bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oogenesis in the Desert Snail Eremina desertorum with Special Reference to Vitellogenesis
Authors: Fahmy Onsy G. 
Published: April 2021

ABSTRACT
The histological structure of the ovotestis is briefly described.
The germinal epithelium gives rise to both categories of germ cells (male and female) as well as to the nurse cells.
During the differentiation of the germinal epithelial cell towards the germ line, it passes through a certain stage, ‘the progerminative indifferent stage’, before it is polarized either towards the male or female line.
A detailed description of the mode of differentiation of the progerminative indifferent cell into the earliest female element is given.
Mitotic multiplication of the early female elements never occurs. Nevertheless the diploid chromosome complement is represented by prochromosomes.
During the oocytic meiotic prophases, parasynaptic conjugation of the chromosomes is quickly followed by relational coiling of the synaptic mates and the formation of the strepsitene double spirals.
The strepsitene double spirals give rise to the diplotene bivalents of the haploid count 28.
The steps of chromatin diffusion that lead to the construction of the typical oocytic germinal vesicle are described.
Changes in size, number, and stainability of nucleoli during oocytic growth are recorded. Extrusion of basiphil material from the nucleolus into the ooplasm is highly probable.
The mitochondrial granules at the beginning of the period of active oocytic growth form a huge zone to one side of the nucleus. Later they increase in number and widely scatter in the ooplasm. It is held (in favour of Harvey’s view, 1929 and 1931) that mitochondria are probably concerned in the chemical synthesis of yolk from raw material provided in the ooplasm.
The Golgi bodies in oocytes are in the form of rods and not vesicular. In the early oocyte they form a group to one side of the nucleus. Eventually they disperse in the ooplasm either singly or in small typical complexes. Each of the latter is constituted of a few rods arranged end to end as if on the perimeter of an irregular circle.
The earliest yolk spheres (largely proteid) appear in the interior of the Golgi complexes or on the concave sides of the separate Golgi rods.
The Golgi rods become severed from the yolk spheres and migrate mainly towards the periphery of the oocyte where they collect in clumps.
The elements of the Golgi clumps become loaded with an unsaturated free fat. The original Golgi rod always preserves its identity and never transforms itself into fat.
Location of Absorbed Carcinogens within the Amphibian Cell
Authors: Waddington C. H. , Goodhart C. B. 
Published: April 2021

ABSTRACT
Cells from explants of newt gastrulae which had been-cultuted in Holtfreter’s standard solution containing the ‘carcinogen 3:4-benzpyrene rendered soluble by caffeine were examined for fluorescence by ultra-violet light. The lipoid constituents of the cells, lipochondria and liposomes, .showed the bright blue fluorescence of benzpyrene in molecular solution and there was also occasionally a structureless blue fluorescence round the nucleus corresponding, perhaps to the so-called ‘Golgi Apparatus’. The yolk platelets were slightly fluorescent but this was probably due to the associated lipides and it largely disappeared in jnoribund preparations, where the lipochondria became detached from the platelets. The nucleus showed ho fluorescence, nor was a fluorescept nucleolus observed. It could be shown that the pyronine-stapling cytoplasmic granules of ribonucleoprotein (microsomes) were not fluorescent and so probably do not have any affinity for the carcinogen. The very smalt fluorescent granules in Brownian movement that had previously been looked upon as ribonucleoprotein microsomes are in fact small liposomes and do not stain with pyronine.
It is suggested that the evocating power of the carcinogenic hydrocarbons is probably not due to cytolytic activation of the evocator, by the killing of some cells in the exposed ectoderm. It may be by physiological activation, operating through a specific action on the lipochondria, leading to their breakdown into liposomes and the release of active evocator substance. Some evidence is produced which suggests that the lipochondria contain ribonucleo-protein, and this fraction of them may constitute the active evocator; this would be congruent with the theories of Brachet (1947). It cannot yet be excluded, however, that the hydrocarbons act as direct evocators, simulating the effects of the naturally occurring substance.
The observation that benzpyrene is not accumulated by nucleoprotein makes it likely that the mutagenic activity of the carcinogens is indirect.
On the Cuticle of the Scorpion Palamneus swammerdami
Authors: Krishnan G. 
Published: April 2021

1. The cuticle of the scorpion Palamneus swammerdami shows the same fundamental layers as that of insects. It consists of a thin outer epicuticle and a thick inner endo-cuticle; the outer layers of the latter are transformed by hardening into an amber-coloured exocuticle.
2. The chemical characteristics of the constituent layers of the cuticle in different regions are described and it is shown that the proteins impregnating the endocuticle during hardening appear to be different from those described in insects and possess resistant properties.
3. The exocuticle in addition to giving evidence of tanning indicates the presence of disulphide bonding. A similar indication is obtained in the epicuticle.
4. The mode of hardening of the cuticle of scorpion is discussed and compared with similar processes in other arthropods.
The Preservation and Investigation of Plant Mitochondria
Authors: Chayen J. , Miles Ursula J. 
Published: April 2021

ABSTRACT
A method for making squash preparations of plant root tip cells is described. This entails the use of an inert preserving substance, polyvinyl alcohol. The advantages of the method are the preservation of the cytoplasmic bodies, including the mitochondria ; the retention of fat droplets inside the cells; the fact that the nucleus remains optically homogeneous; and the fixing of free aldehyde groups and of diffusible substances in the cytoplasm. It is a relatively rapid and simple technique, and the cells produced by it resemble closely those produced by the method for making living squash preparations of such cells.
The Origin of Sensory Neurones in an Insect, Rhodnius prolixus (Hemiptera)
Authors: Wigglesworth B. V. B. 
Published: April 2021

ABSTRACT
Beneath each sensillum in the integument of the insect is a bipolar cell (or group of cells) connected to the sense organ by a distal filament and to the central nervous system by a proximal filament or axon. It is generally believed that this cell is a primary sense cell (vom Rath, 1888; Hanström, 1928), but whether it arises by differentiation from the ordinary ectodermal cells or whether it has migrated outwards from the central nervous system has not been proved.
Cytological Studies of the Acinar Cell of the Pancreas of the Mouse Part II. The Argentophil, Osmiophil, and Sudanophil Substance
Authors: Morgan Winfield S. 
Published: April 2021

ABSTRACT
It is shown by the Aoyama, Mann-Kopsch, and Sudan black techniques that there is a definite series of changes in the pancreas acinar cell of the mouse after the subcutaneous injection of a pre-determined optimum dose of neutral red. These changes are similar to those observed in the fresh tissue. In the fixed preparations they are characterized by the appearance of argentophil, osmiophil, and sudanophil bodies having the position, number, general configuration, and relative size of the neutral red granules and aggregates. It is further observed that there is a shift of this substance from an apical position in the cell to a more basal one, apparently in response to the presence of neutral red.
A Comparative Study of the Spermatophores of three Scyllarid Lobsters (Parribacus antarcticus, Scyllarides squammosus, and Scyllarus martensii)
Authors: Matthews Donald C. 
Published: April 2021

ABSTRACT
In Parribacus antarcticus and Scyllarus martensii mitotic division of germinal epithelial cells produces primary spermatocytes, whereas in Scyllarides squammosus this function of the germinal epithelium is limited to comparatively few large, oocyte-like cells. Metamorphosing spermatids in all three species are expelled from the sacculi of the testis by the rhythmical activity of their germinal epithelium. This probably accounts also for the clumping of the spermatozoa in the collecting tubule; each clump represents the extended contents of a single sacculus. In Scyllarus martensii and Scyllarides squammosus a continuous, cord-like, encapsulated spermatogenic mass traverses the vasa deferentia, whereas in Parribacus antarcticus the spermatogenic mass separates into distinct ampullae which become encapsulated and are further provided with an enveloping sheath. This sheath between adjacent ampullae becomes ribbon-like, twists, and ultimately forms short, doubly twisted peduncles. A secretion of the typhlosole in all three species surrounds the completed spermatophores and forms the homogeneous matrix. Although these three species are anatomically similar, the spermatophores of Scyllarus martensii and Scyllarides squammosus resemble non-pedunculate spermatophores of the palinurids, the astacids, the homarids, and the nephropsids, whereas those of Parribacus antarcticus more nearly resemble the pedunculate spermatophores of certain pagurids. Spermatophoric evidence above does not justify the inference that Parribacus antarcticus occupies a systematic position intermediate between the Macrura and the Anomura.
The Lateralis Organs and their Innervation in Xenopus laevis
Authors: Murray R. W. 
Published: April 2021

ABSTRACT
The innervation and general morphology of the lateralis organs of Xenopus laevis are described. Each group of organs is innervated by two large and two or fewer small fibres. Each of the large fibres gives off a branch to each of the lateralis organs in the group, but the branching of the small fibres is less regular. Each lateralis organ is therefore innervated by two large and up to two small fibres. The large fibres branch extensively at the base of the organ, the small fibres less so, and the nerve endings lie basal to or between the sensory cells. No terminal swellings could be seen. The endings of a particular fibre are not restricted to any one region of the organ.
No special function could be assigned to the dual arrangement of the innervation.
The original accounts of the structure of the lateralis organs were adequate. The recently suggested division of the supporting cells into three types is not justified.
It is probable that a cupula exists on the lateralis organs but it could not be observed. It is suggested that the supporting cells secrete the cupula.
Egg-capsule Proteins of Selachians and Trout
Authors: Brown C. H. 
Published: April 2021

ABSTRACT
The material of the egg-capsules of selachians and the chorion of trout eggs has been examined by physical, chemical, and histochemical methods.
The material of the egg-capsule of selachians has been found to be a quinone-tanned protein.
The chorion of trout eggs is not quinone-tanned but its formation and chemical behaviour allies it with the invertebrate cuticular proteins rather than with the vertebrate keratins.
A Study of the Round Pigment Cells in the Uterus of the Ewe
Authors: Hadek R. 
Published: April 2021

ABSTRACT
The round pigment cells in the uterus of the ewe have been found to contain, in addition to melanin granules, Abnützungspigmente 2 (pigments of ‘wear and tear’). On account of their ability to absorb and store material from the neighbouring tissue, the cells are regarded as phagocytes.
Notes on the Mechanism of Food Movement in the Gut of the Larval Oyster, Ostrea edulis
Authors: Millar R. H. 
Published: April 2021

ABSTRACT
The histology and mechanism of food movement in the stomach of the larval oyster are described. Cilia line the stomach, except the left wall, roof, and upper part of the right wall, which bear the smooth gastric shield. The diverticula contain non-ciliated absorptive cells and ciliated non-absorptive cells. A slender muscle passes round each diverticulum. Food is rotated in the stomach by the style, and also turned over in the sagittal plane. Particles are drawn into the diverticula and returned to the stomach by the rhythmic expansion and contraction of the diverticula.
The Site of Damage in Amoebae Exposed to X-Rays
Authors: Ord M. J. , Danielli J. F. 
Published: April 2021

ABSTRACT
The technique of nuclear transfer was used to study the extent to which X-rays damage nuclei and cytoplasms of Amoeba proteus. Results showed that cytoplasm was directly damaged by the radiations. Cytoplasmic damage with doses below 280,000 r was reversible, though damaged cytoplasm could lethally damage normal nuclei. Damage with doses above 300,000 r caused lethal damage and death occurred without division in 0–3 days. Damage to nuclei was probably a combination of a direct action of the radiations and exposure to reversibly damaged cytoplasm. Nuclei were 2·4 times as sensitive as cytoplasms, the LD50 doses being approximately 120,000 r for nuclei and 290,000 r for cytoplasm. Death due to nuclear damage generally occurred without division within 3 to 6 weeks. Nuclear damage cannot be interpreted in terms of the ‘target’ theory.
The Distribution of Mast-Cells in the Digestive Tract of Laboratory Animals: Its Bearings on the Problem of the Location of Histamine in Tissues
Authors: Mota I. , Ferri A. G. , Yoneda S. 
Published: April 2021

ABSTRACT
The mast-cell distribution in the digestive tract of the rat, dog, cat, and guinea-pig was studied. In the rat mast-cells were present in the tongue, oesophagus, and forestomach, but practically absent from the glandular stomach, duodenum, ileum, and rectum. In the other species, mast-cells were numerous throughout the whole of the digestive tract, presenting a large individual variation. In the tongue and oesophagus mast-cells were found mainly in the submucosa and lamina propria, where they were located near the epithelium. In the stomach, mast-cells were more numerous in the mucosa and concentrated in the muscularis mucosae and between the necks of the glands. In the duodenum, mast-cells were also more numerous in the mucosa, being concentrated in the muscularis mucosae and frequently also in the summit of the villi. In the ileum and rectum mast-cells were less numerous than in the stomach and duodenum, keeping the same disposition as in these. The contribution of the mastcells to the histamine content of the digestive tract is discussed.
Human Saliva as a Convenient Source of Ribonuclease
Authors: Bradbury S. 
Published: April 2021

ABSTRACT
Saliva, heated to 80° C for io minutes and centrifuged to remove mucus, is used as a source of ribonuclease. Slides of mouse pancreas incubated in this for 3 hours at 60° C show complete removal of cytoplasmic basiphilia. Incubation of control slides in distilled water before staining is essential in order to avoid errors due to possible solution of basiphil material in aqueous media. Errors due to incomplete elimination of the salivary amylase are prevented by using the PAS reaction to check the absence of all diastatic activity.
Formaldehyde and phenyl isocyanate are used as specific enzyme inhibitors. If these are added to the saliva before use, the ribonuclease is inactivated, and there is then scarcely any action on the cytoplasmic basiphilia.
With these controls, incubation of slides in prepared saliva, followed by staining with basic dyes, may be used in histochemistry as a means of localizing ribonucleic acid.
Experimental alteration of the peri-renal tissue of protopterus
Authors: Moorhouse D. E. 
Published: April 2021

ABSTRACT
The experiments were carried out on Protopterus aethiopicus in East Africa. They were: the injection of commercial adrenocorticotrophic hormone, hypophysectomy, administration of ACTH after hypophysectomy, artificially induced aestivation, and artificially induced ‘stress’.
The two elements of the lipid tissue show differing reactions to the experiments carried out. The large lipid cells appear to be under direct pituitary control: active secretion follows ACTH administration, hypophysectomy leads to a blocking of secretion. After ‘stress’ and hypophysectomy the small lipid cells develop sudanophil inclusions which are positive to the histochemical tests for steroids. This does not occur after ACTH administration.
The phagocytes of the endothelial system take part in the transfer of material within the peri-renal tissue; this is shown by their cytology after ACTH administration and ‘stress’. Evidence from these experiments indicates that the round pigment cells characteristic of the normal animal are syncytial structures formed by the fusion of phagocytic cells containing pigment and remains of large lipid cells.
The steroid tissue shows little change in these experiments other than a decrease in the amount of steroid material after ACTH, and a more intense staining of the mitochondria after hypophysectomy.
The number of eosinophil leucocytes increases as the result of ACTH administration.
The round cell nodules showed no detectable changes in these experiments.
The development of the malpighian tubules of schistocerca gregaria (orthoptera)
Authors: Savage A. A. 
Published: April 2021

ABSTRACT
1. Schistocerca gregaria Forsk. possesses about 250 Malpighian tubules arranged in twelve groups, situated dorso-laterally, laterally, ventro-laterally, and in the six intervening positions around the posterior end of the mid-gut. The gut forms an expanded ampulla at the point of entry of each group.
2. Each tubule is composed of five rows of cells, spirally arranged. Upper and lower segments are present, as in Rhodnius (Wigglesworth, 1931), the former very short. There is also a spiral trachea.
3. Tubules arise in seven generations, two in the embryo and one in each of the five nymphal instars. The first embryonal generation is composed of six primary tubules, the second of twelve embryonal secondaries. In the other five a variable number of nymphal secondaries is added, with means of 25, 51, 88, 63, and 6 respectively. The six primary tubules are attached distally to the rectum, the embryonal and first and second instar secondaries pass forwards, the fourth and fifth instar secondaries pass backwards, and the third in both directions.
4. The development of any one tubule comprises a period of initiation, a period of mitosis and elongation, and a period of differentiation. The first is restricted to the first few days of the particular stadium, the second takes place throughout the stadium, and the last throughout the life of the tubule.
5. The secondary tubules are arranged in an arc round the periphery of the ampulla. These arcs are perfectly symmetrical, the tubules arising alternately left and right of the mid-line during all the nymphal stages.
6. Tubule buds formed late in the period of initiation may cease to develop until the corresponding phase of the succeeding instar is reached.
7. The origin of tubules from a posterior interstitial ring and its relation to the interpretation of insect gastrulation and the nature of nymphal developmental cycles is discussed.
Tissues for Assessing Histochemical Methods for Calcium
Authors: McGee-Russell S. M. 
Published: April 2021

ABSTRACT
An account is given of three tissues which are suitable for use as standard objects when attempting methods that are said to reveal calcium salts in tissues. The tissues are the digestive gland of the snail Helix, the gut diverticulum of the crab Carcinus, and the left colleterial gland of the cockroach Periplaneta. They contain respectively calcium carbonate, calcium phosphate, and calcium oxalate deposits. The deposits are little, if at all, contaminated with other calcium salts.
Cyclical Changes in the Distribution of the Testis Lipids of a Teleost Fish, Esox lucius
Authors: Lofts B. , Marshall A. J. 
Published: April 2021

ABSTRACT
A study of the cyclical changes in the distribution of testis lipids in the pike reveals a sequence of events comparable with that occurring in seasonal birds. These events include the post-nuptial appearance of cholesterol-positive lipid material which accumulates within the seminiferous lobules, and its subsequent gradual disappearance. A lipid cycle occurs also in the lobule walls, where apparently fibroblasts, in the absence of a true secretory interstitium, become glandular and probably take on an endocrine function. These ‘lobule boundary cells’ seasonally accumulate cholesterolpositive cytoplasmic lipids which suddenly become depleted at the time of the annual pre-spawning assembly.
The pike differs from wild birds in the ‘timing’ of such rhythmical activity. In birds, despite a rapid post-nuptial interstitial regeneration, the tubule cholesterol lingers until spermatogenesis begins during the following late winter or spring. In the poikilothermous pike, on the other hand, the next spermatogenesis begins almost immediately (in June, when the temperature of the water is still rising). It continues without interruption while the length of day and later the temperature decrease, until tbe testis reaches its maximum size in December. ‘Lobule boundary cells’ start to become lipoidal in September, at a time of high temperature but decreasing day-length. The cells are fully charged by December. Both tubules and gland-cells now become inactive. Then in April at the spring period of increasing day-length, and immediately a iter water temperature starts to rise, the boundary cells begin to secrete and the prespawning assembly occurs. This is followed by the shedding of spermatozoa later in ti e month or early in May. The only period of true inactivity is at the height of spermatogenesis during mid-winter and early spring.
The Shrinkage of Air-dried Bacteria prepared for the Electron-microscope
Authors: Ross K. F. A. , Deutsch K. 
Published: April 2021

ABSTRACT
Values for the mean thickness of living bacilli in a number of different cultures of Lactobacillus bulgaricus were obtained from phase-change measurements. These were made with an interference microscope. The bacilli were mounted in media of several different refractive indices. The accuracy of these measurements is not limited by the wavelength of the light used, so that the mean thickness of bacteria can be measured more critically in this way than by an eyepiece micrometer scale.
The values obtained for the mean thickness of the living bacilli were compared with the mean width of similar bacilli measured in electron-micrographs, after they had been prepared for electron-microscopy by drying them in air on formvar. The method used for preparing the bacteria for the electron-microscope is described in detail.
It was found that osmium-fixed air-dried L. bulgaricus so prepared shrink linearly in the plane of the formvar film by 59% ±5%, and similar unfixed bacilli by 51% ±5%. Phase-change measurements through these air-dried bacilli indicated a similar degree of shrinkage, or a slightly greater shrinkage, in the direction at right angles to the formvar film.