bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the development of mouse embryos in vitro. I. The effect of osmolarity and hydrogen ion concentration
Authors: Brinster Ralph L. 
Published: June 2005

AbstractSeveral thousand two‐cell mouse ova were cultivated in vitro, and the effect on development of changing the osmolarity and hydrogen ion concentration of the medium was examined. Statistical experimental design techniques were employed throughout the experiments in order to make the most efficient use of the material available. The two‐cell ova were cultivated for three days, and the percentage which developed into normal blastocysts was used as a measure of the treatment effect.Changing the osmolarity of the medium had a marked effect on the number of blastocysts developing from two‐cell mouse ova. Blastocysts developed in media with osmolarities ranging between 0.2002 and 0.3542 osmols. The optimum osmolarity for the development of two‐cell mouse ova into blastocysts was 0.2760 osmols.The hydrogen ion concentration of the culture medium also had an effect on the development of two‐cell mouse ova into blastocysts. Although blastocysts developed in media with pH's ranging from 5.87 to 7.78, the optimum pH appeared to be near 6.82.
Sperm penetration through the zona pellucida of the sheep egg
Authors: Dziuk P. J. , Dickmann Z. 
Published: June 2005

AbstractSheep eggs were obtained at appointed times from 4 to 16 hours after ovulation and examined for evidence of penetration by spermatozoa. The following observations were made: (1) The fertilizing spermatozoon makes a curved slit in the zona as a result of traversing it. The slit seems to be an open passage. (2) The sperm head of the ram has ventral‐dorsal asymmetry. The flat side of the sperm head always faces the vitellus as it passes through the zona. (3) A fine filament‐like structure was observed extending from the anterior tip of sperm heads embedded in the zona. (4) The site on the zona at which spermatozoa penetrate into the egg is random.
The duodenal progenitor population. I. Age related increase in the duration of the cryptal progenitor cycle
Authors: Thrasher J. D. , Greulich R. C. 
Published: June 2005

AbstractThe duodenal progenitor population has been investigated in four age groups of male Swiss albino mice, utilizing tritiated thymidine and autoradiography following sequential sacrifice of the experimental animals. Parameters evaluated in the different age groups included: (1) duration of the progenitor cycle and its component phases; (2) DNA‐synthetic index; and (3) mitotic index.Analysis of the kinetics of metaphase labeling revealed that the mean duration of the entire cycle lengthens with age, whereas the mean duration of the DNA‐synthetic phase is constant (ca. 7.4 hours) irrespective of age. Estimates of the cycle duration based upon calculations from the DNA‐synthetic index also demonstrate an increase with age, although the absolute values derived in this manner do not agree with those based on metaphase labeling.Determination of the cryptal DNA‐synthetic and mitotic indices disclosed a decrease in the percentage of labeled and/or mitotic cells with increasing age. Thus, the prolongation with age in mean progenitor cycle duration involves an increase in the average time which a duodenal progenitor cell spends in the interphase (G1) portion of the cycle.
The homolog of the pituitary‐adrenocortical axis in the teleost fish Tilapia mossambica
Authors: Basu Juthika , Nandi Jean , Bern Howard A. 
Published: June 2005

AbstractThe effects of hypophysectomy and of hormone treatments on the interrenal of Tilapia mossambica were studied, utilizing measurements of mean interrenal nuclear diameter as an index of interrenal function.Hypophysectomy of Tilapia maintained in isotonic Ringer's solution resulted in a significant decrease in interrenal nuclear diameter after 21 days. This decrease was prevented by treatment of hypophysectomized fish with mammalian ACTH. Mammalian ACTH significantly increased the interrenal nuclear diameters of intact fish maintained in fresh water, but failed to do so in intact Tilapia kept in isotonic Ringer's solution.Administration of cortisol acetate to intact Tilapia reduced the mean nuclear diameter of interrenal cells. The degree of response was both dose and time dependent. Administration of 0.04 mg/day of deoxycorticosterone acetate for 21 days also significantly reduced the mean interrenal nuclear diameter. Treatment with the same dose of DCA for only 14 days, or with a smaller dose for 21 days, failed to induce interrenal atrophy.These results suggest that a pituitary‐interrenal axis, resembling the pituitary‐adrenocortical axis of mammals, exists in Tilapia mossambica.
The duodenal progenitor population. II. Age related changes in size and distribution
Authors: Thrasher J. D. , Greulich R. C. 
Published: June 2005

AbstractTritiated thymidine (H3‐T) autoradiography has been applied to the duodenal progenitor population (crypts of Lieberkühn) in four age groups of male Swiss albino mice to determine: (1) the size and distribution of the progenitor cell pool; and (2) to characterize the role of individual progenitor cells in previously reported age‐related alterations in the proliferative activity of the population.The progenitor cells which incorporated H3‐T extended from the first cell below the crypto‐villal junction to the last cell (Paneth) at the cryptal base in each age group. However, the majority of labeled progenitor cells were restricted to the central region of the crypt, while a smaller number was found in both the upper and basal portions. Thus, the crypt wall was divided into three zones according to the incidence of labeled cells; (1) zone of minimum cell proliferation (upper region), (2) zone of maximum cell proliferation (central region), and (3) zone of Paneth cells (basal region). The labeling incidence of the maximum zone was 3–5 times that of the minimum or Paneth regions.Comparison of the labeling incidence at the different ages revealed an age‐related decrease in the overall frequency of labeled cells throughout the crypt, and particularly in the maximum zone. Estimations of the progenitor cycle duration from the ratio of S‐phase duration to the DNA synthetic index revealed an increase in the progenitor cycle duration with age. It appears that the cycle duration increase, rather than a decrease in the size of the functional progenitor pool, may be the reason for theage‐related change in the proliferative activity.The labeling frequency of progenitor cells was least (about 1%) at the cryptovillal junction and highest (about 50%) in the central region of the crypt. It is concluded that factors in the microenvironment of the duodenal epithelial cell population may be regulating the proliferative activity of the progenitorcells.
Comparative responses of regulative and determinate embryos to metabolic inhibitors
Authors: Markert Clement L. , Cowden Ronald R. 
Published: June 2005

AbstractThe developmental responses of embryos of the tunicate, Ascidia nigra, and the sea urchin, Lytechinus variegatus, to an assortment of antimetabolites was determined by microscopical observation of gross and cellular morphology and by cytochemical tests on sectioned embryos for DNA, RNA, and protein. Actinomycin D, puromycin, and analogs of amino acids and nucleic acid constitutents were all tested in sea water cultures of the two types of embryos, one determinate and the other regulative in developmental behavior. The response of these embryos suggests that the principal synthesis of ribosomes and proteins occurs abruptly at the onset of metamorphosis in Ascidia nigra embryos and more gradually and at earlier stages in Lytechinus embryos. RNA synthesized prior to gastrulation may be messenger RNA, but this RNA is probably not responsible for the determinate properties of ascidian blastomeres since these properties appear earlier, by the 4 to 8 cell stage. The regulative sea urchin embryos were somewhat more sensitive to the antimetabolites used but their responses were similar to those of ascidian embryos.
A comparative study of the responses of mammary tissues from several mammalian species to hormones in vitro
Authors: Barnawell Earl B. 
Published: June 2005

AbstractPrelactating mammary tissues from five mammalian species (laboratory rat, guinea pig, hamster, rabbit, dog) were maintained in organ culture in the presence of insulin, corticoids and ovine prolactin (mammotropin — MH) and/or bovine growth hormone (somatotropin — STH). MH stimulated secretion in all but one species; however, any apparent secretory effect of STH could be accounted for by contamination with MH. Accordingly, these mammals did not demonstrate the interchangeability of MH and STH established for some mouse strains. There are species differences in mammary sensitivity to MH: dog and rabbit are most sensitive, hamster and rat are less sensitive, and guinea pig was unresponsive. No difference in response between Long‐Evans and Sprague‐Dawley rats was detected.Mammary tissues from the dog, guinea pig and rabbit showed some ability to survive in the unsupplemented synthetic medium “199” whereas tissues from the other two species showed little or no viability. Supplementation of the medium with insulin results in improvement in survival of mammary tissues from all species. The further addition of corticosteroid (aldosterone, cortisol or corticosterone) leads to greater augmentation of survival in tissues from all five species, with some indication that the gluco‐corticoid principally characteristic of the species concerned was more effective than the others.
Growth and differentiation in hydra. I. The effect of temperature on sexual differentiation in hydra littoralis
Authors: Park Helen D. , Sharpless Norman E. , Ortmeyer Anne B. 
Published: June 2005

AbstractHydras cultured for long periods at constant temperature (23°, 21°, 18°, 15°, 10°, or 5°C) were exposed to a new, higher or lower temperature for four weeks.It was found that at constant temperature, the percentage of hydras entering sexuality and the duration of the sexual periods decreased with decreasing temperature. There was no sexual differentiation at 5°.No hydras became sexual within four weeks after a decrease in temperature.The results of the temperature rise experiments show that, in general, the percentage of hydras entering sexuality depended on the absolute temperature change. The results indicate that this percentage also depended on the initial and final temperatures.An hypothesis is presented, accounting for sexual differentiation in terms of a temperature effect on an initiator and an inhibitor.
The localization of α‐hydroxy acid oxidase in renal microbodies
Authors: Allen John M. , Beard Margaret E. , Kleinbergs Skaidrite 
Published: June 2005

AbstractThe enzymatic properties and cellular localization of α‐hydroxy acid oxidase have been studied in renal tissue of the rat. The enzyme was most active in the presence of D, L‐ α‐hydroxy valeric acid and D, L‐ α‐hydroxy butyric acid and was inactive in the presence of glycolic acid and D‐alanine. It appeared to have no co‐factor requirement. When subjected to electrophoresis in acrylamide gels, followed by cytochemical development, the enzyme was visualized as a major form accompanied by a minor component. The properties of the major electrophoretic form as determined by cytochemical reaction and densitometric scanning were similar to those determined by quantitative biochemical assay. When subjected to differential centrifugation and density equilibrium centrifugation, particles containing α‐hydroxy acid oxidase sedimented with particles containing D‐amino acid oxidase; α‐hydroxy acid oxidase, therefore, is associated with renal microbodies. The fact that α‐hydroxy acid oxidase transfers electrons to Nitro blue tetrazolium or to Tetra nitro blue tetrazolium made it possible to localize the enzyme by a light microscopic cytochemical procedure. The enzyme was found by this method to be localized predominantly in cells of the proximal tubule. It was present in particles approximately 0.5 μ to 1.0 μ in diameter mainly situated in the basal portions of these cells. These cytochemical preparations probably accurately reflect the cellular distribution of α‐hydroxy acid oxidase and, hence, of those microbodies which contain the enzyme.
Oxidative phosphorylation in the minute mutants of Drosophila
Authors: Farnsworth M. W. 
Published: June 2005

AbstractOxidative phosphorylation was studied in mitochondria isolated from whole 72‐hour larvae heterozygous for nine different Minute mutants with loci on the second and third chromosomes, i.e: M(2)12, M(2)1, M(2)173, M(2)z, M(3)w, M(3)124, M(3)B2, M(3)y and M(3)1. In all Minutes, oxidative phosphorylation was found to be abnormal in that phosphorylation was uncoupled from oxygen uptake to a greater extent as compared to controls. Differences with respect to respiration and/or phosphorylation were also evident between the Minutes themselves. The results strengthen the hypothesis that lesions in oxidative phosphorylation are associated with the Minute phenotype and demonstrate genetic control over this basic cellular process. In addition, if it is assumed that the Minutes are heterochromatic, as believed by many investigators, then the present study indicates a physiological function for heterochromatin.
Development, polarization and regeneration of the ventral iris cleft (Remnant of choroid fissure) and protractor lentis muscle in urodele eyes
Authors: Stone L. S. 
Published: June 2005

AbstractDevelopment of the protractor lentis muscle and the vestige of the choroid fissure, the ventral iris cleft, was studied in Amblystoma punctatum embryos, larvae and young adults. One hundred twenty‐three embryonic eyes in various stages of development were excised, rotated 180° and reimplanted to determine when in development the cleft and muscle become ventrally polarized. In Amblystoma, as the optic cup forms and the ventral region closes, the choroid fissure becomes a deep notch at the mid‐ventral rim of the cup. It remains as a cleft in the iris near the retina as the outgrowing iris obliterates the rest of the fissure. In Triturus v. viridescens the cleft becomes located in the middle of the ventral iris membrane some distance from the ora serrata. The protractor lentis muscle arises from mesenchyme cells at the inner surface of the cornea near the cleft which it enters. In A. punctatum, the polarity of the cleft and muscle is not yet established up to stage 29. From stages 29+ to 33, when the early optic cup is forming, their polarity is labile. Polarity is permanently established soon after at stage 34.After complete ventral iridectomy the cleft reappeared in the regenerated iris. The muscle reappeared in some cases also. Retinal pigment cells locally regenerate the ventral iris and restore to it the capacity to replace a cleft which is similar to the vestigeal structure derived from the choroid fissure.This is another example where dedifferentiated retinal pigment cells restore locally to regenerating tissue the ability to form special structures normal to that region.
Analysis of the vegetalizing action of tyrosine on the sea urchin embryo
Authors: Mastrangelo Molly Fudge 
Published: June 2005

AbstractVegetalization was produced in sea urchin embryos by treatment with D‐ and L‐p‐tyrosine, o‐tyrosine, and m‐tyrosine, for 2 to 6 hours during cleavage. Glycine was without effect on development; phenylalanine produced general effects represented by reduction of both animal and vegetal structures. The vegetalizing action of tyrosine was synergistic with that of lithium or dinitrophenol. However, unlike the latter compounds, tyrosine had no effect on respiratory rate of the embryos.The uptake and the incorporation of algal hydrolysate‐C‐14 and leucine‐C‐14, added to the sea water medium, were lower in sea urchin embryos in the presence of tyrosine or phenylalanine than in untreated control embryos. Inhibition of incorporation caused by phenylalanine was about twice that by tyrosine, and it was postulated that the different effects of these substances on development are related to the degree of inhibition. Neither glycine nor lithium inhibited amino acid uptake.When embryos were treated with tyrosine in the presence of a full complement of those free amino acids normally found in the egg, the vegetalizing effect of tyrosine was annulled. Since the sea urchin depends upon endogenous amino acids for protein synthesis during cleavage, it is suggested that in some way tyrosine limits the endogenous supply of amino acids available for synthesis of the proteins associated with animal structures by inhibiting their release from storage protein.
Origin of the hypoblast in Salmo. I. Does the blastodisc edge turn inward?
Authors: Ballard William W. 
Published: June 2005

AbstractNile blue sulfate stain spots printed upon the teleost blastodisc may penetrate to deep cells. Spots printed upon the periblast just outside the rim of the early blastodisc remain stationary, and when overridden by the spreading disc may transmit their stain to cells of its floor that come progressively in contact with them. Such spots do not give reliable evidence of invagination movements, or of a wheeling‐in of cells that lie inside the cellular envelope though close to the surface. Small spots printed upon the surface at the margin of the blastodisc do not necessarily disappear from the margin, and if they do they cannot subsequently be discovered in the interior. Patterns of chalk particles injected into the blastodisc for the purpose of demonstrating the origin of the hypoblast by a wheeling‐in movement of cells at the rim have produced no such evidence, but show a direct migration of originally internal cells toward the definitive somites. Conclusions drawn from the Salmo fate map and scheme of morphogenetic movements (Pasteels, '36) are not substantiated insofar as they pertain to the origin of the hypoblast and the behavior of cells at the blastodisc rim. There is no inturning of cells to produce the hypoblast, either at the axis or along the germ ring.
Histochemical localization of enzymes in the embryonic chick liver
Authors: Conklin James L. 
Published: June 2005

AbstractOxidative and hydrolytic enzymes were localized histochemically in the developing chick liver and in liver grown as chorioallantoic (CAM) transplants or as explants in organ culture.In the in situ liver, parenchymal cells exhibited an increase in succinate (SDH) and a glycerophosphate (GDH) dehydrogenase activity and a decrease in NADP diaphorase (TPND) during development. NAD diaphorase (DPND) and nonspecific esterase (NSE) activity remained constantly high throughout the period studied. Within the stromal cells, DPND and NSE activity decreased and SDH, GDH and alkaline phosphatase (ALP) increased. The ALP activity of the sinusoidal cells appeared to increase coincident with a redistribution of TPND within the cytoplasm of the parenchymal cells.In CAM transplants, the enzyme activity of all tissues was nearly the same as the five day liver even though the total age of the tissues was 15 days.Liver explants exhibited enzyme activity similar in part to both the 5 and 15 day liver.In both explants and transplants, ALP activity was highest in areas where the parenchymal‐sinusoidal relationship was maintained and absent in areas where the parenchyma and sinusoidal cells were not in contact.
Effects of mammalian hypophysial hormones, placental gonadotrophins, gonadal hormones, and adrenal corticosteroids on ovulation and spawning in hypophysectomized catfish, Heteropneustes fossilis (Bloch)
Authors: Sundararaj Bangalore I. , Goswami Shashi V. 
Published: June 2005

AbstractExperiments were conducted to evaluate the effects of mammalian hypophysial hormones, placental gonadotrophins, gonadal hormones, and adrenal corticosteroids on ovulation and spawning in three‐day hypophysectomized gravid catfish. Of the hypophysial hormones tested (FSH, LH, LtH, STH, TSH, ACTH, and oxytocin), at various dose levels, LH alone consistently induced ovulation and spawning of eggs; administration of 5 mg/fish evoked the best response. The weak response obtained with FSH, STH, or TSH was not due to LH contamination. HCG at a dose level of 100 IU/fish induced ovulation and spawning, whereas in the case of PMS, doses of 250 IU/fish and above were equally effective. None of the gonadal hormones tested (estradiol, testosterone, and progesterone) evoked ovulation or spawning. All the adrenal corticosteroids tested (hydrocortisone, cortisone, and DOCA) proved to be powerful ovulating agents, DOCA (5 mg/fish) being the most effective. These findings indicate that in the catfish, LH and HCG as well as adrenal corticosteroids are effective in inducing ovulation and spawning in three‐day hypophysectomized gravid catfish. The possible mechanisms involved are discussed.
Reciprocal transplantation of eggs between rabbit and ferret
Authors: Chang M. C. 
Published: June 2005

AbstractThirty‐four 2–4 celled ferret eggs were transferred into Fallopian tubes of six 1‐day pseudopregnant rabbits. Two days later ten normal 8–12 celled eggs without mucin coat of 15 transferred to three rabbits were recovered from their tubes and uteri. Four days after transfer none of 19 eggs transferred to the other three rabbits were found, indicating disintegration and disappearance of early ferret eggs in the rabbit uterus.Fifty‐one ferret morulae or blastocysts were transferred into tubes of eight pseudopregnant rabbits. Examined two or four days later, four eggs from tubes were normal and expanded blastocysts. Of 25 eggs from uteri, nine (36%) were expanded and normal but 16 (64%) were expanded and degenerating.Fifty‐eight ferret morulae or blastocysts were transferred into uteri of six 4‐day pseudopregnant rabbits. Examined 2–4 days later all 45 recovered eggs were degenerated, showing incompatibility of ferret blastocysts in rabbit uteri.When 25 1‐day rabbit eggs were transferred into ovarian capsules of three ferrets one and one‐half days after an ovulation inducing injection no cleavage was observed in the eight eggs recovered from tubes and uteri. From 54 rabbit morulae or blastocysts transferred into uteri of six 6‐day pseudopregnant ferrets, all 28 recovered eggs were degenerated and shrunken. No decidual reaction was observed either in rabbit or ferret endometrium.It is concluded that ferret eggs can survive and develop if introduced into the tubes of the rabbit but not into the uterus, whereas rabbit eggs cannot survive if introduced into either the ferret tube or uterus.