bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic expression patterns of tenascin, proteoglycans, and cell adhesion molecules during human hair follicle morphogenesis
Authors: Kaplan Elizabeth D. , Holbrook Karen A. 
Published: February 2005

AbstractThe development of skin appendages such as hair, feathers, and teeth is brought about by reciprocal interactions between epidermal and mesenchymal tissues and is thought to be influenced in part by cell adhesion molecules and components of the extracellular matrix. The developmental distributions of tenascin, neural cell adhesion molecule (NCAM), E‐cadherin, intercellular adhesion molecule 1 (ICAM‐1), chondroitin sulfate proteoglycan (CSPG), and the heparan sulfate proteoglycan perlecan were studied in relation to hair follicle morphogenesis in fetal human skin. Tenascin first appeared in developing skin in focal concentrations at the epidermal‐mesenchymal interface, just prior to, and presumably correlated with, hair follicle initiation. Tenascin immunostaining remained prominent in the basement membrane zone and extracellular matrix of the follicle sheath during subsequent morphogenetic stages. Two forms of tenascin (Mr 250 × 103 and 280–300 × 103), were revealed by Western blots of skin extracts. NCAM immunolabeling was initially present throughout the dermis, and became progressively restricted to the dermal condensation and the follicle sheath. Western blot analysis revealed an isoform of NCAM (Mr 160 × 103) which lacked polysialic acid. At all stages, E‐cadherin staining was diminished on follicle cells situated adjacent to the basement membrane, relative to cells in the follicle interior. Follicle‐specific immunostaining for ICAM‐1 was transient, appearing only at the pre‐germ and hair germ stages of development. Antibodies to three distinct CSPG determinants revealed unique immunolabeling patterns following follicle initiation: One CSPG epitope co‐distributed with tenascin in the follicle basement membrane and follicle sheath extracellular matrix; one CSPG epitope was similarly expressed, and was also found on follicle epithelial cells; and the third CSPG determinant was noticeably absent from the follicle sheath during elongation of the developing appendage. Perlecan was concentrated in the dermal papilla, in addition to its distribution in all skin basement membranes. A model for how these diverse molecules may inter/act to influence human hair follicle morphogenesis is presented. © 1994 Wiley‐Liss, Inc.
Pattern duplication by retinoic acid treatment in the regenerating limbs of Korean salamander larvae, Hynobius leechii, correlates well with the extent of dedifferentiation
Authors: Ju Bong‐Gun , Kim Won‐Sun 
Published: February 2005

AbstractIn the regenerating limbs of Korean salamanders, Hynobius leechii, retinoic acid (RA) induces duplication of skeletal structures in the proximodistal (PD) axis and often in the transverse axes. In the present study, the stage‐dependent effects of RA for the duplication of limb skeletal structures at two amputation levels, the distal stylopodium and the distal zeugopodium, were studied using larval limbs of Korean salamanders. The results showed that the mean level of proximalization (MLP) by RA treatment increased during the stages of dedifferentiation and early bud formation while the MLP declined thereafter in both amputation levels. The decline of the MLP at the later stages of regeneration was due to the high frequency of hypomorphic regeneration or blocked regeneration. When the effects of RA treatment at two amputation levels were compared, the overall trends were similar but the actual timing was delayed for 2–4 days in the proximal level of amputation. Furthermore, the peak level of proximalization was achieved earlier and the peak level remained longer in the distal stylopodial level of amputation compared to the distal zeugopodial level of amputation. Since the histological observations revealed that the dediferentiation period was also extended up to 2–4 days in the proximal level of amputation, the acid phosphatase activity during the course of regeneration was measured to look for a quantitative relationship between the enzyme activity and the states of dedifferentiation. The results show that the level and the duration of acid phosphatase activity in the upper arm regenerates are both higher and longer than those in the lower arm regenerates. Furthermore, RA treatment caused an increase in acid phosphatase activity. Thus our results suggest that the state of dedifferentiation might be closely linked to the extent of proximalization of regenerating limbs by RA treatment. © 1994 Wiley‐Liss, Inc.
Analysis of the in vivo myogenic status of chick somites by desmin expression in vitro
Authors: Borman William H. , Urlakis Kenneth J. , Yorde Donald E. 
Published: February 2005

AbstractExpression of the muscle specific intermediate filament protein, desmin, is an early marker for chick somitic myogenesis. Somites are transient, paired, mesodermal structures adjacent to the neural tube which are formed very uniformly in a cranial to caudal fashion. The developmental somitic expression of desmin in vivo has been reported previously (Holtzer et al. [1991] “Frontiers in Muscle Research.” New York: Elsevier Science, pp 187–207; Borman and Yorde [1994] J. Histochem. Cytochem. 42:265–272). Here we explore the ability of those somitic cells which are desmin negative in vivo to successfully carry out a myogenic program of development in the absence of the surrounding embryonic microenvironment. Somites which are known to be overtly desmin negative in the embryo were explanted and cultured on collagen gels for 4 days. Immuno‐detection of desmin identified a population of somites that could support desmin positive cells in vitro as well as a population of somites that could not. The cranially located somites must remain in the embryo for a greater length of time than the caudally positioned somites prior to each being able to express desmin in vitro. In embryos of many ages there is also a population of somites unable to support desmin expression in vitro. The rate at which this ability to support somitic desmin expression in vitro progresses caudally in the embryo is significantly greater than the rate at which somites form. Notably, the detected expression of desmin in somites in vitro is parallel to the rate at which overt expression of desmin in vivo is detected. The implication for these observations with regard to the regulation of somitic myogenesis is discussed. © 1994 Wiley‐Liss, Inc.
Expression pattern of M‐cadherin in normal, denervated, and regenerating mouse muscles
Authors: Irintchev A. , Zeschnigk M. , Starzinski‐Powitz A. , Wernig A. 
Published: February 2005

AbstractFollowing muscle damage in adult vertebrates, myofibers can be regenerated from muscle precursor cells (satellite cells). During this process, prenatal myogenesis is recapitulated to a large extent, both morphologically and molecularly. A putative morphoregulatory molecule involved in myogenesis is M‐cadherin (Mcad), a calcium‐dependent cell adhesion protein. The expression of Mcad was studied by immunofluorescence in regenerating, denervated, and normal mouse muscles. Our results demonstrate that Mcad is present in satellite cells in normal muscle. Enhanced staining at sites of contact between satellite cells and the parent muscle fiber suggests an additional, spatially restricted expression of Mcad in muscle fibers. Mcad positive cells in normal and denervated muscles did not incorporate bromodeoxyuridine within 24 hr after injection in vivo, indicating that Mcad is expressed on mitotically quiescent satellite cells. Neural cell adhesion molecule (NCAM) co‐localized with Mcad in nearly all satellite cells in denervated muscles but rarely in intact muscles. At early stages of regeneration, Mcad was exclusively and strongly expressed in myoblasts. After fusion of myoblasts into myotubes, Mcad was down‐regulated and was barely detectable on more mature myotubes surrounded by distinct basal lamina sheaths. These observations are in line with the idea that Mcad plays a crucial role in myogenesis. In intact muscle, Mcad might function as a molecular link between satellite cell and muscle fiber. © 1994 Wiley‐Liss, Inc.
Transient expression of type II collagen and tissue mobilization during development of the scleral ossicle, a membranous bone, in the chick embryo
Authors: Watanabe Kazuo , Bruder Scott P. , Caplan Arnold I. 
Published: February 2005

AbstractDevelopment of the chick scleral ossicle was studied with respect to expression of various collagen types, cartilage matrix molecules, and osteoblastic cell surface antigens. The extra‐cellular matrix of the scleral ossicle primordium of stage 35.5 chick sclera and the mesenchyme beneath the conjunctival epithelium was immunoreactive with anti‐type II collagen antibody, giving the impression that certain materials and/or cell clusters surrounded by reactive matrix were descending from the epithelial‐mesenchymal interface to the scleral ossicle primordium. In stage 37 embryos, type II collagen immunoreactivity was restricted to the bone matrix of the scleral ossicles, and persisted through stage 39. However, at stage 41, virtually no type II collagen was detected. In contrast, strong immunostaining of type I collagen was first detected in the developing scleral ossicle at stage 37, coinciding with the formation of mineralized bone matrix. Following the extensive accumulation of type I collagen in bone matrix, type XII collagen was detected at the surface of the bone; both type I and type XII collagen immunostainings then remained. By stage 37, immunoreactivity with a pre‐osteoblastic cell surface marker was detected on cells of the scleral ossicle, and typical osteocytes were subsequently identified by both morphological and specific immunostaining techniques. Antibodies other than for type II collagen, specific to chondrogenic mesenchyme or cartilage matrix, never reacted with the scleral ossicle and its primordium during development. Taken together, these observations indicate that the scleral ossicle is a membranous bone, whose development may not require overt chondrogenesis. Implications of type II collagen distribution during the positioning of scleral ossicles and their early bone matrix formation are discussed with respect to the origin and evolution of endoskeletons in vertebrate animals. © 1994 Wiley‐Liss, Inc.
Qualitative cytochemical localization of pyrimidine deoxyribonucleotide residues in fixed tissue sections
Authors: Smith Stuart W. , Anderson Paul N. 
Published: February 2005

AbstractThe senior author had the good fortune to begin his medical education at Western Reserve University during Dr. Hoerr's second year as Payne Professor of Anatomy. Dr. Hoerr's warm friendliness and his broad interests and competence in, and enthusiasm for the growing field of cellular biology served as a source of inspiration. It is an honor to dedicate a new finding in cytochemistry, a field central in his interests, to the memory of Dr. Hoerr.
Survival of higher animal cells after the formation and dissolution of intracellular ice
Authors: Sherman J. K. 
Published: February 2005

AbstractPresence of ice within cells usually is assumed to assure death, while larger ice formations are assumed to induce greater injury. Evidence is presented which questions these assumptions.MCSA and no. 440 parakeet tumors and C3H mouse skin were studied. Cell structure before freezing (control), while frozen, and after rewarming was correlated with survival on transplantation. Control and rewarmed tissue was fixed in Bouin's fluid and processed routinely. Microscopic sites and appearance of ice artifacts relative to frozen cells were preserved by the author's modified freeze‐drying technique. Tissues were cooled to −75°C and −150°C at rates of from 1°C/min to 40°C/sec and rewarmed at 180°C/min. Tumor transplants were inoculated in and around the pectoralis major muscle of parakeets and followed as to appearance, size and microscopic structure. Using hair color as a marker, ventral to dorsal autografts of 8 mm full thickness circles of skin were made in 4–5 week old female mice.Data showed that (1) nucleus and cytoplasm were sites of ice formation in cooled cells, (2) little or no structural damage occurred in frozen‐thawed tumors while skin often was altered noticeably, (3) % survival of tumors frozen slowly (1°C/min) was equal to that of controls, (4) 17% of frozen‐thawed skin grafts survived, (5) freezethaw survival was greatest following the formation of the largest ice artifacts which were induced during slow freezing, (6) intracellular ice and structural alteration, therefore, need not be incompatible with survival.
Passage of thyroid hormone across the placenta in intact and hypophysectomized rats
Authors: Hamburgh Max , Sobel Edna H. , Koblin Robert , Rinestone Alan 
Published: February 2005

AbstractThe studies were designed to determine whether thyroid hormone traverses the placenta of the rat.1. Pregnant rats were hypophysectomized on the twelfth day of the gestation period. The histological appearance and wet weights of the fetal thyroids at term were determined and found to be the same as that of fetuses of intact mothers. These results indicate that maternal TSH is not required for maturation of the fetal thyroid.2. Intact and hypophysectomized pregnant rats were provided with a diet supplemented with 0.2% propylthiouracil (PTU) added in powdered form starting on the fifteenth day of gestation until term. This treatment led to enlargement of thyroids of fetuses of intact and hypophysectomized mothers.3. Groups of intact and hypophysectomized pregnant rats given the same goitrogenic treatment as group 2 were injected daily with 100, 50, 25 and 12.5 μg of 1‐thyroxin in suspension. Twenty‐five μg of thyroxin were sufficient to inhibit goiter development in fetuses of hypophysectomized rats, while 50 μg was required to prevent the goiter formation in fetuses obtained from intact non‐hypophysectomized pregnant rats.These results suggest that maternal thyroid hormone passes the placenta from mother to fetus. The effectiveness with which thyroid hormone passes from the mother to the fetal circulation is probably influenced in some way by the maternal pituitary.
Fine structure of the goblet cell mucous secretory process
Authors: Freeman James A. 
Published: February 2005

AbstractThe Golgi apparatus has been recognized as the initial site of mucigen accumulation. The mucigen is seen forming within the agranular lamellar membranes and vesicles of the Golgi, enlarging and coalescing with loss of individual mucigen droplet membranes, bulging the cell into its characteristic goblet appearance, and subsequent rupturing of the microvilli plasma membrane with discharge of the mucin. The density of the well developed goblet cell is a function of nuclear and cytoplasmic compression by the mass of mucigen. The fine structure of the “resting goblet” cell is indistinguishable from that of the principal columnar absorbing cells. No morphologic evidence of mucigen formation in the endoplasmic reticulum is found, but continuity is demonstrated between the rough‐surfaced endoplasmic reticulum and agranular Golgi membranes. It is possible that the mucigen or its precursors may be synthesized in the endoplasmic reticulum then transported to the Golgi where it is concentrated into the morphologically recognizable mucigen.
Electromyographic study of the extensor apparatus of the forearm
Authors: Travill A. A. 
Published: February 2005

AbstractAn electromyographic study of the extensor apparatus of the forearm, using a multichannel electromyograph and bipolar needle electrodes, was carried out on 12 subjects. Recordings were obtained concurrently from medial, lateral and long heads of the triceps brachii and anconeus.The investigation confirms that the three heads contract independently during extension of the forearm, that the medial head and the anconeus are always active, and that the lateral head and, to a lesser extent, the long head act as reinforcing auxiliaries. The anconeus was found to be active also during resisted but not free loaded pronation and supination, contrary to commonly held opinion.
Observations on the innervation of human long bones
Authors: Miller Malcolm R. , Kasahara Michiko 
Published: February 2005

AbstractThe innervation of some of the long bones of the extremities of the human was studied by methylene blue immersion. Small myelinated and amyelinated nerve fibers enter the numerous foramina of the epiphyseal and metaphyseal regions of long bones, traverse the thin cortex, and supply the interior of the bone. Small myelinated fibers wind about the trabeculae of the spongiosa or spread out on the undersurface of the articular cartilage. Small knob‐like terminations end in close relationship to the endosteum.Other myelinated nerve fibers have branched free fiber endings associated with the walls of intertrabecular marrow arterioles. Amyelinated nerve fibers are usually associated with vascular walls but may also be associated with the connective tissue of the intertrabecular fat or marrow.Numerous myelinated and amyelinated nerve fibers traverse the nutrient foramen and supply the bone marrow and endosteum of the shaft of the bone.While the Volkmann's canals of the shaft receive nerve fibers from the overlying periosteum, the disposition of these fibers in the shaft of the bone has not been determined.No nerve fibers or endings were ever seen between the lamellae in any location.No function can yet be attributed to any particular type of nerve fiber or nerve ending.
The spinal arachnoid villi of the monkeys Cercopithecus aethiops sabaeus and Macaca irus
Authors: Welch Keasley , Pollay Michael 
Published: February 2005

AbstractThe spinal arachnoid villi have been studied in the monkey by the examination of serial sections of spinal nerve roots, particular attention being paid to the relations of the arachnoid to the dura mater and to the veins which are regularly applied to the emerging roots. Although the roots vary in their content of specialized arachnoid formations, in many, columns and clusters of arachnoidal cells occupy spaces between collagen bundles in the dura mater. In a few, leptomeningeal tissue extends completely through the dura. In approximately one of each six roots examined, arachnoidal tissue formed part of the wall of and projected into a vein associated with the root. This relationship to veins is considered an especially compelling point in dispelling the doubt which has been cast upon the conception of spinal arachnoid villi as specialized structures.
Treatment of nutritional cirrhosis in rats with choline and methionine; with special reference to fibrogenesis and fibroclasia
Authors: Meader Roland D. 
Published: February 2005

AbstractEarly and advanced stages of nutritional cirrhosis were produced in the livers of rats maintained on a choline‐deficient diet for periods of 60 and 150 days respectively. Both cirrhotic groups, i.e., early and advanced, were subdivided into three therapeutic groups and corresponding groups of each cirrhotic stage were treated with comparable supplements of 2% choline, 2% methionine and a combination of both for six months, in order to compare the effectiveness of these therapeutic agents in producing manifestations of progressive repair in both early and advanced stages of nutritional cirrhosis.The efficacy of the various therapeutic regimens on both early and advanced stages of dietary cirrhosis was assessed by comparing the manifestations of progressive repair observed in serial sections of liver at autopsy, after six months of dietary therapy with those observed in serial sections of the same liver obtained by biopsy preceding therapy.Under the conditions of this experiment, early and advanced stages of nutritional cirrhosis responded with complete and almost complete recovery respectively, following six months of dietary therapy with choline or a combination of choline and methionine. Dietary supplementation of methionine alone, failed to produce reparative changes comparable to those of choline.This study does not support the theories of condensation of stroma and attenuation and compression by the expanding nodules of parenchymal cell regeneration for fibrogenesis and fibroclasia.
Microscopy of the response of rodent dentin to injected fluoride
Authors: Yaeger James A. 
Published: February 2005

AbstractRats were injected subcutaneously with 50 mg/kg body weight of sodium fluoride. The hypermineralized and hypomineralized components of the response in incisor dentin were identified in ground sections using contact microradiography and analyzed microscopically for matrix alterations. In demineralized sections the hypomineralized component stained weakly for acid polysaccharide (alcian blue, Hale's iron method), was less dense (interference microscopy) and more birefringent than normal matrix. The hypermineralized component stained intensely for acid polysaccharide and was less birefringent than normal matrix. In the electron microscope, the inorganic crystals in the hypomineralized component were less numerous and larger than normal, while those of the hypermineralized component were more numerous but of normal diameters.These observations indicate that the hypomineralized component results from an inhibition of polysaccharide‐collagen interaction, resulting in a paucity of apatite nucleation sites and a more soluble organic matrix. The hypermineralized component results from an increased period of time for matrix aggregation with the formation of more nucleation sites and therefore more numerous crystals and a less soluble organic matrix. The presence of a hypermineralized component in organic matrix of nearly normal density indicates that mature rodent incisor dentin is less completely mineralized than the bone of mature osteons.
Cellular differentiation in the anuran pronephros
Authors: Jaffee Oscar Charles 
Published: February 2005

AbstractRibonucleic acid (RNA) is detectable histochemically by means of methyl green pyronin staining (controlled with ribonuclease) in the cytoplasm of the proximal tubules of the frog (Rana pipiens). This is seen at Shumway stage 23 when the proximal tubules become differentiated from the remainder of the tubular complex. RNA levels remain high during the process of pronephric differentiation, dropping when this process is completed. The onset of specific renal functions (phenol red transport; protein resorption) during the period of high RNA levels raises the question of the role of RNA in the development of renal function as well as cellular differentiation. Histochemical events accompanying differentiation in the pronephros (periodic acid‐Schiff staining of the brush borders and the appearance of protein resorption droplets) are similar to those found in differentiating meso‐ and metanephric kidneys. Mitochondria in the undifferentiated pronephros are found to be granular in form by vital staining with Janus green B and with iron hematoxylin staining. These organelles do not consolidate into rodlets as found in differentiated meso‐ and metanephric kidneys but remain in their original granular form, as demonstrated by the techniques noted above. Granular mitochondria have been demonstrated in the differentiated pronephros of a month old tadpole.