarded regenerates; four of them exhibited total inhibition of regeneration. Thus, under the conditions of hypophysectomy, normal tail regeneration does not ensue in the adult Diemictylus viridescens.Also, hypophysectomy adversely affects the normal histology of both the endocrine and exocrine parts of the pancreas, as observed by the atrophy of the gland in all hypophysectomized cases. Presumably, the normal function of the gland was altered. This relationship between hypophysectomy and the atrophic pancreas suggests a possible involvement of the pancreas in tail and limb regeneration in the adult newt.
Passage of bovine serum albumin from the mother to rabbit blastocysts I. Passage from the circulation to uterine lumen
Authors: Crutchfield Floy L. , Kulangara Abraham C. 
Published: April 2021

ABSTRACTDutch belted rabbits were given single intravenous injections of 100 or 200 mg/kg doses of bovine serum albumin (BSA). BSA in serum and uterine fluid at various times after injection was estimated by a quantitative radial immunodiffusion test, which could measure a minimum of 40 ng. The presence of BSA in uterine fluid was confirmed by immuno-electrophoresis and double diffusion in agar.BSA passes readily into uterine fluid of non-pregnant rabbits, reaching a peak at 12 h after injection, when its concentration is 7–15 % of that in serum. About 72 h seems to be required for equilibration of BSA between serum and uterine fluid, at which time the concentration in the former is about 5 times that in the latter. The kinetics of the process is discussed. Compared to the above, passage of BSA into uterine fluid of pregnant rabbits (5–7 days post coitum) is restricted in the following ways. Significant amounts of BSA appear in the fluid only after a maternal dose of 200 mg/kg. BSA in uterine fluid reaches a peak at 24 h after injection, when it is only 4·5 % of the serum level. The permeability rate seems to decrease with early gestation.Approximate rates of entry of BSA into uterine lumen of non-pregnant and pregnant rabbits are 0·4 and 0·25 μg/h. BSA seems to be treated like rabbit albumin in its passage across the uterine epithelium. There is no evidence of selection between these proteins.
Embryogenesis of the enteric ganglia in normal mice and in mice that develop congenital aganglionic megacolon
Authors: Webster William 
Published: April 2021

ABSTRACTEmbryological studies on the mouse indicate that, contrary to the classical concept, all the enteric ganglia are from a single, vagal, neural crest source. The immature ganglion cells first enter the gut by way of the newly formed vagal outgrowth at 10 days gestation. The neuroblasts then migrate down the gut in a cranio-caudal direction, being replaced by more neuroblasts from the vagus. By 15 days 12 h the process is complete and ganglion cells are present throughout the gut. The process is continuous and there is no evidence of a lumbosacral origin for any of the intramural ganglia.In mice which develop aganglionic megacolon the process is basically the same except that the neuroblasts appear to migrate at a slower rate than normal. The result is that the migration of the neuroblasts and the elongation of the gut are out of phase so the migrating neuroblasts cannot reach the end of the gut, despite the fact they migrate 6 – 7 days longer than normal.
The polarity of the dental lamina in the regenerating salamander jaw
Authors: Graver Heber T. 
Published: April 2021

ABSTRACTIn and amputated lower jaws of larval Ambystoma maculatum the dental lamina (DL) is replaced from both the anterior and posterior ends of the regenerate area, while in adult Triturus viridescens the DL is regenerated from the posterior stump tissues only. One-fourth and mandibular jaw amputations were performed in such a manner that a short stump of jaw, devoid of DL, remained. Larvae exhibited a posterior regrowth of the DL, while in adults the lamina accumulated at the edge of the regenerate but did not enter the new tissue.Transplantation of a section of jaw from the left to the right side of the mandible resulted in the DL of the inserted piece having a reversed polarity in its new position. In both larval and adult forms, the DL of the transplant established connexions both anteriorly and posteriorly with lamina present. Transverse amputations through the inserted piece resulted in regeneration from the DL in the transplant in an anterior direction. Transplantation of a section of edentulous tissue into normal jaw tissue of the opposite side, or transplantation of a section of normal tissue into the edentulous area of the opposite side resulted in no anterior or posterior regrowth of the DL into the edentulous area.Collectively the results indicate that no anterior – posterior polarity exists in the DL of the larval salamander jaw, since regeneration can occur equally well in both directions. The DL of the adult salamander jaw exhibits an anterior – posterior polarity allowing for regrowth in an anterior direction only.
Inhibition of nuclear migration in the absence of microtubules in the chick embryo
Authors: Messier Paul-Emil , Auclair C. 
Published: April 2021

ABSTRACTInterkinetic nuclear migration was studied in cells of the forming neural tube of cultured chick embryos aged from 1 to 7 pairs of somites. In specimens that were first exposed to 2°C for 3 h, then treated with 4 × 10−3 M monoiodoacetamide and finally transferred to new media to be reincubated for 1 – 2·5 h, it was found that microtubules were absent and nuclear movements blocked. These findings point to microtubules as essential structures for interkinetic nuclear migration. Their relation to the problem of neurulation is discussed.
Cell death and the development of limb form and skeletal pattern in normal andwingless(ws) chick embryos
Authors: Hinchliffe J. R. , Ede D. A. 
Published: April 2021

ABSTRACTThe wingless condition resulting from the action of the sex-linked wingless (ws) gene arises from the precocious appearance of cell death in the anterior necrotic zone (ANZ) of the forelimb-bud at stage 19 (3 days) and its progressive extension beyond its normal area during stages 20 – 23. A similar though less pronounced effect occurs in the hindlimb-bud. Although some wingless hindlimb-buds are normal, others are affected by the precocious appearance of cell death in the ANZ.The ws wingless mutant resembles the different wingless mutant investigated by Zwilling (1956) in that the apical ectodermal ridge (AER) is absent in most ws wing-buds. AER absence could be due to ws mesenchymal cell death interfering with the production of apical ectodermal maintenance factor (AEMF), which Zwilling claims is necessary to maintain the AER which plays an essential role in inducing limb outgrowth.Wingless mutant phenotypes range from birds with rudimentary wings and normal legs through a modal type with forelimbs absent and hindlimbs normal to wingless and legless forms showing a high degree of expressivity. Individual wingless embryos vary in the degree to which the precocious ANZ appearing at 3 days is extended into the limb-bud and the wide range of wingless phenotypic expression is attributed to this variation.Electron microscopic and histochemical analysis of the cell death process in wingless wing-buds revealed the presence of both isolated dead cells and macrophages, which contained intense acid phosphatase activity. These findings are interpreted as showing that isolated dead cells are ingested by neighbouring mesenchymal cells which thus become transformed into macrophages, first ingesting and then digesting further dead cells.A study was made of the origin of the anomalous hindlimb condition, including absence or reduction of the tibia and digits, characteristic of severely affected wingless embryos. Autoradiographic analysis of the pattern of 35SO4 uptake revealed that at stage 24/5 wingless hindlimb-buds which were smaller than normal had a normal prospective fibula region, but that the prospective tibia region was small or absent. Thus the effect of a precocious hindlimb ANZ at stages 19 – 22 is to reduce or delete the pre-axial prospective tibia at stage 24/5.
Cortical-nuclear interactions in cephalopod development: cytochalasin B effects on the informational pattern in the cell surface
Authors: Arnold John M. , Williams-Arnold Lois D. 
Published: April 2021

ABSTRACTCytochalasin B (CB) was applied to early developmental stages of the egg of the squid Loligopealei and defects in cleavage and/or organogenesis were produced. If CB was applied in relatively high dosages (2·0 μg/ml) or for long periods (30 min) to embryos in early cleavage the existing furrows irreversibly disappeared. If precleavage embryos were similarly treated the streaming pattern which forms the blastodisc was interrupted and patches of clear cytoplasm appeared on the zygote surface. Short low dosage pulses (0·2 μg/ml for 10 min) produced cleavage effects correlated with the time of pulsing. If pulsed within 30 min of first cleavage the first furrow did not appear in the majority of cases but the second furrow appeared synchronously with the controls and appeared normal in all respects. If pulsed approximately 30 min or longer before cleavage the first furrow usually appeared on time as a weak surface line. Second cleavage appeared normally. However, the asymmetrical pattern of third cleavage was ‘equalized’ and the blastomeres tended to be of equal size. It was concluded that there are subtle cytoplasmic movement patterns, sensitive to CB, which position the nuclei before each cleavage and thereby determine the cleavage pattern.If embryos were pulsed (0·2 μg/ml for 10 min) at various times during early development, anomalies in differentiation at organogenesis (3–4 days later) were produced which correlated with the time of pulsing. Pulses after germinal layer formation (stage 11) produced no noticeable effects and pulses before the cytoplasmic streaming which produces the blastodisc similarly had very little or no effect. However, pulses during blastodisc formation or early cleavage produced severely affected embryos in which organ displacement, poor tissue and organ differentiation, or organ deficiencies were common. Pulsed embryos were scored and the time of pulsing correlated with the severity of effects. The nuclei of the inductive yolk epithelium were abnormal, frequently being rounded, clumped and/or containing clumped or abnormally diffuse chromatin. It was concluded that the streaming pattern which forms the blastodisc in some way fixes or enhances a pre-existing pattern of developmental information which resides in or at the surface of the egg. Once this pattern is established it is insensitive to CB but it can still be demonstrated by other techniques. This informational pattern apparently influences the nuclei of the yolk epithelium that come to lie in specific regions and controls the expression of their genome so that specific organs are programmed.
Isozymes of lactate dehydrogenase (LDH) in skeletal tissues of the embryonic and newly hatched chick
Authors: Coffin Patricia A. , Hall Brian K. 
Published: April 2021

ABSTRACTThe time of appearance and the relative activity of isozymes of LDH were studied in portions of the skeleton of the embryonic and newly hatched chick by starch-gel electrophoresis. The following tissues were examined for presence or absence of isozymes: mesenchyme of the hind limb as it separated into chondrogenic and myogenic tissue; the development of the cartilaginous model of the tibia and its subsequent replacement by bone; the development of the quadratojugal (a membrane bone) with and without secondary cartilage.LDHX and LDH2 were present in all tissues from the earliest time at which the tissues could be detected histologically. Thus these isozymes are ubiquitous. They were also the predominant isozymes during the first and second weeks of development of all the tissues and continued to predominate in the quadratojugal after hatching.LDH3, LDH4, LDH5 appeared after the initial differentiation of the tissues, arose at earlier ages in cartilage than in bone, and became the predominant isozymes earlier in cartilage (14 days of incubation) than in bone (20 days of incubation).These patterns of isozymes were related to metabolic activity of the developing tissues, especially to aerobic and anaerobic glycolysis.
Genetic inhibition of mesenchymal cell death and the development of form and skeletal pattern in the limbs oftalpid3(ta3) mutant chick embryos
Authors: Hinchliffe J. R. , Thorogood P. V. 
Published: April 2021

ABSTRACTVital staining reveals that in homozygous (ta3/ta3) talpid3 embryos, the areas of mesen-chymal cell death which occur regularly in normal limb development are absent or reduced.The necrotic locus in the central mesenchyme (the ‘opaque patch’) which in the normal chick limb reaches maximum development at stages 24 and 25 is absent or much reduced in talpid3 fore-and hindlimb-buds. Autoradiographic studies, following application of a 2 h pulse of 40 μCi of35SO4 to the vitelline circulation, show that normal tibia and fibula incorporate 35SO4 into chondroitin sulphate at stage 24 and more strongly at stage 26 during the process of chondrogenesis. The mesenchyme in the opaque patch region of normal limbs ceases to incorporate 35SO4 into chondroitin sulphate at stage 24. Talpid3 mesenchyme cells in the equivalent position at stages 24 and 26 continue to incorporate 35SO4, remain viable and become chondrogenic. It is suggested that absence or reduction of this central necrotic locus in talpid3 is causally related to the fusion of radius/ulna and (in some cases) of tibia/fibula characteristic of the later stages (28–35) of talpid3 limb development. This evidence supports the hypothesis that cell death in the opaque patch plays a morphogenetic role in separation of radius/ulna and tibia/fibula.The digital plate of stage 32 normal limbs is characterized by massive necrosis of the interdigital tissue. In talpid3 forelimbs of stages 30–35 interdigital necrosis is absent, and there is no regression of the tissue between the digits (‘soft tissue syndactyly’). In talpid3 hindlimbs of stage 30–35 interdigital necrosis is either absent or much reduced, and there is little or no erosion of the soft tissue between the digits. This evidence supports the hypothesis that the morphogenetic role of interdigital cell death is in causing separation of the digits through shaping and remodelling the contours of the digital plate.
Zur Geschlechtsbestimmung und Gametogenese von Boneilia viridis Rolando
Authors: Leutert Rudolf 
Published: April 2021

ABSTRACT
Sex differentiation and gametogenesis in Boneilia viridis Solando
Large numbers of trochophore larvae of Bonellia viridis (Echiurida) were cultivated either in pure sea water (‘Glaszuchten’) or in sea water containing an intact or fragmented proboscis of an adult female RüsselzuchtenThe ability of these larvae to differentiate into males or females was investigated.
Sex determination for the majority (43–83 %) is metagamic and phenotypic. These findings therefore confirm the results of Baltzer and disprove those of Wilczynski.
When larvae are exposed to the action of the female proboscis, 76 % become males. The sensitive period during which this determination can take place lasts from day 3 to day 16 of larval life. Exceptions to this rule are discussed.
The gametogenesis of Boneilia viridis has been investigated by electron microscopical methods.
In early stages the oogonia of the ovary are already in syncytial contact with the nurse cells. The possible functions of the nurse cells and follicle cells are discussed. Electron micrographs failed to reveal two types of eggs (male- and female-determined eggs, according to Wilczynski).
Spermiogenesis in Boneilia is described. The spermatogonia are situated in paired clusters in the coelomic cavity, and form a syncytial complex. After completion of spermiogenesis, the spermatozoa abandon their syncytial contact.
The fine structure of ripe spermatozoa is described and discussed.
Cell distribution in chimaeric mouse embryos before implantation
Authors: Garner Wendy , Mclaren Anne 
Published: April 2021

ABSTRACT
Eight-cell mouse embryos labelled by prior cultivation in the presence of tritiated thymidine were aggregated with unlabelled 8-cell stages, and allowed to develop in vitro for two further cell divisions. Autoradiographic analysis of the resulting embryos showed that little or no mixing of the two cell populations took place during this period, either in the trophoblast or in the inner cell mass.
Stalk cell differentiation by cells from migrating slugs ofDictyostelium discoideum: special properties of tip cells
Authors: Town C. D. , Stanford E. 
Published: April 2021

ABSTRACTWhen fragments of migrating slugs of D. discoideum are disaggregated and spread on agar containing 1 mM cyclic AMP, cells from all parts of the slug form stalk cells with high efficiency. When cyclic AMP is not added to the agar, normal fruiting of dissociated slug cells can be prevented by overlaying them with cellophane. Under these conditions only cells from the anterior 10% of the slug (the ‘tip’) give rise to appreciable numbers of stalk cells, all other cells remaining amoeboid.By separating distinct cell populations with cellophane we have shown that tip cells can induce cells from other parts of the slug to differentiate into stalk cells. The ability of tips to induce stalk cells is independent of tip age, but the proportion of cells induced depends both on the age of the slug and the part of the slug from which they are derived. The proportion induced is greater in older slugs than in newly formed ones, and in the older slugs is greater in the cells from fronts than from backs.The active substance released by the tip cells may be cyclic AMP.
The establishment of the oral-aboral axis in the ctenophore embryo
Authors: Freeman Gary 
Published: April 2021

ABSTRACTIn a small percentage of normal embryos and in a higher percentage of embryos centrifuged prior to the first cleavage the positions of the polar bodies and the site of the first cleavage furrow do not coincide. These cases have been used to establish whether polar body formation sites or first cleavage initiation sites correlate best with the oral-aboral axis of the embryo. In all cases when the first cleavage is initiated at a site different from the site where the polar bodies were given off, the pattern of the first four cleavages is normal, the segregation of comb plate potential at these stages is normal, and the larvae that form are normal. The extent to which comb plate potential is localized along the oral-aboral axis of the embryo prior to the first cleavage, during the first cleavage and at the 2-cell stage was also examined. These experiments demonstrate that the oral-aboral axis is established at the time of the first cleavage, that cleavage plays a causal role in setting up the axis, and that comb plate-forming potential begins to be localized in the aboral region of the embryo at this time.
Genetic analysis of developmental mechanisms in hydra: III. Characterization of a regeneration deficient strain
Authors: Sugiyama Tsutomu , Fujisawa Toshitaka 
Published: April 2021

ABSTRACTMutant hydra strains showing abnormal development can be isolated through sexual inbreeding of wild hydra. One such mutant strain, called reg-16, regenerates tentacles very poorly following amputation of the head and foot. Tentacle regeneration, however, is significantly enhanced by subdividing the regenerating fragment longitudinally.Lateral tissue implants that induce head formation in wild-type hydra either regress or induce foot formation in reg-16 polyps. These results suggest that regeneration deficiency in reg-16 is due to a defective polarity gradient.A chimaeric strain of hydra was produced by combining interstitial cells (and thus their differentiation products, nerve cells and nematocytes) of reg-16 hydra with epithelial cells of another strain which is capable of normal regeneration. The chimaeras regenerate normally, suggesting that the defect of reg-16 is not located in the interstitial or nerve cells.
Limb-somite relationship : effect of removal of somitic mesoderm on the wing musculature
Authors: Chevallier Alain , Kieny Madeleine , Mauger Annick 
Published: April 2021

ABSTRACT
The aim of this study is to test the ability of the intrinsic wing musculature to develop in the absence of somitic mesoderm.
The experiments were performed on 2-to 2·5-day chick embryos either by replacing the somitic mesoderm adjacent to the wing field with a piece of 9-day chick embryonic midgut or by destroying, through local X-irradiation, not only the somitic mesoderm of the wing level, but also at least three somites (or presumptive somites) anterior and/or three presumptive somites posterior to the wing level.
The replacement of somitic tissue scarcely affected the organogenesis of the forearm musculature, at least when both bones were present. In the other experiments, radio-destruction severely impaired the development of the forearm muscles, which were seldom all present and in most cases were entirely missing. The absence of a given muscle involves the simultaneous absence of the corresponding tendons.
The possible origins of the muscles that formed despite the removal of the somitic mesoderm are discussed.
Cleavage in the chick embryo
Authors: Bellairs Ruth , Lorenz F. W. , Dunlap Tania 
Published: April 2021

ABSTRACT
Chick embryos ranging from the stage of first cleavage to that of about 700 cells were removed from the oviduct and examined by transmission electron microscopy. Beneath the cell membrane is a yolk-free cortical region containing microfilaments. Beneath this lies cytoplasm which contains yolk spheres which are graded in size, the dorsal ones being smaller than the ventral ones. The subgerminal periblast possesses a greater proportion of yolk to cytoplasm than do the cells proper, but it merges with the cytoplasm at the incomplete borders of the ‘open’ cells.
Specialized accumulations of membranes lie in the marginal periblast, and it is suggested that they play a role in cell membrane formation.
(This paper is dedicated to Professor Silvio Ranzi on the occasion of his 75th birthday)
Monomeric and aggregate proteoglycans in the chondrogenic differentiation of embryonic chick limb buds
Authors: Vasan N. S. , Lash J. W. 
Published: April 2021

ABSTRACTProteoglycan heterogeneity was studied during the in vivo differentiation of embryonic chick limb cartilage. Recently, it has been shown that during the differentation of limb cartilage the proportion of the aggregated form of proteoglycans increases whereas the unassociated monomeric forms decrease, and this has been related to the synthesis of two link proteins at a specific stage of differentation. In this study it is suggested that the appearance of the aggregate formation is also due to synthesis of a stable hyaluronic acid binding region of the core protein. Thus, it can be concluded that differential gene expression for these proteins takes place as a differentiation phenomenon.