bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Improved and Rapid Embedding Method
Authors: Chayen J. , Gahan P. B. 
Published: April 2021

ABSTRACT
Plant tissues may be embedded in half the time taken for paraffin embedding if acetone is used as the dehydrating and infiltrating agent, and the tissue is embedded in ester wax. This procedure retains appreciably more lipid material inside the cells than does the more usual technique, even when the tissue has been fixed in osmium tetroxide or in La Cour’s 2BE.
What is the ‘Golgi Apparatus’ in its Classical Site within the Neurones of Vertebrates ?
Authors: Malhotra S. K. 
Published: April 2021

ABSTRACT
A reticulum can be seen by interference microscopy in the cytoplasm of the living neurone of vertebrates. The reticulum consists of irregular, massive bodies and thin strands. There are also well-defined spaces in the cytoplasm, in contact with the reticulum; they are usually crescentic.
The massive bodies are the objects commonly called Nissl bodies. The thin strands are the basiphil threads clearly recognized by Nissl himself as constituting a part of his basiphil material.
The classical ‘Golgi apparatus’ of the cell-body of the neurone of vertebrates consists of a deposit of silver or of osmium on the cytoplasmic inclusions mentioned in the first paragraph, but especially on the basiphil strands, which have a particular affinity for silver.
At the base of the axon there are non-basiphil threads, which are also blackened by the Golgi methods.
Neurosecretion in the Brain of the Larva of the Sheep Blowfly, Lucilia caesar
Authors: Fraser Alastair 
Published: April 2021

ABSTRACT
Six groups of neurosecretory cells were identified in the brain of the mature larva of Lucilia caesar. Five of these groups belonged to the category of medial neurosecretory cells and one to that of lateral neurosecretory cells. The groups differ in position, cell size, staining characteristics, and sequence of activity. It is apparent that only some of the groups are concerned with the process of thoracic gland activation, though all function during metamorphosis. At least one group, not concerned in thoracic gland activation in the non-diapause larva, is continually active during diapause.
The Use of Teased Preparations and Frozen Sections in Quantitative Studies of Mammalian Peripheral Nerve
Authors: Wendell-Smith C. P. , Williams P. L. 
Published: April 2021

ABSTRACT
When teased preparations of peripheral nerve are examined, the highly refractile myelin sheath acts as a convex lens and affects estimates of axon diameter and sheath thickness. The construction of ray diagrams for different axon-sheath ratios indicates that the degree of magnification varies with this ratio. Models and experiments in which teased fibres were immersed in fluids of different refractive index show that magnification also varies with the relative refractive indices of the sheath and the immersion medium. Fibres from the nervus gastrocnemius medialis (NGM) of the rabbit were teased in Ringer’s solution and measurements made with a polarizing microscope. A regression line for 2 × apparent sheath thickness on external diameter was calculated.
Frozen sections (Williams, 1959) of the NGM were prepared, and from these individual fibres were tipped over on to their sides by micromanipulation. A magnification effect similar to that existing in teased fibres was thus introduced and a comparison of their apparent axon diameters was made valid. An analysis of co-variance showed no significant difference in variance, slope, or elevation. It was concluded that these frozen sections provided a satisfactory basis for an estimate of magnification, and that estimates of size relationships made on these frozen sections reflected the natural state as closely as estimates made on isolated teased fibres and corrected for magnification.
A regression line was derived for 2 × myelin sheath thickness on external diameter from intact frozen sections. This line was compared with the regression line for teased fibres and percentage magnification of the axon plotted against external diameter. The graph indicated that this percentage magnification decreased with fibre diameter from over 40% to under 20%.
An Account of Larval Budding in the Compound Ascidian, Hypsistozoa fasmeriana
Authors: Brewin Beryl I. 
Published: April 2021

ABSTRACT
Larval budding in Hypsistozoa fasmeriana is in many ways unique in the subfamily Holozoinae. The stolon, which projects from the left side of the oozooid, is large (235 μ in diameter, 1 · 8 mm in length) and reaches maximal size before severance of buds occurs. The buds arise one at a time and 9 to 14 are formed.
Test forms rapidly between a newly severed bud and the remainder of the stolon. Thus the buds are moved along an arc of a spiral which runs from the left side of the oozooid somewhat anteriorly across the ventral side and posteriorly up the right side. By the end of bud formation the first-formed bud occupies the most posterior position, lying high up on the right side of the oozooid.
Each larval bud develops directly into a blastozooid and by the time the tadpole becomes free-swimming there is a considerable degree of organogenesis. The blasto-zooids together with the oozooid form a ring of zooids tilted slightly away from the vertical. After metamorphosis of the tadpole this ring becomes horizontal, but the tilt is still maintained with the oozooid occupying the most elevated position. Thus in the young colonies the plane of the head is slightly off the horizontal—an arrangement which persists throughout the life of the colony.
The development of larval buds in this ascidian is not delayed until after dedifferentiation of the oozooid, as is the case in the other Holozoinae. The blastozooids function simultaneously with the oozooid. They do not, however, become sexually mature, being presumably of sub-maximal size for the species.
The newly severed bud differs from that of other Holozoinae in having an extensive epicardial tube and a thick mesenchymal layer of densely granulated cells. The epicardium of the blastozooid is formed from the posterior end of the original epicardial tube. It remains single. The neural tube arises from the left peribranchial sac.
H. fasmeriana forms a close link between the sub-family Holozoinae and the subfamily Polyclininae. It resembles the Holozoinae in form of gut, position and mode of origin of the brood pouch, and position of the cardio-pericardium. It shares with the Polyclininae the post-abdominal position of the gonads as well as the structure and organogenesis of the buds.
The Initial Cooling of Tissues in the Freezing-drying Technique
Authors: Zlotnik I. 
Published: April 2021

ABSTRACT
When a mixture of dry ice and pentane is subjected to high vacuum for one hour the temperature of the mixture is reduced to − 125 ° C.
The low temperature of the dry ice/pentane mixture persists for about h and rises only very slowly thereafter.
The chilled dry ice mixture when used for the initial cooling of tissues produces good cytological preservation.
The Cuticle and Wax Secretion in Calpodes ethlius (Lepidoptera, Hesperidae)
Authors: Locke M. 
Published: April 2021

ABSTRACT
Larvae of Calpodes ethlius have an area of integument specialized for the secretion of long hollow filaments of wax. The epicuticle in this region has numerous cratershaped tubercles about 0·5μ in diameter, from the rims of which the filaments are secreted. Rows of tubes 60 A in diameter emerge round the rim of each crater. The wax is supposed to traverse these tubes and they have been termed ‘wax canals’. On the inside the wax canals ramify irregularly. Tubes that appear to be similar occur elsewhere in the epicuticle, where they may be concerned with normal wax secretion. The epicuticle consists of cement, a cuticulin layer 60 to 100 A thick, and an inner dense layer of variable thickness. Microfibres are described in the endocuticle.
A Contribution to the Life-history of the Brachiopod Tegulorhynchia nigricans
Authors: Percival E. 
Published: April 2021

ABSTRACT
This study of the development of a rhynchonellid brachiopod has revealed marked differences from that of Terebratella inconspicua (Percival, 1944). These principally concern the origin of the mesoderm and of the lophophore. The origin of the right and left mesoblastic sacs in Tegulorhynchia and in Terebratella depends on the stage at which the blastoporal groove exerts its influence, earlier in the former, leading directly to their formation, later in the latter, leading indirectly to their formation. The subsequent division into anterior and posterior sacs is similar in both genera. The lophophore of Tegulorhynchia is the product of the anterior lobe, and considerable centripetal movement occurs during the sinking of the centre from which the brachial fold (or buccal lip) is derived. The process of formation of the lophophore in Terebratella can be regarded as a much shortened version of that which occurs in Tegulorhynchia. In the latter genus the origin of the brachial fold is elaborate and protracted, while in the former the brachial fold does not appear until 8 pairs of cirri have been formed.
Histochemical Observations on the Succinic Dehydrogenase and Cytochrome Oxidase Activity in Pigeon Breast-muscle
Authors: George J. C. , Talesara C. L. 
Published: April 2021

ABSTRACT
Histochemical and cytochemical observations were made on the exact localization and distribution pattern of succinic dehydrogenase system and cytochrome oxidase in the pigeon breast-muscle by employing slightly modified methods. Succinic dehydrogenase activity, which was not detected earlier either histochemically or biochemically in the broad white fibres, was demonstrated by using a modified incubation medium under strictly anaerobic conditions, with neotetrazolium as the hydrogen acceptor. The size, localization, and distribution pattern of the histochemically demonstrable diformazan and indophenol blue granules showed a more or less close resemblance to the mitochondrial staining in the individual red as well as white fibres. The occurrence of high oxidative metabolism in the narrow red fibres was revealed by the presence of a large number of succinoxidase-positive granules in these fibres. On the other hand, the presence of fewer, smaller granules indicated very low oxidative metabolism in the broad white fibres.
The presence of the fewer, smaller succinoxidase-positive granules in the broad white fibres nevertheless shows that these fibres too possess mitochondria where at least a certain amount of oxidative activity does take place, and that they are to be considered as analogous to the white fibres of the other vertebrate skeletal muscles. It is also suggested that these granules are to be considered as mitochondria in the general sense and that the distinction between sarcosomes and mitochondria as proposed by previous authors needs reconsideration.
The Histochemistry of the Male Germ-cells of the Nematode Porrocaecum angusticolle, a Parasite in the Vulture
Authors: Nath Vishwa , Gupta Brij L. , Kochhar Devendar M. 
Published: April 2021

ABSTRACT
The cytoplasm of the male germ-cells of Porrocaecum angusticolle contains (1) phospholipid granules, (2) ‘refringent bodies’ consisting of ribonucleoproteins at first, but some masked lipids as well in the late spermatid, (3) mitochondria of the usual lipoprotein nature. The refringent bodies arise in the spermatocytes in close association with the phospholipid granules (‘Golgi bodies’) by the aggregation of cytoplasmic basiphil material. In the spermatids the refringent bodies gradually fuse to form a single cone-like structure which occupies the narrow posterior region of the spermatozoon.
This cone-like structure, judging from its origin in close association with the ‘Golgi bodies’ (acroblasts), is the homologue of the acrosome of a normal flagellate sperm; but it is completely devoid of polysaccharides and seems unable to function as an acrosome, since it occupies a position posterior to the nucleus in the spermatozoon. On the contrary, some polysaccharides have been demonstrated by the authors in the broad anterior region of the spermatozoon, which may be functioning as an acrosome.
The Histochemical Recognition of Lipid in the Cytoplasmic Network of Neurones of Vertebrates
Authors: DAVID G. B. , BROWN A. W. 
Published: April 2021

1. A method for the histochemical demonstration of the lipid of the cytoplasmic network (‘Golgi apparatus’, ‘Nissl complex’) of the neurones of vertebrates was accidentally discovered.
2. Very small pieces of tissue are fixed in Lewitsky/calcium or Flemming/calcium, postchromed, and embedded in gelatine. Frozen sections are cut at 0.5 to 5 µ, and coloured in Sudan black after bleaching.
3. The intensity of the colouring of lipid by Sudan black can be increased by centrifuging the tissue before fixation.
4. The method described in this paper demonstrates lipid in the strands and bodies of the cytoplasmic network of vertebrate neurones. It was shown, in sections subsequently decolorized and then stained in a basic dye, that the sudanophil reticular objects are the Nissl complex.
A Histochemical Study of the Connective-Tissue Sheath of the Nervous System of Periplaneta americana
Authors: Ashhurst Doreen E. 
Published: April 2021

ABSTRACT
The connective-tissue sheath surrounding the nervous system of Periplaneta americana consists of two layers, the neural lamella and the sheath cells beneath it. The neural lamella is composed of a collagen-type protein and neutral muco-polysaccharide. The sheath cells possess numerous lipochondria and mitochondria; the former consist of phospholipid and some cerebroside. The cytoplasm of the sheath cells contains some RNA, glycogen, and lipid.
Stress concentrations in bone
Authors: Currey J. D. 
Published: April 2021

ABSTRACT
Small cavities and notches in an otherwise perfect material will greatly reduce the strength of the material, particularly its tensile strength. They will do this by producing stress concentrations around themselves. It is shown that bone is permeated with such stress-concentrators in the form of canaliculi, osteocyte lacunae, blood-vessels, and muscle insertions. However, in mammalian bone the orientation of the lacunae and blood-vessels is such as to reduce, though not abolish, the concentrating powers of these elements in relation to the dangerous stresses acting in the bone. The smoothness of the diaphysis shaft and the raising of muscle insertions on to cristae will have similar advantageous effects. The larger the defect, the greater the tendency to be orientated favourably.
The reasons for the presence of osteocytes and their associated blood-supply are not known, and a comparison with the acellular bone of some teleosts is not helpful. It is suggested that the lacunae and blood-channels in bone may to some extent increase the robustness of bone by delaying the spread of minute cracks, which must inevitably be present in bone, though they are difficult to demonstrate. The orientation of the lacunae is favourable for this effect, and they are sufficiently close-packed in the bone to ensure that any minute crack will run up against many lacunae before it has travelled roo y.. An examination of artificially produced cracks in cattle and human bone shows that the cracks do stop very frequently on entering lacunae and blood-vessels. The lacunae are more likely to prevent the spread of fatigue cracks than of impact cracks. The crack, running up against a lacuna, could be a stimulus for local reconstruction, so that it would be repaired.
The influence of mature males on the neurosecretory control of ovarian development in the desert locust
Authors: Highnam K. C. , Lusis O. 
Published: April 2021

ABSTRACT
The ovaries of the desert locust are made up of about 100 ovarioles. When females are reared with mature males, the terminal oocytes in the ovarioles develop very much more rapidly than the terminal oocytes of females reared without males. In addition, the percentage of terminal oocytes which are resorbed during development increases more rapidly in females reared without males than in females reared with mature males. This results in a significantly larger percentage of mature eggs being produced by females reared with mature males.
The neurosecretory system contains little stainable material in females whose terminal oocytes are developing rapidly in the presence of mature males, but contains a large amount when the terminal oocytes are mature. In females reared without males, whose terminal oocytes either develop slowly or remain undeveloped, the neurosecretory system shows a precocious accumulation of stainable material. It is concluded that the neurosecretory system is actively extruding secretion when the amount of contained material is small, and that material is accumulating and not being released when it is present in large amount. The presence of mature males somehow brings about the release of material from the female neurosecretory system, with consequent rapid development of terminal oocytes and the production of a larger number of eggs.
A study of Thermosbaena mirabilis (Malacostraca, Peracarida) and its reproduction
Authors: BARKER D. 
Published: April 2021

ABSTRACT
Knowledge of the anatomy of Thermosbaena is extended as follows: (i) The topography of the head and anterior thoracic region, and the orientation and relationships of the mouthparts and anterior appendages are described, (ii) A branchial chamber is located underneath each lateral carapace flap, (iii) ‘Skin’ glands are demonstrated to occur at the bases of the paragnaths, maxillules, and maxillipedes; in the labrum and in the mandibular palps; in the groove leading from the food basin to the paragnath bases; and in the basal segments of the endopodites of peraeopods II-V. The function of these glands is obscure; histochemical tests indicate that they do not secrete mucus, (iv) The posterior aorta is traced from the heart to the level of the first abdominal segment, where it bifurcates into 2 lateral vessels which diverge to each side of the intestine, (v) Four conditions of the female reproductive system are distinguished, namely, the immature, mature, copulatory, and brood-pouch conditions; temporary seminal receptacles are formed by dilatation of the oviducts in the copulatory condition.
An inhalant respiratory current is produced by oscillation of the maxillipede epipodites in the branchial chambers. The exhalant respiratory current emerges via carapace lappets on either side of the head.
Thermosbaena feeds on particles of detritus suspended in a mucilaginous matrix that is probably derived from the mucilaginous sheaths of the Cyanophyceae in the diet. A main food-stream appears to be driven forwards between the peraeopods, through a channel formed by the maxillipede bases to the food basin, and from thence along a ventral groove and between the paragnath bases to the oral cavity. It is possible that the main food-stream is augmented by detritus brought by the inhalant respiratory current, and by lateral feeding currents drawn in from the sides.
Following internal fertilization, early segmentation of the embryo occurs within the ovaries. The blastomeres are first formed within the body of the yolk and subsequently rise to the surface, the segmentation thus resembling that of Hemimysis and Mesopodopsis. The embryos are transferred to the dorsal brood-pouch shortly after segmentation begins, probably by expulsion from the posteriorly directed vaginae while the female is upside down, followed by suction into the brood-pouch with the inhalant respiratory current. The embryos emerge from the brood-pouch as miniature adults with the full complement of peraeopods. There appears to be no transitory 7th abdominal ganglion.
Thermosbaena is probably paedomorphic in certain respects and less primitive than Monodella. There are insufficient grounds for establishing a new malacostracan division Pancarida, as advocated by Slewing (1958), to receive the Thermosbaenacea.
Cyclical changes in the epididymis of the goose, Anser melanotus
Authors: Mehrotra P. N. 
Published: April 2021

ABSTRACT
The epididymis of Anser melanotus consists of three components, the rete testis, vasa efferentia, and epididymal tubules. The histological structure and the relationships between the three components of avian epididymis are similar to those existing in the mammalian epididymis. The epididymis shows periodic changes in its histological structure, which are parallel to the changes in the testis.
The rete testis consists of wide, anastomosing, cavernous channels, the rete tubules, lines with a simple non-secretory epithelium of cuboidal and columnar non-ciliated cells. During the breeding season the diameter of the rete tubules undergoes an appreciable increase. The internal epithelium becomes squamous through considerable distension.
The efferent ducts are lined by groups of columnar ciliated cells alternating with non-ciliated cubical cells, both the types showing secretory activity in the progressive and reproductive phases of the testicular cycle. The internal epithelium of the efferent ducts is thrown into longitudinal folds, leading to the formation of crests and crypts, which give a festooned appearance to the lumen.
The epididymal tubules are lined with columnar ciliated cells. During the onset of reproductive period, the epithelial cells of the epididymal tubules hypertrophy and become secretory. The secreted droplets are discharged into the tubule lumina. During the breeding season the epididymal tubules are filled with sperms. In the refractory phase of the testis cycle the epididymal tubules present an embryonic appearance and have no limiting membrane. Groups of cells similar to those which constitute the lining of the tubules can be seen. These cords of cells become bigger by the division of the pre-existing cells and lumina then appear in the centre, leading to the formation of new tubules.
The epididymal secretion gives a stimulus to the spermatozoa different from that given by the testis; it brings about the ripening changes in the spermatozoa.
There is no influence in the epididymis which can indefinitely preserve the vitality of sperms. The unejaculated spermatozoa left over in the epididymis after the breeding season is finished, either undergo dissolution in the lumina of the tubules or penetrate into the epithelial lining of the efferent ducts and epididymal tubules or even into the surrounding connective tissue, to undergo degeneration there.
The structure and function of the so-called yolk-nucleus in the oogenesis of birds
Authors: Guraya Sardul S. 
Published: April 2021

ABSTRACT
The so-called yolk-nucleus of the young oocytes of birds is situated close to the nucleus. It is a homogeneous, spherical mass with radiating projections. Histochemical tests show it to be rich in RNA. Lipid bodies of diverse nature and mitochondria are aggregated in its vicinity. The yolk-nucleus disintegrates as the yolk-bodies are formed, and meanwhile the cytoplasmic inclusions that had aggregated round it seem to disperse and disappear. When the yolk-bodies have been fully formed, the yolk-nucleus is reconstituted once more as a homogeneous, spherical mass.