bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Absorption of Lipoid by the Intestinal Epithelium of the Mouse
Authors: Baker John R. 
Published: April 2021

ABSTRACT
During the absorption of fat by the intestinal epithelium of the mouse, spindle-shaped particles of lipoid material can be seen in the free border of the epithelial cells. The spindles, which he with their axes at right angles to the surface of the free border, correspond in position with the spindle-shaped canals previously described by the author in various vertebrates.
Phosphatases and Nucleic Acids in Silk Glands: Cytochemical Aspects of Fibrillar Protein Secretion
Authors: Bradfield J. R. G. 
Published: April 2021

ABSTRACTSilk glands of several spiders and caterpillars contain powerful .cytoplasmic phosphatase activity localized along the inner border of the cells next to the gland lumen. Phosphatase activity is also high in the nuclei, particularly the nucleoli. Reservoir regions which secrete no silk lack the phosphatase border.Although it is most easily demonstrated histochemically at pH 9, phosphatase activity in sections or homogenates of the glands is high over a considerable range of pH, from at least pH 5·5 to pH 9·8. It appears to be inhibited both by sulphydryl inactivators and by an abundance of sulphydryl groups. In view of the latter point, it is interesting to note that no sulphydryl groups can be detected in the phosphatase border zone (in the more insoluble constituents which remain in formalin-fixed frozen sections), although the main bulk of the cytoplasm is rich in sulphydryl groups.Except in the non-secretory reservoir regions, silk glands of all the species examined are rich in cytoplasmic ribonucleic acid. Although the latter is abundant in the main body of the cell, it is, however, absent from the phosphatase border zone, so that in the cytoplasm nucleic acid ends where phosphatase begins.This suggests that the phosphatase may be part of a system of enzymes involved in liberating the finished protein from a complex with nucleic acids (which have been concerned either in the synthesis of the protein, or in protecting it from proteases, or both). This possibility is discussed in the light of previous studies of phosphatase-nucleic acid relations in other tissues.
The Formation of the Ootheca by Periplaneta Americana : I. The Micro-anatomy and Histology of the posterior part of the Abdomen
Authors: Brunet P. C. J. 
Published: April 2021

ABSTRACT
The ootheca is of interest because it is composed of quinone-tanned protein. No detailed account of the secretory processes leading to the production of structural protein and tanning agents exists, and this paper is intended as an introduction to such a cytological and histochemical account; it contains a description of the general anatomy of the organs concerned with the formation of the ootheca. These organs are located round the vestibulum, a large intucking of the posterior part of the abdomen.
The colleterial glands open into the vestibulum and secrete most of the protein and tanning agent. The structure of each type of secretory cell of which the gland is composed is outlined.
A new organ, taking the form of a large invagination of the dorsal wall of the vestibulum, is described. The walls of this invagination are secretory, and it is notable that the secretion-product accumulates and is stored within the substance of a modified layer of the endocuticle.
Two types of massed dermal gland cells are described. One type is present mostly on the ventral walls of the ovipositor, and the other towards the posterior end of the vestibulum. The former may not be directly concerned with ootheca formation, while the latter probably secretes the alkali-resistant outer layer of the ootheca.
The relations between the ovipositor and the ‘horned die’ of Kramer and Wigglesworth are discussed.
Preliminary Account of an Electron Microscope Study of Chromosomes from Newt Oocytes
Authors: Tomlin S. G. , Callan H. G. 
Published: April 2021

ABSTRACT
Chromosomes from oocytes of the newt Triturus cristatus camifex have been photographed by means of the electron microscope. These chromosomes are shown to consist of single axial filaments, approximately 200 Å wide, with ‘lamp-brush’ loops attached at intervals along their lengths. Good fixation of the lamp-brush loops has not yet been obtained. These chromosomes are attached in pairs to their homologues at points which, in the past, have been considered to be chiasmata: it has been assumed that the stage is diplotene of the first meiotic division. The singleness of the chromosome strands which we have observed is at variance with observations of diplotene in other material by means of the light microscope.
Observations on Giant Fibres of the Nervous System of Locusta migratoria
Authors: Cook P. M. 
Published: April 2021

ABSTRACT
There are four fibres of giant dimensions in each cord of the abdominal ventral nerve-chain of the locust. These fibres are the axons of large neurons situated in the extreme posterior region of the last abdominal ganglion, and run uninterruptedly through the abdominal nerve-chain to the metathoracic ganglion. Posteriorly these neurons synapse with preganglionic fibres which appear to be cereal nerve-fibres and anteriorly with motor pathways to the metathoracic legs.
Oscillographic observations have been correlated with those from the histological study. The possible function of these pathways has been discussed and comparison made with the cockroach, where a similar organization has been described in detail.
An Electron Microscopic Study of the Muscle-fibres of the Diaphragm
Authors: Bluhm M. M. , Sitaramayya C. 
Published: April 2021

ABSTRACT
Myofibrils of rat diaphragm of various ages, in different states of activity, after denervation, and after acetyl choline contracture, were studied by electron microscopy. A comparative study of other rodent diaphragms and of human diaphragm was also made.
Myofibrils from diaphragm are similar to those of other striated muscles. The differentiation into A and I bands is due to differences in the substance present round the actomyosin filaments in those regions. The Z disk is extra-sarcomere; it-appears even before any differentiation of the fibril into A and I bands is recognizable. At the age of about 42 days, the myofibrils in rat diaphragm are completely differentiated and conform to the adult type. The sarcomere length in adult rat diaphragm is between 2 and 3 μ.
The adult rat diaphragm contains two types of fibrils which differ, though not sharply, in their extensibility and thickness.
The A and I bands react differently to a variety of stimuli. Thus, passive stretching affects the I band almost exclusively, while contraction affects both bands; here, again, the effect depends on the type of contraction; isotonic contraction shortens both A and I, whereas isometric contraction shortens A and lengthens I. In the denervated muscle the A band is shortened. On the whole, the A band seems to play the major role in contraction.
The H disk is intra-sarcomere and appears during contraction, especially when the muscle is stimulated in the stretched state. The M and N lines also are intra-sarcomere. Evidence regarding their nature and appearance is discussed.
The Action of Formaldehyde on Living Cells as Studied by Phase-contrast Microscopy
Authors: Crawford G. N. C. , Barer R. 
Published: April 2021

ABSTRACT
The morphological changes occurring when living cells are fixed in neutralized formaldehyde have been studied in detail with phase-contrast microscopy. The cells used were (1) salamander spermatogonia obtained from the teased testis, and (2) snail amoebocytes growing in tissue culture. The cells were mounted on a slide beneath a coverslip ringed with paraffin wax. Various strengths of formaldehyde made up in saline or distilled water were then introduced while the cells were kept under constant observation by phase-contrast microscopy. The morphological changes during the fixation process were observed for periods of at least 24 hours and the results recorded photographically.
The Tegumental Glands in the Land Isopoda: C. The Lobed Glands: The Properties of their Secretion and their Mode of Action
Authors: Gorvett H. 
Published: April 2021

ABSTRACT
The lobed glands of the Oniscoidea respond to appropriate stimulation by liberating droplets of secretion at the edges of the lateral plates and uropods. The fresh secretion is a clear fluid, which is soluble in water, contains protein, water, perhaps fatty acid, but not mucin, fat, wax, or glycogen. The uropod secretion is very sticky and viscous, slowly soluble in water, neutral in reaction, and without odour; the lateral plate secretion is a watery fluid, freely soluble in water, strongly acid in reaction, and with a pungent smell resembling that of butyric acid. Both secretions solidify rapidly on exposure to air, and both are coagulated by alcohol. Both types of gland secrete only in response to violent stimulation ; this must be both strong and sudden in its application, and often causes fatal injury. The uropod glands secrete more readily than the lateral plate glands. The amount of secretion varies in different individuals of the same species; it is not correlated with the age, sex, or moulting condition of the animal, but may depend on its general condition. The glands empty rapidly when stimulated, cannot repeat the process except at relatively long intervals, and appear to be incapable of secreting continuously. They do not appear to be under nervous or hormonal control, but may be emptied passively by contraction of neighbouring muscles. The significance of these results in relation to the problem of function is discussed.
The Formation of the Ootheca by Periplaneta americana: II. The Structure and Function of the Left Colleterial Gland
Authors: Brunet P. C. J. 
Published: April 2021

ABSTRACT
The anatomy of the left colleterial gland of the cockroach is described. It is convenient to subdivide the gland into four regions. At the posterior end, abutting on to the outlet of the gland, there is no secretory activity and the cells of this region are not unlike normal epidermal cells. Anterior to this region are the three secretory regions of the gland ; of these, the anterior and posterior secrete the structural protein and the constituent cells are equipped with a complex end-apparatus, a thick-walled depression in the apex of the cell in which the final stages of the elaboration of the secretion occur. The body of the end-apparatus contains canalicules which lead to the lumen of the gland. Alkaline phosphatase is abundantly present in this organ. Protein is secreted continuously, and there is no cycle related to oviposition. The third region, between the protein-secreting regions, secretes an oxidase, whose function may well be to oxidize the phenolic tannin-precursor produced in the right colleterial gland when the products of the two glands come together at oviposition.
The gland becomes fully functional some 14 days after the final moult, the immature cells of the nymph developing directly into mature cells characteristic of the region in which they occur. Within each of the main regions the cells show some differences which suggest that there is a wave of change passing along the gland. It appears that the cells of the anterior end of the gland become defunct and the hitherto inactive cells of the posterior end take on a secretory function.
The structural protein has a high phenolic content, and contains no combined carbohydrate. The presence of lipoid in the secretory cells appears to be directly bound up with the secretory processes.
The Multiplication of Vaccinia Virus in Tissue Cultures of Adult Rabbit Skin
Authors: Crawford G. N. C. , Sanders F. K. 
Published: April 2021

ABSTRACT
The optimum conditions for vaccinia virus multiplication in shavings of adult rabbit skin maintained in rocker flasks in a fluid medium have been investigated. Satisfactory virus multiplication occurred in 5 ml. of medium containing 40 per cent, rabbit serum, 40 per cent, phosphate-buffered saline, and 20 per cent, mouse embryo extract; an air atmosphere was used. A growth curve for vaccinia virus grown in vitro under these conditions was obtained by estimating the virus content of cultured skin at known intervals after inoculation. The curve was essentially similar to that obtained by growth of vaccinia in vivo, and could be divided into three phases : (a) during the first few hours infectivity fell, (b) from 10 to 40 hours there was a rapid increase of infectivity, and (c) flattening of the curve started after 40 hours, although some increase of virus continued, until, at 80 hours, the concentration of virus present was at a maximum. An attempt is made to correlate the multiplication of virus with the cytological changes known to occur in infected cells.
The History of the Cytoplasmic Elements During Vitellogenesis in Drosophila Melanogaster
Authors: HSU W. SIANG 
Published: April 2021

1. At least two kinds of yolk are developed in the eggs of Drosophila melanogaster. The origin of the proteid yolk has been traced to precursors sent into the oocyte by the nurse cells, while the minute fatty yolk granules are transformed chondriomites also contributed by the nurses. The behaviour and morphology of Golgi material in the nurses indicate that it may be responsible for a third type of yolk.
2. A yolk nucleus has been found in oocytes of an age when the germinal disk has been pushed to one side. So long as such a structure exists, all the proteid yolk precursors are concentrated and matured within its confine. Soon this structure disintegrates and disappears. But after its disappearance, yolk precursors continue to be sent by the nurses into the oocyte, and there they develop into mature granules apparently without the benefit of a yolk nucleus. On the basis of facts thus far obtained, it is, therefore, difficult to say just what role the so-called yolk nucleus plays in vitellogenesis in Drosophila melanogaster.
3. Golgi material in the nurse cells has been observed to undergo two distinct proliferations. In young nurses, Golgi material occurs in a few discrete bits which, as the nurses grow in size, proliferate into a large number of intertwining threads so arranged as to suggest a net. Then follows a period in which only very few minute granules of Golgi material can be seen. This is definitely a period of scarcity. After this, a second proliferation takes place. This one is carried to such an extreme extent that the cytoplasm of the cells is just black with Golgi material. The Golgi threads, arranged more or less in a parallel fashion and very closely together, present the appearance of pieces of Golgi ‘tissue’. Next, the pieces of ‘tissue’ loosen up into separate threads from which individual Golgi granules arise. These granules enlarge to become vesicles.
4. In the course of development of the nurse cells, the mitochondria also undergo a proliferation. Finally, the chondrioconts break up into granules which enlarge and eventually all transform into droplets of unsaturated fat.
5. My observations point to the conclusion that the oocyte depends upon its nurses for the production of fatty yolk. Proteid yolk granules, however, are developed within the oocyte, though from precursors sent in also by the nurse cells. The follicular cells do not appear to contribute anything to vitellogenesis in Drosophila.
6. An idiosome-like granule has been observed in oogonia, and also in oocytes up to a certain stage of development. For reasons stated elsewhere, it cannot be regarded as an idiosome nor as a centrosome. This structure has not been observed in nurse cells.
Modes of Gastrulation in Vertebrates
Authors: Waddington C. H. 
Published: April 2021

ABSTRACT
The modes of gastrulation in the different classes of Vertebrates are discussed from a comparative point of view, with the particular aim of finding some system which avoids postulating a sharp dualism between the anamniote telolecithal forms, in which the edge of the blastoderm consists of presumptive endoderm, and those of the Amniotes, in which it is ectodermal. It is suggested that the most profitable way of regarding all blastodermic forms is to envisage them as derived from the basic type of blastula by a process in which the roof and floor are squeezed together, so that a flatfish double-layered plate is produced. The concept of the ‘primitive edge’ of such a blastoderm is introduced, and it is suggested that in the amniotes the presumptive ectoderm has expanded greatly beyond the primitive edge, while there has also been a strong convergence towards the dorsal side. The conditions in certain highly yolky amphibian eggs are shortly described, and it is argued that they show conditions similar to those which would be expected on the hypothesis of a squeezing together of the blastula roof and floor.
Cyclic Changes in Polysaccharides of the Papilla of the Hair Follicle
Authors: Montagna William , Chase Herman B. , Malone Janet D. , Melaragno Helen P. 
Published: April 2021

ABSTRACT
In the skin of the mouse the dermal papilla becomes metachromatic and PAS-reactive on the 4th day after the initiation of growth in the hair follicle. This is a stage of follicle development which immediately precedes hair proliferation. Both metachromasia and PAS reaction remain intense until about 18 days, just preceding catagen, or club formation, when they disappear abruptly. During telogen, or the resting stage, the papilla is neither metachromatic nor PAS-reactive. The metachromasia and the PAS reaction of the dermal papilla during the period of active hair proliferation indicate the presence of at least two polysaccharides which are not detectable during the remainder of the cycle.
Growth and Cellular Proliferation in the Early Rudiments of the Eye and the Lens
Authors: Balinsky B. I. 
Published: April 2021

ABSTRACT
It is well known that unequal growth is a major factor in establishing the proportions of the body in animals. It is not so clear what part unequal growth plays in the earlier phases of morphogenesis, that is, in stages when the organ rudiments are first formed and acquire their general shape. The growth of the embryo has been studied successfully in many animals, but not much has been made known concerning the growth processes in stages when the organ rudiments are being formed. In previous papers I have examined the growth and cellular proliferation in the earliest rudiments of the mammary glands (Balinsky, 1950a, 19506). I have now found it desirable to investigate the same processes in organ rudiments of a different type. The organ selected was the lens of the eye throughout the period when it is being formed from cells of the embryonic epidermis. I have also studied the growth of the eye cup in the same stages for comparison.
Observations upon the Recovery of Oxyntic Cells after Prolonged Dosage with Pilocarpine or Histamine
Authors: Menzies Gordon 
Published: April 2021

ABSTRACT
New observations are presented concerning the structure and cytochemistry of the granules in the oxyntic cells of the rat ‘s stomach, in continuation of work already reported (Menzies, 1949, 1952 a and b). The phospholipine component of the granules is slowly regained after being depleted by multiple doses of pilocarpine or histamine. The phospholipine is first regained by the granules in those oxyntic cells situated at the basal ends of the gastric tubules, and later by the remaining cells in the neck of the tubules. An acid phosphatase appears in the oxyntic cells whose granules are about to regain their lipine component, and disappears some time after they have done so. The order in which both the acid phosphatase and the lipine appears (first in the basal cells and later in cells in the neck region) is the same as that in which an acid phosphatase appears when and as the lipine is being shed under experimental conditions (Menzies, 1952 b).
The Cytoplasmic Cytology of Sarcoma 180
Authors: Worley Leonard G. , Spater Herman W. 
Published: April 2021

ABSTRACT
Sarcoma 180 is one of the transplantable, non-metastasizing, connective tissue tumours of the mouse. A bit of sarcoma material, not exceeding 2 mm. in diameter, implanted beneath the skin of the breast as described by Zahl and Drasher (1947), grows within a fortnight into a conspicuous malignant tissue of such proportions that the host usually soon succumbs. Although studies have been made on the nuclear and cytoplasmic cytology of this and closely related tumours (Levine, 1939; MacCardle, 1951, and others), and Ludford and Smiles (1950) have recently compared the structure of mouse sarcoma cells with that of normal fibroblasts as seen in phase-contrast and ultra-violet micrographs, little pertinent work has been published regarding the finer cytological details and there is essentially no information available regarding the cytochemistry of the cytoplasm and its inclusions.
The Development and Structure of the Anterior Region of the Body in the Sabellariidae, with special reference to Phragmatopoma californica
Authors: Dales R. Phillips 
Published: April 2021

ABSTRACT
Attention is drawn to the confusion which has been caused by the loose terminology of the anterior appendages in polychaetes, and more exact connotations are proposed. As the prostomium can be recognized as a comparable unit throughout the Polychaeta, a consideration of its constitution is deferred.
In the present paper the development and constitution of the anterior region of the sabellariid worms are considered. The larval development of Phragmatopoma californica (representing the most highly advanced genus) is described, and the structure of the adult of this species is compared with that of species belonging to other genera.
It is concluded that the opercular stalk arises mainly from the first segment ; that the opercular paleae represent the notochaetae of the first two segments, and that the oral tentacles and the building organ are also developed from the first segment. The prostomium bears a single pair of tentacles.
Experiments on Vital Staining with Methylene Blue
Authors: Harris John E. , Peters A. 
Published: April 2021

ABSTRACT
Some four years ago, with the help of Miss L. Morris, one of the present authors developed a new method of vital staining of the nervous system of the embryo dogfish, Scyliorhinus canicula, using a modification of the old-established rongalit methylene blue technique. The success of this method led to an experimental study of some of the factors involved, and the present account deals mainly with these studies. The work is concerned almost entirely with the penetration of the stain into the tissues; the part, if any, played by the specific chemical combination of nerve-cell constituents with the dyestuff in its final site is not considered.
Cytological Studies of the Acinar Cells of the Pancreas of the Mouse: Part I. The Formation of Neutral Red Granules
Authors: Morgan Winfield S. 
Published: April 2021

ABSTRACT
1. It has been found that during a 12-15 hour period after the subcutaneous injection of mice with a predetermined ‘optimum’ dose of neutral red, there occurs a definite series of changes in the pancreas acinar cell in which neutral red granules are formed as separate bodies, which subsequently come together as aggregates and then disappear from the cell.
2. The cell is not damaged by the cycle of events just described. The response to the presence of neutral red appears to be physiological, not pathological.
3. Evidence is brought forward showing that neutral red granules and aggregates are not vacuoles that pre-existed in the normal cell and were subsequently stained: they are new formations produced by the presence of neutral red in the cell.
4. Little more than one-quarter of the neutral red injected is excreted in unchanged form.