bluuebunny/crossref_metadata_2025_split huggingface dataset:
The structure and topography of stretch receptors in representatives of seven orders of insects
Authors: Osborne M. P. , Finlayson L. H. 
Published: April 2021

ABSTRACT
In Ephemera (Ephemeroptera), Dictyopterygella and Isoperla (Plecoptera), Periplaneta and Blaberus (Dictyoptera), Forficula (Dermaptera), and Dytiscus (Coleoptera) there is a pair of stretch receptors on each side in the dorsal region of most abdominal segments. Each receptor consists of a connective-tissue strand to which is attached a single sensory neuron. One member of each pair is approximately longitudinal and the other approximately vertical in orientation.
In Sialis (Neuroptera-Megaloptera) the longitudinal receptor consists of a muscle-fibre and a neuron; the vertical receptor consists of a neuron with one or two long processes. Connective-tissue fibres are absent from both receptors.
In Limnophilus and Phryganea (Trichoptera) there is a longitudinal receptor only. It consists of a muscle-fibre to which is attached a tube of connective tissue containing the dendrites of the sensory neuron. The caddis receptor resembles closely the lepidopteran receptor.
No abdominal stretch receptors could be found in Rhodnius or Nepa (Hemiptera-Heteroptera), and in Schistocerca and Locusta (Orthoptera) no vertical receptors could be found.
The structure of the dragline control valves in the garden spider
Authors: Wilson R. S. 
Published: April 2021

ABSTRACT
In the ducts of the major and minor ampullaceal glands of Araneus diadematus, special valves have been found which control the output of the dragline. Closure of the duct is achieved by inflation of the valve lips; opening is achieved by deflation. These valvular changes are brought about by groups of muscles attached to the duct.
Experiments on fixation for electron microscopy
Authors: Malhotra S. K. 
Published: April 2021

ABSTRACT
The effect of fixation with acidified solutions of osmium tetroxide (pH 1·5 to 3·5 has been studied on the first (proximal) convoluted tubule cells of the kidney and the pancreatic exocrine cells of the mouse, by electron microscopy. Partially prepolymerized methacrylate was used for embedding. The various membranous structures and the ribosomes retain their individuality even after prolonged fixation in solutions containing 5% acetic acid (pH 1·5). However, the mitochondrial matrix and the ground cytoplasm are not preserved ; the zymogen granules are also partially washed out.
The unmasking of cytoplasmic lipids in rat livers as a consequence of dietary changes
Authors: Gahan P. B. , Bitensky L. , Chayen J. , Cunningham G. J. , Maggi V. 
Published: April 2021

ABSTRACT
The livers from rats fed either on a normal diet containing 20% of protein or on a diet which facilitated liver carcinogenesis and which contained only 5 % of protein supplemented with methionine appeared histologically normal. Histochemical investigation of such livers showed that in the livers of animals fed on the protein-deficient diet there was a large increase in lipid staining. Biochemical investigation of these livers demonstrated that this increase in lipid staining was not due to a significant increase in total lipids nor to a significant decrease in total protein. These findings are discussed in terms of the ‘unmasking’ of the structural cytoplasmic lipids of the liver cells as the consequence of the feeding of an apparently protein-deficient diet.
Skeletal organization in the coral, Pocillopora damicornis
Authors: Wainwright Stephen A. 
Published: April 2021

ABSTRACT
The skeleton of this Hawaiian reef coral was found to contain at least 99’9% by weight of the mineral aragonite, present as submicroscopic crystals in spheritic arrangements. The organic component of the skeleton comprises 0·01 to 0·1 % of the total weight and has 3 microscopic constituents: (1) filaments of lime-boring algae, (2) a dispersed network of fibres 1 μ in diameter, and (3) a transparent, milky, regionally biréfringent matrix of chitin. The chitin was observed to be a spongework of fibrils of average diameter 20 mμ. The chitin fibrils were inferred to be randomly oriented in the plane of the skeletogenic epithelium perpendicular to the direction of growth of the long axes of the aragonite crystals.
The development of the skeleton is traced from the initial mineral deposit by the larva after its attachment, through the formation of the larval skeleton and growth into the fully formed, branching colony. The process of formation of chitin fibrils according to the contour of the skeletogenic epithelium and the later deposition of aragonite crystals as described accounts for the formation of all skeletal elements of Pocillopora.
Evidence is presented for the hypotheses that (1) the amide group of the chitin molecule is responsible for the ability of certain organic substrates to be calcified (thus protein is not a necessary component of such substrates); (2) zooxanthellae in Pocillopora contribute a product of photosynthesis to the coral as the monomer of the chitin matrix; and (3) chitin synthesis thus depends on the activity of zooxanthellae and the rate of chitin synthesis controls the rate of skeletogenesis in Pocillopora.
A study of the replacement mechanism of the pulmonate radula
Authors: Runham N. W. 
Published: April 2021

ABSTRACT
Results obtained from a histological, autoradiographic, and operative investigation of the radulae of two pulmonates have led to the formulation of the following theory of radula replacement. The radula is secreted continually by the permanent odontoblasts and continually moves anteriorly. The superior epithelium of the radular gland is produced by division of cells near the odontoblasts and moves forward at the same rate as the radula; the cells produce materials that harden the radula and then die. The inferior epithelium is also produced by division of cells near the odontoblasts, but initially moves anteriorly at only a quarter of the rate of the radula. The epithelium then changes shape from a columnar to a pavement epithelium. It is suggested that it then moves forward at the same rate as the radula. The pavement epithelium secretes the subradular membrane which may serve to attach the epithelium to the radula, and the supralateral radula tensor muscles are attached to the basement membrane of this epithelium. At the extreme anterior end of the radula the inferior epithelium becomes again columnar and secretes a cuticle continuous with the buccal cuticle. This process detaches the subradular membrane and the radula from the epithelium. The epithelial cells then die and disintegrate. The detached radula and subradular membrane show a change of staining properties suggestive of reversal of the tanning, and they then break up.
Haematopoietic nodules as centres of fat synthesis in the liver of the migratory starling, astor roseus
Authors: George J. C. , Naik D. V. 
Published: April 2021

ABSTRACTA histological and histochemical study of the haematopoietic nodule in the liver of Pastor roseus was made from October to April. The formation and development of the haematopoietic nodule by aggregation of lymphocytes and monocytes was found to be a continuous process, in which new nodules are formed regularly. The older nodules after a certain period of high activity show a considerable decline in the activity of blood-cell formation. The fully formed haematopoietic nodules give rise to different types of blood-cells—erythrocytes, granular leucocytes, lymphocytes, and monocytes. During the pre-migratory period the lymphocytes and monocytes were found to be more numerous in the nodules. It is likely that the number of erythrocytes increases during migration and that the formation of different types of blood-cells depends upon demand. It is concluded that fat is synthesized in the lymphocytes, monocytes, and free-moving reticulo-endothelial cells, but that this synthesis is mainly carried by the reticulo-endothelial cells. The phagocytes may also be the carriers of fat, and it is suggested that they are later modified into fat-cells in the fat-depot. Haematopoiesis in this bird is a normal phenomenon occurring in the liver in all seasons and is not a pathological condition.
The use of methyl green as a histochemical reagent
Authors: Baker John R. , Williams Elizabeth G. M. 
Published: April 2021

ABSTRACT
The cation of methyl green carries two positive charges, that of malachite green only one; but the two dyes behave towards tissue-constituents in almost exactly the same way. These dyes are not specific for chromatin. They colour certain objects that are devoid of DNA, even when they are used in very dilute solution. The granules of cells called Körnchenzellen in the connective tissue of the common snail, Helix aspersa, are strongly coloured by both dyes from very dilute solutions, and thus provide a striking instance of the unspecificity of these dyes.
Malachite green, which is stable and free from contamination by metachromatic impurities, can advantageously replace the methyl green commonly used in mixtures with pyronine.
It is suggested that pyronine may have a greater capacity for penetrating into closetextured objects, such as nucleoli and ribosomes, than methyl and malachite greens.
The fine structure of the body-wall in a free-living nematode, Euchromadora vulgaris
Authors: Watson B. D. 
Published: April 2021

ABSTRACT
The body-wall of adult Euchromadora vulgaris is composed of the 3 layers common to all nematodes, the cuticle, epidermis, and muscle cells. The cuticle is composed of 4 layers, a thin membrane resolvable only by the electron microscope, and 3 layers which can be observed in the light microscope. Histochemical tests show that the cuticle is predominantly protein and contains collagen. Of the 3 main layers of the cuticle, the outermost is about 0.4 μ thick and it is penetrated at regular intervals by grooves which divide the cuticle into annuli. This layer has several features in common with the external cortical layer of the cuticle in Ascaris lumbricoides; it is hardened by disulphide bonds and possibly quinone tanning, and is resistant to collagenase. The middle layer is about 1 to 1.3 μ thick and is formed from a series of overlapping plates. The rod-like bodies of de Man are located in this layer and are hollow. Internally, the cuticle is bounded by a basal lamella about 02 μ thick. The epidermis is thickened to form 4 chords and is composed of a large number of cells, which contain filamentous mitochondria with many cristae, granules of glycogen, and, in the pharyngeal region, pigment spots. The fibrillar zone of the muscle cell contains myofilaments of two types, large filaments 20 to 25 mμ in diameter, which are surrounded by smaller filaments 5 to 7 mμ in diameter. There are filamentous mitochondria, glycogen and a nucleus in the protoplasmic bulb. Covering the muscle cell is a thin membrane, the sarcolemma, which is infolded at regular intervals between groups of myofilaments. The sarcolemma is fused with the basal cuticular layer at both ends of each muscle cell.
The fine structure of RNA-storing archaeocytes from gemmules of fresh-water sponges
Authors: Ruthmann August 
Published: April 2021

ABSTRACT
Gemmules of fresh-water sponges contain about 500 binucleated cells (‘archaeocytes’) which are loaded with reserve substances including ribonucleoprotein, acidophilic proteins, lipids, and polysaccharides. These substances are utilized during the early phase of histogenesis after germination of the gemmules. Apart from the presence of reserve bodies, the basic fine structure of metabolically inactive archaeocytes within the closed system of a gemmule is not fundamentally different from actively metabolizing cells of rapidly growing tissues. In particular, ribosomes, endoplasmic reticulum, mitochondria, Golgi bodies, and RNA-containing nucleoli are present during inactivity as well as after germination and resumption of growth and synthesis. Changes in cellular fine structure after germination include an increased density of the cytoplasmic ground substance, the appearance of small vesicles in the vicinity of the Golgi bodies and of annulate lamellae and a large, cylindrical centriole near the nuclear envelope. Two general conclusions are drawn from these results. Neither the ultra- structural aspect of a cell nor the presence of high concentrations of RNA in cytoplasm and nucleolus is a valid indication of cellular activity or inactivity. The persistence of Golgi bodies and endoplasmic reticulum through long periods of inactivity shows that their structural integrity is not dependent upon continuous energy input, although these intracellular membrane systems are undoubtedly dynamic structures in metabolically active cells.
Movement of palisade in locust retinula cells when illuminated
Authors: Horridge G. A. , Barnard P. B. T. 
Published: April 2021

ABSTRACT
In dark-adapted eyes cisternae of the endoplasmic reticulum collect near the rhabdom and form around it a functionally significant region 2 to 4 μ across, of lowered refractive index. In light-adapted eyes this structure is dispersed as vacuoles in the cytoplasm, and instead mitochondria are crowded round the rhabdom. Onion bodies up to 8 μ. in diameter occur in the retinula cell cytoplasm.
An enzyme histochemical and electron microscopical study of the light organ of the glow-worm, Lampyris noctiluca
Authors: BARBER V. C. , PILCHER C. W. T. 
Published: April 2021

ABSTRACT
The light organs of female specimens of the glow-worm Lampyris noctiluca were investigated by enzyme histochemical tests, lipid stains, and electron microscopy. Differences, both histochemical and in fine structure, were found between the cells of the photocyte and reflector layers. The photocytes contained a vesiculated reticulum, photocyte granules, amorphous granules, and numerous mitochondria. The reflecten layer did not contain the reticulum or the two types of granules and there were fewer mitochondria. Glycogen granules, and spaces possibly caused by the removal of urate during preparatory procedures, were present in this layer but absent from the photocytes.
All the dehydrogenase enzymes, except for glucose-6-phosphate, 6 phosphogluconic, lactic, and β-hydroxybutyric dehydrogenases, which were absent from both layers, showed more activity in the photocyte layer. NADH2 and NADPH2 diaphorase showed no activity in the reflector layer.
A transition zone between the two layers was demonstrated both histochemically and morphologically.
Alkaline and acid phosphatase could not be demonstrated in the light organ. The adenosine triphosphatase demonstrable in the organ was not activated by magnesium but was activated by calcium ions. Lipid was present in both layers of the organ.
The tracheolar supply to the photocytes was good but no tracheolar end organs were observed.
The dehydrogenase activity of the body musculature is also reported upon.
The pericardial cells of Drosophila melanogaster
Authors: MILLS R. P. , KING R. C. 
Published: April 2021

ABSTRACT
The ultrastructure of the pericardial cells of adult female Drosophila melanogaster is illustrated. The data presented suggest that the pericardial cell internalizes by pinocytosis complex and possibly toxic compounds present in suspension in the haemolymph. These compounds are broken down to soluble molecules within lysosome-like vacuoles. The pericardial cells thus behave like the reticulo-endothelial cells of mammals.
A further note on the measurement of the affinity of a dye (Azure A) for histological substrates
Authors: Goldstein D. J. 
Published: April 2021

ABSTRACT
If two histological sections, of thickness np. and znp, and having the same apparent intensity of staining, are at equilibrium with dyebaths of concentration B1 and B2 respectively, the affinity of the histological substrate for the dye is, under defined conditions, given by the expression ΔF° = −RT In I/B, where B is either (i) B2 if the thinner section is stained to saturation, or (ii) B1 if B1 = 3B2. The affinity tends to be greater when measured in a weaker dyebath, as implied in method (ii).
Evidence is presented suggesting that the uptake of the basic dye Azure A by pancreatic basal chromidial substance, goblet cell mucin and intestinal epithelial cytoplasm follows a Langmuir adsorption isotherm to a first approximation, in that, at low dyebath concentrations, the uptake of dye is proportional to the concentration of dyebath with which the substrate is in equilibrium, while in strong dyebaths the uptake approaches a plateau. A deviation from the ideal Langmuir isotherm in dyebaths of moderate concentration, observed in epithelial cytoplasm and to a lesser extent in pancreatic basal chromidial substance, may have been due to interaction between neighbouring dye-binding sites, or to the presence in a single area of sites with different affinities for the dye.
Note on the Cytological Localization of Alkaline Phosphatase
Authors: Lorch Joan 
Published: April 2021

ABSTRACT
In comparing various techniques for the microchemical demonstration of alkaline phosphatase it was observed that with the method of Menten, Junge, and Green (1944) nuclear phosphatase cannot be demonstrated in epithelial cells, whereas with the Gomori-Takamatsu (1939) technique both nuclear and cytoplasmic elements (e.g. brush borders and the Golgi zone) of suitable organs show the presence of the enzyme. The substrate in the method of Menten, Junge, and Green is Ca α- or β-naphthylphosphate in the presence of α-naphthyl-diazonium hydroxide. In the Gomori technique the substrate is sodium-β-glycerophosphate. The failure of nuclear phosphatase to be demonstrated by the first method might be caused by:
Tests by Tissue Culture Methods on the Nature of Immunity to Transplanted Skin
Authors: Medawar P. B. 
Published: April 2021

ABSTRACT
The transplantation of skin from one rabbit to another elicits a reaction that conforms in main outline with that of an actively acquired immunity. The experiments described in this paper were designed to test the hypothesis that the regression of such grafts is secured by the action of antibodies demonstrable in vitro.
Skin from adult rabbits has therefore been cultivated in the presence of serum and growing mesenchymal tissues derived solely from rabbits heavily and specifically immunized against it.
Immune sera and tissues are without effect on the survival, cell-division frequency and migratory activities of explanted skin, and agglutinins for epidermal cell suspensions are not demonstrable in immune sera.
With certain stated qualifications, it has therefore been concluded that the occurrence of free antibodies is not a sufficient explanation of the regression of skin homografts in vivo.
Formalin-Sensitive Cells in Spinal Ganglia
Authors: Bacsich P. , Wyburn G. M. 
Published: April 2021

Spinal ganglia of rabbits and cats were prepared for histological examination in a variety of ways. Dark staining multangular cells are present in sections after fixation with formaldehyde succeeded by (a) alcoholic dehydration; (b) sectioning with the freezing microtome. Sections treated in other ways, including freezing-drying, only have the typical small and large round cells. It is suggested that certain groups of cells, sensitized by formaldehyde fixation, can react by shrinkage on subsequent treatment by alcoholic dehydration or other procedures.
FROM time to time it has been contested that there are different nerve cell types in the spinal ganglia and that, while the typical pseudounipolar cell dominates the cell population, it does not altogether monopolize it. Amongst the first to study the cells of spinal ganglia were Retzius (1894), Dogiel (1896), Lenhossék (1896), Ramón y Cajal (1906), Marinesco (1906), Nageotte (1907), and Marinesco and Minea (1908). Using different histological methods, they all commented on the occasional finding of nerve cells resembling motor cells. Kiss (1932) recorded the presence of a significant number of dark-staining ‘multipolar’ cells in the ganglia of spinal and cranial nerves after formalin fixation and prolonged treatment with osmium tetroxide. On the basis of their appearance, he suggested that they were visceral efferent cells. Blair, Bacsich, and Davies (1935) confirmed the presence of these characteristic cells in spinal ganglia fixed in formalin. They could, however, find no evidence of multiple cell processes. They therefore preferred to describe them as ‘multangular’ rather than multipolar cells, and concluded that any assessment of function would depend on experimental evidence.
The present work is an account of the effect of various methods of fixation, including freezing-drying, on the cytology of spinal ganglia, with special reference to alterations in shape and staining reaction.
The Mechanism of Cell-division A Study with Carbon Monoxide on the Sea-Urchin Egg
Authors: Swann M. M. 
Published: April 2021

ABSTRACT
1. Developing eggs of the sea-urchin Psammechinus miliaris were subjected to carbon monoxide inhibition, which was controlled by changing from green to white light. The behaviour of the eggs was recorded by time-lapse photography.
2. If inhibition is applied before the eggs enter mitosis, their first cleavage is delayed by a time which is roughly equal to the period of the inhibition.
3. If the inhibition is applied when the cells have already entered mitosis, they complete mitosis and cleave with little or no delay, but their second cleavage is delayed by a time which is roughly equal to the period of the inhibition.
4. It is suggested that the necessary energy for the second mitosis and cleavage is being stored up during the first mitosis and cleavage, and that this energy store operates like a reservoir which is continually being filled but siphons out when it is full. Once the energy has siphoned out, it carries mitosis and cleavage through, even though the reservoir is not filling up because of carbon monoxide inhibition.
Surface Forces in the Tracheal System of Insects
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
The mechanism by which the tracheal system becomes filled with air is reviewed. It is concluded that the fluid contents are actively absorbed by the walls of the system. The air often enters from the atmosphere through the spiracles. In some insects the system fills while the insect is submerged in water or while the spiracles are closed. It is shown by means of simple models how the tanning of the lining of the larger tracheae or the secretion of wax over the walls will bring about the liberation of gas from solution when the fluid is subjected to a very slight negative pressure.
The movements of fluid in the tracheole endings of insects are also reviewed. The removal of fluid which takes place during activity, particularly under conditions of deficient oxygen supply, is not caused by secretory activity but by the physical forces produced by the products of metabolism.
The evidence supports the view that the fluid in the tracheoles is a cell sap whose passage up the tracheole under the action of capillarity is opposed by the elasticity or swelling pressure of the cytoplasmic sheath of the tracheoles. It is shown by means of a simple gelatin model how osmotic changes in the surrounding fluid, acting by way of a cytoplasmic sheath, will bring about the absorption of such a cell sap.
A more exact model, illustrating the greater permeability of the inner wall of the tracheole which the proposed mechanism requires, is provided by the anal papillae of mosquito larvae. These structures show the same adaptation to a saline medium as is postulated in the tracheoles of mosquito larvae from salt water.
Alternative mechanisms are discussed. It is suggested that the capillary forces in the tracheoles are probably small. The effects of probable contamination of the tracheole fluid by an oily film (Beament) and the effects of changes in hydrogen-ion concentration on interfacial tensions are illustrated by reference to further models.