bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microvillous cells in ampullae of the lizard inner ear
Authors: Hamilton David W. 
Published: February 2005

AbstractElectron 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

AbstractLeiolopisma 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

AbstractThe 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

AbstractThe 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

AbstractPresumptive 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

AbstractBundles 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

AbstractMorphological 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

AbstractThe 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

AbstractThe 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

AbstractAt 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

AbstractIn 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

AbstractThe 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

AbstractReproduction 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

AbstractHair 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

AbstractSpiroid 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

AbstractThe 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

AbstractThe 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

AbstractThe 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.