bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the Testis Tubule in the Fowl
Authors: Kamar Gamal A. R. 
Published: April 2021

ABSTRACT
Three phases of tubule development can be distinguished in males of the Fayomi breed :
the first 12 weeks, when only slight increase in tubule diameter and cell count occurs. During this period two stages in spermatogenesis are to be found. from the 16th to the 24th week, when rapid increase in tubule diameter and cell count occurs, and all stages of spermatogenesis are present. Sexual maturity, judged by the appearance of the first spermatozoa in the seminiferous tubules, occurs at about 16 weeks and is associated with a rapid increase in the size of the testes. The increase in testis weight is due, however, to increase in length of the tubules rather than to increase in diameter. from the 24th to the 52nd week, when only slight changes occur in microscopical appearance.
The Spermatophores of Dolops ranarum (Crustacea, Branchiura): their Structure, Formation, and Transfer
Authors: Fryer Geoffrey 
Published: April 2021

ABSTRACT
Sperm transfer in the genus Dolops involves the employment of spermatophores. In this respect the genus is unique within the Branchiura.
Proteinaceous wall material is secreted by arborescent spermatophore glands located in the carapace lobes of the male and is passed into a pair of long canals which terminate posteriorly as a pair of spermatophoric vesicles, part of whose walls are glandular. Spermatozoa from the vasa deferentia are injected into these vesicles and become surrounded by wall material. During the mating process the contents of each vesicle are squeezed out through the common genital orifice, where they become con- fluent and form a single, globular spermatophore. While its walls are still soft this is pressed against the base of the abdomen of the female, where it is pierced by two perforated spines at the end of the spermathecal ducts. The spermatophore hardens and remains attached to the female, thus giving the spermatozoa opportunity to migrate through the spermathecal ducts to the spermathecae. Not until after a moult of the female, however, during which the spermatophore is shed with the old cuticle, are the spermatozoa free to enter the eggs, each of which is believed to be pricked by the spermathecal spines during oviposition.
By virtue of the fact that it involves quite different organs and processes in the two groups, spermatophore formation indicates that the Branchiura and Copepoda are not closely related. On the other hand, the process is in no way suggestive of a close relationship of the Branchiura and Branchiopoda, and the isolated position of the Bran- chiura is emphasized.
Ester Wax 1960 : a Histological Embedding Medium
Authors: Steedman H. F. 
Published: April 2021

ABSTRACT
A modification of the original formula (Steedman, 1947) is given which still retains the softness of infiltrated tissues. The section, both wax and specimen, flattens on water. The sections of a ribbon adhere during flattening. Adhesion of sections to the slide is good. The room temperature for successful ribboning may vary from 17° to 25° C or higher.
The Interstitial Cell in the Testis of the Foetal Sheep
Authors: Baillie A. H. 
Published: April 2021

ABSTRACT
The testes of 18 foetal sheep, of crown-rump length from 2·8 to 40 cm, have been studied by the PAS, Sudan black, and plasmal tests. Typical interstitial cells differentiate from mesenchymal precursors; the nucleus alters first, becoming ovoid and vesicular; then the cytoplasm increases in amount, its processes become fewer and smaller, sudanophil lipid droplets appear, and the result is a lipid-laden epithelioid cell. Two atypical forms of interstitial cell have been noted: the first has groups of eosinophil granules in its cytoplasm, the second is shrunken and has a pycnotic nucleus. The interstitial cell of foetal sheep, unlike that of poikilotherms, contains no glycogen. The PAS-positive polysaccharide / protein granules found in the interstitial cells of adult homiotherms are absent from the interstitial cells of this foetal homiotherm. While sudanophil lipids appear at an early stage, Schiff-positive lipids (plasmalogens, acetal phosphatides, and possibly steroids) are entirely absent from the interstitial cells of the foetal sheep.
The Nerve-net of the Sea-Anemone Metridium senile : the Mesenteries and the Column
Authors: Batham E. J. , Pantin C. F. A. , Robson E. A. 
Published: April 2021

ABSTRACT
The actinian nerve-net has been examined in the mesenteries and column of Metridium senile (L.) after staining with silver and with methylene blue. Modified staining methods are described. The synaptic nature of the junctions between bipolar nerve-cells, of their expanded terminations over the muscle-field, and of their contacts with the neurites of sense-cells is reviewed. The neurites always run in the space between the epithelium and underlying muscle. They follow the distribution of the main contractile systems, including the passage of circular fibres beneath the mesenteries. The richer innervation of the retractor surface of a mesentery compared to the radial is correlated with the ability of this hypertrophied muscle to contract rapidly. The distribution of nerve-cells and sense-cells in the mesenteries and column is related to physiological evidence concerning the through-conduction pathways, facilitated and slow contractions, and other aspects of the behaviour of Metridium. It is concluded that although features such as reciprocal inhibition in the column are still unexplained, there is as yet no histological or physiological evidence for double innervation of the muscles in this anemone. The terminations of sensory neurites, on musclefibres or elsewhere, have not yet been seen in any actinian.
The Chemical and Physical Nature of the Visible Regions of Mouse Ascites Tumour Cells, and of the Cells of Solid Tumours grown from them
Authors: Ross K. F. A. 
Published: April 2021

ABSTRACT
A new technique was used to embed separate mouse ascites cells of 7 different strains in a supporting medium so that they could be sectioned, and a number of histochemical tests were carried out on this material. The results of these were in good general agreement with the findings of Love & others (1953, 1956), who investigated the histochemical properties of dried smear preparations of ascites cells of very similar strains; but certain important differences were found, notably the present investigation revealed the presence of phospholipid in almost all the lipid droplets in the cytoplasm. No important differences were found in the histochemical properties of the cells of the 7 different strains examined, nor between these and the cells of subcutaneous solid tumours grown from them.
The solid content of the cytoplasm, nuclear sap, and nucleoli of the living cells of 6 of these 7 strains were measured by immersion refractometry and interference microscopy. The mean total solids in the cytoplasm were, in all strains, near to 14% w/v and the concentration in the nuclear sap was usually a little lower than this. The total solid in the nucleoli was approximately 50% w/v. Intact living cells were also isolated from the solid tumours by means of a special ‘homogenizer’, and the total solid in their cytoplasm was in all cases identical with that of the ascites cells from which they were derived.
From these data it seems probable that the chemical and physical characteristics of many different strains of ascites cells, including those of carcinomatous, sarcomatous, and leukaemic origin, do not differ markedly from one another; and are also probably not very different from those of the cells of the solid tumours from which they were originally derived.
Phase Microscope Studies of Living Blood-cells of the Tunicates under Normal and Experimental Conditions, with a Description of a New Type of Motile Cell Appendage
Authors: Andrew Warren 
Published: April 2021

ABSTRACT
The living blood-cells of tunicates have been studied by means of phase contrast microscopy. The species used were Ascidia atra Lesueur, Ecteinascidia turbinata, and Clavelina picta, all of which are common in the Bermuda region. Blood-cells in blood taken directly from the heart, or from the vessels, or elsewhere, particularly in the tunic of Ecteinascidia turbinata and Clavelina picta, were observed for periods ranging up to 24 h.
A new type of appendage is described for those cells which we have called vacuolate cells (‘Q cells’ of Fulton, ‘signet-ring’ and ‘colorless morula cell’ of George). Individual cells show from 1 to 5 appendages, which are beaded and actively undulate. Fragments from the appendages continue to undulate. Such fragments bear some resemblance to blood-platelets of higher vertebrates in their strongly adhesive properties.
In view of the morphological features, motility characteristics, and apparent functions, the terms lymphocyte and macrophage are considered appropriate for the finely granular and coarsely granular amoebocytes. No active swimming motions of the orange cells, nor of any other corpuscles were seen; but all of the types of cells, coloured and colourless, with the exception of the vacuolate cells, exhibit amoeboid progression.
No transformation of vacuolate into green cells was brought about in our experiments with varying strengths of acid, contrary to the earlier findings of Fulton. Many types of blood-cells in the tunicates have ‘fixed cell’ counterparts in the tissues. It is suggested that the large ‘bladder cells’ of the tunic of A. atra Lesueur may be such counterparts of the vacuolate cells of the blood.
The Shell of Acridid Eggs
Authors: Hartley J. C. 
Published: April 2021

ABSTRACT
The shell of the newly-laid egg of Locusta migratoria is composed of a chorion and an outer layer, here termed the extrachorion. The development of the chorion and extrachorion has been followed. The structures of the egg-shells of Schistocerca gregaria, Ramalea microptera, and 6 species of British grasshoppers are also described and are found to conform to the same pattern. The chorion has a meshwork structure which may be filled with air or water. Wound repair in the eggs is also noted.
The Development of the Polychaete Haploscoloplos fragilis
Authors: Anderson D. T. 
Published: April 2021

ABSTRACT
The eggs of Haploscoloplos fragilis, laid in gelatinous cocoons, develop as yolky trochophores which add 4 segments before hatching on the 6th day and two more during a pelagic phase before settling and the onset of feeding on the 10th day. The 6 (embryonic) segments bear a metatroch and 5 amphitrochs. The embryo also has an akrotroch, prototroch, telotroch, and neurotroch. All cilia disappear after settling, when the embryo shows resumption of segment formation. Anterior to the first trunk segment lie the prostomium and mouth region. The latter becomes subdivided by an annulus, but later fuses with the first trunk segment as the peristomium. All other segments become chaetigerous, the 5 embryonic being of thoracic type, the postembryonic abdominal. At the posterior end of the body lies the pygidium, with the segment-forming growth zone immediately in front of it.
The development of trunk segments in two series, embryonic and post-embryonic, is characteristic of ariciids, as is the fusion of the first trunk segment with the mouth region to form the peristomium. It is possible that the mouth region incorporates at least one other cephalized segment.
Ariciid eggs vary in size among species. No direct relationship exists between egg size and pelagic development. The mode of oviposition also varies. Whether or not a pelagic phase occurs depends on the stage at which the embryo becomes free in the water, which is governed in turn by properties of the cocoon (e.g. jelly viscosity). A pelagic phase is always associated with enhanced ciliation, while in non-pelagic development ciliation is reduced. The basic ciliation (akrotroch, prototroch, metatroch, telotroch, and neurotroch) is usually supplemented by additional segmental bands.
Some Aspects of the Cytology of Polycelis nigra
Authors: Skaer R. J. 
Published: April 2021

ABSTRACT
The triclad, Polycelis nigra, has been found to be fully cellular. Gland-cells, undifferentiated cells, and the cell-bodies of muscle-cells, make up the parenchyma. The fine structure of the component cells of the parenchyma, nervous, and excretory systems, testis, pharynx, and epidermis is described. Acidophil secretion granules, produced by certain parenchymatous gland-cells, have a characteristic, doubly-banded ultrastructure which is not invariably associated with the property of adhesiveness. The parenchymatous cell-body of the muscles is often up to 10 μ from the musclefibre, to which it is joined by tenuous cytoplasmic connexions. The muscle-fibre itself consists of coarse and fine sets of hexagonally arranged myofilaments, but is unbanded. The basement membrane of the epidermis is composed of fine, banded fibrils, apparently randomly arranged in the plane of the membrane. Permeating the epidermis at a level just above the basement membrane is a system of extracellular spaces, which may have a hydrostatic function and assist in the extrusion of secretion granules. Epidermal sense organs, whose fine structure resembles the basal body of the cilia, are considered to have a functionally significant distribution on the surface of the animal. The rhabdites have been shown to develop in special cells of the parenchyma. Such rhabdite-forming cells, together with their contained rhabdites, have been found apparently passing through the basement membrane of the epidermis. As all the epidermal epithelial cells contain rhabdites, it is suggested that the epidermis as a whole is renewed by centrifugal migration of rhabdite-forming cells. The rhabdites themselves appear to consist of arginine and some tyrosine, together with a purine, probably adenine. They may be an excretory product.
The Development of the Malpighian Tubules in Dysdercuskoenigi (Hemipt er a, Pyrrhocoridae)
Authors: Srivastava U. S. , Bahadur I. 
Published: April 2021

ABSTRACT
Dysdercus koenigi has two pairs of Malpighian tubules, each pair arising from a vesicle and forming a closed loop. The vesicles are connected dorsally, and the tubules are differentiated into proximal and distal regions with refractive granules in the latter and brush border in both.
In winters at Allahabad the embryonic period lasts about a fortnight, and on the 9th day, 4 small buds arise apparently from the anterior end of the proctodaeum. These grow rapidly and become tubular; their tips fuse, but the lumina remain separate. At this stage the met-enteric membrane (Henson, 1946a) stretches over the anterior end of the proctodaeum and an interstitial ring is differentiated, so that the zone of the origin of the tubules lies anteriorly to it and posteriorly to the met-enteric membrane. Meanwhile the basal part of each tubule swells and the two swellings of each side fuse, thus forming a vesicle on each side. A dorsal outgrowth from each vesicle meets its fellow of the opposite side. The tubules continue to elongate, at the same time becoming narrower, and ultimately only 3 cells can be seen in a cross-section. The tubules grow in 3 phases—(1) active mitosis, (2) of cell multiplication and cell rearrangement, and (3) of cell rearrangement and cell enlargement. Finally, the tips of each pair fuse completely and their lumina become continuous.
In the newly hatched first nymph the tubules are uniform throughout, but in the later part of this stage they become differentiated into proximal and distal regions and the striated or brush borders appear. Thus the embryonic development continues for some time in the first nymph. Once this condition has been reached, cyclical changes involving increase in the diameter of the tubules, in the size of the nuclei, and in the number of cells in the proximal region occur in each nymphal stage, but before each ecdysis the diameter decreases slightly. Thus the adult condition is reached in 5 distinct steps, corresponding to the 5 instars.
Henson’s view that Malpighian tubules are endodermal is considered plausible, but his view regarding the primitive number of tubules is not accepted.
The Histochemistry of the Radula of Patella vulgata
Authors: Runham N. W. 
Published: April 2021

ABSTRACT
When first secreted the radula consists of chitin and protein. In the bases and cusps of the teeth the reactions for tyrosine, tryptophane, and chitin become negative, and are replaced by reactions for amino groups and argentaffin material. The bases of the teeth become impregnated with iron. Subsequently the reactions for amino groups and argentaffin material become negative in the cusps and they then become impregnated with iron and silica. Very few changes have been observed in the radular membrane.
It is suggested that the occurrence of quinone tanning might account for these histochemical changes observed in the radula, but phenols derived from tryptophane would appear to be more important in the tanning of the radula than those derived from tyrosine.
Tyrosinase Activity in the Pigmented Cells of the Nucleus Substantiae Nigrae. I. Monophenolase and Diphenolase Activity
Authors: Marsden C. D. 
Published: April 2021

ABSTRACT
The method of formation of black pigment in cells of the nucleus substantiae nigrae has been investigated by employing histochemical techniques which detect tyrosinase, the enzyme responsible for melanin formation in skin melanocytes. Frozen sections of the mid-brains of adult monkeys and cats were incubated in L-tyrosine, to detect the monophenolase activity of tyrosinase; other sections were incubated in L-dopa to detect the diphenolase (dopa oxidase) activity of the enzyme. The dopa, but not the tyrosine, was converted into melanin by the cells of the nucleus substantiae nigrae, resulting in blackening of the cytoplasm.
The intensity of blackening of nigra cells resulting from incubation in L-dopa depended on physical factors. The optimum pH of the reaction ranged between 6·8 and 7·4; the optimum temperature was 37° C; the concentration of substrate employed and the duration of incubation were additional factors which influenced the intensity of the reaction. The conversion of dopa to melanin by nigra cells was prevented by general enzyme inhibitors and by specific inhibitors of tyrosinase, which confirmed the specificity of the reaction for the diphenolase activity of tyrosinase.
The significance of the presence of diphenolase activity, in the absence of monophenolase activity, in adult nigra cells has been discussed in relation to pigment formation in the brain.
Some Modifications of Holmes’s Silver Method for Insect Central Nervous Systems
Authors: Blest A. D. 
Published: April 2021

ABSTRACT
Two main modifications of Holmes’s method are described. In both the amount of silver nitrate in the impregnating bath is increased, and larger quantities of higher pyridine derivatives are substituted for pyridine. The preferred method for general purposes employs 2· 4% 2:6 lutidine at pH 8· 4, and gives a bluish picture with improved selectivity of fibre staining. The use of 1 · 6% 2:4:6 collidine gives a reddish picture, with highly selective fibre staining, and sharp resolution of neurosecretory cells. Minor modifications of pre-treatment and reduction procedures are also described.
Tyrosinase Activity in the Pigmented Cells of the Nucleus Substantiae Nigrae: II. Further Observations on Monophenolase Activity
Authors: Marsden C. D. 
Published: April 2021

ABSTRACT
In a previous investigation of tyrosinase activity in the cells of the nucleus substantiae nigrae of adult cats and monkeys, diphenolase, but not monophenolase activity, was detected. This is possibly due to inhibition of monophenolase. When the copper radicle in tyrosinase is oxidized, monophenolase cannot be detected, but reducing agents activate and unmask this component of tyrosinase.
The effects of reducing agents in activating monophenolase have been investigated. Tyrosine is converted to melanin by monophenolase in adult nigra cells of the cat and monkey when the enzyme is activated by the reducing agents L-dopa, L-ascorbic acid, and L-adrenaline. Variations in physical factors influence the intensity of the activated monophenolase reaction resulting from incubation of sections in tyrosine-dopa mixtures; the reaction is inhibited by general enzyme inhibitors and specific tyrosinase inhibitors.
The significance of the results in relation to tyrosinase activity in adult nigra cells is discussed.
Secretory Structures associated with the Neurosecretory System of the Immature Scorpion, Heterometrus swammerdami
Authors: Habibulla Mohammad 
Published: April 2021

ABSTRACT
Certain previously unknown structures, probably endocrine in nature, are described. The blind ‘end-organ’ which is present and shows signs of activity in the pre-moult stage shows no noticeable sign of activity in the post-moult stage. In certain respects it is comparable to the ‘anterior organ’ of spiders, which has been homologized with the prothoracic glands of insects.
In the rostral region of the scorpion, where the rostral nerve ramifies, an accumulation of leucocytes is found; these show signs of secretory activity. Both at the origin of the rostral nerve and also where it ramifies, neurosecretory material is seen. This rostral structure is comparable in certain aspects with the rostral organ of spiders. Leucocytes occur not only in the rostral organ but also in association with the ‘endorgan’.
The presence of two ganglionic masses, above and below the stomodaeal commissure, suggests the possibility of the sympathetic (stomatogastric) ganglion of the scorpion being a composite structure consisting of the frontal ganglion, the corpus cardiacum, and possibly the hypocerebral ganglion. A hypocerebral ganglion is absent in the adult.
On the Identity of the ‘Neurofibrils’, ‘Nissl complex’, ‘Golgi Apparatus’, and ‘Trophospongium’ in the Neurones of Vertebrates
Authors: David G. B. , Brown A. W. , Mallion K. B. 
Published: April 2021

ABSTRACT
Classical histological methods demonstrate 4 cytoplasmic networks in fixed vertebrate neurones: ‘neurofibrils’, ‘Nissl complex’, ‘Golgi apparatus’, and ‘trophospongium’. The work described in this paper was undertaken to find out whether the 4 networks of classical histology correspond to 4 structures recognizable as such in the living neurone, or to only one structure, which may be coloured in characteristic ways by the classical methods. A single continuous network, comprising features traditionally associated with the four classical networks of the fixed cell, can be isolated by micro-dissection and detected by interference microscopy in living vertebrate neurones. When living neurones are centrifuged at a moderate angular velocity, a single continuous network remains visible under the interference microscope. There does not appear to be enough clear space left for 3 other voluminous structures. When living neurones are centrifuged at a high angular velocity, a single continuous network is pushed to the centrifugal pole of the cell. The remainder of the cell then contains only small separate objects. A single continuous network can be detected by interference microscopy in the cytoplasm of fixed, unstained neurones. When the same cells are dyed by a Nissl method, the cytoplasmic network seen in the unstained cells becomes deeply coloured. When the same cells are bleached and then silvered by a Golgi method, the objects that before had bound the dye now are blackened by the reduced silver. The same effect is obtained when the Nissl method is used after silvering. It is inferred from the results of these experiments that there is only one cytoplasmic network in living normal adult vertebrate neurones. This network is demonstrated in fixed neurones of the same type with varying degrees of faithfulness by the classical methods. It is suggested that the terms ‘neurofibrils’, ‘Nissl complex’, ‘Golgi apparatus’, and ‘trophospongium’ be abandoned.