bluuebunny/crossref_metadata_2025 huggingface dataset:
Grain boundary character distributions in Ni‐16Cr‐9Fe using selected area channeling patterns: Methodology and results
Authors: Crawford Douglas C. , Was Gary S.
Published: February 2005

Selected area channeling patterns imaged on an SEM are digitized and displayed on the screen of a Macintosh computer, on which the user selects channeling bands that are measured to determine orientation. Grain boundary misorientations are found using the orientation information for pairs of grains adjacent at grain boundaries, and the boundaries are classified as low angle boundaries (LABs), coincident site lattice boundaries (CSLBs), or general boundaries (GHABs) based on the misorientation information. The technique was implemented to analyze the grain boundary character distributions (GBCDs) in Ni‐16Cr‐9Fe. The GBCDs of solution annealed material were similar to those expected in an aggregate of randomly oriented polycrystals. However, sequential thermomechanical treatments (5% tensile strain + 945°C:75 min + 2% tensile strain + 890°C:15 h + 3% tensile strain + 890°C:20 h or 9% compressive strain + 890°C:20 h + 9% compressive strain + 890°C:20 h + 3% compressive strain + 890°C:15 h) applied after the solution anneal lowered the proportions of GHABs in the GBCDs from 76–79% to 47–64%. The CSL‐enhanced GBCDs of both the tensile‐deformed samples and the compression‐deformed sample appear to have evolved mainly through impingement of twin and twin‐related boundaries during recrystallization; the CSL‐enhanced GBCD of a compression‐deformed sample appears to have been influenced by grain rotation processes to a greater degree than were the tensile‐deformed samples. The CSL boundaries in the CSL‐enhanced GBCDs were, in general, closer to the exact CSL misorientations than were those in the near‐random GBCDs of the solution annealed material. An analysis of the distribution of misorientation axes did not indicate any correlation between grain misorientation texture and GBCD evolution.
Microvascular architecture of the elastase emphysemic hamster lung
Authors: Hossler Fred E. , Douglas John E. , Verghese Abraham , Neal Larry
Published: February 2005

Vascular corrosion casts of normal and elastase‐induced emphysemic hamster lungs, prepared with a low viscosity resin mixture consisting of Mercox and Sevriton, were observed by scanning electron microscopy. Casts were quantitated by measuring vascular volume or determining non‐alveolar air space using confocal laser scanning microscopy. Normal lung casts were characterized by well‐organized fields of alveoli (about 70 μm in diameter) connected by distinct alveolar ducts. Emphysemic lung casts exhibited numerous bullae (often as large as 0.5 mm in diameter). The vasculature of the bullae indicated that they were formed by destruction of alveolar walls and subsequent coalescence of numerous alveolae. Remnants of alveolar walls, consisting of shallow ridges of capillaries, lined the bases of the bullae. Vascular volumes expressed as cast volume/total tissue volume were calculated at 20% and 12% for uninflated and inflated lungs, respectively, for both control and emphysemic lungs. Four months after elastase instillation, non‐alveolar air space of the emphysemic lungs was increased by 73% over controls. These observations indicate that elastase emphysema results, initially, in remodeling of the alveolar structure (bullae formation) and loss of surface area for gas exchange, rather than from extensive loss of vasculature. Vascular corrosion casting is a useful technique for monitoring emphysema both morphologically and quantitatively.
The third joint of the canine jaw
Authors: Scapino Robert P.
Published: February 2005

The dog mandible has three joints — two temporomandibular and one symphyseal joint. In studies of jaws and their mechanics usually only the temporomandibular joints are considered. The symphysis is consistently neglected and because of this, remarkable features of the temporomandibular joints have never been noted.

The symphysis has special connective tissue arrangements and its own vascular and nerve supply. Along the anterosuperior part of the symphysis, a strip of fibrocartilage, and running more or less parallel to it, strong cruciate ligaments bind the symphyseal plates together. Small arteries run into the symphyseal joint and it is drained by an anastomosing venous plexus. The posterior, ligamentous, portion is laced with a profuse network of nerves.

The temporomandibular joint is unusual in that its joint disc is powerfully anchored to the skull medially and to the outer pole of the mandibular condyle laterally. The temporomandibular joint disc thus acts as a ligament that halts lateral movement of the condyle just as the carnassial teeth are aligned for cutting function. As the mandible moves laterally, the space between the posterior ends of the symphyseal plates widens: at the same time it narrows anteriorly. The cruciate ligaments control this movement and stabilize the symphyseal joint by preventing direct lateral displacement of the symphyseal plates. The fibrocartilage cushions this movement and also mediates rotational movements about the longitudinal axis of the mandible when crushing molar teeth come into function.
The relation of amicronuclearity to stomatogenic activity during conjugation in several ciliates
Authors: Diller William F.
Published: February 2005

Early in conjugation, both in micronucleate and amicronucleate ciliates, the original oral structures degenerate and are quickly succeeded by new rudiments which may or may not attain functional competency. These changes were followed in matings of amicronucleate Oxytricha fallax and, in somewhat less detail, of amicronucleate Paramecium multimicronucleatum and P. trichium.

In the ex‐conjugants of Oxytricha the new peristomes did not reach complete structural development: they bore a deficient number of adoral membranelles and lacked an undulating membrane along the right border. Numerous isolated pairs gave rise to ex‐conjugants, all of which died within a few days. Macronuclear changes in conjugation seemed normal.

In P. multimicronucleatum most of the ex‐conjugants lacked a buccal cavity. Either the second generation oral apparatus had failed to develop or had disappeared quickly after it did arise. An occasional ex‐conjugant possessed an oral opening which could have been the persisting original buccal cavity, or a possible new one. Isolated pairs yielded 80–100% lethality. The discrepancy from 100% is explainable on the basis of precocious separation of a small number of pairs before their macronuclei had reached irreversible skein formation, as judged by stained specimens. The macronuclear changes were somewhat different from those of micronucleate conjugation.

P. trichium amicronucleate conjugations were studied only from cases in mass cultures, all of which died out. Although most of the ex‐conjugants lacked buccal cavities, there was a higher percentage of individuals with mouths than was true for P. multimicronucleatum.
An autoradiographic study of RNA synthesis in isolated salivary glands of Drosophila hydei. II. Interferometric studies
Authors: Pollister Arthur W.
Published: February 2005

Interferometric measurements were made on sections of salivary glands mounted in oils of refractive indices 1.410, 1.460, and 1.500, estimating optical path differences as fringe displacement with a Leitz double‐beam interferometer microscope. From these data the mean concentrations (in mg/cm2/micron) of 55 cells of three glands were computed as follows: karyoplasm, 0.027±0.0026; cytoplasm, 0.048 ± 0.0024; nucleolus, 0.066±0.0041. From these concentrations it was computed, according to Maurer and Primbsch (Exp. Cell Res., 33: 8–18) that the correction factors for four micron sections were: karyoplasm, 0.203; cytoplasm, 0.114; nucleolus, 0.083. The reciprocals of these fractions (5.0, 8.8, and 12.0) are the correction factors of Arnold (J. Morph., in press) by which measured silver grain densities on autoradiographs are multiplied to give corrected (i.e. potential) densities.
The development of the skull of Psammophis sibilans. II. The fully formed chondrocranium
Authors: Kamal A. M. , Hammouda H. G.
Published: February 2005

The fully formed chondrocranium of the Egyptian snake, Psammophis sibilans has been described in detail. The tectum synoticum is very broad and there is apparently no tectum posterius. The notochord is completely embedded in the occipital condyle. The connection between the condyle and the odontoid process persists to the fully formed stage. There is only one commissure, representing the anterior basicapsular commissure, connecting the auditory capsule to the basal plate. The fisura metotica is continuous postero‐dorsally with the fissura occipitocapsularis. The distal bent end of the shaft of the columella auris represents the processus dorsalis, and the nodule that separates from it and fuses with the quadrate is the intercalare. The interorbital septum, orbitosphenoid cartilages, basitrabecular processes and planum supraseptale are completely absent. The concha nasalis is of the simplified type, the active factor in its formation is the folding of the olfactory epithelium. The solum nasi is greatly reduced and comprises the floor of the cupola anterior, the composite lamina transversalis anterior, cartilago ectochoanalis, cartilago hypochoanalis and ectochonal plate. The branchial arches are completely absent. The pterygoquadrate is represented only by the quadrate cartilage. The ceratohyals are extremely long.
The development of the skull of Psammophis sibilans. III. The osteocranium of a late embryo
Authors: Kamal A. M. , Hammouda H. G.
Published: February 2005

The osteocranium of a late embryo of the Egyptian snake, Psammophis sibilans (age, 58 days; total body length, 190 mm) has been described. Attention was given to the relation of the different bones to the adjacent cartilages of the chondrocranium as well as to the topographical relation of the bones to each other in the late embryonic state. Several adjacent bones have not yet come in contact with each other. The membrane‐bones make their appearance shortly before any sign of ossification in the cartilaginous cranium. The maxillary, palatine and pterygoid premordia have a slight earlier appearance than the other bony premordia. The lacrymal, postfrontal, squamosal, jugal, quadratojugal and epipterygoid bones are completely absent. The laterosphenoid bone is never performed in cartilage. The whole columella auris is ossified.
The adult and larval morphology and life history of the entoproct Barentsia gracilis (M. Sars, 1835)
Authors: Mariscal Richard N.
Published: February 2005

The morphology of the entoproct Barentsia gracilis (M. Sars, 1835), has been studied primarily by routine light microscopy techniques supplemented with observations by electron microscopy. In general, the B. gracilis adult is similar in structure to other members of the Pedicellinidae. Differences noted include: the presence of conspicuous fibers, probably collagenous, which appear to reinforce the stalk‐ calyx connection, the presence of a distinct glandular‐ appearing area (also present in the larva) of unknown function, and the presence of two rows of latero‐ frontal cilia on the tentacles. The first detailed morphology of an entoproct larva is also presented and the striking similarity to the adult noted. Due to the confused state of Barentsia systematics, it was found that B. gracilis, B. geniculata, and B. benedeni may very well be the same animal. This is due to the great variability, apparently due to ecological factors, found in the key taxonomic characters such as stalk morphology. The feeding behavior of the adult is described and the larval feeding and rejection mechanism is reported for the first time. The larva, while still in the brood pouch, uses its ciliary girdle to remove food from the parent's food groove. The larval feeding current is generally similar to that of the adult, with modifications which are related to the lack of tentacles in the larva. The larva differs from the adult in having special ciliated rejection pathways for the removal of excess food particles.
Microvillous cells in ampullae of the lizard inner ear
Authors: Hamilton David W.
Published: February 2005

Electron microscopy of membranous labyrinths in Anolis carolinensis, Gonatodes biteanatus and Ameiva chrysolaema reveals the presences of cells of complex structure located adjacent to sensory areas in all ampullae. Microvillous cells are characterized by extensive infolding of basal cell membrane, with clefts extending to level of the basal portion of the nucleus. Each compartment thus formed is filled with mitochondria, ribosomes and glycogen. Lateral and basolateral interdigitations with surrounding cells are present. Supranuclear cytoplasm is composed of numerous mitochondria, extensive Golgi apparatus and dense populations of ribosomes and glycogen. Smooth endoplasmic reticulum is the most common reticulum present, although there is scattered granular reticulum. Toward lumen of ampulla, cells are constricted and a small portion of cytoplasm extends between supporting cells to bulge into lumen. Long, slender, branching microvilli project from luminal border into endolymph.

Supporting cells resemble those found in adjacent sensory areas, with undulating luminal membranes, few mitochondria, scattered (but abundant) ribosomes and polysomes, considerable endoplasmic reticulum, extensive Golgi apparatus, lateral and basolateral interdigitations with other supporting cells and microvillous cells. Also present are large vacuoles containing elongate, randomly‐ oriented crystalline material.

General morphology of microvillous cells suggests that they are involved in ion transport and in maintenance of electrolyte balance in endolymph. The role of glycogen in this process is discussed, as is the general problem of endolymph formation.
Sexual cycle of the lizard, Leiolopisma fuscum, a tropical australian skink
Authors: Wilhoft Daniel C. , Reiter Edward O.
Published: February 2005

Leiolopisma fuscum were obtained monthly between October, 1959, and March, 1960, in northeastern Australia, latitude 16°44'S. Gross as well as histological changes observed in the gonads and accessory sex structures of lizards of both sexes revealed seasonal variation in reproductive activity, which reached a peak in December and January. During March the gonads and accessory sex structures regressed in size but by October both sexes were again reproductively active.

The reproductive activity of L. fuscum, and open forest form, was compared with that of L. rhomboidalis, a related inhabitant of the rainforest. Differences in the reproductive activity of the two species were attributed to differences in the habitats and in the climatic stimuli, especially annual rainfall, associated with these habitats.

Leiolopisma fuscum which occurs over much of coastal northern Australia and part of southern Papua, is far more widespread than the other species. Its cyclic reproductive pattern is probably more typical of the genus. The reproductive cycle of L. rhomboidalis is probably adaptively specialized for conditions in the rainforest, where the physical environment is subject to less seasonal variation.
Regional differences in skin gland differentiation in Rana pipiens
Authors: Verma Kusum
Published: February 2005

The paper deals with the study of development of skin glands in normal and in thyroxine treated Rana pipiens larvae. The development of skin glands in various regions is found to be sequential. The glands also undergo development at different rates in different regions. At high thyroxine concentrations the mucous glands were found to differentiate faster than serous glands. Hormone treatment, besides precocious skin maturation brings about temporal separation of otherwise simultaneous events. The findings emphasize the intrinsic, qualitative differences of cells of the skin system.
Morphogenetic studies of the rabbit XXXV. Pleiotropic effects of the dachs gene and the gradient growth pattern
Authors: Sawin P. B. , Trask Muriel
Published: February 2005

The pleiotropic effects of the dachs gene (Da) upon the skeleton have been studied in alizarin stained preparations and roentgenograms in 412 skeletons of progeny (aged 31–90 days) of three possible genotypes obtained from heterozygous parents. Basically they arise as direct or indirect manifestations of retardation, including reductions in size, deficiency in numbers of skeletal units, compensatory induction of accessory units, and overgrowth of adjacent normal units. These lead to homeotic shifts or displacement in position, crowding, and fusion. Vertebral borders anterior to v. 20 are displaced forward; those posterior tend to be backward, and the initial appearances of the epiphyses are also affected. Epiphyses of the vertebrae and long bones and the carpals and tarsals as maturity indicators are precocious as they are in retarded conditions of man, and this is enhanced in heterozygotes simulating overdominance or one gene heterosis. As indicators of premature maturation they have semblance of dysheterosis. Of particular significance is the manner in which these diverse pleiotropic effects exemplify the genetic concept of overdominance, modify the species or strain gradient pattern and the similarities of the mechanism of action to processes already revealed experimentally in the laboratory by various investigators. Extension of such study by qualitative and quantitative methods opens an approach to both genetic and environmental factors affecting normal and abnormal growth which can be tested in many ways. It would be particularly effective in study of the syndrome of effects induced by radiation, hypoxia, and other teratogenic agents.
The effects of RNA synthesis inhibition and of protein synthesis inhibition on embryonic induction and cell differentiation in Rana pipiens
Authors: Ansevin Krystyna D.
Published: February 2005

Presumptive epidermis cells of Rana pipiens gastrula (stage 11) was induced in vitro by LiCl to differentiate into melanophores. The period from the moment when the inductor was introduced to the cells to the moment of their morphological differentiation was arbitrarily divided into three stages: “A” — The time interval during which the cells were exposed to LiCl, “B” — The period of several hours immediately following the cells' contact with the inductor, and “C” — The period of time immediately preceding formation of pigment in the cells. During one of these three stages the cells were treated with one of the three inhibitors: actinomycin, puromycin or ethionine. Differential sensitivity of the activated cells to the inhibitor during these three stages was revealed by their subsequent differentiation. Puromycin when applied at stage “A” increased pigmentation of melanocytes. Actinomycin acting during stage “B” in some cases caused differentiation of mesenchyme‐like cells instead of melanophores. Ethionine presented to the cells at stage “C” promoted differentiation of a characteristic cell type which could not be identified with any normal histological species.
Disposition of nerve fibers in the regenerating limb of the adult newt, Triturus
Authors: Salpeter M. M.
Published: February 2005

Bundles of nerve fibers invade the early regenerating limb of the adult newt Triturus. These fibers are unmyelinated and are only partly enveloped by accompanying Schwann cells. Isolated fibers make intimate contact with mesenchymatous cells. The fine structure of such contact regions suggests possible functional nerve terminations.
Sense organs of the lateral line system in some electric fish of the Gymnotidae, Mormyridae and Gymnarchidae
Authors: Szabo Thomas
Published: February 2005

Morphological aspects of lateral line system of Gymnotidae, Mormyridae and Gymnarchidae were studied: “Ordinary” and specialized sense organs were identified and their somatic distribution and their relation to the lateral line nerves established. An attempt was made to classify the specialized sense organs of the lateral line system in these families. The morphological results are discussed in relation to recent physiological data permitting identification of one of the specialized sense organs as a newly recognized sense organ, the electroreceptor.
The sudanophilic lipid of normal and regenerating limb tissues of the adult newt, Diemictylus viridescens
Authors: Schmidt Anthony J.
Published: February 2005

The most intense and widely distributed sudanophilic responses of cryostat‐sectioned newt limb tissues were obtained with a simultaneous fix and stain procedure of 1:1 10% formal‐calcium and sudan black B. Droplets and globules of lipid mixtures and rodlets (mitochondria) were typical responses distributed within the epidermis, subcutaneous glands, dermis and other connective tissues, striated muscle (also with positive fibrils), tunics of blood vessels, and blood cells. A prominent droplet response was located subjacent to the adepidermal basement membrane. The myelin of brachial nerve stained intensely.

In regenerating limbs, the wound epithelium response was comparable to that of epidermis. Post‐amputational lipophanerosis of injured muscle and brachial nerves was observed. The retrograde degeneration of nerve myelin was extensive, and continued into the early differentiative phase of regeneration. Lipid‐engorged macrophages were prominent among the injured tissues, distal to these, and within the wound epithelium.

The regeneration blastema revealed a large quantity of sudanophilic lipid. Prominent droplet and rodlet responses were typical of the myelinating regenerating nerves. The response of regenerating muscle equaled that of the mature stump fibers. The cells of the regenerating chondroskeleton contained sudanophilic lipid.

Organic solvents such as acetone, ether, chloroform and chloroform:methanol reduced or prevented the sudanophilic responses. Sudan red 7B revealed less lipid than did sudan black B. A fixation effect was demonstrated with post‐chromated formalcalcium, and chromic‐formalin fixed sections. In the latter preparations, swollen‐bodies, identified as mitochondria, stained intensely.
The development of the centrum of Hypogeophis rostratus (Amphibia, Apoda) with special reference to the notochordal (intravertebral) cartilage
Authors: Lawson R.
Published: February 2005

The development of the centrum and the notochordal (intravertebral) cartilage in Hypogeophis is described. The notochordal cartilage is produced in each vertebra by certain areas of the notochordal epithelium and there is no indication of the invasion of the notochordal sheath by mesenchyme cells. The bands of cartilage are of constant occurrence and persist in the adult vertebrae.

The vertebrae are autocentral and the centrum is produced (independently of the neural arches) by a tube of circumnotochordal mesenchyme cells.
Further studies on the effect of tetracycline on the developing skeleton of the chick embryo
Authors: Rolle Gloria K. , Bevelander G.
Published: February 2005

At intervals from 2 to 13 days of incubation, 2.5 mg of tetracycline hydrochloride was injected into the yolk sac of chick embryos. The femurs and mandibles were examined histologically at intervals between 10 and 17 days of embryonic age.

The abnormalities which result include inhibition of mineralization of the developing osteoid trabeculae, retardation of erosion of the long bone cartilage model, and abnormal calcification of the cartilage matrix in the long bones. The major effects on cartilage maturation appear to occur after cellular hypertrophy has taken place and thus are found only in cartilage models which are being replaced by bone.

While tetracycline does cause some retardation in the rate of osteoid deposition, the drug appears to affect intramembraneous bone formation in the mandible and femur primarily by retarding or temporarily inhibiting the rate of mineralization of the osteoid matrix.

The results of this study indicate that the effects produced by tetracycline on developing bones are dependent upon the concentration of the drug and not upon the time of administration.
Properties of isolated frog liver and kidney nuclei
Authors: Stack Carol R. , Mateyko G. M.
Published: February 2005

In order for a nuclear preparation to be used for analytical purposes, the method of isolation and composition of the suspension medium must be carefully examined. Accordingly, satisfactory techniques for the isolation of frog liver and kidney nuclei were developed. The medium for frog liver nuclei consisted of: 55% glycerol, 0.001 M magnesium chloride, 0.033 M sodium β‐glycerophosphate and/or 0.002 M KH2PO4, K2HPO4 (pH 6.8), however, the addition of 0.15 M sucrose was essential for satisfactory isolation of kidney nuclei. Inclusion of sucrose (0.15 M) in the isolation medium promoted nucleolar swelling and a decrease in nuclear volume in liver cell nuclei. Nucleolar migration and extrusion were noted in solutions with high cationic content.

The morphological appearance of isolated nuclei was found to be extremely sensitive to the ionic strength of the isolation medium, as was the isolation procedure in toto. Effects were considered to be the result of precipitation and swelling of nucleoprotein. Dissociation of nucleoprotein was considered to be associated with temperature change. The uptake of supra‐vital dyes aided in recognition of the morphological alterations and was also an indicator of nuclear viability.

Trypsin readily altered the nuclear membrane and a rapid decrease in nuclear density occurred, but the nucleolus remained intact. The diverse response of liver and kidney nuclei as compared with the nucleated red blood cells (a contaminant) to treatment with trypsin was noted and its implications discussed.
Sexual segment of the kidney of the Indian house lizard, Hemidactylus flaviviridis Rüppell
Authors: Sanyal M. K. , Prasad M. R. N.
Published: February 2005

The morphology, seasonal variation and histochemistry of the sexual segment of the Indian house lizard, Hemidactylus flaviviridis are described.

The sexual segment is the hypertrophied portion of the secondary and the tertiary collecting ducts of the kidney in males. The cells of the sexual segment are columnar and are loaded with secretory granules which are predominantly localized in the apical portion. These granules are either free or occasionally clumped to form an “aggregate” towards the basement membrane and are released into the lumen by apocrine secretion. Development of the sexual segment is synchronous with the spermatogenic activity of the testis and maximum development occurs in March and April when the lizards copulate. The sexual segment is secretory from the beginning of October to the end of May and is regressed during sexual quiescence (June and July). It is not developed in females and young of both sexes in any season of the year.

Histochemically, the sexual segment granules are saliva resistant and PAS positive, sudanophilic and are positive to the tests for phospholipid, choline and acid phosphatase. An intense esterase activity was localized in the mucosa of the oviduct and cloaca of the female. Sperms are mixed with sexual segment secretions and are transferred to the female during copulation. A possible role for the lipid‐rich sexual segment secretion as a source of energy for sperms in the female reproductive tract is discussed.
The reproductive cycle of the western whiptail lizard (Cnemidophorus tigris) in Southern Arizona
Authors: Goldberg Stephen R. , Lowe Charles H.
Published: February 2005

Reproduction in Cnemidophorus tigris at Tucson, Arizona follows a seasonal cycle in which gonadal size is minimal in September‐October. Male reproductive organs gradually recrudesce during the winter months spent underground. After the lizards emerge from hibernation in March‐April the testis, seminiferous epithelial height and tubule diameter gradually increase in size through April and May, reaching maximum size in June‐July followed by rapid regression in August. Mating is first observed in the field in May. The ovaries undergo a period of heavy yolk deposition from early April to May, and remain functional until August. A thick circumtesticular subtunic layer of equivalent interstitial material (Leydig cells) is reported and described for the testis of Cnemidophorus.
The origin and development of alopecia in mice homozygous for strong's luxoid gene
Authors: Forsthoefel Paulinus F. , Fritts Mary L. , Hatzenbeler Lawrence J.
Published: February 2005

Hair follicles are initiated in mice homozygous for Strong's luxoid gene at the normal times. The dermis from 16 days of gestation to nine days after birth lags in development. The adipose layer instead of enlarging at the normal time of three days after birth delays until nine days. The growth of the first cycle hairs is inhibited, particularly on dorsal surfaces. Some follicles of all types degenerate. The surviving follicles enter telogen at seven days after birth, after forming only short unpigmented or poorly‐pigmented hairs. Many follicles immediately begin a second cycle of growth, in which more normal hairs develop and a substantial adipose layer forms. No alopecia develops on ventral surfaces, but growth of the first cycle ceases and the second cycle commences earlier than normal; the hairs formed are abnormal. Abnormal hair growth in Strong's luxoid homozygotes may be a result of the retarded growth of the dermis or both defects may be secondary to a more fundamental defect.
Microanatomy of the heart and associated structures of two scorpions, Centruroides sculpturatus ewing and Uroctonus mordax thorell
Authors: Randall Winnifred C.
Published: February 2005

Spiroid orientation of the circumferential heart wall muscles is described for Centruroides sculpturatus Ewing. This muscle arrangement accounts for differences in ostial position when the heart of this species is compared to that of Uroctonus mordax Thorell. Other differences, such as number of lateral arteries present, cannot be explained on the basis of circumferential muscle orientation.

The histology of the heart and associated vessels, but not the supraneural vessel, was found to be similar in both species. The lateral, posterior, communicating and sternal arteries all possess a muscularis composed of irregularly spaced, apparently branched, striated muscle fibers. External to this is a covering of connective tissue. The lumina of these arteries, the aorta, and the supraneural vessel are lined with a homogeneous, PAS‐positive membrane. This membrane is also seen in blood vessels which penetrate the nervous system. It was not observed in vessels accompanying major nerves.

Findings are compared to those of other authors. Differences in the structure of the hearts of these two species are discussed in relation to the microanatomy of other arachnid hearts.
Effects of dissociating agents on the fine structure of embryonic chick thyroid cells
Authors: Robert Hilfer S. , Hilfer Eva K.
Published: February 2005

The processes of dissociation and reaggregation were studied in thyroids from 16‐day chick embryos by means of electron microscopy. The purpose was to gain specific knowledge of the effects that dissociating agents have upon cells.

Fixation after a soak in trypsin showed little effect on secretory cell structure but resulted in marked swelling and detachment of connective tissue elements and disorganization of the basement lamella of the follicles. After an additional exposure to ethylenediaminetetraacetate (EDTA), however, the channels of the endoplasmic reticulum and the Golgi vesicles became swollen and separations appeared between adjacent secretory cells. Since detachment did not occur in the region of the junctional complex, agitation was required to achieve suspension of the cells. Even this treatment resulted in only a small proportion of individual cells, the majority being in the form of small clumps or chains. Transfer of the suspensions to nutrient medium and reaggregation produced pellets which rapidly formed follicles in organ cultures. The individual cells showed the same degree of complexity as in follicles in vivo.

The results are related to the known effects of trypsin and EDTA on cells. The significance of morphogenesis in aggregates prepared from cells of older embryonic organs is also discussed.
Tooth replacement in the frog Rana temporaria
Authors: Lawson R.
Published: February 2005

The development and replacement of teeth in the frog Rana temporaria is analyzed by dividing the life cycle of the tooth into a number of stages. These stages are identified by the examination of alizarin whole mounts. The dentition in this species is fairly complete and the percentage of functional loci is approximately 74. The teeth in alternate loci are usually at about the same stage in development. The low percentage of non‐functional loci is accounted for by the retention of functional teeth over a large fraction of the total life cycle time and the relatively rapid ankylosis of replacement teeth. It is suggested that tooth replacement is essentially a process which involves teeth in alternate loci and that the replacement waves (which connect alternate loci) run parallel to the longitudinal axis of the jaw and are of infinite length. This basic pattern is obscured by many breaks which occur in the replacement waves. The presence of such breaks may be accounted for by variations in the time intervals between the successive stimuli which initiate the Zahnreihen, or simply by the acceleration or deceleration of the development of teeth in one or more loci.
The transport of 3H‐l‐histidine through the Schwann and myelin sheath into the axon, including a reevaluation of myelin function
Authors: Singer Marcus , Salpeter Miriam M.
Published: February 2005

The view is commonly held that the exclusive source of axonal substance is the neuronal cell body. The results of the present study, employing techniques of light and electron microscope autoradiography, indicate that substances of metabolic importance may reach the axon from intercellular fluids by way of the Schwann and myelin sheath. Tritiated l‐histidine was injected intraperitoneally into the newt, Triturus viridescens, and the label was found in the Schwann cell body, myelin,

We use the terms myelin and myelin sheath synonymously, as generally employed in modern anatomical literature, for the array of packed Schwann cell wrappings around the axon of the peripheral nerve fiber. In biochemical literature the term myelin is used rather loosely sometimes to imply the chemical substratum of the myelin sheath or its lipoidal fraction.

and axoplasm. Nerve separated by transection from its neuronal cell bodies was labeled about as densely as intact nerve. Moreover, pieces of nerve immersed in the isotope also incorporated the labeled molecule. These results have led us to reassess traditional views of the function of the sheaths surrounding the axon.
A Comparative electron microscopic study of cytoplasmic microtubules and axial unit tubules in a spermatozoon and a protozoan
Authors: Burton Paul R.
Published: February 2005

Cytoplasmic microtubules and axial unit tubules were studied in both sectioned and negatively‐stained material. Walls of microtubules of frog lung‐fluke (Haematoloechus medioplexus) spermatozoa have a helical substructure, while those of the flagellate, Trypanosoma lewisi, are composed of ten longitudinally‐oriented filaments. Cross‐bridges occur between some filaments of trypanosome microtubules. Doublet tubules of axial units in both cell types are structurally similar to the trypanosome microtubules, which may indicate similarity of function. Microtubules of fluke spermatozoa appear to be somewhat rigid, are resistant to sonication, and are considered to be mainly supportive. Circular profiles of wall subunits are seen in transverse sections of microtubules of both cell types and in doublet tubules of the trypanosome. Comparisons are made between sectioned and negatively‐stained material; while negative‐staining better reveals the fundamental substructure of microtubular elements, some distortion appears to occur. In connection with this research, a brief preliminary article demonstrated the presence of subunits in the walls of cytoplasmic microtubules of fluke spermatozoa (Burton, '66). Also, it was shown that the wall of these tubular elements possesses a helical structure, and a diagrammatic representation of the wall structure was set forth.
The morphology and function of accessory reproductive glands in the lophophores of Phoronis vancouverensis and Phoronopsis harmeri
Authors: Zimmer Russel L.
Published: February 2005

The enigmatic lophophoral organs of phoronids are demonstrated to by accessory sex glands. In the hermaphroditic Phoronis vancouverensis, each mature adult has two pairs of such glands: female nidamental glands that facilitate the temporary brooding of the embryos and male accessory spermatophoral organs that function in spermatophore elaboration. Functional males of Phoronopsis harmeri have complex accessory spermatophoral organs while females of this non‐brooding dioecious species lack accessory sex glands.

In both species, coelomic spermatozoa are accumulated within the nephridia and passed en masse into the partially enclosed spermatophoral organs. There each sperm mass is molded into a characteristic shape and encased in one or more membranes before release as a spermatophore into the ambient water. The structure of the spermatophore is characteristic for each species and is correlated with the functional morphology of the distinctive spermatophoral organs.

The existence of spermatophores, the non‐primitive nature of the spermatozoa, and additional features of reproductive biology dictate that fertilization is internal in these species, but attempts to determine the means of sperm transfer proved futile. Reproductive potential and behaviour of male Phoronopsis, means of gamete segregation in Phoronis, and general pattern of reproductive biology for both phoronids were also studied.
Proliferative response in experimentally injured frog lens epithelium: Autoradiographic evidence for movement of DNA synthesis towards the injury
Authors: Rafferty Nancy S.
Published: February 2005

In order to follow the movement of cells involved in the proliferative response induced by wounding, changes in the cell population of three regions of normal and injured frog lens epithelium were studied with respect to DNA synthesis and mitosis using autoradiography following intraperitoneal injection of H‐3‐thymidine. The injured lenses comprised two groups: one subjected to labeled thymidine at 40 hours post‐injury when the proliferative response begins, the other at 72 hours when the proliferative response is at its peak. Lenses were fixed at increasing intervals after injection.

The data show that a central injury initiates proliferation in a large number of cells; this response appears at first mainly among the cells in the outlying proliferative (pre‐equatorial) zone, as judged by the number of labeled nuclei and mitoses seen there in the first few hours after injection in the 40 hour preparations. At later intervals labeled cells and mitoses appear centrally adjacent to the wound. And in the 72 hour preparations, the greatest concentration of reactive cells is adjacent to the wound. There is also thinning out of labeled cells in the proliferative zone and greater dilution of exposed emulsion grains over nuclei adjacent to the wound with time, suggesting that outlying cells migrate centrally, dividing en route. However, interpretation of these data is limited by the finding that H‐3‐thymidine injected intraperitoneally into the frog is not cleared rapidly from the circulation; the serum after 24 hours retains about 20% of the radioactivity (measured by scintillation counting) present at 15 minutes post‐injection.
The carotid sinus in lizards with an anatomical survey of the ventral neck region
Authors: Sidky Younan A.
Published: February 2005

The anatomy of the ventral neck region of the scincid lizards Chalcides ocellatus and Scincus scincus is presented and is found to be similar to that of other lizards as described in the literature. The internal carotid artery arises by 3‐5 roots from the dorsal side of the ascending limb of the carotid arch. During its first part, the internal carotid artery is completely divided into two nearly equal channels. The carotid sinus is more complicated in Chalcides than in Scincus. In lizards, it may be homologous to the carotid labyrinth of fishes and amphibians. Around the origin of the internal carotid artery are two kinds of epithelioid cells scattered in the adventitial connective tissue: a‐ large cells with rounded, faintly stained nuclei, and little, clear cytoplasm; b‐ cells with small darkly stained nuclei. Both kinds of cells appear to represent different levels of secretory activity. The number of the large cells increases with greater complexity of the carotid sinus. The cells also increase in size and number during summer (sexual period); this is especially true in younger animals. The epithelioid cells are considered to be homologous to the carotid body of higher vertebrates. The carotid sinus and epithelioid cells together form a closely interrelated system which may be intermediate between the carotid labyrinth of fishes and amphibians, and the carotid body of birds and mammals.
Sense organs on the antennal flagella of earwigs (Dermaptera) with special reference to those of Forficula auricularia
Authors: Slifer Eleanor H.
Published: February 2005

Five types of sense organs have been found on the antennal flagellum of Forficula auricularia Linnaeus: (1) tactile hairs; (2) long, thick‐walled chemoreceptors; (3) short, thick‐walled chemoreceptors; (4) thin‐walled chemoreceptors and (5) coeloconic chemoreceptors. Earlier workers have placed the first three of these in a single class. The structural characteristics and distribution of these five kinds of sensilla on the antenna are described. All of the types except the third have been reported previously for other species but short, thick‐walled chemoreceptors have not been described before. They are remarkable for the presence of (1) a broad pad‐Like structure that absorbs dyes readily at the distal end of the peg and (2) a spheroid body, over a micron in diameter, on the dendrite of each olfactory neuron at the point where it narrows to assume the structure of a cilium. The antennal sense organs of a few specimens of Chelisoches morio (Fabricius), Labidura riparia (Pallas) and Euborellia annulipes (Lucas) were also examined.
Biomechanics of prehensile oral mucosa
Authors: Scapino Robert P.
Published: February 2005

Large dogs are able to deliver a powerful bite that generates considerable stress in the anterior, prehensile part of the jaws.

In the upper jaw most of the biting force is borne by the anterior teeth. The palatal mucosa provides little resistance to deformation. It is easily compressed and rather mobile.

In the lower jaw, the mucosa covering the upper surface of the symphysis receives a sizeable portion of the biting force. It is firmly attached to the underlying bone and possesses special connective tissue arrangements that enable it to transduce locally applied pressure to tension distributed over a broad area.
The structure of the carotid bifurcation in the lizards Tiliqua occipitalis and Trachysaurus rugosus
Authors: Rogers D. C.
Published: February 2005

The origin of the internal carotid artery in the lizards Tiliqua occipitalis and Trachysaurus rugosus has been shown to be both extremely variable and complex. In the dense connective tissue investing the junction of the internal carotid artery and the summit of the carotid arch are groups of cells associated with sinusoids derved from arterioles arising from the neighboring great vessels. The conspicuous epithelioid cells in these groups resemble the mammalian carotid body glomus and amphibian α cells. Nerve fibers showing no obvious synaptic specializations pass to and over these cell groups. It is suggested that these cell groups and sinusoids are comparable to mammalian carotid body glomeruli. A similar group of cells has been described in the concavity of the summit of the fourth aortic arch. This cell group, however, gives a distinct chromaffin reaction.
Three shapes of mitochondria in femoral muscle of the cockroach, Leucophaea maderae fabricius
Authors: Hagopian Martin
Published: February 2005

Three distinct types of mitochondria as related to shape, position, and size in the femoral muscle of the cockroach, Leucophae maderae, are described. The elongated mitochondria are interposed between the myofibrils and are oriented parallel to the long axis of the fiber. Surface indentations on these mitochondria for surrounding structures indicate their permanent position. The oval mitochondria are situated under the sarcolemma. These organelles have a parallel orientation to the underlying muscle fiber but no alignment with respect to the “sarcomeric repeat” and thereby suggest that this type is mobile. The Y‐shaped mitochondria are observed in the intermyofibrillar sarcoplasm. Their paired processes are on each side of the Z‐disc and imply that the Y‐shaped mitochondria are a sessile type. The cristae in all three categories of mitochondria display a tightly packed and complex arrangement.
Oxytalan fibers in the periodontal ligament of the Caiman and the Alligator (Crocodilia, Reptilia)
Authors: Soule John D.
Published: February 2005

Histological examination of the fibrous and cellular connective tissue components of the periodontal ligament in the Caiman and the Alligator reveals the presence of reticular fibrillae, collagenic, elastic, and oxytalan fibers, as well as fibrocytes, osteoblasts, cementoblasts and epithelial rests. The oxytalan fibers differentiated by the peracetic acid aldehyde‐fuchsin method are most numerous in the coronal region, radiating from the primary cementum into the periodontal ligament a short distance. Oxytalan fibers in fewer numbers are found interspersed between the oblique and the horizontal principal fiber bundles. Inasmuch as the crocodilian teeth have continuous replacement and thus a relatively short functional life, the oxytalan fibers of the Caiman and the Alligator appear to be proportionally fewer in number than they are in the mammalian periodontal tissues. The presence of the oxytalan fibers and epithelial rests in the Order Crocodilia (Crocodilia) adds to the number of dental structures shared with the Class Mammalia (Mammalia) (mammals) such as a stellate reticulum, a primary and secondary cementum and a periodontal ligament. This furnishes additional histological evidence for evaluation of the phylogenetic position of this group.
Histochemical patterns in the proventriculus of the developing chick
Authors: Hinsch Gertrude W.
Published: February 2005

The proventriculus of White Leghorn chick embryos (stages 29–45) newly‐hatched chicks, and adult chickens were frozen, sectioned in a cryostat and treated histochemically to identify localizations of alkaline and acid phosphatase, adenosine triphosphatase, 5‐nucleotidase, nucleotide‐diphosphatase, non‐specific glycerophosphatase, glucose‐6‐phosphatase, non‐specific esterase and succinic dehydrogenase. Ribonucleic acid, proteins and acid mucopolysaccharides were identified in tissues fixed in FAA.

Acid phosphatase, nucleotide‐diphosphatase, adenosine triphosphatase, succinic dehydrogenase, ribonucleic acid and proteins were present in the cells of the deep glands at all stages of development. Alkaline phosphatase and 5‐nucleotidase were found only in mesenchymal derivatives of the proventriculus. After the chick begins swallowing and digesting albumen, enzymatic activity increased and non‐specific esterase became very reactive.

The surface epithelium is covered with a mucous coat. Ribonucleic acid, non‐specific esterase, acid phosphatase and nucleotide‐diphosphatase were localized in the basal portions of the epithelial cells. The functional significance of these different patterns is discussed.