bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurociliary synapses in Pleurobrachia (Ctenophora)
Authors: Horridge G. A. , Mackay B. 
Published: April 2021

ABSTRACT
Synapses of a typical form, with synaptic vesicles of 30 to 45 mµ diameter, on one side of a synaptic cleft of 10 to 12 mµ, are found near the bases of the long ciliated cells which make up the comb plates. The side containing the vesicles is interpreted as a section of a nerve fibre terminal in contact with the ciliated cell. Occasionally nerve-cell bodies, identified by similar vesicles, are encountered. These nerves are probably ramifications of the ectodermal nerve net which spreads over the whole animal and which transmits the inhibition of the ciliary waves when the animal is touched. Distinctly different nerve fibres, which run from the apical organ along the ciliated grooves to the end of the comb rows, are able to initiate a ciliary wave along the comb row. The excitatory nerves appear as rather empty axons which mingle with the bases of the ciliated cells. The question of the propagation of excitation between these axons, between the ciliated cells of a comb plate, and between comb plates, remains open, although regions where excitatory axons and ciliated cells make contacts between themselves and with each other have some resemblance to electrically transmitting synapses.
Observations on the nervous system of the flight apparatus in the locust Schistocerca gregaria
Authors: Guthrie D. M. 
Published: April 2021

ABSTRACT
The hair sense-organs of the head are part of a sensory system affecting the activity of motor neurones to the flight muscles. They possess curved hollow hair shafts inserted in a complex socket. A large neurone is present beneath the socket and is partly surrounded by a large formative cell, the trichogen-tormogen cell. The distal process passes up into the expanded base of the hair shaft. Fine connexions between the outer region of the formative cell and the inner part round the neurone process, possibly limiting angular sensitivity, can be seen in some specimens, although the form and fine structure of the hair shaft is almost certainly important in this respect.
The axons from the 5 areas of hair organs are collected together into a dorsal tegumentary nerve, those from area three forming a short subocellar nerve. Electronmicrographs of this nerve show that there are a number of large fibres (1 to 5 μ), and many more smaller fibres (1· to 0·1 μ) with no sheaths. There were estimated to be 5,500 fibres in each dorsal tegumentary nerve.
Within the central nervous system, the dorsal tegumentary fibres may follow one of 4 routes, as follows. They may (i) pass forward into the protocerebrum, (ii) end in zones of terminals in the deutocerebral region, (iii) a few thick fibres pass down into the suboesophageal ganglion and then cross over to the opposite side giving off collaterals before descending to the pterothoracic ganglia, (iv) most of the fine descending fibres probably end at the suboesophageal level, a proportion of them crossing over here.
The motor neurones to the longitudinal indirect muscles M81 and M82 consist of 4 anterior and 1 posterior cell respectively, and possess large and striking cell bodies, whose collaterals could be seen in the dorsal zones of motor terminals. The probable internuncial links between the sensory and motor arcs are outlined.
An electron microscopical study of neutral red granules in mouse exocrine pancreas
Authors: Byrne Jennifer M. 
Published: April 2021

ABSTRACT
The neutral red granule cycle in the mouse exocrine pancreas was studied with the electron microscope in order to discover what changes appear at an ultrastructural level in cells treated with neutral red.
There are no changes in the endoplasmic reticulum, the nucleus, the Golgi apparatus, the zymogen granules, or the mitochondria of stained cells when compared with normal tissue. Osmiophil inclusions are found which in their size and distribution correspond to the neutral red granules seen under the light microscope. Such inclusions are not seen in normal tissue. They resemble morphologically the lysosomes of various tissues.
Observations on the development of certain cell types in the fundic region of the rabbit’s stomach
Authors: Menzies Gordon 
Published: April 2021

ABSTRACT
Pre-oxyntic cells, arising from a non-mucoid cell, appear on the 20th or 21st day of foetal life. Cells of Twort appear first at the end of the 4th week after birth. Combined oxyntico-peptic cells are occasionally found in the 2nd, 3rd, and 4th weeks after birth. Another type of cell, demonstrated by Wigglesworth’s method, is found in the 4th week after birth.
Localization of a bound lipid fraction in the pancreas of the mouse
Authors: MAGGI VIVIANE , CARBONELL A. W. 
Published: April 2021

ABSTRACT
The pancreas of adult and old mice of various ages has been shown to contain a lipid fraction which is not normally stainable, but which is unmasked by the action of the lipid-solvent methanol : chloroform (1:2 v/v) and hence becomes stainable by the acid haematein reaction. This fraction seems to be contained in the zymogen granules of adult and old mice, but is absent from the pancreas of 1- to 2-week-old animals.
Circadian organization of chitin in some insect skeletons
Authors: Neville A. C. 
Published: April 2021

ABSTRACT
A circadian clock is shown to be involved in the control of macromolecular orientation of chitin by cells secreting and organizing insect endocuticle. Daily organization of locust endocuticle into alternating lamellate and non-lamellate layers persists in constant temperature (36 ° C) and constant darkness for at least 2 weeks; the freerunning period is then about 23 h, so that after a number of days the circadian clock is 180° out of phase with the astronomical clock, with which it is normally phased. The rhythm is almost independent of temperature, with a Q10 of 1·04, as contrasted with a Q10 of 2·0 for the actual rate of increase of endocuticular thickness. Locust epidermal cells differ in response to specific imposed environmental conditions according to their location in the integument. In some cells, constant low temperature uncouples chitin lamellogenesis from the circadian clock, provided that illumination (light or dark) is constant also: the result is continuously lamellate endocuticle. In other cells constant light acts as an uncoupling factor, provided that temperature (high or low) is constant also: the result in this case is continuously non-lamellate endocuticle.
The circadian rhythm of chitin lamellogenesis persists in a cave cricket (Dolichopoda linderi). A similar circadian lamellogenesis rhythm occurs in the endocuticle of nymphs and adults of the cockroach Periplaneta americana. A crossed-fibre multiple-ply endocuticle in the legs and wings of giant toe-biter water bugs (Belostomatidae) also displays circadian organization, the chitin macromolecules in any one layer lying in parallel fibres, at an angle of approximately 60° to those in the next layer.
It is suggested that daily organization of the skeleton may be a general feature of arthropods. Examples include the phenomena of timing of chitin lamellogenesis; chitin crossed-fibrillar organization; degree of fluorescence of the rubber-like protein resilin; and mineralization of crayfish gastroliths.
Some Observations with the Phase-contrast Microscope on the Neurones of Helix aspersa
Authors: Thomas Owen Lewis 
Published: April 2021

ABSTRACT
Although various investigations have contributed to the development of phase-contrast microscopy from the time of Abbe, the production of a completed microscope available for use in biological and allied fields has been a comparatively recent achievement (Köhler and Loos, 1941). A good review of this promising advance is given by Bennett (1946).
The neurones of Helix aspersa have been chosen for the present study as these cells are large and easily isolated in a fresh state, as well as for their having already been the subject of a number of cytological investigations (Kolatchev, 1916; Brambell, 1923; Brambell and Gatenby, 1923; Boyle, 1937). The following observations are limited to a description of the appearance of the neurofibrils in these cells together with a description of some very small particles shown to be present in their protoplasm, distinct from and of a much smaller order than the mitochondria. A further communication is on hand concerning some observations on the other inclusions and organoids of these cells.
Growth and Regeneration in the Tracheal System of an Insect, Rhodnius prolixus (Hemiptera)
Authors: Wigglesworth V. B. 
Published: April 2021

ABSTRACT
The tracheoles in Rhodnius are simple or branched tubes, usually 200–350 μ in length, each formed within a single cell, the nucleus of which lies at about 75 μ from the point of origin. They taper gradually from a diameter of 0·7–0·8 μ to end blindly at about 0·2 μ.
Once laid down the tracheoles persist unchanged throughout the life of the insect; unlike the tracheae they do not shed their lining cuticle at moulting (cf. Keister on Sciara). New tracheae and tracheoles arise by the outgrowth of columns of cells from the sides or endings of existing tracheae at the time of moulting.
The tips of the tracheoles migrate actively towards regions of deficient oxygenation, drawing the tracheae after them. Movements up to one millimetre have been observed. This is the mechanism by which implanted organs are provided with a tracheal supply in the absence of moulting.
The outgrowth of new tracheae and tracheoles is greatly stimulated in regions of deficient oxygenation. This is the mechanism of ‘tracheation’ of implanted organs when moulting takes place.
If the insect is reared in reduced concentrations of oxygen, there is an increase in the number of large tracheae developed. This is particularly evident in the wing lobes. The general pattern of wing venation is not affected by this altered tracheal arrangement, but minor changes may occur. These are briefly discussed.
A Technique for the histochemical demonstration of polyphenol oxidase and its application to egg-shell formation in helminths and byssus formation in mytilus
Authors: Smyth J. D. 
Published: April 2021

ABSTRACT
The distribution of polyphenol oxidase in quinone-tanning systems may be demonstrated in frozen-dried sections by incubation in 0·2 per cent, aqueous catechol at 40° C. for 15–60 minutes. A red colour develops at the enzyme site. The evidence for the view that the egg-shell in trematodes, in certain cestode groups, and in turbellarians, is a quinone-tanned protein secreted by the so-called ‘vitelline’ glands, is summarized. The ‘vitelline’ cells, in addition to giving positive reactions for proteins and phenols, give a strongly positive reaction with the catechol polyphenol oxidase test. The catechol technique may also be applied to whole helminths fixed in 70 per cent, alcohol, and serves as a useful whole mount stain for the shell-producing regions of the female genitalia. In Mytilus the catechol technique reveals the presence of polyphenol oxidase in an ‘upper’ or enzyme gland in the foot. It is suggested that in Mytilus the byssus is formed from a phenolic protein secreted from the phenol gland, which on contact with polyphenol oxidase can undergo ‘auto-quinone tanning’.
A Study of the Kultschitzky (Argentaffin) Cell with the Electron-microscope, after Fixation by Osmium Tetroxide
Authors: Christie A. C. 
Published: April 2021

ABSTRACT
1. The Kultschitzky cells of the alimentary canal of man and the guinea-pig were studied with the light-microscope, buffered osmium tetroxide being used as fixative.
2. The Kultschitzky cells of the guinea-pig were shown by the electron-microscope to contain spheroidal granules having a maximum diameter of 0·3 μ. These granules are considerably darkened by fixation for only 4 hours in 1% osmium tetroxide solution.
3. The opinion that the granules of the Kultschitzky cell are only an artifact of formaldehyde fixation is denied.
Activity of the Brain/Gorpora Cardiaca System during Pupal Diapause ‘Break’ in Mimas tiliae (Lepidoptera)
Authors: Highnam K. C. 
Published: April 2021

ABSTRACT
Pupal diapause in Mimas tiliae can be terminated by keeping the pupa for at least 4 weeks at 3° C. The adult emerges about 15 days after transfer to 25° C.
Histological examination shows that the neurosecretory cells in the brain are inactive in the diapausing pupa, but they elaborate intracellular material during the first 3 weeks at 3° C. The material is passed to the corpora cardiaca. The neurosecretory cells are again inactive by the end of the low-temperature period.
The brain/cardiaca system shows little sign of secretory activity during the subsequent period at 25° C. The corpora cardiaca undergo phagocytosis and reorganization during this time. This suggests that conditions for further development are established by the end of the low-temperature period. This hypothesis is supported by the fact that development of the non-endocrine organs begins immediately the pupa is transferred to 25° C after 4 weeks at 3° C.
Extirpation and implantation experiments involving the brain, with and without its associated corpora cardiaca, support the histological results, indicating that the brain is necessary for diapause development at 3° C and that the corpora cardiaca are involved in the release of the brain factor.
Dimethyl Hydantoin Formaldehyde: A new Water-soluble Resin for Use as a Mounting Medium
Authors: Steedman H. F. 
Published: April 2021

ABSTRACT
Dimethyl hydantoin formaldehyde resin dissolved in water or in 70 ml ethyl alcohol+30 ml water is put forward as a solution suitable for the mounting of insects, small Crustacea, &c. Its chief advantage over other water-soluble resins is its high solubility in water, its excellent adhesion to glass, its low viscosity even in high percentage solutions, and its hardness on drying.
The Uptake of Intravital Dyes by the Testis
Authors: Grant J. H. 
Published: April 2021

ABSTRACT
The vital staining reactions of the normal and ischaemic testis were investigated in 20 rats by the use of varying amounts of trypan blue and Unna’s polychrome methylene blue. The experiments showed that it was possible to distinguish both true and reticulo-endothelial interstitial cell types. The implications of this subdivision are discussed and their importance in relation to neoplasms of the Leydig cells stressed. The distribution of mast cells in the testis is described.
Studies on the growth of tissues In vitro
Authors: Willmer E. N. 
Published: April 2021

ABSTRACT
A method is described by which cells in the zone of outgrowth of cultures in flasks can be photographed at definite intervals over long periods of time. The rate of growth of chick heart tissue when growing in the presence and absence of embryo extract has been investigated. A numerical value, the growth index, has been calculated which expresses the mitotic activity of the culture during the periods of observation. In plasma alone the growth index is approximately 3 after 20 hours of growth and falls to zero at the 70th hour if the fluid medium above the plasma (in this case Tyrode) is not renewed. In plasma and embryo extract-(fluid medium embryo extract unchanged) the growth index is approximately 9 after 30 hours of growth, and falls to zero at about the 140th hour. If the fluid medium is frequently renewed with fresh embryo extract the growth index quickly falls to 3, and in the one case followed for more than 4 days it remained fluctuating about that level for the next 6 days, in fact for as long as it was practically possible to prolong the experiment. It is suggested that the method has many applications in connection with problems associated with the growth rates of tissues and organisms.
Intracellular Recordings From Interneurones and Motoneurones During Bilateral Kicks in the Locust: Implications for Mechanisms Controlling the Jump
Authors: Gynther I. C. , Pearson K. G. 
Published: April 2021

ABSTRACT
Intracellular recordings were made from the neuropile processes of thoracic neurones of Locusta migratoria during bilateral kicks of the hindlegs. Electromyographic (EMG) recordings showed that the pattern of flexor and extensor tibiae muscle activity during kicks in this extensively dissected preparation was similar to that seen during a jump. Intracellular recordings from hindleg flexor and extensor motoneurones and from 13 identified interneurones revealed additional features of the motor programme for jumping and kicking and of the mechanism which triggers these events.
There was a discrete burst of activity in the fast extensor tibiae (FETi) moto-neurone at the end of the co-contraction phase, generated by a system that appeared to be separate from that triggering the kick. The excitatory connection from FETi to flexors was not responsible for initiating flexor activity and was of little functional importance in maintaining this activity during the co-contraction phase. The initial flexor excitation came from another, unidentified, central source.
A pair of identified interneurones, the M-neurones, discharged with a high frequency burst just prior to the kick. Since these neurones inhibit hindleg flexor tibiae motoneurones, this observation provides further support for their proposed role as the neurones responsible for triggering kicks and jumps. Our data do not support the proposal that the activation of the M-neurones depends on them receiving progressively increasing proprioceptive input during the co-contraction phase. Throughout co-contraction, the M-neurones were hyperpolarized. Their activation was rapid and strong enough to cause them to discharge at rates as high as 400 spikes s−1. We suggest that the pulse-like activation of the M-neurones is produced centrally by a higher order system of interneurones.
Another pair of previously identified interneurones, the C-neurones, were not necessary for the generation of the co-contraction phase of the motor programme. Their pattern of activity and their known connections indicated that they provide additional excitation to the flexors and extensors towards the end of co-contraction.
Many other interneurones discharged either during co-contraction or when a kick was triggered. We conclude that the system generating the motor programme for a kick (jump) is more complex than proposed in previous studies.
Sprouting by Undamaged Adult Molluscan Neurones: Putative Role for Changes in Haemolymph Osmoregulation
Authors: Maetzold D. J. , Bulloch A. G. M. 
Published: April 2021

ABSTRACT
Sprouting of undamaged, adult neurones has been observed in a number of situations. For instance, in the peripheral nervous system of vertebrates, intact motoneurones exhibit terminal sprouting in response to axotomy of contralateral motoneurones (Rotshenker, 1979; Rotshenker & Tal, 1985) and in the central nervous system, neurones have been observed to sprout and occupy synapses vacated by lesioned fibres (Cotman, Nieto-Sampedro & Harris, 1981; Tsukahara, 1981). Furthermore, evidence also exists for dendritic sprouting and regression in the mature, human brain (Buell & Coleman, 1981). The plastic properties of the neurones of the freshwater pulmonate Helisoma have been examined in a number of regeneration and sprouting studies (e.g. Murphy & Kater, 1980; Bulloch & Kater, 1982; reviewed by Bulloch, 1985a). Recently, it was demonstrated that sprouting and retraction of a central neurite occurred from an undamaged adult neurone of Helisoma in response to stress (Bulloch, 1984). Specifically, sprouting occurred in a pair of buccal neurones, L5 and R5, and aestivation and body wall incision were the most effective treatments examined. Body wall incision results in haemolymph loss, and aestivation results in a loss of water and thus an increase in haemolymph osmolarity (Machin, 1975). These observations raise the possibility that the sprouting of neurones L5 and R5 may occur in response to changes in haemolymph osmoregulation. The current study directly tested the hypothesis that Helisoma neurones can sprout in response to a change in blood osmolarity. This was achieved by exposing snails to hyperosmotic and hyposmotic pond water which has known effects on blood osmolarity (Khan & Saleuddin, 1979).
Measurement of Colloid Osmotic Pressure of Microlitre and Sub-Microlitre Volumes
Authors: Riegel J. A. 
Published: April 2021

ABSTRACT
This paper describes two devices for the measurement of colloid osmotic pressure (COP) in volumes of fluid of 0·5 μl or larger. Both devices are based on a design introduced by Hansen (1961) in which COP is measured directly. An ultrafiltration membrane is clamped over a fluid-filled reference chamber which communicates with the sensitive surface of a blood pressure transducer. When colloid-containing fluid is placed on the upper surface of the membrane, fluid is drawn out of the reference chamber, lowering the hydrostatic pressure there. If the membrane is impermeable to the colloid, the pressure drop in the reference chamber is directly proportional to the COP of the colloid-containing fluid.
Feeding Rank and Brain Serotonergic Activity in Rainbow Trout Oncorhynchus Mykiss
Authors: Winberg Svante , Carter Cris G. , McCarthy Ian D. , He Zhong-Yang , Nilsson Göran E. , Houlihan Dominic F. 
Published: April 2021

ABSTRACT
Two methods for assessing the status of an individual rainbow trout Oncorhynchus mykiss within a group hierarchy, radiographic determination of individual food intake and analysis of brain serotonergic activity, were compared. The results showed that individual food intake, measured as the average share of the group meal, and brain serotonergic activity, measured as brain levels of 5-hydroxyindoleacetic acid (5-HIAA) or as 5-HIAA/5-HT (serotonin) ratios, were inversely correlated with each other, suggesting that both methods could be used as indicators of the position of the rainbow trout in a dominance hierarchy. In addition, specific growth rate correlated significantly with brain 5-HIAA/5-HT ratios.
The results indicate that the increase in brain 5-HIAA/5-HT ratios in subordinate individuals is caused by an increased use (release) of 5-HT in these fish, and not by an increase in the level of tryptophan, the amino acid precursor of 5-HT. The relationships between social rank, food intake, growth, stress and brain serotonergic activity of fish in a social hierarchy are discussed.
Correlations Between Call Characteristics and Morphology in Male Cricket Frogs (Acris Crepitans)
Authors: Mcclelland Blinda E. , Wilczynski Walter , Ryan Michael J. 
Published: April 2021

ABSTRACT
We investigated the relationships among spectral and temporal advertisement-call characteristics and the sizes of the laryngeal and ear components thought to underlie the generation and reception of species-specific vocalizations in male cricket frogs (Acris crepitans). We tested the predictions that the volumes of the structural elements necessary for acoustic communication would be correlated with various parameters of the vocalizations. The anatomy of laryngeal and ear structures was reconstructed from serial sections of the heads of male cricket frogs of two subspecies collected from several sites across the range of this species in Texas, USA. The relationships among the anatomy and call parameters were assessed using several univariate and multivariate analyses. Highly significant univariate correlations among the laryngeal components suggest that the temporal and spectral characteristics of the calls are not independently produced. Dominant frequency correlates strongly with most of the other call and morphological characteristics. Removing body size effects, however, removes the relationship between dominant frequency and the volume of the whole larynx and ear. This is also the case for call pulse rate, indicating that for this species both spectral and temporal call parameters are biomechanically related to laryngeal size which is, in turn, largely mediated by body size. General body size effects might also explain the existence of significant relationships between ear size and temporal characteristics of the call that probably do not have a functional basis.