bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphatases in the neurones of Locusta migratoria
Authors: Lee Rosemary S. 
Published: April 2021

ABSTRACT
Frozen sections of motor neurones in the thoracic ganglia of Locusta migratoria were treated for thiamine pyrophosphatase activity and for acid phosphatase activity. The TPPase-positive bodies range from 0·5 to 1·25 μ. diameter and appear to be the small, membrane-bound inclusions described by Ashhurst and Chapman (1962) in their electron-microscope work; these are the smaller lipochondria of Shafiq (1953). The acid-phosphatase-positive bodies range from 1 to 2·5 μ diameter and seem to be the lamellar aggregates described by Ashhurst and Chapman that are very similar to γ-cytomembranes, and which are the larger lipochondria of Shafiq. It is concluded that the enzyme content of the γ-cytomembranes is very different in this cell from their content in the vertebrate neurone, and doubt is thrown on the usefulness of TPPase activity as a marker for the Golgi apparatus in invertebrate tissue.
An adrenergic nervous system in sea anemones
Authors: Dahl Erik , Falck Bengt , Mecklenburg Claes Von , Myhrberg Harry 
Published: April 2021

ABSTRACT
A new method for the demonstration of certain mono-amines by means of fluores- cence microscopy was applied to the tentacles and oral disk of the sea anemones Metridium senile and Tealia felina.
A fluorescent substance was found in the cells and fibres of the tentacular ecto- dermal nervous system.
This nervous system probably has a double sensory and motor function.
Localization of enzymes in certain secretory cells of Helix tentacles
Authors: Lane Nancy J. 
Published: April 2021

ABSTRACT
Secretory cells in the optic tentacles of the snails, Helix aspersa and H. pomatia, have been investigated for the cytoplasmic localization of certain enzymes. The collar cells, considered to be neurosecretory, and the lateral oval cells, were those examined. Acid phosphatase activity is found in the cytoplasm of both cells, in scattered spheroids called the β-bodies. This enzymatic activity indicates that the β-bodies may be lysosomes, as does their ultrastructural appearance. In the 2 cell types, the activity of both alkaline phosphatase and thiamine pyrophosphatase is localized in crescentic bodies considered to correspond to the Golgi lamellae, and in some of the β-bodies. The latter enzyme also exists in the cortices of the a-bodies which, like the β-bodies, are lipid-containing globules. The activity of both cytochrome oxidase and succinate dehydrogenase is found, not only in granules, rods, and filaments interpreted as the mitochondria, but also on the cortices of some or all of the β-bodies. It is concluded that in invertebrates, the lipochondria may be the sites of activity of many different enzymes which in vertebrates are restricted to distinct cell organelles.
Electron microscopy of the ovary of Fasciola hepática
Authors: Gresson R. A. R. 
Published: April 2021

ABSTRACT
The external wall of the ovary of Fasciola hepática is a membrane-like structure in contact with a non-cellular material in the ovary. An intercellular region containing an amorphous material of moderate electron density is present in the ovary. The primary oocytes are provided with peripheral processes that extend into the intercellular region. The oocytes do not proceed beyond the prophase of the first meiotic division until after they leave the ovary. The nucleolus of the primary oocyte contains vacuole-like areas and emits granular material to the nucleoplasm; some of this material may move to the cytoplasm. Pores are present in the nuclear envelope. In older oocytes narrow bridge-like structures connect the nucleolus and the nuclear envelope. The nuclear envelope of the primary oocyte undergoes replication. It is continuous with the endoplasmic reticulum and the plasma membrane. The location of the mitochondria is correlated with the phases of growth of oogonia and oocytes. The mitochondria possess irregularly arranged cristae. Small, round or oval nutritive bodies are present in the peripheral cytoplasm of older oocytes. It is suggested that areas of relatively high density containing vacuole-like structures represent the Golgi complex.
The effect of certain fixatives on particles of a globular protein: an electron-microscopical study
Authors: Deutsch K. , Fischer E. , Krause W. 
Published: April 2021

ABSTRACT
Particles (regarded as molecules) of bovine serum albumin have been studied by electron microscopy both in the untreated state and after fixation with osmium tetroxide, formaldehyde, and potassium permanganate. All three fixatives, especially potassium permanganate, increased the density of the particles considerably.
The giant mitochondria of ctenophore comb-plates
Authors: Horridge G. A. 
Published: April 2021

ABSTRACT
The elongated cells which bear the continually active giant cilia of the combs contain numerous large mitochondria, up to 8 μ by 6 μ in size, which are filled with irregular tubular cristae. The ciliated cells are up to too p long, but only io p wide, and from their centrally situated nucleus can be traced a succession of stages, tentatively interpreted as the formation, growth, erosion, and final dissolution of mitochondria. Small ones occur near the nucleus in the region of the nuclear membrane, which may there be irregular, puffy, and electron dense. Some small mitochondria are surrounded by amorphous material which stains heavily with lead ; others lie against the nuclear membrane, as if in intimate relation with it. Cristae of mitochondria which are interpreted as juvenile are filled with an amorphous material ; some of the cristae open to the outside of the mitochondrion. Towards the ciliated end of the cells the appearance of the mitochondria suggests that they are breaking down; this is the region where food particles are eroded and where the cilia consume energy. Here the mitochondria are shrunken and around them are numerous vesicles ; their cristae are fewer and they open into the cytoplasm. Similar vesicles, which are apparently of mitochondrial origin, are extruded between the cilia from the cells. The proposed cycle of generation and disintegration of mitochondria, based upon morphology, is so far an unproved hypothesis.
Nucleolar changes in differentiating myoblasts
Authors: Ross K. F. A. 
Published: April 2021

ABSTRACT
Unlike most embryonic cells, myoblasts do not normally divide when they undergo differentiation to form ‘muscle straps’ and subsequently muscle fibres. Their nuclei retain their individuality, and consequently this material is particularly suitable for studying the fate of nucleolar material during a process of cell differentiation.
Measurements were therefore made with an interference microscope on the nucleoli of living chick myoblasts in tissue culture preparations ; and values for their volume, dry mass, and % solid content were obtained at three distinct stages of the differentiation process, the uninucleate stage, the binucleate stage, and the multinucleate stage. It was found that the nucleoli of binucleate myoblasts had, on the average, less than half the dry mass and less than half the volume of the nucleoli of the uninucleate cells. The changes in the volumes of the nucleoli were especially striking, and it was subsequently demonstrated, by means of sequences of photomicrographs of myoblasts in developing cultures, that, during the process of association and probable fusion of two uninucleate myoblasts to form a binucleate cell, one or more of the nucleoli can be observed to shrink visibly in their linear dimensions.
As an explanation of these results it is suggested that, during the process of differentiation and tissue building characterized by the association and apparent fusion of two myoblasts, relatively large amounts of RNA or RNP may pass from the nucleoli into the cytoplasm so that the nucleolar material becomes temporarily depleted ; and that subsequently, after the cells have joined, this regains its former level. Some support for this suggestion was provided by the finding that the mean values for the dry mass and volume of the nucleoli in the multinucleate myoblasts were intermediate between those of the uninucleate and binucleate myoblasts, because the multinucleate cells are the product of both recent and less recent fusions of cells.
Chitin lamellogenesis in locust cuticle
Authors: NEVILLE A. C. 
Published: April 2021

ABSTRACT
The organization and functions of cuticular lamellae, a structural feature common to all arthropod skeletons, have been studied by growth experiments analysed with the polarizing light microscope. Use has been made of the daily incremental growth of locust solid endocuticle, in which morphogenesis of chitin lamellae (lamellogenesis) can be experimentally altered by varying light and temperature at the time of deposition. Locust endocuticle is all deposited after ecdysis and is composed of alternating night zones (lamellate) and day zones (non-lamellate), distinguishable morphologically, histochemically, mechanically, and morphogenetically. Chitosan tests, confirmed by chromatography, show that the lamellae contain chitin. Endocuticle grown in constant light at constant temperature is non-lamellate; it still contains the same proportion of chitin as normally lamellate cuticle, indicating that lamellogenesis is mainly a periodic process of permanent change in organization of chitin crystallites, occurring at deposition.
Lamellogenesis in solid cuticle is independent of chitin synthesis and of chitin pore-canal fibril formation. Swelling, mechanical, and form-birefringence tests combined with histological observations show that lamellate cuticle is structurally more highly organized but less well oriented than non-lamellate cuticle. One possible function of lamellae is in stabilizing the three-dimensional chitin framework. Normally in night conditions each chitin lamella is individually determined within about 30 min, and lamellae are continuous over large areas of cuticle. The structure and formation of chitin lamellae in locust solid and rubber-like cuticles are compared. Threedimensional birefringence analysis of the locust hind tibia has revealed three chitin components: (1) chitin lamellae with the chitin crystallites oriented predominantly parallel to the plane of the cuticle surface ; (2) chitin pore-canal fibrils, running radially through the cuticle; (3) chitin fibrils oriented longitudinally along the leg axis. Of these, the lamellae and longitudinal fibrils can be morphogenetically altered by suitable techniques.
The Phylogeny of the Stomach-Infusorians of Ruminants in the Light of palaeontological and parasitological Data
Authors: Dogiel V. 
Published: April 2021

ABSTRACT
1. The members of the family Ophryoscolecidae exhibit several (5) grades of progressive evolution.
2. An analysis of distribution of different species and genera of Ophryoscolecidae indicates the course of evolution of the family in the several branches of Ruminants where these Infusorians have been sufficiently studied; these branches are: family Camelidae and families Cervidae and Bovidae.
3. A comparison of the distribution of different Ophryoscolecidae with the palaeontological occurrence of their hosts leads to the conclusion that the genera of Ophryoscolecidae arose at different periods, the more complicated ones appearing later than the simpler.
4. The genera Entodinium and Anoplodinium seem to date from the Eocene, while Eudiplodinium and Epidinium appeared only in the Oligocene; the genus Ostracodinium is of a still later descent, and may have arisen in the Miocene. The latest of all to differentiate were the genera Opisthotrichum, Polyplastron, Ophryoscolex, and Caloscolex, belonging to the fourth and fifth, that is, to the highest grades of morphological complexity. Their origin cannot be traced farther back than the end of the Miocene or the beginning of Pliocene.
5. These conclusions are supported by the differences in feeding habits of different Ophryoscolecidae. The more specialized feeding on cellulose-particles has been developed in the higher Ophryoscolecidae, the lower members of the group (Entodinium and Anoplodinium) exhibiting a more diversified diet, combined sometimes with predaceous habits.
6. The need for a study of the yet unknown Infusorian fauna of Lama, and especially of Giraffidae, is emphasized, and some suggestions as to the origin of an aberrant genus of Ophryoscolecidae (Troglodytella from anthropoid apes) are given.
The Use of Basic Dyes and Ribonuclease for the Cytochemical Detection of Ribonucleic Acid
Authors: BRACHET J. 
Published: April 2021

1. Basic dyes (methyl green/pyronin, and toluidin blue), in conjunction with ribonuclease, may be used to detect the cytochemical localization of ribonucleic acid. This technique has been examined critically.
2. The fixative used is important and results vary with different materials. It is suggested that Zenker and Serra fixation should be compared in preliminary investigations. Unexplained anomalies arise in the use of frozen-dried material.
3. Details are given of the methods of use of ribonuclease and of the dyes, and a general technique is given for preliminary investigations.
4. It is concluded that there is a general parallelism between intensity of staining with basic dyes and content of ribonucleic acid, but there is no evidence yet available to justify the use of such staining for the quantitative estimation of ribonucleic acid.
Nuclear Transplantation in Amoebae. II: The immediate results of transfer of nuclei between Amoeba proteus and Amoeba discoides
Authors: Lorch I. J. , Danielli J. F. 
Published: April 2021

ABSTRACT
1. A description is given of a method for replacing the original nucleus of an amoeba by a nucleus from another amoeba. This method has been used to study transfers of nuclei within a species (homotransfers) and between species (heterotransfers). The species used were A. proteus and A. discoides.
2. Removal of the nucleus from an amoeba inactivates the animal, so that movement is sporadic and unco-ordinated, digestion ineffective, and death results after 10—20 days.
3. Renucleation results in reactivation with both homo-and heterotransfers. Reactivated homotransfers normally are able to divide and form mass cultures. Heterotransfers are less often able to divide and very seldom form mass cultures.
4. Amoebae taken at random from a mass culture divide after an interval which appears to be composed of a lag t; in which the processes leading to division are inactive, followed by an interdivision period id during which preparation for division is active. Experiments are given showing the effect of nuclear transfer on Z; and td.
5. After heterotransfer nuclei of either species may grow and divide in foreign cytoplasm. Before the first division after heterotransfer a cytoplasmic effect on nuclear size is observable, and after the first division the cytoplasm has a dominant effect in determining nuclear diameter.
6. When curves are plotted of the frequency of occurrence of nuclei of various diameters in pure cultures, maxima are found in the curves characteristic of the species. After nuclear transfer the cytoplasm and nucleus both have a strong influence in determining the position of the maxima.
7. Studies of the form assumed by heterotransfers show that, although there is a measurable influence of the nucleus on the form soon after transfer, this influence disappears almost entirely in 6-12 days, after which the determination of form is almost entirely cytoplasmic.
8. The results given under points 4, 5, 6, and 7 are based on the study of animals immediately after transfer and for the subsequent two divisions only. Longer-term effects will be discussed in another paper.
The Tinctorial Behaviour of Human Mast Cells
Authors: Montagna William , Eisen Arthur Z. , Goldman Allen S. 
Published: April 2021

ABSTRACT
Mast cells in the skin differentiate from perivascular fibroblasts. The cells nearest the walls of the blood-vessels contain mostly sparse and small mast granules; in those farther removed from the blood-vessels the granules are more numerous and coarse. With weak solutions of toluidine blue, mast granules reveal maximal chromotropy at pH 5·0. At lower pH values not all of the granules stain; at higher ones the granules and the intergranular cytoplasm stain progressively more orthochromatically. After digestion with ribonuclease and staining with toluidine blue buffered to pH 4·0 or 5·0 the mast granules are cherry red and all traces of orthochromatic staining are abolished; when stained at pH 6·0 or above, however, the cytoplasm and the granules attain a strong blue stain as if they had not been digested in the enzyme. Preparations fixed in Helly’s fluid may be washed in running water overnight and the mast granules show no diminution in chromotropy. The same sections may be stained, destained, and stained again at any desired pH with excellent results. Both the cytoplasm and the granules are Schiff-reactive, but the granules stain more intensely than the background. Sections stained with the periodic acid/Schiff technique and subsequently stained with toluidine blue reveal the mast granules brilliantly metachromatic, suggesting that the metachromatic and the Schiff-reactive substances, although co-existent, may be in fact separate elements. Mast granules, according to these tinctorial reactions, then, may contain 4 substances: (a) a protein cytoskeleton stainable with toluidine blue buffered to pH 6·0 or above; (b) some ribonucleic acid removable with ribonuclease and stainable with toluidine blue buffered to pH 5·0 or below; (c) an acid mucopolysaccharide which stains metachromatically ; and (d) a Schiff-reactive substance.
Dermal Nerve-endings in Rana and Bufo
Authors: Whitear Mary 
Published: April 2021

ABSTRACTIn the skin of Rana and of Bufo there are certain coarse medullated nerve-fibres which give off unmyelinated branches dividing repeatedly to form richly varicose endings at various levels, but mainly in the stratum spongiosum of the dermis. There is no capsule. These fibres are of a type distinct from those medullated fibres which end freely in the epidermis. Their function is discussed: it is possible that they are fast nociceptive fibres.
Refractometry of Living Cells: Part III. Technical and Optical Methods
Authors: Barer R. , Joseph S. 
Published: April 2021

ABSTRACT
Full details are given in this paper for carrying out the measurement of the refractive index of living cells by the method already discussed in Parts I and II of this series (Barer and Joseph, 1954, 1955). The method of preparing and storing immersion media is described as well as the dialysis technique used for adjusting pH, and in certain cases salt concentration. Methods of measurement applicable to single cells and to cell populations are discussed. It is shown that the numerical results can be used to obtain the concentration of solids, concentration of water, total wet mass and density, and concentrations in terms of wet weight of tissue. The underlying optical principles are discussed in some detail.
The structure of the germinal epithelium of the fowl testis with special reference to the presence of multinuclear cells
Authors: Lake P. E. 
Published: April 2021

ABSTRACT
The effects of histological fluids on the cells of the germinal epithelium of the fowl testis have been studied with a view to confirming the fact, evident from studies of living cells, that the formation of multinuclear cells in the process of spermatogenesis is a normal occurrence. It is considered that in the most rapidly dividing germ-cells the cytoplasm is not in a very concentrated state and the usual methods of fixation, by diffusing fluids into the testis, result in disruption of the cytoplasm, especially in multinuclear cells. Methods of fixation were selected which preserved the latter in sufficient numbers to follow their development. It appears that the two secondary spermatocyte nuclei, produced after the first meiotic division of the primary spermatocyte, tend to remain together forming a binucleate cell, which becomes four-nuclear after the second meiotic division. These nuclei, now haploid, are capable of frequent multiplication within the cell before each, then designated a spermatid, eventually becomes transformed into a spermatozoon. The significance of post-meiotic multiplication is discussed.
Muscle Receptor Organs in Grasshoppers and Locusts (Orthoptera, Acrididae)
Authors: Slifer E. H. , Finlayson L. H. 
Published: April 2021

ABSTRACT
A pair of muscle receptor organs is present in each of the abdominal segments from the first to the tenth in the Acrididae. They are associated with the dorsal longitudinal muscles and each consists of a single, heavily encapsulated sensory neurone with numerous dendrites which end on a long, slender muscle-fibre which has its origin near the anterior end of the segment and is inserted on the anterior border of the segment next posterior to it.
Internal Structure of Avian Melanin Granules : An Electron Microscope Study
Authors: Carr J. G. 
Published: April 2021

ABSTRACT
The black melanin granule of the Brown Leghorn male is a separate particle of complex structure, differing from the brown granules of the female, chick down, and Rhode Island Red.
It is feasible to study the granules in the electron microscope directly in the intact feather.
Properties of Slime-Mould Amoebae of Significance for Aggregation
Authors: Shaffer B. M. 
Published: April 2021

ABSTRACT
When all available food has been consumed, the amoebae of Dictyostelium and Polysphondylium aggregate towards collecting centres; this movement involves chemotaxis. Just after they have finished feeding, the amoebae adhere little or not at all to one another if they come in contact; they do not secrete the chemotactic agent acrasin, and cannot orient in an acrasin gradient. Later they become able to respond to an acrasin gradient, if this is great enough. In the absence of one, they may be sufficiently adhesive to form loose amorphous associations, or, depending on the species and the environment, still be quite separate. Amoebae with similar properties may be released by the spontaneous break-up of aggregated masses. In some species, amoebae that are unaggregated may lose their sensitivity to acrasin after a few hours. The elongated amoebae attracted to a source of acrasin may condense into streams. Stream amoebae move at varying speeds; they adhere strongly to others of the same species and to a variable extent to those of different species. They secrete the acrasin characteristic of their own species. Along a stream, there is often no continuous centrifugal decrement in secretion, as far as can be detected. The amoebae in it can be guided by the direction in which their adherent neighbours are flowing, though if they are exposed to an adequate acrasin gradient they will respond to it. Commonly, an adjacent stream or a centre planted beside them is not strong enough to attract them, unless they are freed to some extent from the influence of their neighbours, especially those ahead of them. Except for their being effectively non-motile and more nearly isodiametric, the amoebae in a centre are similar to those in a stream and may secrete acrasin at much the same concentrations as these do. With both types, there may be short-term fluctuations in secretion, and in at least one species a long-lasting decrease. The dimensions and gross appearance of an aggregation at the population densities used are partly determined by the time intervals over which the amoebae become acrasin-sensitive and centres are initiated, and by the relationship between these.