bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron microscopic studies on the thyroid gland of a teleost, seriola quinqueradiata
Authors: Fujita Hisao , Machino Mitsuo 
Published: February 2005

AbstractThe thyroid gland of normal specimens of the teleost, Seriola quinqueradiata, about 50–70 cm in length, obtained in April, were studied with the electron microscope. The apical surface of the follicular cell is irregular in outline and has fewer microvilli than that in higher vertebrates. The rough‐surfaced endoplasmic reticulum is well developed throughout the cytoplasm of the follicular cell, as in the higher vertebrates, and free ribosomes are widely distributed in the matrix of the cytoplasm.In all the follicular cells, there are several less dense or moderately dense droplets which are considered to be derived from Golgi elements. In some droplets occur aggregates of numerous wavy, fine filaments and crystal consisting of groups of thick needle‐like fibrils. Each fibril is 110–120 Å in diameter and composed of three layers comprising a less dense layer 35–40 Å thick, between two layers 35–40 Å in thickness. Dense granules such as those commonly found in the higher vertebrates were not observed in the thyroid cell of this fish, though a few round or oval bodies, which might be lysosomes, containing small vesicles, membranous structures, or wrapped whorled lamellae were noticed.The fine structure of the pericapillary region is similar to that of the higher vertebrates, though the endothelial pores are not observed.
The extracellular compartment of the cerebral cortex
Authors: Bondareff William 
Published: February 2005

AbstractSpecimens of mouse and rat cerebral cortex, fixed by immersion in osmium tetroxide and by perfusion with formalin‐osmium tetroxide were prepared for electron microscopy. The extracellular compartment, consisting of interendothelial cell spaces, capillary basement membranes and extracellular spaces between adjacent elements of neuropil, formed a morphological continuum with capillary lumina. A delicately fibrillar, extracellular matrix characterized the basement membranes and extracellular spaces of the neuropil. Desmosome‐like junctional complexes occurred between endothelial cells and between adjacent neuroglial cells.It is suggested that in the cerebral cortex molecular species from blood which pass through the basement membranes are further distributed in the cytoplasm of astrocytes. Astrocytic cytoplasm appears, then, to have assumed the histophysiological function of the connective tissue ground substance in other parts of the body. The relative constancy of the extracellular compartment as determined physiologically may relate to electro‐osmotic phenomena.
The pattern of innervation of the extrinsic ocular muscles and the intra‐orbital ganglia of the albino mouse
Authors: Mahran Zaghloul Y. , Sakla Francois B. 
Published: February 2005

AbstractThe innervation of extra‐ocular muscles of albino mice, aged 1, 10, 20, 30 annd 120 days, was studied in serial sections cut in the three main planes. Some orbits were fixed in Bouin's and others were fixed in a mixture of: 5% potassium dichromate, 5% mercuric chloride and 5% potassium chromate. All sections were stained with Holmes' silver stain. The following nerve endings were described:(a) Preterminal nerve fibers parallel to the muscle fibers end in 1–3 motor endplates in several muscle fibers and others form several en grappe end‐plates on one muscle fiber. (b) The muscles are rich in muscle spindles which have very thin capsules. Two spindles may lie side by side. (c) One or more nerve fibers form spirals around muscle fibers.Multipolar nerve cells were found:(a) Within the sclera, (b) Within the short ciliary nerves, (c) A complete ganglion formed of 20 cells was found along the inferior division of the oculomotor nerve.Unipolar nerve cells were seen along the nasociliary nerve. Harder's gland was innervated by a peri‐acinar plexus which sent nerve fibers between the cells as nerve endings. The significance of the findings was discussed.
The use of D‐L ethionine in the transplantation of pancreatic tissue in hamsters
Authors: House E. L. , Pansky B. , Jacobs M. S. , Strebel R. , Payan H. 
Published: February 2005

AbstractIn order to eliminate the adverse effects of the secretion of the exocrine tissue on the islets in the pancreatic transplants the hosts were injected with D‐L ethionine. Twenty‐six male hamsters were divided into two groups. All animals received subcutaneously 1 mg per gram of body weight per day of a 5% aqueous solution of ethionine. In addition, each received 3 mg of cortisone (25 mg per ml) two days before transplant and 1 mg on the fifth and twelfth post‐transplant days. In group I, the ethionine was begun seven days before transplant and was continued for six days after neonatal pancreas was placed in the cheek pouches of the hosts. In group II, ethionine was started on the day of transplantation and was continued for 13 days. Growth and differentiation were checked for up to 56 days. Growth in both groups was comparable to that in animals receiving cortisone alone. Histological examination revealed neither cyst formation nor interstitial secretion leakage in any of the ethionine animals. In both groups, the differentiation of islets was far superior to that found in untreated hamsters, with 85% of the hosts in group I and 55% of those in group II showing islets.
The conducting system of the heart of the house sparrow, Passer domesticus indicus
Authors: Yousuf Najma 
Published: February 2005

AbstractIn the heart of Passer the specialized conducting tissue develops earlier than the nervous elements. The sinuatrial and the atrioventricular nodes appear simultaneously at the 15 mm stage and the atrioventricular bundle at the 23 mm stage. During development the sinuatrial node shifts its position due to the gradual absorption of the sinus venosus into the right atrium. The caudal end of the interatrial septum is enlarged to accomodate the compound atrioventricular node. In the adult bird the bundle branches extend through the atrioventricular valves of their sides and reach the other wall of the ventricular cavity. Among the specialized tissues, the sinuatrial region is the first to receive the nerve supply. The atrioventricular nodal and bundle regions are innervated by the ganglia present at the atrioventricular sulcus. The ganglionic cells are bipolar or multipolar. The nerve fibers terminate in “end‐bulbs.” Only the atrioventricular node shows a few fine nerve fibers within its substance. No direct nerve connection is present between the nodes and the bundle. It seems that the nervous elements present in the regions of the specialized tissues are concerned only with the control of the activity of these structures.
Variations in the circle of willis in Macaca mulatta
Authors: Kassell Neal F. , Langfitt Thomas W. 
Published: February 2005

AbstractThe circle of Willis was dissected in 75 Macaca mulatta monkeys, and the anatomy is described and compared with several series of human specimens. The principal difference between monkey and man is the presence of a single distal anterior cerebral artery in the former, and the most common anomaly in the moneky is an anterior communicating artery proximal to the junction of the anterior cerebral arteries.A large vessel joining the internal carotid arteries and an accessory branch of the anterior cerebral artery, probably communicating with the external carotid circulation, were found in a small number of our specimens. In man the posterior communicating is significantly reduced in diameter far more frequently than the anterior communicating artery, whereas the reverse situation obtains in the monkey.In general, the intracranial distribution of blood in the moneky is the same as in man, because the similarities in the normal anatomy and variations i the circle of Willis outweight their differences. However, physiological data on collateral cerebral circulation will be more meaningful when it is based on the arterial anatomy in each preparation.
Fine structural observations of the absorption of lipid particles in the small intestine of the rat
Authors: Rostgaard RøRgen , Barrnett Russell J. 
Published: February 2005

AbstractGlobules or particles of material, 50 Å to 1000 Å in diameter, stained with Pb++ to become dense, occurred between, on, or within the microvilli of the absorptive cells of the proximal jejunum of rats which had been fasted for 48 hours and fed corn oil one hour before sacrifice. This material was demonstrable in tissues fixed in glutaraldehyde, osmium tetroxide, or both fixatives providing Pb++ staining occurred. No or very little stainable material was present in fasted rats. These findings were correlated with in vitro studies on negatively stained or Pb++ stained solutions of micelles. The absorption of particulate lipid by the microvilli of the epithelial cells of the small intestine is discussed.
The fine structure of differentiating fibroblasts in the incisor pulp of the guinea pig
Authors: Han Seong S. , Avery James K. , Hale Lawrence E. 
Published: February 2005

AbstractThe differentiation of the fibroblast was followed in the dental pulp of continuously growing incisors of the guinea pig. Based on the ultrastructure, the processes of differentiation of the fibroblasts might be conveniently broken into three stages; Stage I – period of early differentiation, Stage II – period of maturation and functioning, and Stage III – period of regression.During Stage I the cell had structural characteristics shared by other less differentiated cells. The endoplasmic reticulum was poorly developed, showing vesicular to tubular profiles. The ribosomes were abundant but were mostly distributed in free form. Mitochondria were small and had irregular interiors.Stage II was characterized by a striking development of the rough‐surfaced endoplasmic reticulum, which appeared in various shapes and sizes. The Golgi complex was enlarged, and contained some fibriller materials in dilated portions of its membraneous elements. Other features described in the cytoplasm of fibroblasts from other sources were confirmed.Stage III was characterized by the decrease in size and number of various cytoplasmic constituents and was considered to represent cells in the state of regression.
Timing of maturation and fertilization of the sheep egg
Authors: Dziuk P. J. 
Published: February 2005

AbstractEggs of sheep were recovered at known intervals before or after controlled ovulation. They were examined for cytoplasmic and nuclear changes. The vesicular nucleus in the follicular egg persists to 15 hours before ovulation when the chromatin becomes more compact and dense. The first metaphase lasts from 13 hours before ovulation to shortly before ovulation. The formation of the first polar body occurs from four hours before ovulation to ovulation. Normally sheep eggs have formed the first polar body by the time of ovulation and are in the seocond metaphase. Cumulus cells and corona cells are present on the egg at ovulation and for a few hours afterwards. Sperm penetration does not begin ordinarily until at least three hours after ovulation. The male pronucleus forms from 3 to 9 hours after ovulation at about the same time as the female pronucleus. Pronuclei fusion occurs 11 to 22 hours after ovulation. The first mitotic division takes place usually 19 to 24 hours after ovulation although 2‐called eggs were seen at earlier times.
Intimal hypertrophy in coronary arteries and considerations of the papillary muscle arteries (man)
Authors: Boucek Robert J. , Takeshita Ruth , Brady Al H. 
Published: February 2005

AbstractIntimal hypertrophy is located irregularly along the coronary arteries. These irregular formations appear related to areas where accentuated intramural physical forces develop. Intimal hypertrophy develops diffusely around ostia of secondary branches apparently due to its anisotropic expansion with each pulse pressure wave. Discrete intimal hypertrophy occurs near the ostium of branch arteries which are guarded by a circumferential muscle. Diffuse intimal hypertrophy occurs in arteries supplying the posterior papillary muscles, and conversely, a barely detectable intima is seen in the arteries to the anterior papillary muscles or in the branch arteries to the ventricular wall. Intimal hypertrophy may be related to areas where naturally occurring shear or radial forces are accentuated. Regional intimal hypertrophy is present by 12 years of age in man and increases in amount and in its diffuseness with age.
Anatomy of the sinus node, AV node and os cordis of the beef heart
Authors: James Thomas N. 
Published: February 2005

AbstractThe bovine sinus node is in a location similar to that in the human and canine hearts, but it contains no central large artery whereas the sinus node in the other two species is distinctly organized about such an artery. This suggests the bovine sinus node may function as a more primitive structure. The arterial supply of the bovine sinus node originates from the proximal left circumflex artery. The AV node and bundle are similar in all three species in location and internal anatomy. The human and bovine AV node and bundle are supplied by a single artery entering from the posterior wall of the heart, while the dog has an equally large branch to this region from the septal artery.The os cordis is a large constant bone lying near the junction of the interatrial and interventricular septa of the beef heart and extending anteriorly into the AV valve rings, especially the right. The AV node lies parallel to the os cordis on its right atrial side and the AV bundle courses beneath the bone. Possible functions of the os cordis are considered.
The origin of the lymphocytes in the appendix and tonsil iliaca of the embryonic and neonatal rabbit
Authors: Ackerman G. Adolph 
Published: February 2005

AbstractThe appendices and tonsils iliaca of 198 embryonic and neonatal rabbits between 26 days of gestation and 18 days after birth have been examined. Special cytological and histochemical techniques and light and phase microscopy have been employed in order to determine the origin of the lymphocytes in these lympho‐epithelial organs.Sequential developmental and cytological changes in the appendices and tonsils iliaca of the embryonic and neonatal rabbit indicate that the first lymphocytes are of small and medium size and appear by the twenty‐ninth day of development, viz., two to three days prior to birth. Lymphoblasts are not evident until a short time after birth when the lymphocytic nature of these organs has been established. The first lymphocytes in the appendix and tonsil iliaca appear to develop in situ by the direct transformation of reticular or mesenchymal cells. Lymphocytes tend to migrate toward the mesenchymal condensation of the so‐called domed elevations of the appendix and tonsil iliaca or remain in the connective tissue beneath these domed structures. In addition, lymphocytes enter the appendix and tonsil iliaca via the blood stream at or immediately after birth. These lymphocytes intermix with other lymphocytes in these organs and undergo proliferation within the lamina propria and developing lymphocytic nodules.Morphological evidence strongly suggests a dual origin or source of the lymphocytes in the developing appendix and tonsil iliaca of the rabbit; a population of lymphocytes derived originally from reticular cells and a population of lymphocytes derived extra‐appendiceally possibly of thymic (epithelial) origin. Neither the origin of lymphocytes or lymphocytic precursors from appendiceal epithelial cells nor the derivation of lymphocytic nodules from appendiceal crypts could be substantiated in this investigation. The mode of origin of lymphocytes and subsequent manner of lymphocytic development in the appendix and tonsil iliaca of the embryonic and neonatal rabbit differ markedly from that observed in the embryonic thymus and bursa of Fabricius.
Presence of a ‘cell coat’ rich in carbohydrate at the surface of cells in the rat
Authors: Rambourg A. , Neutra Marian , Leblond C. P. 
Published: February 2005

AbstractTo find out whether or not mammalian cells have a surface coat, over 50 cell types were examined in rat tissues stained with the periodic acid‐Schiff technique for glycoproteins or the colloidal iron technique for acidic carbohydrates.With both techniques, nearly all cells investigated are outlined by a thin, but definite band of stained material, indicating the existence of a surface layer. The surface layer is uniform in leucocytes, fibrocytes and other cells of mesenchymal origin. This is true in neurons too, although associated structures may also be stained. In simple epithelia, the layer appears thicker at apical than at lateral and basal surfaces. (At the basal surface, the layer separates the cell from the basement membrane, which is itself colloidal iron negative and therefore is not part of the cell coat.) Finally, the layer is usually interrupted at the tight junction of terminal bars (where the cell interspace disappears as the plasma membranes of adjacent cells fuse). This finding confirms that the layer is not part of the plasma membrane itself but is a surface ‘cell coat.’In agreement with biochemical data, the staining properties indicate the presence of glycoprotein(s) and acidic residues in the coat of rat cells.
Glomerular ultrastructure in the kidney of a hibernating animal
Authors: Zimny Marilyn L. , Rigamer Elmore 
Published: February 2005

AbstractKidney samples were obtained from ten hibernating and ten control 13‐lined ground squirrels. Citellus tridecemlineatus. The tissue was fixed in cold buffered 2% osmium tetroxide, dehydrated in graded alcohols and embedded in Maraglass. Sections were made with glass knives on a Porter‐Blum microtome and viewed with RCA‐EML and RCA‐EMU 3 electron microscopes. Observations and comparisons were made of the glomerular capillaries in samples from both groups. In comparison with data on other animals reported in the literature, the basement membrane of the renal glomerulus of the control ground squirrel is approximately twice as thick, averaging 2,000–2,500 Å in width. Hibernation results in several structural modifications of the glomerular ultrafilter as follows: (1) the endothelial pores are decreased in number and size; (2) the podocytic foot processes are swollen and the slit pores reduced in size; and (3) the basement membrane thickens, averaging 4,000–5,000 Å in width, and becomes irregular in contour. It is concluded that the porosity of the glomerular ultrafilter decreases during hibernation. This aids in explaining the decrease in the rate of urine formation which occurs during this time of lowered body temperature and metabolic depression.
Initiation of irreversible differentiation in vaginal epithelium
Authors: Barker Thomas E. , Walker Bruce E. 
Published: February 2005

AbstractOvariectomized mice were given estrogen and progesterone either independently, or simultaneously, or in sequence. Thymidine‐H3 was also injected, and the tissues were radioautographed. Analysis of modulation and differentiation was based on the morphological changes seen in cell populations identified by the presence or absence of radioactive nuclei. Estrogen induced cells newly formed in the basal layer to differentiate into a stratified squamous, keratinizing epithelium but did not convert the slowly proliferating surface cells. Progesterone accelerated basal cell proliferation, although this effect was expressed about a day later than when estrogen was used. When both hormones were used in succession, neither could do more than modify the appearance of the cells produced under the influence of the other hormone. However, either hormone could cause proliferation, migration and differentiation of cells from the same basal cells that had previously been the source of cells induced to differentiate by the other hormone. Therefore, the same basal cells can give rise to either stratified squamous or mucous epithelium. Shortly after cells leave the basal layer under the influence of one hormone they cannot be induced to follow the opposite path of differentiation by reversal of hormone treatment. That is, estrogen or progesterone can induce true differentiation as cells leave the basal layer, but only modulation above this level. Consequently, the initiation of relatively irreversible differentiation in this system is closely associated with the stage at which a cell is produced by mitosis from a less differentiated cell and does not appear related to obvious cytoplasmic differentiation.
The melanocytes in the epidermis of the rhesus monkey (Macaca mulatta)
Authors: Yun Jeung S. , Montagna William 
Published: February 2005

AbstractThe epidermal melanocytes which, except in the ears, face and friction surfaces, are normally nonmelanotic become gradually DOPA positive and melanogenic after exposures to ultraviolet light. Peak melanogenic activity is attained after 23 exposures (over a one‐month period). With continued treatment, however, both DOPA positivity and melanogenic activity decline. After 46 exposures (over a two‐month period) the population of DOPA positive melanocytes is about one‐half of that found after 23 exposures. The population of Langerhans cells, normally high in untreated skin, drops steadily as the melanocytes become melanogenic. When, after 46 exposures, the active melanocyte population drops, that of the Langerhans cells rises. There is, thus, an inverse relation between melanocyte activity and the number of Langerhans cells.
Time and duration of DNA synthesis in rabbit eggs after sperm penetration
Authors: Szollosi Daniel 
Published: February 2005

AbstractRabbit eggs 11–18 hours after mating were incubated with tritiated thymidine for 30 minutes, fixed in osmium tetroxide and prepared for autoradiography. DNA synthesis in both pronuclei takes place between 3–6 hours after fertilization. The presynthetic and synthetic periods are short, followed by a long postsynthetic period.
The teratogenic effect of tetanus toxin on the central nervous system of the early chick embryo
Authors: Corliss Clark E. , Fedinec Alexander A. , Robertson G. Gordon 
Published: February 2005

AbstractChick embryos, incubated at 38–39°C to stages 8–11 (Hamburger‐Hamilton staging), were injected (under the vitelline membrane) with ten MLD (mice) per 0.05 ml of tetanus toxin or with avian physiological saline solution. Seventeen hours after the injection the embryos were harvested and fixed in Bouin's solution. Selected control and experimental specimens were sectioned for histological study.Observations of gross specimens show that open neural folds of younger embryos are more susceptible than are the more extensively closed tubes of older embryos. The progressively more caudal restriction of toxin‐susceptible sites with increasing age is a manifestation of this correlation with the degree of closure at injection time.Study of serial sections establishes the concentration of lesions almost exclusively in neural tissue, especially in the alar region of the neuraxis. Tetanus‐induced lesions include encephaloschisis, myeloschisis and platyneury at various levels of the neural tube. These basic defects are comparable to those reported after treatment with many CNS teratogens.Suggestions are made concerning the possible effect of tetanus toxin on biochemical interactions that might lead to aberrations from the normal morphogenesis of the central nervous system.