bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Morphology of the Gut of the Brown Trout (Salmo trutta)
Authors: Burnstock G. 
Published: April 2021

ABSTRACT
In the trout gut a short oesophagus containing only striated circular muscles opens into a large cardiac stomach possessing inner circular and outer longitudinal smooth muscle-coats, as well as a muscularis mucosae. About 45 pyloric caeca come off the intestine, which, while containing muscle-coats, does not possess a muscularis mucosae. In the rectum, the longitudinal muscle is as thick as the circular muscle-coat, but in other regions the circular muscle is dominant, especially in the pyloric stomach where it is over 10 times as thick as the longitudinal layer. The mucosa is distinguished by the presence of a prominent layer of dense collagen, the stratum compactum, which is perforated only by nerves and blood-vessels. This layer forms a firm and relatively inextensible (approximately 10% extensibility) basis to the gut-wall. It limits the extensibility of the smooth muscle to 75 % radially in the stomach and 25% radially and longitudinally in the intestine. In contrast, the stomachs of the pike and perch, which do not possess a stratum compactum, extend up to 200%. A detailed description of the regional junctions and sphincters gives a basis for the interpretation of events occurring in the living system. Valves at the junction of the pneumatic duct with the oesophagus, and between the duodenum and pyloric stomach, serve to prevent the regurgitation of gas and semi-digested food respectively. A complex sphincter mechanism exists at the pylorus, and to a lesser extent at the antrum. A series of about five circular muscle-constrictors represents the anus. It is suggested that the cells forming the stratum granulosum, a layer closely associated with the stratum compactum, are composed of active fibroblast cells producing collagen. The rectum contains a muscular annulo-spiral septum of unknown function which protrudes into the lumen.
A Histological and Histochemical Study of the Brown and Yellow Adipose Tissue of the Bat, Hipposideros speoris
Authors: George J. C. , Eapen J. 
Published: April 2021

ABSTRACT
A study of the histology and histochemical reactions for lipase, alkaline phosphatase, acid phosphatase, adenosine triphosphatase, succinic dehydrogenase, lactic dehydrogenase, phospholipids, cholesterol, sulphydryl groups, and water-insoluble aldehydes and ketones in the brown and yellow adipose tissue of the bat (Hipposideros speoris) revealed that the two types of adipose tissue differ in histological structure as well as physiological activity. The histological structure of the two types of adipose tissue was found to be different, resembling that of the two corresponding types of the rat. The brown adipose tissue showed a higher concentration of succinic dehydrogenase, lactic dehydrogenase, phospholipids, cholesterol, and sulphydryl groups. No detectable difference between brown and yellow adipose tissue was, however, found with respect to lipase, alkaline phosphatase, acid phosphatase, adenosine triphosphatase, and waterinsoluble aldehydes and ketones.
The Ontogeny and Comparative Anatomy of some Protocerebral Sense Organs in Notostracan Phyllopods
Authors: Dahl Erik 
Published: April 2021

ABSTRACT
An investigation of the ontogeny of some of the protocerebral sense organs of Triops was carried out. Attention is called to the presence of a frontal proliferation zone of great importance in the growth of the nauplius and compound eyes. With respect to the nauplius eyes it is shown that to the small tripartite nauplius eye present at hatching additions are contributed partly by the dorso-lateral lobes of the brain, partly by the proliferation zone. This complicated mode of derivation of the nauplius eye is reflected in the arrangement of the nerves. The so-called upper lateral nauplius eye nerve in Triops is shown to be the remnant of the connexion between the nauplius eye and the ganglion opticum of the compound eye, and the evidence suggests that it is not really to be regarded as an optic nerve of the nauplius eye. It is shown that the proliferation zone is mainly or exclusively responsible for the formation not only of the distal part of the compound eye but also of the ganglion layer of the lamina ganglionaris and of the distal part of the ganglion layer of the medulla. The dorsal paired frontal organs as described by Claus (1873)are identified with a group of sensory cells situated above the lateral nauplius eye in the adults of Triops, and the ontogenetical processes involved in their dislocation are traced. The group of cells in the neighbourhood of the ganglion opticum supposed by Wenke (1908) and Hanstrôm (1931) to be identical with the frontal organs found by Claus (1873) probably constitute a neurosecretory organ. It is shown that despite great topographical differences the ontogeny of the protocerebral sense organs of Artemia in many respects follows the same pattern as in Triops.
The Botryoidal and Vaso-fibrous Tissue of the Leech Hirudo medicinalis
Authors: Bradbury S. 
Published: April 2021

ABSTRACT
The botryoidal and vaso-fibrous tissues of the leech Hirudo medicinalis have been studied morphologically and histochemically. It is concluded that the cells forming these tissues represent cells of the vessel and sinus walls which have swollen as a consequence of the accumulation of pigment granules in their cytoplasm. This swelling is much more pronounced in the cells of the botryoidal tissue. These tissue systems are in communication with each other and with the contractile and non-contractile haemolymph vessels.
Apart from the pigment granules, few cytoplasmic inclusions were seen in the cells of the botryoidal tissue, but numerous granules are present in the vaso-fibrous cells : these granules are about I µ in diameter and contain phospholipid. The brown pigment of the botryoidal tissue seems to consist of a masked iron compound, which probably occurs in combination with the protein which forms the framework of the pigment granule; the pigment of the vaso-fibrous tissue is green, and contains no iron, but reacts to the tests for bile pigments.
These tissues are considered to represent ‘kidneys of accumulation’ for the iron and the bile pigment which probably represent the by-products of a breakdown of the blood used as food. The amount of botryoidal tissue is significantly greater in old than in young leeches.
Contractility and Hydroplasmic Movements in the Hydroid Clytia johnstoni
Authors: Hale L. J. 
Published: April 2021

ABSTRACT
The investigation is based on observations of the living animal and on time-lapse films, and is supplemented by histological preparations. The material was cultured in the laboratory.
A short region just behind the growing tip of a stolon is contractile, pulsating every 4 or 5 min but occasionally at longer intervals. This causes the hydroplasm (contents of coelenteron) to ebb and flow in the coelenteron not only directly, but also by pressure transmitted by the fluid between the coenosarc and perisarc. There is evidence that where a stolon has more than one contractile region, they beat independently. The contractile cells do not possess muscle-tails, and contractile fibres have not been detected by light microscopy.
The hydranth stomach also has slow contractions which are peristaltic towards the stalk. They usually occur at irregular intervals but are occasionally regular. They cause movement of the hydroplasm into and out of the hydranth. There is evidence that hydranths are stimulated to expand and contract by arrival of hydroplasm pressed there by another contractile region of the colony. Longitudinal muscle-tails are present on the ectoderm cells of the stomach and tentacles, but these are probably concerned with retraction of the hydranth into its hydrotheca.
Although the endodermal flagella beat actively when the hydroplasm is in motion, they are not the cause of hydroplasmic flow.
The possible mechanism of these slow contractions is discussed in relation to contractility in other coelenterates.
Differences in the Blood-supply of Bone of Different Histological Types
Authors: Currey J. D. 
Published: April 2021

ABSTRACT
‘Laminar’ bone, commonly found in artiodactyls and dinosaurs, is described. It consists of a series of bony laminae arranged like tree-rings round the marrow cavity, each lamina being between o-i and o-2 mm thick. Sandwiched between each lamina and the next is an effectively two-dimensional network of blood-vessels. Laminar bone grows in a series of spurts ; a sheet of woven-fibred bone is formed very quickly, not actually on the pre-existing sub-periosteal surface, but separated from it by a space. The new bone is held clear of the original surface by an occasional bridge of bone. The space so formed is filled in slowly by parallel-fibred lamellar bone, and while this is going on more woven bone, with spaces, may be formed by the periosteum.
The vascularization of laminar bone on the one hand and bone composed of haversian systems on the other is compared, chiefly in cattle. Laminar bone has a more intimate blood-supply than haversian bone, and it has a larger surface area of bloodchannel per unit volume. The volume of channel per unit volume is about equal in the two types of bone. The mean distance between anastomoses is less in laminar than in haversian bone. The cement-line round haversian systems hinders the passage of materials through the canaliculi. The osteocytes in the interstitial lamellae are thus in a worse position for obtaining foodstuffs and disposing of waste products than osteocytes in laminar bone a similar distance from the nearest blood-vessel.
It is suggested that the formation of haversian systems in laminar bone interferes with the latter’s blood-supply and leads to the formation of further haversian systems.
A Note on the Innervation of the Integument in Amphioxus, and its Bearing on the Mechanism of Cutaneous Sensibility
Authors: Bone Quentin 
Published: April 2021

ABSTRACT
Previous conclusions as to the innervation of the integument of amphioxus are discussed, and it is shown that in addition to the system of free nerve-terminals described by Lele, Palmer, and Weddell (1958), the skin of certain regions of the body contains specialized sensory cells and encapsulated nerve-endings. The cells of origin of the free nerve-terminals in the skin are described, and it is shown that they fall into several morphologically different categories. In the light of these observations it is suggested that the innervation of the skin of amphioxus does not provide unequivocal evidence for the view that the different cutaneous sensations are determined by different discharge patterns in the same fibres of the nerve-rami leading from the skin.
The fine structure of the normal chorio-allantoic membrane of the chick-embryo
Authors: Rangan S. R. S. , Sirsat Satyavati M. 
Published: April 2021

ABSTRACT
The chorio-allantoic membranes of White Leghorn chick embryos at 10 to 12 days after laying were fixed in Palade’s buffered osmium tetroxide or in Luft’s potassium permanganate.
After fixation in these two ways the general appearance is similar, but there are differences in certain tissue elements. Cell membranes are well preserved after fixation in KMnO4. Certain lipid inclusions in the cytoplasm of the cells of the allantoic layer are well seen after fixation by OsO4, but not after KMnO4; in their places empty vacuoles are seen.
Details of the structure of the red blood-corpuscles are more clearly seen after fixation in KMnO4.
Naked axons and symmetrical synapses in coelenterates
Authors: Horridge G. A. , Mackay Bruce 
Published: April 2021

ABSTRACT
Examination of sections of the marginal ganglion of the jellyfish Cyanea and the hydromedusan Phialidium by the electron microscope, in a region where nervous tissue is readily identified on account of its abundance, reveals the following features.
Nerve-cell bodies and axons are crowded together without special glial cells. The axons form a layer between the cell-bodies and the mesogloea and the spaces between them are continuous with other intercellular spaces and with the mesogloea.
Features typical of nerve-cells in other animals are mitochondria, Golgi region (= γ-cytomembranes), neurotubules (= canaliculi) about 16 mμ wide, and several types of vesicle ranging in size from 50 to 200 mμ, including synaptic vesicles of 50 to 100 mμ.
Features not typical of nerve-cells are the modified (possibly sensory) cilia on the dendrites of bipolar cells and the absence of clumps of Nissl substance and neurofilaments.
Synapses between axons (or with a perikaryon) have a synaptic cleft of 18 to 22 mμ and a crowded row of synaptic vesicles within the neurones on each side of the synapse.
Studies of an amoebo-flagellate, Naegleria grüberi
Authors: Pittam M. D. 
Published: April 2021

ABSTRACT
The amoeboid and flagellate phases of Naegleria grüberi were examined by phase- contrast microscopy, cytochemical techniques, and conventional staining methods. Some electron micrographs were taken. Results showed that lipid was confined to the cytoplasmic globules, cell membrane, and mitochondria. Glycogen was absent, but a polysaccharide, probably a protein-carbohydrate complex, was generally distributed throughout the cytoplasm and was particularly abundant in the food vacuoles. Particular attention was paid to the mitotic figure, with the result that stage I of mitosis, in which RNA-protein and DNA-protein particles were dispersed throughout the nuclear area, is claimed as being a constant and essential occurrence in the initia- tion of mitosis. After stage I, the RNA and DNA took up and remained in sharply demarcated areas of the mitotic figure. No lipid or carbohydrate was present in the mitotic figure.
During the transformation from amoeba to flagellate, some of the mitochondria concentrated at the point on the periphery of the organism where the flagella later emerged, and in the fully formed flagellate appeared as a dense cap at the bases of the flagella. Electron micrographs showed that the mitochondria had a double limiting membrane and an internal system of tubules similar to those described in Acanth- amoeba.
A counting method for measuring the volumes of tissue components in microscopical sections
Authors: Douglas Hally A. 
Published: April 2021

ABSTRACT
Several methods are available for estimating the relative volume of a tissue component from a study of tissue sections. These methods are all based on the fact that the mean relative area of a component in a series of random sections through a tissue is a consistent estimate of its relative volume in the whole tissue. Thus the problem is basically one of measuring area in a section, which can be done by the following simple counting method.
The method consists of placing a regular pattern of points in the form of a square lattice upon the section image, and counting the number of points over the section TV, and over the component n. The method also measures absolute area, and where d is the distance between adjacent points, This capacity to measure absolute area means that the method is particularly suitable for determining a component which has a low relative volume.
The accuracy of the method is influenced by several factors including the size of the grid mesh, and the relative area, shape, and spatial arrangement of the component. With reasonable care the error will not be larger than that of a truly random system of points, as expressed by the following: wherep is the relative area of the component, and the relative standard error (R.S.E.) is S.E./relative area of component.
The method is equally applicable to either light or electron microscopy. A series of measurements on electron micrographs of rat cardiac muscle revealed a close agreement between the counting method and planimetry.
The method is rapid, simple and accurate, and requires no complex apparatus.
The innervation of the aesthetasc hairs of Panulirus argus
Authors: Laverack M. S. , Ardill D. J. 
Published: April 2021

ABSTRACT
The aesthetasc hairs that occur on the outer ramus of the antennule of Panulirus argus are heavily innervated. Approximately 350 neurones are present at the base of each hair, and dendrites pass up into the hair lumen.
These dendrites end one-third of the distance to the hair tip. They are composed of paraciliary structures that extend beyond the surrounding sheath. The hair lumen is in contact with the external environment through a pore at the end of the hair.
The sensory cells are surrounded by sheath cells along the axons and as far distally as the sensory cell nucleus. Distally the dendrites are also sheathed by glia and hypodermal cells. The distal region of the sense cell body is not invested, the cell membranes are closely applied one to another and interdigitation occurs.
The role of Lampbrush Chromosomes in the formation of Nucleoli in Amphibian Oocytes
Authors: MACGREGOR H. C. 
Published: April 2021

Theories concerning the mode of origin of peripheral nucleoli in amphibian oocytes have been examined and tested.
In Triturus cristatus the giant fusing loops of the 3 shortest lampbrush bivalents resemble nucleoli when viewed in phase contrast and may be considered as possible sites of production of nucleoli. Giant fusing loops, however, differ from peripheral nucleoli in certain important respects, and animals lacking giant fusing loops on their lampbrush chromosomes nevertheless have normal peripheral nucleoli. Therefore, similarity in appearance between objects attached to lampbrush chromosomes and free peripheral nucleoli may not be significant.
In oocytes of T. c. carnifex, T. c. karelinii, and T. c. danubialis, peripheral nucleoli do not increase in number during the lampbrush phase of oogenesis, except by division of pre-existing nucleoli towards the end of oogenesis. There are about 1,000 nucleoli per oocyte nucleus in each of these sub-species.
In T. c. cristatus there are more nucleoli in large oocytes than in small ones, and it seems likely that in this sub-species the giant fusing loops add to the existing population of nucleoli in an oocyte by successively growing and shedding new nucleoli. A similar situation probably holds in Plethodon cinereus.
Hexaploid oocytes from triploid females of Ambystoma jeffersonianum have 3 times as many nucleoli as diploid oocytes from diploid females of the same species. The number of nucleoli in an amphibian oocyte nucleus is therefore related to the number of sets of chromosomes in the cell.
In yolky oocytes from hypophysectomized newts most peripheral nucleoli are firmly attached to the inner surface of the nuclear membrane; whereas in similar oocytes from unoperated or gonadotrophin-treated animals none of the nucleoli is so attached.
On the basis of these observations 2 mechanisms are suggested for the formation of amphibian oocyte nucleoli. The first of these mechanisms probably operates in T. c. carnifex, where all peripheral nucleoli are formed before or soon after the chromosomes assume the lampbrush form, and no part of a lampbrush chromosome is involved in a process which adds to the existing population of nucleoli. The second mechanism probably operates in T. c. cristatus, where most of the peripheral nucleoli are formed before the lampbrush phase of oogenesis but a nucleolar organizer on the lampbrush chromosomes continues to grow and detach nucleoli throughout oogenesis. Both these mechanisms are discussed in terms of what is known of the chemical composition and function of peripheral nucleoli.
The Structure of the Cornea as Revealed by Polarized Light
Authors: Naylor E. J. 
Published: April 2021

ABSTRACT
Studies of corneal sections in polarized light indicate that there are about too lamellae in the cat cornea; the coefficient of fibre birefringence is 0·0030.
No evidence was found of preferential orientation of fibre directions. Corneal disks examined by an immersion technique show that the cornea exhibits both form and intrinsic birefringence of positive sign with a micellar refractive index of 1·50-1·52. The values of both form and intrinsic birefringence in various fixatives can be explained on the basis of swelling, which is both inter- and intra-micellar. The micellar volume according to the Wiener relationships does not exceed 3 per cent.; possible causes of this are discussed.
MEASUREMENTS of the retardation of the cat cornea as a whole (Stan-worth and Naylor, 1950) can be analysed mathematically (Stanworth and Naylor, 1952) and indicate that the coefficient of birefringence of the constituent fibres of the cornea is about 0·0028. In order to investigate this value experimentally, antero-posterior sections 15 μ thick were prepared from fresh cat corneae by freezing methods or from formalin-fixed corneae by prior embedding in paraffin wax. When these were examined under the polarizing microscope it was found that the retardation varied considerably according to the method of preparation and the mounting medium employed, indicating that the corneal birefringence is in great part due to the form or textural variety. The investigation was therefore extended and approached from two aspects, the microscopic and the sub-microscopic structure.
The Sarcosomes of Heart Muscle
Authors: CLELAND K. W. , SLATER E. C. 
Published: April 2021

1. A study of the distribution of the granules in rat heart-muscle fibres confirmed the early morphological findings. We prefer to describe these granules under the name of sarcosomes, first introduced by Retzius.
2. In sections, heart sarcosomes are seen as rods in close association with the anisotropic disks of the myofibrils. The rod-shape is believed to be due to compression of the sarcosomes between adjacent myofibrils. Isolated sarcosomes which retain the elasticity of those in the living state would be expected to be spherical.
3. Preparations of sarcosomes isolated with hypertonic sucrose contained many rods. Spheres were obtained with isotonic saline or sucrose. Water, ethylene glycol, or glycerol gave greatly swollen and otherwise altered sarcosomes.
4. In hypotonic media, sarcosomes underwent a series of partially reversible morphological changes termed ‘transformation’. These changes, which are caused by penetration of water into the sarcosomes, are described in detail.
5. Studies of ‘transformation’ gave clear evidence that the intact sarcosome is composed of a central body in the form of a gel surrounded by a membrane. As the tonicity of the medium was decreased, the body progressively disappeared, leaving eventually a large vesicle surrounded by the membrane. In this condition the membrane readily breaks up into particles which contain all the enzymes which constitute the respiratory chain, but is devoid of most dehydrogenases and phosphorylating enzymes.
6. On standing in isotonic media the membrane is rapidly damaged, causing penetration of solutes so that the sarcosomes transform in much the same way as in hypotonic media. This ‘spontaneous transformation’ was greatly delayed by the calcium-chelating agents versene or citrate and by adenosine diphosphate or triphos-phate, and was accelerated by calcium.
The Supposed Pre-pupa in Cyclorrhaphous Diptera
Authors: Whitten Joan M. 
Published: April 2021

ABSTRACT
The pre-pupal cuticle generally described for Diptera Cyclorrhapha is here considered to be an inner layer of larval endocuticle rather than the cuticle of a distinct prepupal instar. Chemical and microscopical evidence is given. The mechanism of rupture of the operculum is also discussed in connexion with endocuticle secretion, sclerotization, and subsequent water loss.