bluuebunny/crossref_metadata_2025_split huggingface dataset:
The action of phenyl-thiourea on melanogenesis in Xenopus laevis
Authors: Sims R. T. 
Published: April 2021

ABSTRACT
From Xenopus laevis tadpoles which possessed conical hind-limb buds with pigmented melanophores the caudal two-thirds of the tail was amputated. One group of these animals was kept in tap-water and another group in 0·01% phenyl-thiourea in tapwater while regeneration of the tails took place. After one month the tails of the operated animals together with tails from a control group of normal animals at the same stage of development were examined histologically. In the normal tail melanin was only absent from the region of the ventral fin immediately behind the anus: in the untreated regenerate melanin was only absent from the major part of the ventral fin: in the treated regenerate melanin was absent from the whole regenerate. Branched DOPA-positive cells situated beneath the epidermis and each accommodated by a circle 0·05 mm in diameter were present in the normal tails, untreated regenerates, and treated regenerates. They were present only in the regions lacking melanophores in the normal tail and untreated regenerate, but in the animals treated with phenylthiourea they were present in the unpigmented regenerate and in the pigmented part of the tail-stump. The pigmented melanophores were DOPA-negative. Cells which were stained by the hexamine-silver technique and Schmorl’s reaction were found only in the regenerate of the treated tadpoles. It is suggested that the DOPA-positive cells are potential melanophores. In the normal tail and untreated regenerate tyrosinase activity was present without promelanin granules and in the treated regenerate tyrosinase activity was present with promelanin granules. The negative response of pigmented melanophores could reflect a loss of tyrosinase activity as pigmentation of the granules is completed. Phenyl-thiourea does not inhibit melanogenesis in vivo by acting on a metabolic process essential for the normal activity of the cell, or by inhibiting the production and action of tyrosinase, or by preventing formation of promelanin granules, as these were all present in the treated animals. A test-tube experiment showed that phenyl-thiourea inhibits the autoxidation of DOPA. It is suggested that the drug acts by combining with an intermediate produced during the conversion of tyrosine to melanin.
Observations on a highly specific method for the histochemical detection of sulphated mucopolysaccharides, and its possible mechanisms
Authors: Heath I. D. 
Published: April 2021

ABSTRACT
Whereas basic dyes in aqueous solutions stain chromatin, all mucins, mast cells, the ground substance of cartilage, and epidermis, it has been shown that a 0·03 % solution of basic dye in 5% aluminium sulphate produces a highly specific staining reaction for sulphated mucopolysaccharides. The best dyes are nuclear fast red (Herzberg) and methylene blue. Acid dyes in solutions of aluminium salts are induced to stain the ground substance of cartilage. These observations have been confirmed in a number of species.
Other metallic ions have similar properties and the use of green and purple chromic salts indicate that co-ordination plays a part in the reaction.
Methylation, saponification, and sulphation experiments show that the sulphate group is essential. This has been confirmed by using pure chemical substances in gelatin models. Oxidation of keratin with performic acid, which produces sulphonic groups, causes hair (previously negative) to react. From this it is suggested that sulphonic groups may also react, and that the reactive groups need not be attached to mucopolysaccharides. It is further suggested that the specificity of sulphated mucopolysaccharides is due to the fact that they are the only substances present in the tissues with a sufficient concentration of sulphate groups.
Experiments with solochrome azurine show that the aluminium is attached to all tissue elements irrespective of their nature. It is suggested by analogy with the work of others on the action of mordants that this attachment is by co-ordinate linkage.
Acid dyes of strong and weak type buffered to a variety of pH levels show that ionization plays little if any part in the staining of the sulphated elements, but may be of considerable importance in the staining reactions of the other tissue elements. By analogy with solochrome azurine, which is known to co-ordinate with aluminium, it is suggested that the dye is attached, by means of a further co-ordinate bond, to the metal. It is suggested that the sulphate group may owe its specificity to its strongly acid character, and the fact that such groups are capable of forming extremely stable complexes with metallic ions.
It is concluded that this is a highly specific method of staining sulphated mucopolysaccharides, depending upon the formation of a link by a metallic ion between the tissues and the dye, in the fashion of a true mordant. The ability of the dye to attach itself to the metallic ion depends finally upon the resultant of the electrostatic charges on the tissues and the metallic ion.
Experiments on the action of mordants 2. Aluminium-haematein
Authors: Baker John R. 
Published: April 2021

ABSTRACT
Unmordanted haematein in aqueous solution varies in colour from yellowish orange at pH 3 to bluish magenta at pH 9.
In the presence of aluminium sulphate, the colour of solutions of haematein at any particular pH depends on the number of aluminium atoms to each molecule of haematein. At pH 4·6 the colour varies from yellowish orange through dull red to rose as the number of aluminium atoms to each molecule of haematein is increased from 12. The facts suggest that such solutions contain both uncombined haematein and an aluminium-haematein compound.
From about pH 5 upwards the aluminium-haematein compound is insoluble. Although the dominant colour is blue, a considerable proportion of red light is transmitted.
The blue colour attaches itself to tissue-constituents like a typical cationic (basic dye. It combines principally with the nucleic acids of chromatin; but if these are extracted from the tissues, it attaches itself to the acidic proteins of chromatin, and the appearance given is much the same.
In differentiation by acid, the mordant is set free from the tissue.
Chromatin that has been reddened by acid during or after dyeing becomes blue from about pH 5 upwards. Neutrality or alkalinity is not necessary for blueing.
The dull red aluminium-haematein compound present in acid solutions acts (like the blue) as a cationic dye.
When aluminium and haematein are used (as iron and haematein usually are) by the two-bath method, chromatin is dyed blue but collagen and certain other tissue-constituents yellowish. An exhaustive series of experiments shows that the yellowish colour is due to unmordanted haematein.
At room temperature haematein is about 17 times more soluble in ethylene glycol than in ethanol, and 21 times than in water. In 25% aqueous solution ethylene glycol is a suitable solvent for practical use. A solution in this solvent containing aluminium and haematein in the proportion of 8 atoms of the metal to one molecule of haematein may conveniently replace Mayer’s Hdmalaun and similar mixtures.
The fine structure produced in cells by primary fixatives.
Authors: Mercuric chloride I. , Baker John R. , Luke Barbara M. 
Published: April 2021

ABSTRACT
The exocrine cells of the mouse pancreas were fixed in mercuric chloride solution, embedded in plexigum, and examined by electron microscopy. The cytoplasm was found to be coagulated as a continuous substance containing innumerable subspherical cavities, mostly between 40 and 200 mµ in diameter and separate from one another. The zymogen granules were preserved, but no trace remained of mitochondria or Golgi apparatus. The nuclear sap was coagulated as a coarse network with thickenings at the nodes. Lumps of electron-dense material (? DNA) were present at the periphery of the nucleus and round the nucleolus.
The proteins of the cell appear to have been fixed by mercuric chloride, but the membranous constituents, which rely for their form on a phospholipid component, are not clearly recognizable. The lipids have presumably been lost during dehydration and embedding.
On colouring epon-embedded tissue sections with Sudan black B or Nile blue A for light microscopy
Authors: McGee-Russell S. M. , Smale N. B. 
Published: April 2021

ABSTRACT
Sections of osmium-fixed tissues embedded in epon 812 colour with either Sudan black B or Nile blue A solutions to reveal a variety of detail by direct microscopy with normal apochromatic or semi-apochromatic objectives. The clarity of the coloration gives a picture fully comparable to that seen by phase-contrast microscopy. The plastic is not removed. 1μ sections or thinner sections down to green or gold, are mounted on clean glass slides by drying down from 20% acetone/water after flattening on a hot plate. Colouring is carried out at room temperature in Sudan black B (saturated solution in 70% alcohol) for 1 to 2 h. The result is a reversed or negative effect, for the epon plastic takes the stain avidly, but dense elements of the tissue do not, and appear white against a blue background of stained plastic. Lipid droplets retain a capacity to colour, becoming dark blue to blue-black. Nile blue sulphate (1% aqueous solution) colours thin sections of tissue in 1 to 2 h at 60° C, acting apparently as a basic dye on most cell elements, and also colours lipid droplets dark blue. After both techniques the sections are mounted in Farrants’s medium.
The cytology of the digestive and salivary glands of the limpet, Patella
Authors: Pugh D. 
Published: April 2021

ABSTRACT
As reported by earlier investigators, the epithelium of the digestive tubules is composed of two cell-types. One type of cell is glandular, the other type is absorptive and digestive, and to a lesser extent secretory. The latter type of cell also contains glycogen and numerous lipid globules, so that the digestive gland as a whole contains a large quantity of reserve food material. The epithelium of the digestive duct possesses a single cell-type ; the cells are ciliated and heavily pigmented, and they produce a viscous secretion.
The salivary gland is a compound tubular gland. The cells elaborate a secretion containing protein and probably some carbohydrate.
A study of the adrenal tissue of the male African bullfrog, Rana adspersa
Authors: Moorhouse Douglas E. 
Published: April 2021

ABSTRACT
The structure of the adrenal tissue was investigated by both histological and histochemical techniques.
It is shown that the adrenal contains 4 types of tissues; these are named the steroid, Stilling, lymphoid, and chromaffin tissues.
The structure of the adrenal in the bullfrog does not provide any evidence to support a theory of zonation within the cortical tissue of the Anura, as suggested by some authors.
There is no alteration in the appearance or numbers of the ‘ summer cells’ of Stilling that can be correlated with the time of year or with the sexual activity of the animal. For this reason it is considered preferable to call these ‘ Stilling cells’, as was suggested by Magath (1915). There is evidence that structural differences are to be found between the Stilling cells and the granulocytes found in the lymphoid tissue.
Observations on the oxyntico-peptic cells in the proventricular mucosa of Gallus domesticus
Authors: Menzies Gordon , Fisk Alan 
Published: April 2021

ABSTRACT
1.The cells described contain two types of granule. One type colours with Bowie’s technique, the other is Bowie-negative.
2.Both types of granule are Altmann-positive.
3.Neither type of granule is preceded by a PAS-positive granule during development.
4.The Bowie-positive granules are discharged after eating and after injection of pilocarpine or histamine.
5.There is no evidence that any of the Bowie-negative granules are discharged.
6.The cytoplasm in the cells is rich in RNA, but this is absent from the granules.
7.No intracellular canals are seen in the cells.
8.An infranuclear Golgi network is present after 3 days’ starvation. After feeding it changes its form and position and may become paranuclear. After injection of histamine or pilocarpine similar though more marked changes occur and the network in a few cells assumes a supranuclear position.
9.A line of granules that colour densely with Sudan black in a sudanophil ‘lake’ is present at the luminal border of the cells. It has not yet been possible to decide on their exact nature.
The fully formed intermoult cuticle and associated structures of Podura aquatica (Collembola)
Authors: Noble-Nesbitt J. 
Published: April 2021

ABSTRACT
The cuticle overlying most of the body consists of 2 major layers only, the lamellate endocuticle and the epicuticle, and is very thin (1 to μ). Three major cuticular layers are found in the slightly thicker cuticle of certain areas (2 to 3 μ thick) and in the thickest regions (8 to 10μ)a distinct sclerotized exocuticle is present. The epicuticle consists of 1 to 4 laminae, the ‘inner’, ‘cuticulin’, ‘wax’, and ‘cement’ layers, and the distribution of these laminae is described. The outer surface of the cuticle is thrown into major tubercles of approximately 3 μ pitch, with minor tubercles super-imposed upon them. Modification of the cuticle at the bases of setae is described and related to the mechanical requirements of the setal insertion and suspension. The nature of the muscle insertion is also considered. The epidermis is fully cellular and the cells contain the granules of black pigment which impart the black coloration to the insect. Specializations of the epidermis in the regions of ocelli, setae, muscle insertions, and the vesicles of the ventral tube are described, along with modifications of the overlying cuticle.
Studies on the ovarian follicle cells of Drosophila
Authors: King R. C. , Koch Elizabeth A. 
Published: April 2021

ABSTRACT
Studies are described of the ultrastructure of the follicle cells which invest the oocyte of Drosophila melanogaster at the time of vitelline membrane formation. Of particular interest are organelles made up of endoplasmic reticulum organized into a husk of concentric lamellae which surround lipidal droplets. These epithelial bodies are seen only at the time the vitelline membrane is being formed, and it is assumed therefore that the lipidal material of the epithelial body may be utilized somehow in the fabrication of the vitelline membrane. Cytochemical studies have shown this membrane to contain at least 5 classes of compounds; a protein, two lipids (which may be distinguished by differences in their resistance to extraction by various solvents), and 2 polysaccharides (1 neutral and 1 acidic). Studies were made of vitelline membrane formation in the ovaries of flies homozygous for either of 2 recessive, female-sterile genes (tiny and female sterile). In the case of the ty mutation vitelline membrane material is sometimes secreted between follicle and nurse cells, while in the mutant fes vitelline membrane is observed in rare instances to be secreted between follicle cells and an adjacent layer of tumour cells. In the latter case the vitelline membrane shows altered cytochemical properties. The fact that vitelline membrane can be secreted by follicle cells not adjacent to an oocyte demonstrates that it is the follicle cell rather than the oocyte that plays the major role in the secretion of the precursor material of the vitelline membrane. Subsequently the follicle cells secrete the egg-shell, or chorion, which is subdivided into a dense, compartmented, inner endochorion, and a pale, outer exo-chorion. A description is given of the ultrastructure of the follicle cells during the secretion of the endochorion and the exochorion. The endochorion contains a protein, a polysaccharide, and a lipid, all of which may be distinguished cytochemically from the vitelline membrane compounds. The exochorion contains large amounts of acidic mucopolysaccharides. Specialized follicle cells form the micropylar apparatus and the chorionic appendages. The formation of the chorion and chorionic appendages is discussed in the light of information gained from abnormalities of the chorions and chorionic appendages seen in ty and/s 2-1 oocytes. Subsequent to the time the egg leaves the ovariole a layer of waterproofing wax is secreted between the vitelline membrane and the chorion.
A histological study of the peripheral receptors in the thorax of land isopods, with special reference to the location of possible hygroreceptors
Authors: Jans D. E. , Ross K. F. A. 
Published: April 2021

ABSTRACT
By double embedding whole isopods in paraffin wax and celloidin, after fixing them in Bodian’s fluid, it was possible to obtain complete sets of undamaged serial sections through the thoracic and abdominal regions of females of Oniscus asellus L. and Porcellio scaber Latr., and also some incomplete series through males of these species and a species of the genus Armadillidium. These sections were stained by the methods of Bodian and of Holmes to show the nerve-fibres. They were then carefully studied, and the distribution and the morphology of all peripheral nerve-endings and receptors in the body were determined as completely as possible.
In all, 6 different types of terminations were found; and in some cases it was possible to draw valid inferences about their probable function from a consideration of their location and their morphology alone. Three of them are probably tactile. The function of the other three is much more uncertain; but one of them, a group of pit-like terminations situated on the under side of the lateral plates on each side of the thoracic segments, is particularly suitably located to function as a receptor of temperature or humidity, and morphologically it bears some resemblance to certain proven hygroreceptors in other arthropods. This particular termination and one of the other types, consisting of ventrally situated partially retracted hairs, do not appear to have been described previously in the land isopods.
The vital staining of Amoeba proteus
Authors: Byrne Jennifer M. 
Published: April 2021

ABSTRACT
The effect of keeping Amoeba proteus in dilute basic dye solutions was studied. It was found that Nile blue, neutral red, and neutral violet in particular, and also brilliant cresyl blue, methylene blue, Bismarck brown, thionin, toluidine blue, and azures A and B act as vital dyes, while at comparable molarities crystal violet, dahlia, safranin, methyl green, Janus green, and Victoria blue are lethal, and do not produce any stain-ing until after death. Azure C, basic fuchsin, and particularly pyronine G are relatively harmless, but produce no vital staining.
All the vital dyes stain the food vacuoles, and all produce small, darkly stained granules in colourless vacuoles in the cytoplasm. The latter do not exist in the unstained amoeba. Some of the dyes colour vacuoles around the crystals. These crystal vacuoles also seem to be induced. A few of the dyes colour the spherical refractive bodies, which are at least in part phospholipid.
All the basic dyes used with the possible exception of azure C, methyl green, and pyronine G attach to the external membrane of A. proteus in an orientated manner, as shown by the increase in birefringence of the external membrane induced by these dyes. It is particularly those dyes that act as vital dyes that produce a very pronounced increase in the birefringence of the external membrane.
The sense organs on the antennal flagellum of aphids (Homoptera), with special reference to the plate organs
Authors: Slifer Eleanor H. , Sekhon Sant S. , Lees A. D. 
Published: April 2021

ABSTRACT
The cuticular parts of the aphid plate organ consist of an outer and an inner layer. Both are transparent and in the space between them are many fine branches of the half dozen, or more, sensory neurones which lie below the plate. Each dendrite narrows, a short distance above its cell body, and assumes the structure of a cilium with 9 pairs of peripheral fibrils, a ciliary collar, and basal bodies with rootlets. Distally the dendrite loses its ciliary structure, passes through one of several openings in the inner cuticular layer of the plate and branches repeatedly. The only formed cytoplasmic elements so far identified within the branches of the dendrites are neurofilaments. The outer cuticular layer of the plate is perforated by a large number of small openings. Groups of filaments leave the surface of the dendrite branches and enter these openings. The filaments have a diameter close to 10 mμ and resemble the neurofilaments within the dendrite branches.
‘Chloride cells’ in the gills of fresh-water teleosts
Authors: Datta Munshi J. S. 
Published: April 2021

ABSTRACT
Specialized cells of several kinds, namely, (a) mucous-gland cells, (b) large bior tri” nucleate glandular cells, and (c) mast cells occur in the gills of some species of freshwater teleosts.
The typical ‘goblet’ type of mucous glands are present in large number in freshwater species, such as Catla catla, Labeo rohita, Ophiocephalus punctatus, and Mastacembalus armatus. In Catla catla, these glands respond to the ‘chloride test’. This indicates that, besides discharging mucus, they also play some part in the elimination of chloride. In Ophiocephalus punctatus, Ciarias batrachus, and Heteropneustes fossilis only some of the mucous cells give a positive reaction with the AgNO3/HNO3 test for chloride. This may mean that a few of them are in a state of active secretion of chlorides, while others are in a non-secretory phase.
Large eosinophil glands with 2 or 3 nuclei also occur, chiefly in the siluroids. The function of these hypertrophied multicellular glands is not clear.
Judged by the AgNO3/HNO3 test, Catla catla possesses the highest number of chloride cells. In Hilsa ilisha, Rita rita, Ophiocephalus striatus and Mastacembalus armatus, only a ‘network of silver’ exists on the surface of the primary and secondary lamellae.
The ‘chloride cells’ are said to be a characteristic of marine fishes in which an extrarenal mechanism for the elimination of excess of salts from the body fluid is necessary for correct osmo-regulation. These cells are also said to make their appearance in fresh-water fishes that have been experimentally subjected to a saline medium. The presence and occurrence of ‘chloride cells’ in fresh-water fishes living in their natural habitat is, therefore, interesting. The discovery of the presence of actively secreting chloride cells in certain species of fresh-water teleosts and their mucoid nature are new results reported here.
The histochemistry of the saccus vasculosos of Notopterus chitala (Teleostei)
Authors: Sundararaj Bangalore I. , Prasad M. R. N. 
Published: April 2021

ABSTRACT
The saccus vasculosus of Notopterus chitala is situated posteriorly to the pituitary gland. It consists of a number of loculi surrounded by blood sinusoids. The loculi open into a number of collecting channels which unite and ultimately drain into the third ventricle of the brain. The loculi are lined by a layer of pear-shaped ‘coronet cells’. The coronet cell has an apical protrusion provided with hairs, each ending in a globule. The coronet cells contain glycogen, especially in the apical protrusions and in the globules. Phospholipid, alkaline phosphatase, and mitochondria are concentrated in the apical protrusion and globules. There are also mitochondria round the nucleus. The Golgi element is not only present in the characteristic Golgi zone but occasionally round the nucleus as well. It has been stated by other authors that acid mucopolysaccharides are synthesized in the coronet cells of the rainbow trout and ‘secreted’ into the lumen of saccus vasculosus. However, acid mucopolysaccharides are not histochemically demonstrable in the coronet cells of Notopterus. The observations recorded in this paper indicate that the coronet cells in the saccus vasculosus of Notopterus are secretory and that glycogen is abundant in them.