bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cytological and biochemical studies of anucleolate Xenopus larvae
Authors: Wallace H. 
Published: April 2021

ABSTRACT
A larval lethal mutant of Xenopus laevis lacks true nucleoli but possesses analogous intranuclear organelles, here termed blobs, which are smaller and more numerous than nucleoli. Cytochemical tests reveal that blobs (like nucleoli) contain ribonucleic acid (RNA), arginine, and alkaline phosphatase, but probably no Feulgen-positive material. Anucleolate larvae are deficient in cytoplasmic RNA. By biochemical methods the nucleic acid content of anucleolate embryos is found to be normal at the tail-bud stage, but does not increase after this. By the time they hatch, anucleolate larvae are deficient in both RNA and deoxyribonucleic acid (DNA). The implications of this and related mutations on the formation and function of the nucleolus are considered. The term ‘blob’ is justified in that it would be misleading to regard such organelles as nucleoli produced by normally latent organizers.
The uptake of dyes by extracted phospholipids and cerebrosides
Authors: Byrne Jennifer M. 
Published: April 2021

ABSTRACT
It was found that basic dyes were without exception taken up by lecithin, cephalin, and sphingomyelin, while the typical acid dyes were not taken up by any of the phospholipids. However, the weakly acidic dyes aurantia, eosin Y, eosin SS, and erythrosin were taken up by all phospholipids, although to a smaller extent than the basic dyes.
Basic dyes were taken up by cerebrosides, but to a smaller extent than by the phospholipids. The basic metachromatic dyes gave a strongly metachromatic reaction with cerebrosides. None of the acid dyes tried was taken up by cerebroside.
The direct observation that basic dyes were taken up less strongly by cerebrosides than by phospholipids was confirmed by spectrophotometric readings.
Basic dyes were found to be insoluble in olive oil, with the exception of Bismarck brown, neutral red, acridine orange, Nile blue, and chrysoidine. The acid dyes tried were without exception insoluble in olive oil.
Oleic acid took up all basic dyes and some acid dyes.
It is suggested that a chemical reaction is at least in part responsible for the uptake of basic dyes by conjugated lipids.
Experiments on fixation for electron microscopy I.Unbuffered osmium tetroxide
Authors: Malhotra S. K. 
Published: April 2021

ABSTRACT
The effect of fixation with a simple solution of osmium tetroxide in distilled water was studied by electron microscopy. Exocrine cells of the pancreas and cells of the proximal tubule of the kidney of the mouse were used as test-objects. Partially prepolymerized methacrylate was used for embedding. There did not appear to be any marked disorganization of the cell inclusions. The appearance of the inclusions in the electron micrographs was similar to what is generally seen after fixation with the buffered osmium tetroxide solution of Palade.
A study of the intestinal epithelium of the goldfish Carassius auratus: its normal structure, the dynamics of cell replacement, and the changes induced by salts of cobalt and manganese
Authors: Vickers T. 
Published: April 2021

ABSTRACT
The normal structure of the intestine of the goldfish is described, with special attention to the character of the mucosal epithelium.
The rate of epithelial replacement has been determined by the use of colchicine, and found to vary between 6 days for the upper intestine and 9 day’s for the lower parts. The colchicine data have also been used to determine the duration of a normal mitosis, which has been found to be between 2 and 3 h.
Cobaltous and manganous salts have been shown to cause a considerable but transient increase in the level of mucification which can be ascribed to the formation of new mucous cells; although there sometimes appears to be formation of mucoid substances in the principal cells, there is no evidence that these cells undergo transformation into goblet cells or that goblet cells ever become principal cells after they have lost their secretion.
It is suggested that mitosis in the intestine produces cells initially capable of both modes of differentiation, and that the effect of the metal ions is to increase temporarily the likelihood of mucous differentiation.
Observations on histological methods involving the use of phosphotungstic and phosphomolybdie acids, with particular reference to staining with phosphotungstic acid /haematoxylin
Authors: Bulmer D. 
Published: April 2021

ABSTRACT
An attempt has been made to elucidate some of the factors involved in differential staining of tissues with Mallory’s phosphotungstic acid /haematoxylin, and to find out how far these factors are applicable to other histological methods in which phosphotungstic or phosphomolybdic acid is used. Sections have been subjected to various pretreatments to find whether specific chemical groupings are responsible for any of the staining reactions, but the results obtained are not always easy to interpret.
The most important single factor in determining the staining reaction of a tissue material with PTAH appears to be its relative permeability to the two colour-complexes of the PTAH mixture. The red complex, of larger molecular size, penetrates collagen; muscle-fibres are penetrated mainly by the smaller blue complex, while red bloodcorpuscles fixed with formaldehyde are not penetrated by either. The staining reactions of muscle and red blood-corpuscles can be altered by a methylation procedure, by treatment with performic acid or formic acid, or by mild alkaline hydrolysis; but this appears to be due to alteration of permeability rather than to chemical alteration of any specific dye-binding groups. The effects of blocking reactions indicate that the binding of both complexes is to basic groups in the tissues, though it is possible that hydroxyl groups and carboxyl groups may also be involved.
It appears that similar factors control the differential staining with other techniques which involve the use of complex acids (Baker, 1958), and that the chemical specificities which have been claimed for some of them are not well founded.
The relation between the Nissl and Sudan black pictures of the motor neurones of the spinal cord of the adult horse, with special reference to the cytoplasmic inclusions
Authors: Perbøll Ove 
Published: April 2021

ABSTRACT
The motor neurones of the spinal cord of the horse, fixed in neutral formaldehydecalcium, embedded in paraffin, and sectioned, are easily coloured with Sudan black dissolved in propylene glycol or in tertiary butanol. No procedure for ‘unmasking’ lipids is necessary.
Any effect due to electropolar bonds are excluded by blocking and extraction procedures. The true lysochrome effect is confirmed by the removal of the colour by lipid solvents and the absence of stable sudanophilia and of background colouring. No brown colour suggestive of decomposition products is seen, and this is further confirmed by absorption spectra of the Sudan black solutions.
The structures revealed are in the main identical with those of ordinary Nissl preparations made, for instance, by Einarson’s chromalum/gallocyanin stain. In addition, however, structures closely similar to ordinary Nissl bodies are seen in the axon hillock and in the axon. This suggests that in these situations Sudan black colours corpuscles that are lacking in ribonucleic acid (presumably endoplasmic reticulum devoid of ribosomes).
The nature of the lipids revealed by Sudan black in these cells has not been determined histochemically. Extraction in pyridine either before or after fixation had no definite effect on the colouring of the Nissl bodies or of the nucleus.
The histochemical recognition of lipids in the cytoplasmic network of neurones has recently been reported by David and Brown (1961). The present paper supports the findings of these authors. Different material and methods were used, but the colouring agents were the same.
Histochemical differentiation of the basement membrane of the mouse seminiferous tubule
Authors: Baillie A. H. 
Published: April 2021

ABSTRACT
The ground substance of the testis of the albino mouse is PAS-positive but not meta-chromatic, and probably highly aggregated. The basement of the seminiferous tubules is intensely PAS-positive, metachromatic, and possibly not so highly aggregated.
The reactivity of the ground substance to the PAS reaction and toluidine blue is tentatively ascribed to the presence of chondroitin sulphate C: this compound, previously known to contain N acetyl-galactosamine, glucuronic acid, tyrosine and tryptophane, is associated with arginine.
The genesis of the basement membrane of the seminiferous tubule is shown to include the formation of a sheath of atypical elongated fibroblasts, the secretion of a PAS positive, metachromatic substance associated with arginine between this sheath and the seminiferous tubule, the appearance of mitochondria in the cells of the sheath, and lastly, the acquisition of alkaline phosphatase by these fibroblasts and its spread to the intervening ground substance. These changes are thought to be related to the structural and nutritional requirements of the seminiferous tubules.
In its intense positive reaction to PAS and in its metachromasy, the basement membrane of the seminiferous tubule agrees with the ground substance adjacent to sites of active protein metabolism, such as growing tumours, embryonic organs, hair follicles, and skin.
The cuticle of cysticerci of Taenia saginata, T. hydatigena, and T. pisiformis
Authors: Siddiqui E. H. 
Published: April 2021

ABSTRACT
The structure of the cuticle of the cysticerci of 3 species of Taenia was studied by means of optical and electron microscopy. In all 3 species the cuticle is composed of 3 layers and covered with hair-like processes. The middle layer, which comprises the bulk of the cuticle, varies in thickness from head to bladder, but there are no differences in thickness between the species studied. The hairs are composed of a core representing an extension of the middle layer and are covered by a continuation of the outer layer. The arrangement of these hairs varies in the species studied.
Experiments on fixation for electron microscopy 4. The sodium veronal buffer
Authors: Malhotra S. K. 
Published: April 2021

ABSTRACT
Michaelis’s sodium acetate /sodium veronal buffer is generally used for holding the pH of fixing solutions for electron microscopy at about pH 7·3 to 7·5. The acetate, however, has no buffering action on the alkaline side of neutrality. Experiments were therefore made to study the effect on preservation of cellular constituents when sodium acetate is omitted from Palade’s (or its variants) and Luft’s fluids. Exocrine cells of the pancreas, convoluted tubule cells of the kidney, and the testes of the mouse were used as test-objects, n-butyl methacrylate (generally partially prepolymerized) and epikote 812 were used for embedding. The preservation visualized in the micrographs did not seem to suggest any marked differences in the quality of fixation from that produced by fixation in Palade’s and Luft’s fluids. However, there is some evidence that comparable micrographs could be produced by fixation in simple solutions of OsO4 in distilled water and subsequent embedding in suitable media.
A histochemical study of the Golgi apparatus or ‘acroblast’ of the spermatid of the snail, Helix aspersa
Authors: Bradbury S. , Meek G. A. 
Published: April 2021

ABSTRACT
The acroblast of Helix spermatids is a duplex structure: it consists of an ‘externum’ (which appears dark by positive phase-contrast microscopy and becomes impregnated with osmium) enclosing a region called the ‘internum’.
Histochemical studies show the externum to be composed principally of phospholipid and to contain glycolipid, alkaline phosphatase, and an enzyme which splits thiamine pyrophosphate. The internum contains neutral mucopolysaccharide. Ribonucleic acid and acid phosphatase are not present in the acroblast.
These histochemical results suggest a homology between the invertebrate acroblast and the Golgi apparatus in vertebrate cells.
The sensory neurones and sensilla in the abdomen and thorax of the blowfly larva
Authors: Osborne M. P. 
Published: April 2021

ABSTRACT
The peripheral nervous system in the Phormia larva consists of bipolar neurones that end in specialized sensilla, and bipolar or multipolar neurones with ramifying distal processes. The former are associated with the cuticular sensilla and chordotonal organs. The latter (a) constitute a sub-epidermal nerve-plexus with processes that occasionally run over skeletal muscles, (b) innervate specifically orientated strands of connective tissue, the longitudinal, vertical, and ventral stretch receptors, and (c) innervate the tracheal epithelium, imaginai buds and associated pedicels, and the nerve-sheaths.
Thiamine pyrophosphatase, acid phosphatase, and alkaline phosphatase in the neurones of Helix aspersa
Authors: Nancy J. Lane 
Published: April 2021

ABSTRACT
All three phosphatases have been found to be localized mainly in the cortices of bodies which have the distribution, size, and shape of the ‘blue’ and yellow lipid globules. Colouring neurone preparations with the lysochrome Sudan IV, either before or after incubation for thiamine pyrophosphatase or acid phosphatase activity, shows a sudano-phil reaction in the medullary spaces surrounded by the cortices that hydrolyse both phosphates. It is concluded that the acid phosphatase and thiamine pyrophosphatase activities, which in vertebrates are present in the lysosomes and Golgi lamellae respectively, are mainly found, in these invertebrate neurones, in the phospholipid lamellae which form the externa of certain of the lipid globules present in the cytoplasm.
The tegument and associated structures of Fasciola hepatica
Authors: Threadgold L. T. 
Published: April 2021

ABSTRACT
The cuticle of light microscopy is shown by electron microscopy to be a surface layer of protoplasm which is an extension of areas of nucleated protoplasm lying deep in the parenchyma. The cuticle therefore exists at two levels. The external level is syncytial, consisting of plateaux separated by branching valleys. This level contains apical pinocytotic vesicles, numerous mitochondria, endoplasmic membranes, large basal and other vacuoles, and dense spines. Tube-like evaginations from the base of the external level connect it to the individual areas of flask-shaped protoplasm which compose the internal level. Each of these areas of protoplasm contains a nucleus, great numbers of mitochondria, some vacuoles and diffuse inclusions, and the Golgi bodies.
The histochemistry and function of the cuticle is discussed in the light of this new knowledge of cuticular ultrastructure, and a comparison is made between the cuticle of Cestoda and Trematoda.
The nerve-net of a swimming anemone, Stomphia coccinea
Authors: Robson Elaine A. 
Published: April 2021

ABSTRACT
The nervous system of this anemone has been examined in an attempt to study the pacemaker system, previously thought to be localized in the median zone of the column. No clear-cut nerve-ring has been found. The whole column, however, is characterized by the presence of large multipolar nerve-cells in the endoderm, to which pacemaker activity is provisionally attributed. There are several thousand of these cells and their neurites connect with those of other nerve-cells and sense-cells in the column, and with the mesenteric nerve-nets. The column nerve-net, of which the multipolars form part, conducts slowly and fatigues easily. Present physiological evidence from Stomphia and other coelenterates does not invalidate the suggestion that the multipolar cells may also function as a pacemaker system.
Other features of the nervous and sensory systems are very like those of other anemones (e.g. Calliactis, Metridium). The column, mesenteries, and oral and pedal disks are briefly described; much information is still lacking. As expected, sense-cells are aggregated along the angles of the mesenteries except in the pharynx. Their neurites connect with the column nerve-net, and with the mesenteric nerve-nets. A well-developed network of bipolar nerve-cells on the retractor surface may be regarded as a rapid through-conduction tract. As in Metridium and Calliactis the radial nerve-net on the opposite face of the mesentery is similar but much sparser. The ectodermal surface of the oral disk, as described by the Hertwigs, shows a criss- cross network of bipolar nerve-cells together with radial rows of small multipolar nerve-cells above the septa. These might perhaps have a proprioceptive function. In the endoderm of the pedal disk, sense-cells are numerous but nerve-cells few. These features are discussed only in so far as they may be related to the swimming behaviour of Stomphia.
An electron microscopical study of the innervation and sarcoplasmic reticulum of the fibrillar flight muscle of Drosophila melanogaster
Authors: Ahmad Shafiq S. 
Published: April 2021

ABSTRACT
The peripheral nerves of Drosophila are of the ‘tunicated’ type; their mesaxons are derived from several independent invaginations of the lemnoblast plasma membrane and possess septate desmosomes.
Fine branches of the nerves and tracheoles penetrate deeply into the fibres of the flight muscle and draw the sarcolemma in with them. The myoneural junctions occur on the invaginated portions of the sarcolemma. The axons shed their lemnoblastic elements and become closely apposed to the muscle plasma membranes at the junctions.
The sarcoplasmic reticulum of the flight muscle seems to consist mainly of the extensive infoldings of the sarcolemma and their processes, as in Tenebrio. ‘Dyads’ formed by the association of isolated vesicles with the membranous infoldings are present in Drosophila. Most of these ‘dyads’ seem to be in register with the myofibrils, two pairs being associated with each sarcomere.
The union of protein and nucleic acid in the living cell and its demonstration by osmium staining
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
The greater part of the osmium tetroxide that is reduced and bound by living cells in neutral solution is taken up by unsaturated lipids. The protein in mitochondria, muscle-fibres, connective tissue, red blood cells, See., takes up a smaller amount of osmium; but the basic proteins that are combined with DNA and RNA in the chromosomes, nucleoli, and cytoplasm do not react: their reactive groups are presumably held in salt linkages with the phosphate residues of the nucleic acids.
If the cells are exposed to an acid medium (0.001 M acetic acid or saturated carbonic acid) these salt linkages are weakened, and chromosomes and cytoplasmic nucleoprotein will now take up large amounts of osmium and stain intensely with ethyl gallate. This effect of hydrogen ion concentration is reversible within the living cell.
By the application of a series of blocking reagents it is concluded that the chief reactive groups on the proteins are the guanidino group of arginine, the e-amino group of lysine, the iminazole group of histidine, and the pyrrolidine group of proline. Tryptophane and cystein, though highly reactive, are perhaps less important quantitatively.
Studies on the receptors in the cerebral vesicle of the ascidian tadpole. 2. The ocellus
Authors: Dilly Noel 
Published: April 2021

ABSTRACT
Electron microscope observations of the photoreceptor of the tadpole larva of Ciona intestinalis show the ocellus to consist of about 10 cells. It is made up of 3 parts: a pigment cup, a lens system, and a retina. A single cup-shaped cell filled with membrane-bound pigment granules lies between the lens and the retinal cells. Part of the lens cell is contained within its concavity. The pigment granules are arranged to keep stray light from falling upon the photoreceptor endings.
The lens system has 3 lens vesicles arranged in a line along the main axis of the pigment cup cell. The spherical vesicles are usually contained within a single cell. Each vesicle is separated from the rest of the lens cell cytoplasm by a single-layered sphere of mitochondria. No membrane separates the vesicle contents from the rest of the lens cell cytoplasm.
The retinal cells lie above the dorsal arm of the pigment cup cell, and have tubular processes that pass through it to end as piles of membranes closely applied to the lens cell. Morphologically the photoreceptor units of the ascidian tadpole closely resemble the visual cells of the vertebrates, the piled photoreceptor membrane corresponding to the outer segment of the vertebrate rod cell and the tubular part to the connecting piece of a retinal rod.
The fine structure of certain secretory cells in the optic tentacles of the snail, Helix aspersa
Authors: Lane Nancy J. 
Published: April 2021

ABSTRACT
In Helix aspersa, the cytoplasm of the collar cells that surround the tentacular ganglion contains spheroidal granules of low electron density (α-bodies), and β-bodies that contain electron-dense vesicles within the size range of elementary neurosecretory granules. Mitochondria and lamellar Golgi complexes are also present. Mitochondria, a-bodies, fibrils, objects resembling multivesicular bodies, and moderately electrondense granules are found in the lengthy processes into which the collar cells are drawn out.
One process of each bipolar collar cell seems to merge into the tentacular ganglion. This consists of neurones with processes that contain mitochondria, vesicles of various sizes, filaments, and electron-dense granules similar to elementary neurosecretory granules.
The lateral cells that line the dermo-muscular sheath encasing the optic tentacles contain in their cytoplasm an endoplasmic reticulum with many ribosomes, mitochondria, Golgi complexes, and many electron-lucent globules. These globules seem to be elaborated by the lamellar Golgi bodies. There are also electron-dense inclusions, which may be lysosomes, that are scattered sparsely between the other globules and cytoplasmic components. All these structural details are similar to those found in some mucus-secreting cells.
The possible nature and origin of the tentacular secretory cells are discussed.
Further observations on the secretory cells in the optic tentacles of Helix, with special reference to the results of vital staining
Authors: Lane Nancy J. 
Published: April 2021

ABSTRACT
When the collar cells or the lateral cells in the tentacles of Helix aspersa are stained with neutral red and other vital dyes, uptake of the dyes occurs chiefly in the lipoidal β-bodies. Janus green B and dahlia are taken up by the mitochondria.
In vitally-coloured preparations, no ‘peri-nuclear bodies’ are present in the collar and lateral oval cells, such as were previously found in these cells after post-osmication for 14 days. Fixed preparations of similar cells, post-osmicated for different periods, indicate that the peri-nuclear dictyosomes are artifacts due to over-impregnation with osmium.
In addition to the lateral oval and lateral processed cells, which lie at intervals along the inner surface of the dermo-muscular sheath in Helix, unicellular calcium glands are found, lying immediately beneath the epithelial surface; these are far more numerous in H. pomatia than in H. aspersa. They contain granules of a calcium salt suspended in a matrix of mucopolysaccharide, and apparently produce the whitish mucoid secretion that is extruded on to the surface of the tentacles when the animal is disturbed. There is no evidence to suggest that the lateral cells are concerned in the production of this mucoid secretion.