bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the vascular bed in the rabbit ear: Scanning electron microscopy of vascular corrosion casts
Authors: Morris Judith L. , Bevan Rosemary D. 
Published: February 2005

AbstractThe development of the vascular bed in the rabbit ear was investigated using vascular corrosion casts from animals of various ages. Examination of the casts revealed that the arrangement of the major auricular arteries and veins was determined before birth and was maintained during postnatal growth of the ear. Furthermore, the number of arteries branching off the central ear artery and the lateral arteries did not increase with increasing ear length. Scanning electron microscopic examination of lateral segments of adult ear casts revealed many anastomoses between marginal arteries and veins. These arteriovenous anastomoses (AVAs) occurred singly, in pairs, or in clusters of three to six. Their size and shape were variable, even in the same cast. The central segment of many AVA casts showed surface impressions of endothelial cell nuclei which were different from the impressions on adjacent arteries and veins. Arteriovenous anastomoses were also detected in ear casts from animals as young as 8 days. The density of AVAs in lateral ear segments ranged from 95–165 cm−2 in 8‐ to 11‐day‐old rabbits to 80–115 cm−2 in adults. However, estimates of the total number of AVAs in the lateral ear margin indicated that AVAs continued to be formed at a steady rate during growth of the ear. During the early neonatal period the cutaneous capillary plexuses developed prominent tufts projecting toward the skin surface, which were apparently associated with developing hair follicles. These capillary tufts were not seen in casts from fetal or adult rabbits.
Morphology of the exocrine glands of the frog skin
Authors: Mills John W. , Prum Bruce E. 
Published: February 2005

AbstractFrog skin contains three distinct types of exocrine glands: granular (poison), mucous, and seromucous. The granular gland forms a syncytial secretory compartment within the acinus, which is surrounded by smooth muscle cells. The mucous and seromucous glands are easily identifiable as distinct glands. The serous and mucous secretory cells are arranged in a semilunar configuration opposite the ductal end and are filled with granules. Within the acinus, located at the ductal pole of the gland, are distinct groups of cells with few or no granules in the cytoplasm. In both the mucous and seromucous gland there is a cell type with abundant mitochondria; the one in the mucous gland is located in the region adjacent to the secretory cells. The duct of these glands is two‐layered, with the individual cells appearing morphologically similar to the layers of the skin epithelium as the duct traverses the skin. The duct appears to be patent throughout its length. The morphological heterogeneity and distinct distribution of the cell types within the gland acinus may be indicative of a functional heterogeneity that allows the production of distinctly different types of secretion from the same gland type, depending on the type of stimulus.
Inhibition of axoplasmic transport in the developing visual system of the rat: IV. Quantitative golgi, electron microscopic, and histochemical analyses of the maturation of the visual cortex
Authors: Matthews Murray A. , Riccio Robert V. 
Published: February 2005

AbstractIntraocularly injected colchicine suppresses axonal transport within the developing rat's optic nerve throughout the critical period of visual system development. This results in a stunting of retinofugal terminals and relay neurons in the lateral geniculate nucleus. The present study focuses upon the effects of this unique form of developmental deprivation on the maturation of the visual cortex. Colchicine, in concentrations of from 10−5 to 10−2M, was injected into the eyes of albino rats at birth or at 5, 10, or 15 days of age. Litters were killed at 5 to 50 days after this single injection, and the brains were processed for Nissl, rapid Golgi, histochemical, or electron microscopic analysis. The following results were obtained: (1) Planimetry of coronal sections of the striate cortex revealed a reduction in the thickness of the cortex and in the ratio of neuropil area to neuronal soma area contralateral to the injected eye which was confined principally to layer IV, lower layer III, and upper layer V. This effect was inversely related to postnatal age at injection and directly proportional to colchicine concentration. (2) A rapid Golgi analysis of 51 pairs of layer V pyramidal neurons in control and experimental cortex demonstrated a reduction in the number and size of spines along the portion of the apical dendrite passing through lower layer III and IV following colchicine administration at birth or 5 or 10 days of age but no significant change in the branching pattern of the entire dendritic arbor. (3) Electron microscopy revealed a reduction in the number of small, asymmetric synaptic complexes with the result that the average size of remaining profiles was increased in layers III and IV. (4) Histochemical analysis of cortical succinic dehydrogenase and cytochrome oxidase revealed a distinct band of intense enzyme activity in lower layers III and IV in normal cortex at 20–30 days of age. This band was significantly reduced in intensity after neonatal injection of colchicine as shown by densitometric measurements and comparison of experimental and control cortex. It is concluded that the geniculocortical projection, while not affected directly by colchicine administration, is altered by the secondary effects of axonal transport suppression, leading to an alteration in the establishment of cortical synaptic patterns and arborizations of their postsynaptic neurons whose dendrites are located in those layers recipient to this projection.
Computer ranking of the sequence of appearance of 100 features of the brain and related structures in staged human embryos during the first 5 weeks of development
Authors: O'Rahilly Ronan , Müller Fabiola , Hutchins Grover M. , Moore G. William 
Published: February 2005

AbstractThe sequence of events in the development of the brain in staged human embryos was investigated in much greater detail than in previous studies by listing 100 features in 165 embryos of the first 5 weeks. Using a computerized bubble‐sort algorithm, individual embryos were ranked in ascending order of the features present. This procedure made feasible an appreciation of the slight variation found in the development features. The vast majority of features appeared during either one or two stages (about 2 or 3 days). In general, the soundness of the Carnegie system of embryonic staging was amply confirmed. The rhombencephalon was found to show increasing complexity around stage 13, and the postoptic portion of the diencephalon underwent considerable differentiation by stage 15. The need for similar investigations of other systems of the body is emphasized, and the importance of such studies in assessing the timing of cogenital malformations and in clarifying syndromic clusters is suggested.
Muscle fiber type composition of the rat hindlimb
Authors: Armstrong R. B. , Phelps R. O. 
Published: February 2005

AbstractThe purpose of this study was to estimate the absolute and relative masses of the three types of skeletal muscle fibers in the total hindlimb of the male Sprague‐Dawley rat (Rattus norvegicus). For six rats, total body mass was recorded and the following weights taken from dissection of one hindlimb: 32 individual major muscles or muscle parts, remaining skeletal musculature (small hip muscles and intrinsic foot muscles), bone, inguinal fat pad, and skin. The fibers from the 32 muscles or muscle parts (which constituted 98% of the hindlimb skeletal muscle mass) were classified from histochemistry as fast‐twitch oxidative glycolytic (FOG), fast‐twitch glycolytic (FG), or slow‐twitch oxidative (SO), and their populations were determined. Fiber cross‐sectional areas from the same muscles were measured with a digitizer. Mass of each of the fiber types within muscles and in the total hindlimb was then calculated from fiber‐type population, fiber‐type area, and muscle‐mass data. Skeletal muscle made up 71% of the total hindlimb mass. Of this, 76% was occupied by FG fibers, 19% by FOG fibers, and 5% by SO fibers. Thus, the FG fiber type is clearly the predominant fiber type in the rat hindlimb in terms of muscle mass. Fiber‐type mass data are compared with physiological (blood flow) and biochemical (succinate dehydrogenase activities) data for the muscles taken from previous studies, and it is demonstrated that these functional properties are closely related to the proportions of muscle mass composed of the various fiber types.
Adrenergic innervation of the developing chick heart: Neural crest ablations to produce sympathetically aneural hearts
Authors: Kirby Margaret , Stewart Donald 
Published: February 2005

AbstractAblation of various regions of premigratory trunk neural crest which gives rise to the sympathetic trunks was used to remove sympathetic cardiac innervation. Neuronal uptake of [3H]‐norepinephrine was used as an index of neuronal development in the chick atrium. Following ablation of neural crest over somites 10–15 or 15–20, uptake was significantly decreased in the atrium at 16 and 17 days of development. Ablation of neural crest over somites 5–10 and 20–25 caused no decrease in [3H]‐norepinephrine uptake. Removel of neural crest over somites 5–25 or 10–20 caused approximately equal depletions of [3H]‐norepinephrine uptake in the atrium. Cardiac norepinephrine concentration was significantly depressed following ablation of neural crest over somites 5–25 but not over somites 10–20. Light‐microscopic and histofluorescent preparations confirmed the absence of sympathetic trunks in the region of the normal origin of the sympathetic cardiac nerves following neural crest ablation over somites 10–20. The neural tube and dorsal root ganglia were damaged in the area of the neural‐crest ablation; however, all of these structures were normal cranial and caudal to the lesioned area. Development of most of the embryos as well as the morphology of all of the hearts was normal following the lesion. These results indicate that it is possible to produce sympathetically aneural hearts by neural‐crest ablation; however, sympathetic cardiac nerves account for an insignificant amount of cardiac norepinephrine. The adrenal medulla is the most likely source of cardiac norepinephrine in sympathetically aneural hearts.
Intrinsic innervation of the atrioventricular junction of the rat heart
Authors: Moravec M. , Moravec J. 
Published: February 2005

AbstractAlternate serial semithin and thin sections of the glutaraldehyde‐fixed interatrial septum and atrioventricular junction of adult rat were examined in light and electron microscopes. The animals were pretreated with a false precursor of catecholamines, i.e., with 5‐OH‐dopamine, in order to differentiate the adrenergic component of the intrinsic nervous system. According to the light microscope data, two kinds of ganglia can be distinguished at the level of the interatrial septum. Those of the first kind are composed of large pale cells with voluminous nuclei. Those of the other kind resemble acinuslike clusters of small osmiophilic cells. Another small ganglion is invariably associated with the distal edge of the bundle of His. At the electron‐microscope level, two types of ganglionic cells are found in the meshes of the peri‐ and intranodal plexus: (1) small neurons (10 μm) with richly developed neuropiles, and (2) large 5‐OH‐dopamine contrasted neurosecretory cells (up to 25 μm) containing electron‐dense vesicles typical of sympathetic neurons. Numerous glomeruli with dendrodendritic and axodendritic connections are also found in the vicinity of the specialized tissue; and, in the nodal interstitium, several clusters of small chromaffin cells (5 μ) and a network of multipolar satellite cells similar to the interstitial cells of Cajal can be distinguished. Our data suggest that the microanatomical and cytological organization of the terminal innervation of the node of Aschoff‐Tawara and of the bundle to His resembles that of the myenteric plexus. The physiological significance of these ultrastructural data for the local control of electrophysiological properties of the atrioventricular junction is briefly considered.
Alterations in epithelial glycocalyx of rabbit uteri during early pseudopregnancy and pregnancy, and following ovariectomy
Authors: Anderson Ted L. , Hoffman Loren H. 
Published: February 2005

AbstractPseudopregnant, pregnant, and ovariectomized rabbits were utilized to study hormonal mediation of uterine epithelial surface negativity and glycocalyx morphology, and to seek local effects of blastocysts at sites of implantation. A loss of surface negativity [polycationic ferritin (PCF) binding] by day 6 of pregnancy or pseudopregnancy was noted, accompanied by alterations in epithelial glycocalyx. Uteri from estrous animals, or ovariectomized animals receiving oil or estradiol injections, bound PCF and exhibited a “globular” glycocalyx. Uteri from day 6 pseudopregnant or pregnant animals, or ovariectomized animals receiving progesterone injections, did not bind PCF or exhibit a globular glycocalyx. Both PCF binding and the globular character of the epithelial glycocalyx were sensitive to neuraminidase and trypsin treatment, suggesting sialoglycoprotein contribution to surface negativity. Implanting blastocysts had no detectable local effect on surface negativity, but did induce local reduction of epithelial glycocalyx at sites of implantation. Results of this study suggest that uterine epithelial glycocalyx alterations during the preimplantation period reflect a general response to prosgesterone stimulation, primarily qualtitative in nature, related to the acquisition of receptivity to ovo‐implantation.
Carbohydrate determinants involved in mammalian fertilization
Authors: Ahuja Kamal K. 
Published: February 2005

AbstractDuring fertilization in mammals, the male and female gametes undergo a form of highly complex cell‐cell recognition whereby a nonspecific initial binding is followed by a species‐specific penetration of the zona pellucida. Recent data from many species have demonstrated the involvement of surface carbohydrates in regulating fertilization at both these stages. The potential benefits as well as drawbacks of three major techniques used so far are discussed, and the need for a cautious interpretation of the data is emphasized. During capacitation, the carbohydrate components of the entire surface of spermatozoa undergo striking changes which may be linked to the concurrent metabolic events within motile spermatozoa, leading to the appearance of egg‐specific glycoconjugates in a time‐dependent manner. A multiple set of glycoproteins on the sperm surface, possessing oligosaccharides synthesized by the lipid‐linked pathway, are probably required during different stages of fertilization, including sperm‐oocyte fusion. The oviductal glycosaminolycans may also be involved in regulating the timing and species specificity of mammalian fertilization by masking the sperm receptor sites on the zona and triggering the physiological acrosome reaction. Future biochemical and highresolution localization studies involving specific probes for surface glycoconjugates, glycosyltransferases, and hydrolytic enzymes should greatly aid our understanding not only of the role of the individiual surface macromolecules but also of the surface domains to which they are localized.
Sperm surface components involved in the control of the acrosome reaction
Authors: Oliphant Gene , Reynolds Al B. , Thomas Ted S. 
Published: February 2005

AbstractSeveral lines of evidence suggest that decapacitation of sperm occurs normally in the male reproductive tract, and as a result the acrosome is stabilized and the acrosome reaction is controlled. Since the defining experiments in 1951, where decapacitation was reversed in the female reproductive tract by capacitation, investigations have pursued the molecular events of this process. This review attempts to examine critically the older literature and compare that perspective with the current theories. The theories for decapacitation of sperm include the possible role of a peptide decapacitation factor, a glycoprotein‐mediated steroid transfer to the sperm, masking of a galactosyl transferase by some macromolecule‐containing carbohydrate, preclusion of calcium influx by a binding protein, and sperm interaction with the acrosome stabilizing factor. Although these theories are diverse, there are some unifying aspects. However, there remain some major unanswered questions. For example, although we point to some circumstantial evidence that infers a single decapacitation factor, this needs to be further substantiated. It is concluded that with the purification of a macromolecule involved in capacitation, specific proposals on the mechanism of capacitation, and new tools to evaluate the capacitation process, it is likely that another decade will not pass without emergence of a unifying molecular theory of sperm capacitation.
Mammalian gamete interactions: What can be gained from observations on living eggs?
Authors: Gaddum‐Rosse Penelope 
Published: February 2005

AbstractStudies on fertilization have involved a variety of investigational techniques from the simple to the very complex. Perhaps the most direct approach has been the observation and photographic recording of the interactions of living gametes in vitro. The purpose of this paper is to review the major contributions that have been made, by means of this technique, to our knowledge of mammalian fertilization, and to examine its advantages and limitations.Some of the events of mammalian fertilization that have been observed in living eggs and are reviewed herein include (1) sperm penetration through the zona pellucida, (2) contact of the fertilizing spermatozoon with the oocyte surface and the subsequent incorporation of the sperm head into the oocyte cytoplasm, (3) the formation and disappearance of the incorporation cone, (4) the gradual incorporation of the sperm flagellum, (5) surfac movements of the oocyte after activation, and (6) the formation of the second polar body. One advantage of studying living eggs is the opportunity it affords to witness events as they actually occur and, under favorable circumstances, to observe the whole series of events in individual eggs. Only by this mechanism can certain features of the process be fully appreciated and accurate data obtained on the timing of events. With the addition of time‐lapse photographic methods, some of the more subtle changes become more amenable to study. Among the limitations of the technique are its limited resolution and the necessity for examining the gametes outside their normal in vivo environment.
Mammalian fertilization as seen with the scanning electron microscope
Authors: Phillips David M. , Shalgi Ruth , Dekel Nava 
Published: February 2005

AbstractFor several years we have been looking at mammalian gametes and their interactions with the scanning electron microscope (SEM). Examining the images produced by the SEM has given us a three‐dimensional view of sperm, eggs, and egg investments. We are particularly impressed with the structural variation among gametes of different mammalian species. In this short report we examine the structure of mammalian spermatozoa, eggs, zonae pellucidae, and cumuli. Our observations and those of others have led us to believe that variation in gamete structure and function may have evolved as a mechanism for reproductive isolation of mammalian species.
The basement‐membrane‐like matrix of the mouse EHS tumor: II. Immunohistochemical quantitation of six of its components
Authors: Grant Derrick S. , Kleinman H. K. , Leblond C. P. , Inoue S. , Chung A. E. , Martin G. R. 
Published: February 2005

AbstractThe presence of six substances—laminin, type IV collagen, heparan sulfate proteoglycan, ontactin, fibronectin, and the amyloid P component—was investigated immunohistochemically in the matrix of the Engelbreth‐Holm‐Swarm (EHS) mouse tumor after it had been fixed in formaldehyde (with or without a brief preliminary glutaraldehyde fixation), embedded in Lowicryl K4M, and sectioned for processing through the protein A‐gold sequence. Enumeration of the number of gold particles per sequare micrometer of matrix sections demonstrated that the six substances were present in distinct amounts. The results for each substance were fairly consistent throughout the matrix in three experiments. Furthermore, the available evidence indicated that, with the exception of the amyloid P component, the substances were associated with the cord network of the tumor matrix. Finally, the use of a reconstituted basement membrane containing known amounts of laminin, type IV collagen, and heparan sulfate proteoglycan as a standard, led to the conclusion that, in the tumor matrix, the relative content of laminin to type IV collagen to the proteoglycan was in a ratio of 1:0.6:0.03, suggesting molar ratios of approximately 1:1:0.2, respectively.
The basement‐membrane‐like matrix of the mouse EHS tumor: III. Immunodetection of the amyloid P component in basotubules
Authors: Inoue S. , Leblond C. P. 
Published: February 2005

AbstractImmunohistochemical methods were applied to the ultrastructural localization of the amyloid P component in the EHS tumor matrix. First, the preembedding approach was used by exposing frozen sections of tumor to antiserum against the mouse amyloid P component followed by the peroxidaseantiperoxidase sequence. Second, using the postembedding approach, Lowicryl K4M sections of the tumor were exposed to antiserum against the amyloid P component and subjected to the protein A‐gold procedure. In both cases, the immunostaining was restricted to structures which appeared in longitudinal section as fairly straight rods and in cross section as 7‐ to 10‐nm pentagonal or roughly circular profiles outlining a lumen with a central dot. Since these features are characteristic of basotubules, it is concluded that the basotubules of the tumor matrix possess the antigenicity of the amyloid P component and presumably contain this substance itself. Similar experiments carried out on the thick basement membrane known as Reichert's membrane demonstrated that its basotubules also possessed amyloid P‐component antigenicity. It is likely, therefore, that the amyloid P component is a constituent of basotubules.