bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibition of thyroxine induced tail resorption in vitro by pituitary grafts from different stages of metamorphosis
Authors: Derby A. 
Published: June 2005

AbstractIt has been previously demonstrated that isolated pieces (discs) from the tail fins of tadpoles (R. pipiens), survive in vitro for several weeks and respond to thyroxine by undergoing resorption. In addition, discs into which tadpole pituitary glands have been implanted or discs that have been injected with either prolactin or growth hormone undergo a delayed pattern of resorption on expsoure to thyroxine when compared to discs treated with thyroxine alone.Pituitaries were taken from early prometamorphic, climax and froglet stages and were implanted into tail discs cut from tadpoles in early prometamorphosis. These discs were maintained in thyroxine solutions. As controls, unimplanted discs were treated with thyroxine or maintained in Hanks solution. In a second series of experiments, tail discs were cut from tadpoles at progressive stages of prometamorphosis and treated with thyroxine solutions.The results demonstrate that pituitaries taken from different stages in the life cycle of this animal differ in their capacity to inhibit thyroxine induced tail resorption. The most effective inhibition is demonstrated by early prometamorphic pituitaries, followed by climax pituitaries. Froglet glands exhibit little activity. The results also demonstrate that the response of tail tissues to thyroxine increases during early prometamorphosis and with increasing rapidity during the last third of this period. These results are in harmony with the concept that amphibian metamorphosis may be dependent upon a bihormonal system in which thyroid hormone promotes while a prolactin‐like hormone counteracts this process.
Histopathology of skin allograft rejection in larval Rana catesbeiana
Authors: Baculi Buena S. , Cooper Edwin L. 
Published: June 2005

AbstractFirst‐ and second‐set skin allografts were exchanged and single autograft controls performed in American bullforg larvae at 25 ± 1°C. Rejected allografts, along with lymph glands, thymus, spleen, liver, kidney and intestine, were examined for histopathologic changes. First‐set survival times showed a range of 18–23 days and rejection was initiated by dissemination of pigment cells throughout the epidermis. Breakdown of the epidermis and invasion of the dermis by lymphocytes and fibroblasts began during the first week. Concomitant with breakdown during the second week, re‐epithelialization of the graft periphery and formation of a new, highly cellular dermis occurred. The dermis was the last to be destroyed, which prior to its destruction appeared initially as a thick, homogeneous, eosinophilic, almost acellular mass, gradually replaced by a cellular connective tissue. Increased numbers of mitoses, large lymphocytes and blast cells appeared in the lymph glands, spleen and liver prior to cellular infiltrations of allografts; small lymphocytes, however, still predominated. Eosinophils became prominent in the epidermis, kidneys and liver during the early stages of rejection.Second‐set survival ranged from 7–10 days and rejection was much more abridged with less congestion. Although the onset of rejection was variable, once it was initiated the process went to completion acutely. Lymphocytic and fibroblastic reactions were more intense than in first‐set rejection; small lymphocytes were quite prominent in lymph glands, spleen, liver and intestine. Lymphoid follicles in the liver and intestinal wall were generally larger than in the first‐set group. All control autografts were normal, intact skin; the control sections through intestines showed very minimal lymphocytic accumulations.
Histology and ultrastructure of untreated forty‐eight‐hour canine renal transplants
Authors: Lemanski Larry F. , Bertke Eldridge M. 
Published: June 2005

AbstractThe histology and ultrastructure of 48 hour renal transplants between unrelated canines was studied. Included in the investigation were eight normal, four autografted, and four allografted kidneys. The autografted organs showed no histological or ultrastructural changes when compared to normal contralateral controls. Light microscopy of the 48 hour allografts revealed extensive leukocytic infiltration and general cellular disruption with accumulations of lipid material and desquamated cytoplasm. Ultrastructural changes in glomeruli of allografted organs included thickening of the capillary basal lamina, enlargement and fusion of podocyte processes, accumulation of debris in the capillary lumens, and increase in blood platelets within the capillaries. Cells of both proximal and distal convoluted tubules showed mitochondrial swelling and disruption, cytoplasmic vacuolization, and accumulations of lipid material. Evidence of endothelial disruption in intertubular capillaries was observed. No changes were observed in the loops of Henle, collecting ducts or larger blood vessels. The results showed that tissue destruction reached an irreversible state by the 48 hour stage of allografting. The presence of plasma cells at this early stage implicated them in the rejection reaction.
Changes in level of activity of NAD‐dependent and NADP‐dependent isocitrate dehydrogenases during the development of the chick spinal cord
Authors: Burt Alvin M. 
Published: June 2005

AbstractThe specific activities of threo‐Ds‐Isocitrate:NAD oxidoreductase (E.C.1.1.1.41; NAD‐ICDH) and threo‐Ds‐Isocitrate:NADP oxidoreductase (E.C. 1.1.1.42; NADP‐ICDH) were measured in the brachial spinal cord of chick embryos ranging in development from 3.5 to 21 days' incubation. The activity of NAD‐ICDH increased gradually throughout the developmental period studied and appeared to be similar ontogenetically, with other enzymes of the citric acid cycle. The ontogenetic pattern of NADP‐ICDH, on the other hand, was quite different. The enzymatic activity increased rapidly from 3.5 to 7 days' incubation and then increased at a slower rate throughout the remainder of development. The temporal changes in activity of both enzymes are discussed in relation to other enzymes of intermediary carbohydrate metabolism and to the processes of neuroblastic growth and differentiation. The results of this study suggest that NADP‐ICDH is the major source of reduced NADP for the reductive syntheses associated with neuroblastic growth and differentiation whereas glucose‐6‐phosphate dehydrogenase and the pentose cycle provide the major source of NADPH during the preceding period of rapid proliferation and early differentiation.
Sperm migration prior to fertilization in the hydroid Gonothyrea loveni
Authors: Miller Richard L. 
Published: June 2005

AbstractThe medusiform, gamete‐bearing sporosacs (meconidia) of Gonothyrea are pushed out of the gonangium but remain attached to its distal end. The female meconidium is known to secrete a substance capable of attracting the sperm chemotactically. If sperm approaching the female meconidium pass close enough to one of its tentacles, they stick to the tentacle by their tails and appear to be suspended a few microns above the surface of the tentacle ectoderm cells. They then begin to migrate along the tentacle, eventually arriving at the base where they can enter the meconidium. The direction of movement while on the tentacle surface cannot now be directly related to the source of the chemotactant. The propulsive source is the sperm flagellum, though the beat is markedly suppressed over most of its length. An extracellular surface coat is probably responsible for both the adherence to the tentacle and the suppression of motility of the flagellum. Comparative tests using other genera show that the sperm of Campanularia flexuosa does not stick to the female Gonothyrea meconidium tentacles, but those of C. calceoliferaa do. The specificities are maintained in the reverse case, as well as when active extracts are used against the sperm.
Differentiation of ganglionic cells in Hydra
Authors: Davis Lowell E. 
Published: June 2005

AbstractThe differentiation of ganglionic cells in Hydra has been studied at the level of the electron microscope. These cells originate solely from interstitial cells and not from pre‐existing nerve cells. In addition, the evidence suggests that ganglionic cells do not represent a stage in the development of other nerve cells, i.e., neurosensory and neurosecretory cells. Some of the major cytoplasmic changes in fine structure during differentiation include the formation of neurites, development of Golgi complexes, the appearance of microtubules throughout the neurites, the presence of numerous ribosomes, most of which eventually disappear during development. It is believed that the three types of neurites described may reflect different forms of basically one type of neurite.
Effects of temperature on the kinetics of malate dehydrogenases in the developing eggs and adult muscle of Ascaris lumbricoides (Nematoda)
Authors: Barrett John , Fairbairn Donald 
Published: June 2005

AbstractThe effects of temperature on the kinetics of the different cytoplasmic malate dehydrogenases which are present during the life cycle of Ascaris lumbricoides were studied. Aerobic development of the eggs occus below 32°C, whereas anaerobic energy metabolism in adults occurs at 38–40°C. Eggs developed for one day have one cytoplasmic MDH (MDH‐1), fully developed infective 21‐day eggs have 3 dehydrogenases (MDH‐1, 2, 3) and adult muscle has the same three isozymes but in proportions favoring MDH‐2 and 3. Values for Vmax, energy of activation, and the thermal stability of the total enzyme or of individual isozymes were not clearly correlated with temperature changes occurring during the life cycle. In contrast, the apparent Michaelis constants (Kma) were directly correlated. The Kma of MDH‐1 and MDH‐3 passed through minima at 25°C and 38°C, respectively; the Kma of MDH‐2 showed no clear minimum. The distribution of the isozymes during development was such that the Kma of total malate dehydrogenase at one day, 21 days, and in adult muscle was minimal at 25°C, 30°C, and 38°C, respectively. The result are considered in terms of epigenetic adaptation, i.e., malate dehydrogenase in one‐day eggs and adult muscle is adapted to function efficiently at temperatures normal to those stages, whereas infective eggs also possess large amounts of isozymes which are probably only functional during the succeeding stages of development.
Protein biosynthesis after lens rotation: An immunoelectrophoretic analysis in the chick embryo
Authors: Génis‐Gálvez J. M. , Castro J. M. 
Published: June 2005

AbstractAn experimental, immunological analysis was performed to observe whether induced fiber cell formation in the chick lens can be correlated with the biosynthesis of a specific crystallin. As a result of lens inversion, epithelial cells abruptly elongate. In these elongated cells crystallin determinants were uniquely predominant These results seem to indicate that the quiescent genome of lens epithelial cells can be activated with an appropriate artificial stimulus. Moreover, biosynthesis of delta crystallin, at least initially, seems to be strongly correlated with morphological features of lens fiber differentiation.
Regeneration in the sea cucumber Leptosynapta. II. The regenerative capacity
Authors: Smith Gerald N. 
Published: June 2005

AbstractThe dependence of survival and regeneration in the holothuroid Leptosynapta crassipatina (Apoda) on the oral complex—the mouth, the nerve ring, the calcareous ring, and the water vascular system—was investigated. The effect of surgical deletion of parts on survival and regeneration was determined. In isolated sections of the oral complex, the disk including the nerve ring and calcareous ring was able to survive and regenerate. Even small fractions of this disk began regeneration. Regeneration capacity and survival capacity were tested independently by deletion of parts from half animals. Regardless of the deletion, normal morphallactic posteriad regeneration occurred in animals surviving beyond five days. This was true even when the entire oral complex was deleted. Thus, no part of the oral complex is necessary for regeneration of posterior parts.Survival of a high percentage of the population was restricted to populations lacking a coelomic cavity (i. e., isolated pieces of the oral complex), or to those with a complete water vascular system. Simple section of the connection between the tentacular ampullae and the water ring leads to death in all animals with a coelomic cavity. A role for these parts in oxygenation of the coelomic fluid is suggested.Finally, the ability of the organism to regenerate deleted parts was tested. Missing parts posterior to the oral complex can be regenerated. In addition, lateral parts of the oral complex and the tentacles can be regenerated. Regeneration away from the disk containing the calcareous ring and the nerve ring always occurs. Regeneration towards this disk never occurs.
The Hi agglutinogen of chickens: Basis for cell transformations
Authors: Scheinberg S. L. 
Published: June 2005

AbstractInvestigations on the Hi substance, a red cell agglutinogen of chickens were continued. The objective was to understand the nature of the cyclic changes which red cells possessing the Hi substance undergo. It was postulated that in Hi birds the erythrocyte precursor cells possess the Hi agglutinogen; that binding of serum proteins to estrogen occurs in laying hens and in birds injected with estrogen and that the attachment of serum protein to the Hi sites of young cells results in non‐reactive cells. Support for the hypothesis was obtained in a variety of tests. Red cells were found to be reactive with anti‐chicken IgG in agglutination tests and red cells of estrogen injected birds were less reactive than non‐injected birds. Young cells from a non‐injected male were more reactive with Pisum arvense than the total red cell population with the converse the case with anti‐IgG. It was also possible to inhibit the agglutinability of embryonic cells for Pisum arvense by coating such cells with plasma from the embryo's male parent. This coating can be inhibited by molecules that specifically inhibit the in vitro agglutination reaction with Pisum arvense, i.e., D‐melezitose. The attachment of IgG therefore specific for Hi sites.
Expression of the paternal genes for glutamate‐oxaloacetate transaminase (GOT) during embryogenesis in Xenopus laevis
Authors: Johnson Kurt E. , Chapman Verne M. 
Published: June 2005

AbstractGenetic differences in soluble glutamate‐oxaloacetate transaminase (GOT) electrophoretic mobility have been used to determine the time of expression of paternal genes in Xenopus laevis embryos. Maternal isozymes in unfertilized eggs persist through the first two days of development. Paternal‐type bands appear at three days of development when embryos are Stage 37 (gill circulation). The time of expression of paternal GOT genes appears to occur at the same stage as in R. pipiens ♀ × R. palustris ♂ hybrids. These results are discussed in terms of the genomic control of early amphibian development.
Regeneration of locally irradiated salamander limbs following superficial skin incisions or nerve transection
Authors: Conn H. , Wessels S. , Wallace H. 
Published: June 2005

AbstractIt is well known that prior local irradiation inhibits the ability of larval salamanders to regenerate an amputated limb, and that implantation of various non‐irradiated tissues at the site of amputation restores this ability. Neither wounds in the irradiated region, nor wounds in the non‐irradiated shoulder, promote regeneration. A superficial slit in the skin stretching from non‐irradiated tissue to the irradiated site of amputation, however, restores the ability to regenerate. It is presumed that non‐irradiated cells migrate down the slit during wound‐healing and are thus present at the site of amputation and stimulate regeneration.Transection of the nerve roots following local irradiation of the limb permits a regrowth of non‐irradiated axons into the irradiated limb. Such limbs recover both sensory and motor co‐ordination and the ability to regenerate. Non‐irradiated sections of nervous tracts (axons, Schwann cells and connective tissue sheaths) also promote regeneration when transplanted into irradiated limbs.Since a nerve supply is almost always needed for limb regeneration, yet an irradiated nerve is sufficient for this purpose, no special sensitivity of nerves to x‐rays is implied by these experiments. The normal function, regrowth and trophic effects of axons appear to be unimpaired by exposing the entire neuron to doses of irradiation that inhibit limb regeneration.
Effects of gonadotropins and testosterone on the testes of prepubertal mice
Authors: Hitzeman Sister Jean Walter 
Published: June 2005

AbstractPituitary follicle‐stimulating hormone FSH supports the synthesis of testicular proteins prior to the onset of spermatid formation. Supplementary FSH enhances the activities of certain enzymes that generate reduced nicotinamide adenine dinucleotide phosphate (NADPH) and induces the division and differentiation of Leydig cell precursors. In addition, exogenous FSH counteracts the effects of continued treatment with testosterone on Leydig cells up to the third week postpartum and offsets the effects of the steroid on the weights of the prepubertal testis and seminal vesicles. In its antagonism of testosterone and its activation of glucose‐6‐phosphate dehydrogenase (G6PDH), FSH clearly differs from the interstitial‐cell‐stimulating hormone ICSH during the first wave of spermatogenesis in the mouse testis.
An analysis of the formation of ciliary primordia in the hypotrichous ciliate Urostyla weissei. II. Results from ultraviolet microbeam irradiation
Authors: Jerka‐Dziadosz Maria 
Published: June 2005

AbstractLocalized UV irradiation and protargol staining were used to study the development of cirral primordia during regeneration of the promers of Urostyla weissei. The aim was to analyze the role of preexisting structures in the formation of primordia.The preexisting frontal cirri were removed by UV irradiation and formation of a new ciliary streaks was observed. When one of the disaggregating old cirri was removed the rest dedifferentiated normally and in the precise place where the irradiated cirrus had been several new kinetosomes appeared. Thus, the formation of these kinetosomes does not depend on the presence of preexisting ciliature at this site. The results provide further support for the hypothesis of integrated cortical activation combined with localized competence of formation sites.
Fine structure of the neural fat‐body sheath in the stick insect and its physiological significance
Authors: Huddart Henry 
Published: June 2005

AbstractThe interganglionic connectives of the stick insect ventral nerve cord are surrounded by a fat‐body sheath, additional to the glial layer, perineurium and neural lamella found in other insects. The sheath is composed of a series of single‐cell lobes, bound together by an extracellular lamella of collagen fibrils in a mucopolysaccharide matrix. Each sheath cell contains a storage area of glycogen granules, fat‐droplets and protein secretory granules, and a secretory area with abundant granular endoplasmic reticulum which produces the protein granules. The fat‐body sheath appears to actively regulate the electrolytes in the extraneural space within the sheath. The low sodium and high potassium of the haemolymph, which are unfavourable for normal central nervous system activity, appear to be regulated in the extraneural space to surround the nerve elements with a fluid more favourable for impulse conduction. The presence of the fat‐body sheath is almost certainly related to the unusual haemolymph composition in the stick insect, and similar diffusion barriers may well be present in other herbivorous insects of unusual haemolymph composition.
Reciprocal fertilization between the ferret and short‐tailed weasel with special reference to the development of ferret eggs fertilized by weasel sperm
Authors: Wu J. T. , Chang M. C. 
Published: June 2005

AbstractEpididymal spermatozoa of short‐tailed weasels (Mustela erminea) were inseminated into the uterine horns of ferrets (M. furd) and vice versa. When examined 46 hours to six days after injection of HCG for the induction of ovulation, 67 of 86 ferret eggs (78 %) were fertilized by weasel spermatozoa as shown by the enlargement of sperm head, formation of pronuclei, and the cleavage of eggs. The number of chromosomes in a few mitotic plates of cleaving eggs was much smaller than the diploid number of both the ferret and weasel. Implantation of ferret eggs fertilized by weasel spermatozoa occurred on days 13–14, similar to the ferret but different from the long delayed implantation in the weasel. On days 24–28 only seven of 39 implantation sites (18%) from six ferrets contained hybrid fetuses of varying sizes, which were much smaller than ferret fetuses. A nearly full‐grown hybrid fetus was obtained on day 42 from one of three ferrets, but no young was born from another three animals kept to day 54. Weasel eggs could be fertilized by ferret spermatozoa but their developmental potential was not determined.
Fertilization of frog body cavity eggs enhanced by treatments affecting the vitelline coat
Authors: Elinson Richard P. 
Published: June 2005

AbstractAmphibian eggs which have not been coated with jelly in the oviduct (body cavity eggs) are not fertilized when placed with sperm. When body cavity eggs of the frog Rana pipiens were briefly treated with trypsin and then inseminated in a water‐extract of the jelly (egg‐water), however, high frequencies of fertilization were obtained. A low frequency of fertilization of trypsin treated eggs but not of untreated eggs was obtained even in the absence of egg‐water. Similar results were obtained when eggs were pretreated with cyanide. Both trypsin and cyanide produced a visible weakening of the vitelline coat, the extracellular coat surrounding a body cavity egg. When a rip was made in the vitelline coat and the eggs were inseminated in egg‐water, fertilization occurred. The success of these three pretreatments in producing fertilization of frog body cavity eggs strongly suggests that the vitelline coat is a block to fertilization of these eggs.The fertilized body cavity eggs exhibited considerable difficulty in completing
gastrulation. Those that began neurulation often had abnormalities of the pos
terior end. However, tadpoles that appeared to be normal could be raised from
fertilized body cavity eggs.
Localization of phosphatase activity on the membranes of the mammalian sperm head
Authors: Gordon Mildred 
Published: June 2005

AbstractEpididymal and ejaculated rabbit sperm and ejaculated human sperm were incubated at pH 7.0 and pH 9.0 to test for phosphatase activity. With the substrates tested, ATP, ADP, AMP, ITP, p‐nitro‐phenyl phosphate, and glucose‐6‐phosphate, enzymes capable of dephosphorylating ATP at pH 7.0 were localized on the periacrosomal portion of the plasmalemma in epididymal but not in ejaculated sperm. The enzyme was active without divalent cations. In both epididymal and ejaculated sperm the outer membrane of the acrosome was reactive at pH 9.0 with ATP and Ca++. These strikingly different properties of the phosphatases on the plasmalemma and acrosome membrane indicate that the enzymes may be adapted to respond to particular environmental stimuli and function in tandem to bring about the capacitated state and acrosome reaction. The fact that the plasmalemmal enzyme could not be elicited in ejaculated sperm suggests that seminal plasma may contain an inhibitor for this enzyme which is removed in utero. Calcium ions are necessary for activation of acrosomal proteinases. During capacitation in the uterus, the plasmalemmal psphatase may move exogenous Ca++ into the cytosol surrounding the acrosome, thus stimulating the acrosomal membrane enzyme which may then transport Ca++ into the acrosomal vesicle. Calcium ions may also bind the plasma lemma to the outer acrosome membrane and so prepare the membranes for the acrosome reaction.