bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lymphoid changes during antibody synthesis in larval Rana catesbeiana
Authors: Baculi Buena S. , Cooper Edwin L. 
Published: June 2005

AbstractThymectomy, splenectomy and/or lymphadenctomy affect antibody synthesis to a soluble antigen, hemocyanin, in bullfrog larvae. Tadpoles were divided into seven groups and these into three subgroups: Experimentals— A: operated and immunized by hemocyanin or allografts; Controls—B: operated but non‐immunized; Controls—C: one group unoperated and immunized. With regard to the spleen, good correlation between antibody titer and degree of splenic regeneration was observed. Structurally, the white pulp contained numerous small lymphocytes but in the red pulp, the number of blast cells and lymphocytes increased. The spleen may be the main organ involved in larval antibody synthesis. The lymph glands seem secondary; lymphadenectomized larvae showed no regeneration of lymph glands and antibody titers were lower than in sham‐operated controls. Compensatory hypertrophy of the remaining gland in unilaterally lymphadenectomized larvae was absent. With regard to cell types, lymph glands showed a picture similar to active nodules, i.e., the core of the cords consisted of blast cells and larger lymphocytes surrounded by layers of small lymphocytes. Thymic regeneration occurred in all tadpoles and, of much interest, titers were always highest in this previously thymectomized group. Observations on thymectomized tadpoles suggest a thymus stimulating effect on certain peripheral lymphoid organs, notably the spleen. The thymus in frog larvae may be important in antibody synthesis during later stages when the capacity to develop cellular immunity has already matured.
Experimental studies on a new lethal trait in Mexican axolotls of the Wistar Institute white strain
Authors: Humphrey R. R. 
Published: June 2005

AbstractAn additional lethal gene (y) in white Mexican axolotls of the Wistar Institute stock, first discovered in 1965, is believed to have arisen by mutation only two generations earlier. Larvae homozygous for y develop normally for about two weeks after hatching, and become recognizable at that time by the cessation of growth in the forelimbs. Death occurs at the age of five to seven weeks.Experimental studies (transplantation, parabiosis) suggest that gene y deter‐
mines metabolic deficiencies in all cells of the embryo. Forelimb transplants
produce limbs which cease growth and differentiation and persist as short
stumps which, even though partially replaced by host tissues, lack capacity
for normal differentiation or for regeneration after amputation. Transplants
including Wolffian duct and the primordia of gonad and mesonephros produce
non‐functional mesonephric tubules and gonads in which the germ cells
degenerate and disappear. In parabiosis with a normal cotwin a mutant larva
may be kept alive for several months but shows extensive degeneration and
disappearance of muscle fibers, and eventual loss of gastrointestinal epithelium
and glands, gonads, and mesonephros. The growth of the normal cotwin is
greatly inhibited, probably because its vital organs are overburdened as those
of its lethal partner cease to function. Only one pair reached the age of six
months, with the normal member attaining a length of only 25 mm, one‐fourth
or less the length of normal larvae of that age.
Relationship between pattern of cell migration from the germinal layer and changing patterns of differentiation in the lizard epidermis
Authors: Flaxman B. A. , Maderson P. F. A. 
Published: June 2005

AbstractDuring renewal of the lizard epidermis, the rate of new cell production varies cyclically from a low level (resting stage) to a high level (renewal stage). Renewal involves the formation and shedding of an “epidermal generation” in which cells of the outermost layers synthesize beta keratin whereas cells of the inner layers synthesize alpha keratin. The cells are derived sequentially from a morphologically homogeneous basal layer. Tokay geckos were injected with a single pulse of tritiated thymidine at the end of the resting stage, 24 hours prior to the onset of epidermal renewal. Sequential biopsies were taken and analyzed by radioautography. Twenty‐four hours after the pulse, labeled nuclei were found only in the basal layer. During the subsequent four to five days, both labeled and unlabeled mitoses were present in the basal layer. Although at least seven new layers of cells were added above the basal layer during this same four to five day period, none of their nuclei were labeled. Most of these cells would normally subsequently synthesize beta keratin. The first cells with labeled nuclei emerged from the basal layer after this four to five day delay. These cells would normally go on to synthesize alpha keratin. The labeling index in the basal layer, which was less than 10% at 24 hours after injection, rose to about 50% and fell coincident with emergence of cells destined to form alpha keratin. Thus, these cells must have divided more than once before leaving the basal layer. The studies indicate that the pattern of migration of cells from the basal layer plays an important role in the emergence of a new pattern of differentiation.
Regeneration of sialic acid‐containing components of embryonic cell surfaces
Authors: Collins Michael F. , Holland Karen D. , Sanchez Reynaldo 
Published: June 2005

AbstractSialic acids such as N‐acetylneuraminic acid have been found at the surfaces of various cells. They may play an important role in intercellular adhesion and hence in animal morphogenesis. This work demonstrates sialic acid at the surfaces of seven‐day chick embryo neural retinal cells and its regeneration after enzymatic removal.Neural retinas were excised and dissociated with trypsin. The cells were
incubated in a solution of Vibrio cholerae neuraminidase. The enzymatic treat
ment released sialic acid which was assayed by thg thiobarbituric acid method
of Warren. The enzymatic treatment also reduced the cellular electrophoretic
mobility from 1.1 to 0.4 × 10−4 cm/sec/volt/cm measured in 0.067 molar phos
phate buffer at pH 7.5.Cells which had been treated with neuraminidase were cultured in a modified
Eagle's minimum essential medium for up to 24 hours. During the period of
culture, the replacement of surface material was observed in two ways. First
was the progressive return of electrophoretic mobility to the pre‐neuraminidase
level. Second was the progressive return of sialic acid at the cell surface to the
original level. The latter was shown by second neuraminidase treatments and
determinations of sialic acid released.Effects of neuraminidase upon the reaggregation of cells cultured on a
gyratory shaker in Eagle's medium were investigated. Neuraminidase was not
effective for dissociation of neural retina.
Host‐transplant relationship of cultured mouse embryos
Authors: Fisher D. L. , Smithberg M. 
Published: June 2005

AbstractThe host‐transplant relationship of cultured mouse embryos was studied in mice of strain 129/SvSl. Immature females were superovulated and embryos obtained at the four cell stage were cultured in vitro for 48 hours using Brinster's technic. At the conclusion of the culture period, 80.9% had developed to blastocysts. These were transplanted by direct uterine insertion into one to four day pseudopregnant nulliparous hosts three to seven months of age.Transplants to a one day host are lost 24 hours after transplant. The trans
planted four day old embryos implant and develop into fetuses most success
fully in two day pseudopregnant hosts. The blastocysts are retained in the
uterine lumen for up to 72 hours before implantation. Transplantation to three
day hosts allowed fetal development but at a much lower percentage than with
two day hosts. Blastocysts were found to be retained in the uterine lumen
for up to 48 hours. A very low percentage of transplants to four day hosts did
implant, but no fetal development occurred. It is apparent that a critical
period of adjustment and interdependence between embryonic development
and uterine receptivity is required before implantation of the cultured embryo
can proceed. Embryos which implant develop according to post implantation
age, not embryonic age, and are delivered according to the normal uterine
gestation time.
Sarcomere length increases in developing crustacean muscle
Authors: Govind C. K. , Atwood H. L. , Lang Fred 
Published: June 2005

AbstractMeasurements of sarcomere length in the tonic claw opener muscle and in the tonic (superficial) and phasic (deep) abdominal extensor muscles in crayfish and lobster revealed a two‐fold increase from the time of hatching to the adult stage. Initially sarcomere length is longer in tonic than in phasic muscles and the tonic muscles have a faster rate of increase than the phasic muscles.
Phosphatase active antigens in sea urchin eggs and embryos. II. A comparison between the activities in unfertilized eggs and plutei
Authors: Westin Monica 
Published: June 2005

AbstractPhosphatase activities in sea urchin eggs and plutei were investigated by means of histochemical staining of immunoprecipitates. Two protein fractions were obtained by extraction in a hypotonic medium and by detergent treatment of the residual pellet. Three distinctly different phosphatase activities were discerned, nucleoside diphosphatase (EC 3.6.1.6.), acid phosphatase (EC 3.1.3.2.) and alkaline phosphatase (EC 3.1.3.1.).The nucleoside diphosphatase activity, which was confined to one antigen, was present in both water soluble and detergent extracts and at roughly the same concentration in eggs and plutei. By means of a monospecific antiserum the immunological identity of this antigen was established in all instances.The acid phosphatase activity, which was displayed by ten detergent extracted antigens in eggs, was only found in five detergent extracted antigens in plutei. This decrease in number of enzyme active antigens was also reflected by a general decrease in activity as assessed by quantitative determinations. Furthermore, by means of absorbed antisera it was established that two or three of the acid phosphatase active antigens were “egg specific.” Another acid phosphatase active antigen, which was common to both developmental stages, was investigated by a monospecific antiserum. While this antigen was found in both soluble fractions, it was only enzymatically active when extracted with detergent.Alkaline phosphatase active antigens were only found in the detergent extract of plutei. However, immunoprecipitates with this activity appeared both with antiserum against unfertilized eggs and with antiserum against plutei. This suggests that the egg contained the antigens in an enzymatically inactive form.
Reproductive performance of male and female phenotypes in three sex chromosomal genotypes (XX, XY, YY) in the killifish, Oryzias latipes
Authors: Fineman Robert , Hamilton James , Chase Gary 
Published: June 2005

AbstractThe present study investigates the juvenile and adult reproductive performance of Japanese killifish, Oryzias latipes, which were successfully sex‐reversed by feeding them male or female sex hormones during the fry stage. Sexual maturation of these laboratory grown fish of three known genotypes (XX, XY, YY) occurred earliest in untreated genotypes, next in genotypes treated with male hormone (methyl testosterone) and female hormone (estrone), respectively. The delay in sexual maturation caused by early exogenous, sex‐hormone treatment may represent a disturbance in the delicate neural‐gonadal axis. However, the degree of response was also strongly influenced by the animal's sex chromosomal genotype. XX fish, normally phenotypic females, were affected more by the male hormone than by the female hormone. XY and YY fish, normally phenotypic males, were delayed more by the female hormone than by the male hormone. This specific sex hormonesex genotype interaction also influenced adult reproductive performance (sperm or egg production). Differences in the metabolism of male and female sex hormones by the XX, XY and YY fish are probably responsible for these interesting findings.
Regeneration of the retina in the adult newt, Triturus cristatus, following surgical division of the eye by a limbal incision
Authors: Levine Robert 
Published: June 2005

AbstractThe regeneration of a retina in adult Triturus cristatus, following surgical division of the eye by a limbal incision, was studied. In agreement with recent reports, it was found that the regenerating retina is derived from two sources; the retinal pigment epithelium and the pars ciliaris retinae. However, following a limbal incision, most of the retina appears to be derived from the retinal pigment epithelium in the posterior part of the eye.An unexpected finding of this study was that large cyst‐like spaces form in the fundal region of the eye, between the regenerating retina and the retinal pigment epithelium. These spaces appear between five and eight days postoperative and persist long enough (until 25 to 30 days post‐operative) to disrupt the fundal portion of the regenerating retina and to cause it to lag behind the rest of the regenerate, in its development.The relationship of these observations to the genesis of positional markers in the regenerating retina is discussed.
Morphology and kinetics of spermatogenesis in Xenopus laevis
Authors: Kalt Marvin R. 
Published: June 2005

AbstractThe light microscopic characteristics of spermatogenic stages of the germ cell line in the anuran, Xenopus laevis, have been described as they appear in both nuclear squash preparations and plastic embedded thick sections of intact testes. Tritiated thymidine autoradiography was employed to unequivocally identify stages. Using this methodology, it was determined that the premeiotic DNA synthetic period occurs in a cell which is morphologically indistinguishable from a late secondary spermatogonial cell. In addition, kinetic studies with tritiated thymidine were employed to determine the duration of meiotic prophase and spermiogenesis in Xenopus. Results indicate that at 18°C, the most rapidly maturing cells in the testis spend four days in leptotene, six days in zygotene, twelve days in pachytene, one day in diplotene, one day in meiotic division, and twelve days in spermiogenesis. An estimate for the duration of the premeiotic S stage was indirectly calculated from combined data to yield a value of six to seven days. Pooled spermatocyte counts measuring the frequency of occurrence of individual stages produced results which correlated closely with estimates obtained by tritiated thymidine labelling. Individual counts, however, show wide variations between testes from single animals and between testes from different animals, whether sacrificed together or at different times of the year. Nevertheless, in all cases, both morphology and labelling patterns indicate that spermatogenesis is continuously active. The variation observed in individual testes appears to be the result of waves of non‐random entry of spermatogonial stem cells into the population of cells irreversibly committed to differentiation.
In vivo and in vitro fertilization of hamster, rat and mouse eggs after treatment with anti‐hamster ovary antiserum
Authors: Tsunoda Y. , Chang M. C. 
Published: June 2005

AbstractRabbit antiserum against hamster ovary was examined on agargel diffusion plates against several hamster tissues, and also against rat and mouse ovarian extracts. Unabsorbed anti‐hamster ovary antiserum showed eight to nine precipitin bands for hamster ovary and four to eight bands for other tissue extracts, but no bands against sperm antigens. Anti‐hamster ovary antiserum also showed three to four bands for rat and one to two bands for mouse ovarian extracts.The present experiments confirmed previous reports for the hamster and mouse that treatment of eggs with anti‐ovary antiserum blocked in vitro fertilization and that the extent of the inhibition was related to the formation of a precipitate on the zona pellucida.A single injection of anti‐hamster ovary antiserum inhibited fertilization in mice but not in rats. In vitro fertilization of mouse eggs was also inhibited in the presence of such antiserum.
Inhibition of early postimplantation development of cultured mouse embryos by bromodeoxyuridine
Authors: Spindle Akiko I. 
Published: June 2005

AbstractMouse embryos were treated with 5‐bromodeoxyuridine (BrdUrd) for 24 hours at various preimplantation stages to determine its effect on early postimplantation development. The inhibitory effect of BrdUrd (10−7 to 10−6 M) on trophoblast outgrowth and inner cell mass (ICM) development was least severe when embryos were treated at the 2‐cell stage and was most severe when they were treated at the morula stage. When embryos were treated at the blastocyst stage, the inhibitory effect on trophoblast outgrowth decreased, but that on ICM development remained severe. The severity of inhibition, particularly that on ICM development, appeared to be related to decreased cell numbers in BrdUrd‐treated embryos. However, increasing the cell number by aggregating two ICM's isolated from BrdUrd‐treated blastocysts did not increase their chance of survival or of forming two primary germ layers. This indicates that the decrease in cell numbers alone is not the cause of the failure of BrdUrd‐treated embryos to develop.The mechanism of BrdUrd inhibition was studied by adding thymidine or deoxycytidine during BrdUrd treatments. A 10‐fold excess of thymidine completely protected embryos from the inhibitory effect of BrdUrd. A 10‐fold excess of deoxycytidine was less effective. Autoradiography indicated that both thymidine and deoxycytidine protected embryos by interfering with the incorporation of BrdUrd into the DNA.
Phylogenic distribution of limb regeneration capacity in adult Amphibia
Authors: Scadding Steven R. 
Published: June 2005

AbstractLimb regeneration was studied in 13 adult amphibian species in which regeneration had not previously been investigated. Limb regeneration was not exhibited by four anuran species: Pseudacris triseriata, Hyla squirilla, Hyla crucifer, and Bufo quercicus. Among the adult urodeles studied, normal regeneration was observed in five species: Ambystoma laterale, another Ambystoma jeffersonianum complex species, Eurycea bislineata, Plethodon cinereus, and Plethodon glutinosus. Limb regeneration was absent or heteromorphic in individuals of Siren intermedia and Ambystoma maculatum. Regeneration was not exhibited at all by adult Necturus maculosus, and Ambystoma tigrinum. The phylogenic distribution of limb regeneration capacity, in the 41 species of amphibians for which information is presently available, is reviewed and discussed.
Cell proliferation and renewal in the small intestinal epithelium of metamorphosing and adult Xenopus laevis
Authors: McAvoy J. W. , Dixon K. E. 
Published: June 2005

AbstractIntestinal folds of adult Xenopus laevis are formed by the proliferation of groups of cells in the tadpole epithelium at metamorphosis. As the folds increase in number and in height, mitoses become confined to the troughs and a gradient of decreasing mitotic activity from troughs to crests is formed. This pattern of cell proliferation was confirmed in autoradiographic studies with [3H]thymidine. Migration of cells from the fold troughs to the fold crests was also demonstrated by thymidine autoradiography and the epithelium renewal time was approximately 16 days. Thus cell proliferation and cell specialisation in the small intestinal epithelium of adult X. laevis are inversely correlated.
Spermiogenesis of Nautilus pompilius. I. General survey
Authors: Arnold John M. , Williams‐Arnold Lois D. 
Published: June 2005

AbstractDifferentiation of the spermatids, from secondary spermatocytes to mature spermatozoa in the spermatophores, is described for Nautilus pompilius. Early in development the spermatids have large cytoplasmic bridges which connect groups of cells which remain linked even when the residual cytoplasm is shed. The nucleus undergoes considerable elongation and the nuclear envelope loses its cisterna except in the centriolar fossa and adjacent to the acrosome. Condensation of the chromatin involves formation of dense sheets which run parallel to the long axis of the nucleus and eventually fuse to make a uniformly dense structure. The mitochondria migrate to one pole of the secondary spermatocyte where they apparently fuse to make two large mitochondria which elongate and eventually lie in grooves the whole length of the cylindrical nucleus. The centrioles are composed of nine sets of doublet microtubules and both migrate into the centriolar fossa. A massive manchette is formed which has extensive cross linked microtubules. The acrosome appears to arise from part of the Golgi apparatus and is a complex conical structure at the apex of the mature spermatozoan. The residual cytoplasm is shed by fusion of vesicles apparently derived from the nuclear envelope. Massive amounts of glycogen appear around the head in late spermiogenesis. Proximally, the flagellum has a sheath outside the microtubules which distally breaks up into nine coarse accessory fibers and further distally disappears. Nautilus sperm morphology is compared with the ultrastructure of other cephalopod spermatozoa and it is speculated that the differences found are greater than might be expected if the mechanisms of sperm transfer and fertilization were the only controlling forces determining the evolution of spermatozoan ultrastructure.
Respiratory exchange and transport of oxygen in Nautilus pompilius
Authors: Johansen K. , Redmond J. R. , Bourne G. B. 
Published: June 2005

AbstractRespiratory exchange of oxygen and the role of the hemocyanin‐containing blood in gas transport have been studied in the cephalopod Nautilus pompilius.Nautilu has a blood O2 capacity of 2.30 ± 0.57 vol%. The oxygen affinity is high compared to that of other cephalopods, P50 being 16.9 mmHg at pH 7.45 and 18°C. The n‐value (Hill coefficient) is 2.7 under those conditions. The Bohr factor, Ø, is low (i.e. −0.20). The temperature sensitivity, expressed by Δ, = −9.8 Kcal·MolHCY−1.Average values for circulating blood Po2 are 99.2 (± 31.7 mmHg SD) for arterial and 20.4 (± 12.9 mmHg) for venous blood. Arterial blood is fully O2 saturated while the average venous O2 saturation is about 65%.Direct measurements of ventilation average 296 ml·kg−1·min−1 while breathing rates vary between 40–60 min−1 at 18–20°C. Breathing rates and ventilation increase during locomotor activity and exposure to hypoxic water.The results are compared and analysed with available data for other cephalopods. Nautilus, one species of Octopus and the squid Loligo show ascending transport efficiency for O2 correlated with increasing metabolic rates.