bluuebunny/crossref_metadata_2025 huggingface dataset:
An alternative method of estimating the cranial capacity of Olduvai Hominid 7
Authors: Vaišnys J. Rimas , Lieberman Dan , Pilbeam David
Published: May 2005

The cranial capacity of Olduvai Hominid 7 is estimated to be 690 cc, with a standard uncertainty range of 538 to 868 cc. The estimate is derived from a systematic consideration of the relationships between Bregma‐Asterion chords and cranial capacities obtained from a large sample of Homo sapiens and Pan troglodytes and from available fossil hominids. The estimation technique is applicable to other characters and specimens.
A comparison of methods for measuring cortical bone thickness
Authors: Chumlea W. Cameron , Mukherjee Debabrata , Roche Alex F.
Published: May 2005

Repeated measures of periosteal and endosteal widths of the left second metacarpal from two samples of radiographs were made independently with either a dial caliper or an electronic digitizer connected to a microcomputer. In addition, periosteal and endosteal bone widths of a common sample of radiographs were measured with dial calipers and the electronic digitizer. Dial calipers and an electronic digitizer are both very reliable, but intraobserver errors produced with the use of the digitizer are significantly less than those produced with the use of dial calipers. However, measurements made with the electronic digitizer are systematically larger than corresponding widths measured with dial calipers, but this difference is very small.
Sperm/egg interaction: The specificity of human spermatozoa
Authors: Bedford J. M.
Published: May 2005

Human spermatozoa display unusually limited affinities in their interaction with oocytes of other species. They adhered to and, when capacitated, penetrated the vestments of the oocyte of an ape‐the gibbon, Hylobates lar‐ both in vivo and in vitro. On the other hand, human spermatozoa would not even attach to the zona surface of sub‐hominoid primate (baboon, rhesus monkey, squirrel monkey), nor to the non‐primate eutherian oocytes tested. Among the apes the gibbon stands furthest from man. Thus, although the specificity of human spermatozoa is not confined to man alone, it probably is restricted to the Hominoidea. This study also suggests that the evolution of man and perhaps the other hominids has been accompanied by a restrictive change in the nature of the sperm surface which has limited and made more specific the complementary surface to which their spermatozoa may adhere. For the failure of human spermatozoa to attach to the zona surface of all non‐hominoid oocytes stands in contrast to the behaviour of spermatozoa of the several other mammals studied which, in most combinations, adhered readily to foreign oocytes, including those of man. Taxonomically, the demonstration of a compatibility between the gametes of man and gibbon, not shared with cercopithecids, constitutes further evidence for inclusion of the Hylobatidae within the Hominoidea.
Trigeminal nerve endings in gingiva, junctional epithelium and periodontal ligament of rat molars as demonstrated by autoradiography
Authors: Byers Margaret R. , Holland G. R.
Published: May 2005

Tritiated‐L‐proline was injected into the right Gasserian ganglion of mature rats for incorporation into proteins being carried by rapid axonal transport to nerve endings. The distribution of the nerve endings in molar gingivae and periodontium was subsequently mapped in serial sections by autoradiography. We found that sensory nerve terminals are most prominent in two regions of the free gingiva: (1) In the junctional epithelium there is a rich innervation of the basal epithelial layer with many endings penetrating several cell layers. (2) In the crestal epithelium arborized endings are present, especially on the marginal side of the crest. In the attached gingiva a few terminals are found in the epithelium with more in the lamina propria; the latter appear to be encapsulated. The periodontal ligament is only moderately labeled with silver grains located over nerve bundles, over nerves associated with blood vessels, and over a few apparent endings in the apical region. In the cementum no labeled endings are seen. Labeling of Gasserian cell bodies primarily reveals specific intra‐epithelial nerve endings in gingival crest and junctional epithelium. The absence of major labeling of the periodontal ligament supports the view that many nerves in that region are derived from cell bodies in the mesencephalic nucleus.
Fine structure of the human synovial lining cell in osteoarthritis: Its prominent cytoskeleton
Authors: Meek William D. , Raber Brian T. , McClain Oza M. , McCosh Jeff K. , Baker B. B.
Published: May 2005

The cytoskeleton of the human osteoarthritic synovial lining cell (SLC) consists of an extensive number of vimentin intermediate filaments (IFs) in addition to microfilaments and microtubules. The IFs are especially prevalent in the SLC processes, but are commonly seen in a paranuclear arrangement. Processes, ending in numerous microvilli and blebs, project into the joint space. Scanning electron microscopy (SEM) further reveals the processes that may parallel the synovium surface for a short distance. IFs extend to the termination of such processes. Numerous pinocytotic vesicles and extensive rough endoplasmic reticulum (rER) are characteristic of the type B cells. Lysosomes and long microvilli identify the type A cell. Punctate adherens, gap junctions, and cilia are the cell membrane specializations of the osteoarthritis (OA) synovium. A comparison with synovium from rheumatoid arthritis (RA) patients is made in order to assess the effect of this inflammatory disease on the SLC cytoskeleton, cell type relationship, and cell arrangement. The prominent cytoskeleton appears to play an important role in the architecture of the synovium. Our findings are further presented in the form of a drawing which in some aspects could describe the morphology of the normal synovium.
Formation and release of vesicles from the basal surfaces of rat eye non‐pigmented ciliary epithelial cells: A novel secretory mechanism?
Authors: Eggli Peter S. , Graber Werner , Van Der Zypen Eugen
Published: May 2005

When rat ciliary body is processed by high pressure freezing and freeze substitution, numerous membrane‐bound vesicle profiles are seen in the vitreous associated with the pars plana and in the valleys between the ciliary processes. They consist of a homogeneously distributed fine granular matrix and varying numbers of ribosome‐like structures. The mechanism by which these vesicles are secreted appears to follow an apocrine‐type pattern, albeit at the basal cell surface. Matrix material accumulates between the basal plasma membrane of non‐pigmented ciliary epithelial cells and a cortical layer of cytoskeletal components; the blebs thus formed protrude through a discontinuity in the basal lamina and, by a progressive narrowing of the neck region, are eventually pinched off, giving rise to free vesicles.

Under conventional aqueous chemical fixation conditions, most of these vesicles are washed away or their contents solubilized and extracted, which accounts for their not having been identified hitherto as genuine morphological structures. They are nonetheless apparent, albeit in reduced numbers and mostly empty. Such vesicles are also observed in tissue processed according to several other chemical fixation techniques, namely, conventional fixation in the presence of the cationic dye ruthenium hexamine trichloride, simultaneous glutaraldehyde/osmium tetroxide fixation, and microwave fixation. In the latter instance, comparable vesicle preservation to that obtained by high pressure freezing/freeze substitution may be achieved if fixation is followed by cryoprotection, plunge freezing, and freeze substitution instead of conventional post‐fixation and dehydration procedures.
Cell and matrix biology of the suprapatella in the rat: A structural and immunocytochemical study of fibrocartilage in a tendon subject to compression
Authors: Ralphs James R. , Benjamin Michael , Thornett Andrew
Published: May 2005

The structure, ultrastructure, histochemistry, and immunohistochemistry of the suprapatella have been described in the rat. The suprapatella is a fibrocartilaginous sesamoid within the tendon of quadriceps femoris that articulates with the femoral condyles during flexion of the knee joint and reduces the amount of bending required at the tendon‐bone junction. The cells of the suprapatella were much larger and more numerous than those in the associated tendon and were packed with vimentin‐containing, intermediate filaments. The tendon cells contained far fewer filaments. The cells of both regions contained actin and tubulin. Histochemical and immunohistochemical studies showed that the suprapatellar cells were embedded in a matrix that is rich in chondroitin sulphate, but does not contain keratan or heparan sulphate. The fibrocartilage of the adjacent attachment zone of the quadriceps tendon also contained chondroitin sulphate, but in addition was rich in type II collagen. The structure of the suprapatella was similar to that of the fibrocartilaginous regions of tendons that pass around bony pulleys. However, there were differences in matrix composition that could reflect functional differences between the fibrocartilages.
Changes in ovarian morphology and serum hormones in the rat after treatment with dehydroepiandrosterone
Authors: Lee Mong‐Ting , Anderson Everett , Lee Gloria Y.
Published: May 2005

This investigation was designed to study ovarian and hormonal changes in the after treatment with dehydroeplandrosterone (DHEA). We identified a heterogeneous experimental group of animals with respect to ovarian histology: group I, corpora lutea (Cls) + cysts; group II, CLs + no cysts; group III, no CLs + cysts; group IV, no CLs + no cysts. Histological sections of these ovaries showed healthy and atretic follicles in different stages of cytomorphosis and degeneration. The aforementioned histological groups were also heterogeneous according to their hormonal profiles. Serum androgens, estrogens, and prolactin concentrations are significantly increased in DHEA‐treated animals as compared with controls. There was no significant difference in follicle stimulating hormone between the with cysts and rats without cysts after DHEA treatment. After 20 days of DHEA treatment, rats with CLs have very high levels of luteinizing hormone. Luteinizing hormone and prolactin levels are significantly higher in rats with cysts than in rats without cysts after 10 days of DHEA treatment. As has been shwon in this inquiry, androgens and estradiol levels in rats with cysts after DHEA treatment are higher than those in rats without cysts after DHEA treatment. Therefore, this study suggests that the ovarian cystic condition developed after DHEA treatment in rats, is associated with higher levels of circulating androgens, estradiol, and prolactin.
Morphometric study of the human neonatal ovary
Authors: Forabosco Antonino , Sforza Chiarella , De Pol Anto , Vizzotto Laura , Marzona Laura , Ferrario Virgilio F.
Published: May 2005

A morphometric analysis, based on mathematical evaluations and stereological methods, has been used to study five left neonatal ovaries, removed from full‐term neonates with a 46, XX karyotype free from malformations of the genital apparatus.

Each ovary was completely cut obtaining serial sections and one 1‐μ‐thick section every 1,000 μ was examined. Ovarian length ranged from 9 to 17 mm (mean 13 mm), width from 3.5 to 7 mm (mean 5.7 mm), thickness from 2.5 to 5 mm (mean 4 mm), and volume from 82.23 to 198.3 mm3 (mean 125.88 mm3). In the ovarian cortex, primitive cortical tissue accounted for 10‐20% of the total volume, follicles for 10‐25% and interstitium for 35‐45%; 10‐30% of the organ consisted of inner medulla. The total follicle number ranged from 130,000 to 385,000 per ovary, with an average of 266,000 with 95% being represented by primordial follicles. In all ovaries examined follicular growth was still in process, with follicles at different stages of development.
Immunochemical localization of extracellular materials in bone marrow of rats
Authors: Hamilton Rebecca , Campbell Ferrell R.
Published: May 2005

The distribution of type I collagen, fibronectin, laminin, and heparan sulfate was studied in marrow of rats by indirect immunofluorescence. Most of the type I collagen of marrow is associated with large blood vessels and connective tissue trabeculae, but type I collagen was also localized in a delicate meshwork throughout the marrow and in the basement membrane of the sinusoidal endothelium. Fibronectin is partially co‐distributed with type I collagen, but is much more widely distributed. Sheets or septa of fibronectin‐rich material divide the marrow into small compartments that contain and appear to separate clusters of developing blood cells. These septa may serve as a substrate for anchorage and migration of blood cells. Labeling of laminin was observed in the basement membranes of blood vessels, of fat cells, and of the sinusoidal wall, but only scattered labeling was seen in other extracellular materials. Heparan sulfate proteoglycan was poorly labeled in the extracellular matrix of marrow.
Organization of the membrane skeleton in spreading mouse blastomeres. I. Morphological analysis
Authors: Sobel J. Sabina , Szczesny Thaddeus M.
Published: May 2005

Differentiation in the mouse embryo begins at the 8‐cell stage when the blastomeres spread against each other in a process called compaction. The spreading behavior of blastomeres on lectin‐coated coverslips mimics that of blastomeres in the embryo, and we have utilized this model system to obtain an en face view of the membrane skeleton in the spreading blastomeres. Embryos were cultured on the coverslips for periods ranging from 20 sec to 6 hr, and the cells were disrupted to expose the cytoplasmic face of the adherent membranes and their associated filaments. The “membrane lawn” preparations were fixed, critical point dried, rotary shadowed, and the replicas examined by transmission electron microscopy.

Using this technique we found that the plasmalemma of rounded blastomeres is associated with a lacy 3‐dimensional filamentous meshwork that is transformed into a thin mat of densely woven filaments when the cells flatten. The overall organization of the membrane skeleton is similar in flattening 2‐ and 8‐cell embryos, but there are significant differences in the time required for spreading to take place, in the means whereby the membrane skeletons are reorganized, and in the extent of maximal flattening. The significance of these observations for the compaction process is discussed.
Talpid2 mutant chick limb has anteroposterior polarity and altered patterns of programmed cell death
Authors: Dvorak Leah , Fallon John F.
Published: May 2005

The talpid2(ta2) chick mutant is of interest for the study of limb pattern formation. Talpid2 is a simple Mendelian recessive lethal mutation which affects the mesoderm and results in short, spade‐like, polydactylous wings and legs. Here, we describe ta2 limb development with particular attention to those aspects of ta2 which may illuminate the process of normal limb development. From the onset of budding, ta2 limb buds are significantly wider than normal buds along the anteroposterior axis. They lack the normal anterior and posterior necrotic zones and have variable development of the central opaque patch. Interdigital programmed cell death is variable and may result in development of distal phalanges without more proximal ones. Talpid2 wing vasculature is similar to that of normal wings, but ta2 legs are supplied by four large blood vessels. Feathers form regular, parallel rows, similar to normal feathers, but ta2 embryos lack the loose mesenchyme which separates the feather buds. Finally, and most significantly, ta2 wings and legs display anteroposterior polarity. Anterior and posterior limb skeletal elements can be clearly distinguished from one another within the ta2 phenotype. Our observations suggest that the ta2 mutant may be useful in analyzing programmed embryonic cell death and anteroposterior limb pattern formation.
Differentiation of the anterior body wall and truncal epidermis and associated co‐migration of cutaneous nerves and mesenchyme
Authors: Munger G. Torrey , Munger Bryce L.
Published: May 2005

The present study examines the relationship between the migration of mesenchyme and associated cutaneous nerves that are involved in the closure of the anterior body wall in embryonic mice and rats by light and electron microscopy. The sternum is formed by the migration of condensations of mesenchyme originating in the dorsolateral body wall known as sternal bands. In the course of analyzing this process in rodent embryos we have identified similar paired caudal extensions of the sternal bands that are responsible for the closure of the abdominal wall following resolution of the umbilical hernia, and we suggest these bands of mesoderm should be referred to as the abdominal bands. Both the sternal and abdominal bands are associated with the development of the segmental spinal nerves and their cutaneous terminal branches. The first cutaneous nerve to reach the skin surface in rats is the later cutaneous nerve (LCN) at E13.0 days followed by the posterior and anterior cutaneous nerves (PCN and ACN) at E13.5 days. The ACN co‐migrates with the sternal and abdominal bands, and terminal branches of axons from the ACN approach the epidermis during this migration. Differentiation of the epidermis could be recognized as a change in shape of epidermal cells from squamous to cuboidal, and this initial differentiation coincides with the onset of cutaneous innervation, beginning at the site of the LCN and following the extent of innervation of the PCN as well as the migration of the mesodermal bands and associated ACN. The paired ACN's meet in the ventral midline at E16.5 in rats as the sternal bands fuse, and terminal axons from both nerves densely innervate the midline skin. The wave of cutaneous differentiation in the trunk is associated with the onset of cutaneous innervation, and this process is associated with the co‐migration of bands of mesoderm that close the anterior body wall.
The use of the optical disector to estimate the total number of neurons in the developing chick lateral motor column: Effects of purified growth factors
Authors: Nurcombe Victor , Wreford Nigel G. , Bertram John F.
Published: May 2005

Competition between neurons for limited amounts of trophic factors is believed to be the basis for large‐scale neuronal death during the normal development of the vertebrate nervous system. In this study, an unbiased stereological counting method, an optical disector/Cavalieri combination, was used to estimate the total number of motor neurons in the lateral motor column of the developing chick and to assess the effects of four growth factors on neuronal numbers. The total number of neurons in lateral motor columns at embryonic day 6 (E6), E8, E10 and E12 were 18,747 ± 1,369 (mean ± SD), 15,037 ± 1,816, 10,245 ± 940, and 8,802 ± 797, respectively. Daily exposure from E6 to E9 to three of the growth factors (basic fibroblast growth factor, bFGF; leukemia inhibitory factor, LIF; nerve growth factor, NGF) had no effect on total neuron number at E10. However, exposure to ciliary neurotrophic factor (CNTF) from E6 to E9 significantly increased (P < 0.05) the number of neurons in the lateral motor column (13,610 ± 725, compared with 10,058 ± 204 in normal saline controls). These results are in agreement with previous reports of large scale neuronal death in the developing chick lumbar lateral motor column between E6 and E12 and confirm that exposure to growth factors such as CNTF can mitigate the course of normal ontogenetic cell death. The optical disector/Cavalieri combination is an efficient method for counting neurons: on average, following sectioning and staining, less than 30 min was required to estimate the total number of motor neurons in a lateral motor column with a coefficient of error of approximately 10%.
Widespread release of peptides in the central nervous system: Quantitation of tannic acid‐captured exocytoses
Authors: Morris John F. , Pow David V.
Published: May 2005

Tannic acid methods have been applied to capture the exocytosis of peptide‐containing granules from peptidergic neurons. The captured exocytoses have been quantitated to assess the proportion and amount of peptide released at different parts of the neuronal membrane. Examination of hypothalamic synaptic boutons shows that only about one‐half of the peptidergic vesicles is exocytosed into the synaptic cleft and also that exocytosis also occurs from undilated peptidergic axons. Study of the magnocellular neurosecretory system reveals that all parts of their extensive terminal arborization appear to be equally capable to exocytose peptide. Only about one‐half of their peptide is released from their nerve endings, which abut the capillaries. The remainder is released much deeper in the lobules of secretory tissue where its principal target(s) could be the pituicytes and/or neurosecretory axons. Dendrites of magnocellular neurons are also capable of releasing peptide by exocytosis and dendrites could release sufficient oxytocin and vasopressin to account for the peptide known to be released into the hypothalamus.

We conclude that peptidergic neurons release substantial amounts of peptides from all of their processes and that this must be taken into account when considering what functions those peptides might serve.
Gonadotropin‐releasing hormone mRNA in the rat: Distribution and neuronal content over the estrous cycle and after castration of males
Authors: Malik Karl F. , Silverman Ann‐Judith , Morrell Joan I.
Published: May 2005

The decapeptide gonadotropin‐releasing hormone (GnRH) stimulates release of luteinizing hormone (LH) and follicle‐stimulating hormone (FSH) from the anterior pituitary. In the present study we used a 51‐base oligonucleotide probe and in situ hybridization to study the neuronal content of GnRH mRNA at several time points in the estrous cycle and 7 days after castration of male rats. GnRH mRNA containing cells were found in the medial septum (SEPT), the vertical and horizontal limbs of the diagonal band of Broca (DBB), and throughout the preoptic area (POA) from the organum vasculosum of the lamina terminalis (OVLT) to its caudal merger with the anterior hypothalamus.

The number of neurons producing detectable quantities of GnRH mRNA was not different either among females killed at 0700 h proestrus, 1000 h estrus, or 1900 h of diestrus 1 or between intact male rats and male rats killed 1 week after castration. We did, however, detect a significant difference in the number of GnRH mRNA producing neurons between males and females (P < 0.05), where females had 20% more labeled cells.

We detected no significant difference in the relative copy number of GnRH mRNA molecules (grains per labeled cell) either over the estrous cycle or between intact and castrate males. However, females overall had 24% more grains per labeled cell than males (P < 0.05). These results suggest that gonadal steroid regulation of GnRH both over the estrous cycle and after short‐term castration of males is mediated primarily by cellular processes subsequent to GnRH gene regulation. Furthermore, these results suggest that biosynthetic activity of GnRH is higher in females than in males.
Effect of paraformaldehyde fixation on localization and characterization of insulin‐like growth factor‐I (IGF‐I) receptors in the rat brain
Authors: King Michael G. , Baskin Denis G.
Published: May 2005

In order to design an approach for localizing IGF‐I receptors within the intact CNS, the effect of paraformaldehyde (PAF) fixation on receptor binding was examined. Cryostat sections of rat brains, which were perfused with O to 10% PAF, were incubated in 125I‐IGF‐I and assayed for binding under equilibrium conditions. Binding was quantified from 10 brain regions, involving laminae and nuclei from median eminence, thalamus, hippocampus, choroid plexus, pyriform cortex, and cerebral cortex, by computer densitometry of film autoradiographs. The specific binding, saturation curves, Bmax and Ka, ligand specificity, and binding reversibility of IGF‐I binding sites were not significantly affected by 1% or 2% PAF. However, 4% PAF elevated IGF‐I receptor total binding, nonspecific binding, and Ka, and decreased Bmax, presumably by increasing the number of tissue‐receptor interconnections, Only nonspecific 125I‐IGF‐I binding persisted when 10% PAF was used. These results indicate that tissue perfused with 2% PAF can be used for localizing IGF‐I receptors by autoradiographic binding methods.
Medial nucleus of the amygdala in the adult Syrian hamster: A quantitative Golgi analysis of gonadal hormonal regulation of neuronal morphology
Authors: Gomez Diana M. , Newman Sarah Winans
Published: May 2005

The medial nucleus of the amygdala (Me) processes both chemosensory and hormonal input. In the male Syrian hamster the integrity of this nucleus is essential for normal reproductive behavior. To determine if gonadal steroids modulate neuronal structure in this nucleus, the morphology of Golgi‐stained neurons in the anterior and posterior regions of Me were compared in castrated and reproductively intact adult hamsters.

In castrated males, neurons in the posterior, but not the anterior, region of Me undergo structural changes, as indicated by a decrease in the mean highest dendritic branch level and mean somal area compared to intact males. To further elucidate the importance of testosterone and its metabolites in maintenance of neuronal structure in the adult, seven groups of male Syrian hamsters were studied. Animals were castrated and received a blank silastic capsule or a capsule filled with either testosterone, dihydrotestosterone, or estradiol. or two capsules containing both metabolites, dihydrotestosterone and estradiol. Two groups of reproductively intact animals were included: brains from one group were processed simultaneously with the castrated and hormone‐treated groups (control intact group), and the other group was processed at the beginning of the experiment. Animals were tested for mating behavior and flank glands were measured to test whether the capsules were effective in releasing the hormones into circulation. After a 12‐week survival period, the brains were processed with Golgi stain and well‐impregnated neurons from the posterior Me were quantitatively analyzed for somal area, highest dendritic branch, total dendritic length, and density of spines. All the measures analyzed revealed a consistent pattern of response to the different gonadal steroids. Castration resulted in a decrease in the mean somal area, the mean highest dendritic branch, and the percentage of neurons with tertiary branch segments. Dihydrotestosterone treatment also resulted in a significant decrease in somal area, mean highest dendritic branch, and percentage of neurons with tertiary dendritic branches. In addition, the total dendritic length and spine density on terminal dendrites were reduced in these brains. The remaining hormone treatment groups were not significantly different from the control group. These results suggest that in orchidectomized male Syrian hamsters, testosterone or its aromatized form, estradiol, but not dihydrotestosterone, is sufficient to maintain the normal morphology of the neurons in the posterior part of the medial nucleus of the amygdala.
Dendritic and synaptic properties of collicular neurons: A quantitative light and electron microscopical study of Golgi‐impregnated cells
Authors: Albers F. Johannes , Meek Johannes
Published: May 2005

The present study deals with a light‐ and electron microscopic morphometric analysis of Golgi‐impregnated neurons in the superior colliculus of rats with the purpose to unravel inter‐ and intralaminar differences in their dendritic and synaptic organization. In particular, layer IV was studied and compared with its boundary layers III and V.

The results show that collicular cells in layer IV basically form a homogeneous population with respect to the number of primary dendrites, the total length of impregnated dendrites, and the diameter, ellipticity, and orientation of dendritic fields and somata of Golgi‐impregnated neurons.

Somata of reconstructed small cells in layer III and IV as well as V have all a similar density of about 40 synaptic contacts per 100 μm2 surface. However, the cell bodies of large multipolar cells in layer V have a slightly but significantly larger synaptic density (about 50 per 100 μm2). Dendrites of large and small collicular cells had no significantly different synaptic densities (43 and 48 per 100 μm2, respectively).

In conclusion, the present results show only minor dendritic and synaptic differences between individual cells in the same layer, as well as in neighboring layers, which implies a low degree of cellular and synaptic intra‐ and interlaminar differentiation. It is discussed that this organization differs markedly from that in other visual centers, including the collicular homologue, the tectum of lower vertebrates, and the mammalian visual cortex, where pronounced inter‐ and intralaminar differentiations exist. Such an organization may provide a framework of laminar specificity by which distinct cell types may select a restricted set of input out of all information available. The present quantitative investigation suggests that a similar framework is not present in the superior colliculus.
Anatomical relationships between sensory afferent arborizations in the cricket cercal system
Authors: Jacobs Gwen A. , Nevin Rocky
Published: May 2005

The anatomical relationships between sensory afferents within a topographic map in the cricket cercal sensory system were studied using a computer‐based reconstruction system developed in our laboratory. Individual identified mechanosensory afferents were characterized physiologically, stained with cobalt, silver intensified, and reconstructed in three dimensions. All reconstructions were scaled to a common standard. The results indicate that there is very little variability in the position or extent of the terminal arborization of identified mechanosensory afferents. The topographic map was divided relatively equally into four regions representing each of the four classes of afferents studied. These regions were discrete but not completely segregated. Approximately 30% of the topographic map contained regions of overlap between two or more classes or afferents.
Verification of the disector method for counting neurons, with comments on the empirical method
Authors: Pover Carolyn M. , Coggeshall Richard E.
Published: May 2005

The empirical and disector methods are unbiased sampling methods for determining numbers of neurons. The present study verifies and thus calibrates these methods by determining true numbers of ganglion cells in serial reconstructions and then using each method to estimate the same populations. The empirical method gives accurate counts but is laborious (inefficient). Five separate disector analyses, distinguished by height (h), were done for each ganglion. The findings are: (1) that the estimates are consistently low when h is minimal (reference and look‐up sections are adjacent), but (2) the estimates are accurate when h is greater (one to four sections intervene between reference and look‐up sections). We ascribe the difficulties with the first disector to “lost” or “invisible” caps. We emphasize that we would not have known of the problem unless we verified our counts. If there is suspicion that difficulties with profile recognition might occur, we recommend that serial sections of an appropriately chosen sample of tissue be prepared and 500–1,000 neurons (or, more generally, particles) be reconstructed. Then the method of choice can be used on the issue of choice to make certain of the necessary accuracy before proceeding with the main study.
Layered collagen fabric of cerebral aneurysms quantitatively assessed by the universal stage and polarized light microscopy
Authors: Canham Peter B. , Finlay Helen M. , Dixon Jan G. , Ferguson Sarah E.
Published: May 2005

We evaluated the effectiveness of the Universal stage, an instrument for measuring three‐dimensional orientation of birefringent materials, for studying the collagen fabric in the wall of brain aneurysms. Vessels from autopsy were fixed at normal arterial distending pressure with 10% formalin, and prepared for polarized light microscopy, with paraffin embedding and staining with picrosirius red for birefringent enhancement. Quantitative data were obtained from tangential and oblique sections (7 μm thickness) of an intact 8 mm aneurysm, a 1.5 mm aneurysm, and a tangential section (3 μm thickness) of a cerebral artery. Sections of full‐size aneurysms seen through the microscope, adjusted either for plane or circularly polarized light, revealed distinctive layers of collagen across the aneurysmal wall, which at higher magnification were further subdivided. Three‐dimensional measurements, numbering 1,082, were made by use of the Universal stage attachment to the polarizing microscope. They were plotted by computer‐controlled graphics on Lambert projections and analyzed by circular statistics. When assessed layer by layer, the collagen spanned a full range of orientations relative to the tangential plane. The circular standard deviation, a measure of the spread of alignment about the mean, was as low as 10° for coherently organized collagen and as high as 40° for the least coherently organized collagen, values characteristic of either the organized tunica media, or the least organized tunica adventitia of cerebral arteries. Although there was a marked thinning of the wall of one aneurysm, there was no evidence of structural weakness based only on the directional organization assessed by our measurements.
Morphometry and magnetic resonance imaging of the human brain in normal controls and Down's syndrome
Authors: Weis Serge
Published: May 2005

A new powerful stereological tool for exact quantification of brain structures on magnetic resonance imaging (MRI) scans was used. Applying Cavalieri's principle, unbiased estimation of volume can be obtained. The method was applied to estimate the volume of different brain structures from normal controls. Data were used for comparison with data obtained by analyzing the brains of persons with Down's syndrome. A normalization procedure based on volume of cranial cavity is introduced and its advantages discussed, as is the coefficient of error as an indicator for the precision of the measurement.
Correlated biochemical and radioautographic studies of protein turnover in developing rat incisor enamel following pulse‐chase labeling with L‐[35S]‐ and L‐[methyl‐3H]‐methionine
Authors: Smith C. E. , Dahan S. , Fazel A. , Lai W. , Nanci A.
Published: May 2005

The movement of proteins into and out of enamel was followed over time using a highly sensitive microprecipitation technique to quantify the amount of TCA‐insoluble radioactivity present within small pieces of freeze‐dried enamel and cells (enamel organ) dissected from the mandibular incisors of rats injected with L‐[35S]‐methionine. Conventional image processing techniques were also used to estimate the number of silver grains over enamel and cells in radioautographs of mandibular incisors from rats similarly injected with L‐[methyl3H]‐methionine. Data from both techniques indicated that the average half‐life for labeled proteins secreted into enamel was about 8.9 days. Typically, radioactive proteins accumulated in increasing amounts for 8 hours after which they were lost slowly up to 4 days and more rapidly thereafter when enamel formed during the secretory stage underwent maturation. The half‐life for radioactive proteins in cells was only about 20.7 hours. No significant accumulation of radioactivity could be detected in the TCA‐soluble or TCA‐insoluble fractions of cells as enamel development proceeded. Results from this study suggest that radioautographs provide an accurate estimate of changes occurring to proteins in enamel and cells except at early time intervals (less than 1 hour) when a high percentage of total radioactivity is present within the TCA‐soluble fraction of cells.
An electron microscopic study on the presence of proteoglycans in the mineralized matrix of rat and human compact lamellar bone
Authors: Sauren Yvonne M. H. F. , Mieremet René H. P. , Groot Cornelis G. , Scherft Johannes P.
Published: May 2005

The presence of proteoglycans (PGs) was studied in compact lamellar rat and human bone at the electron microscopic level. With the cationic dye cuprolinic blue (CBI), PGs could be demonstrated in the mineralized bone matrix. The amounts of PGs appeared to be equal in the different lamellae and osteons. More CBI‐positive material was found in the outermost lamella of the cortex, in the perilacunar matrix around the osteocyte lacunae, and around the canaliculi. Enzyme digestion with chondroitinase ABC demonstrated that the CBI‐positive rods consisted of PGs. These observations amplify biochemical studies in which PGs have been isolated from the mineralized bone matrix. The presence of CBl‐positive rods in the mineralized matrix suggest that PGs do not have to be removed completely to make the matrix calcifiable.
Symmetrically banded collagen fibrils: Observations on a new cross striation pattern in vivo
Authors: Mallinger Rudolf , Kulnig Werner , Böck Peter
Published: May 2005

Collagen fibrils with a symmetric banding pattern, an as yet overlooked component of the extracellular matrix, were found in the reticular layer of the basement membrane of human sebaceous glands. In longitudinal sections this newly described banding pattern is D‐periodic (D = 67 nm) resembling the period length of native type collagen fibrils. In cross sections the symmetrically banded fibrils are irregularly outlined. The period length and the symmetric banding pattern led to the assumption that collagen molecules are staggered by the distance D, similar to native type collagen fibrils, but are arranged antiparallel. This hypothesis was tested by antiparallel superposing transparent photocopies of native type fibrils. In addition, schematic drawings of the cross striation pattern of native type fibrils were superposed in reverse directions by means of computerized image‐manipulation. A model of molecular alignment was evolved from these experiments, which is characterized by two features: (1) pairs of antiparallel collagen molecules are D‐staggered and (2) the two molecules of a pair are slightly shifted from precise register. The proposed model is the only one correlating with the data obtained from direct measurements on symmetrically cross striated fibrils. The fibrils described in the present study represent a supramolecular aggregate of collagen previously not observed in vivo.
Lysosomal integral membrane proteins exhibit region and cell type specific distribution in the epididymis of the adult rat
Authors: Suarez‐Quian Carlos A. , Jelesoff Nicole , Byers Stephen W.
Published: May 2005

The epididymis, a post‐testicular site required for maturation and storage of spermatozoa, is actively involved in exocytic and endocytic events, two phenomena likely to depend on the integrity of the lysosomal system. To study the lysosmal system of the epididymis, five monoclonal antibodies, previously characterized as recognizing five distinct lysosomal integral membrane proteins (LIMPs 1–5), were used as molecular probes of lysosome distribution in cells lining the epithelium. Immunocytochemical localization of LIMPs, using biotin‐streptavidin immunoperoxidase methodology, was performed on frozen sections of adult rat epididymides and in cell cultures prepared from either the caput or cauda epididymis. In frozen sections, a heterogeneous distribution of the different LIMPs along the length of the epididymis was observed. For example, the distribution of LIMP 1 (35–50 K) was detected in all cells of the caput and quite dramatically in clear cells of the distal caput, corpus, and cauda epididymis, but specifically not in the principal cells of the distal caput, corpus, and cauda. In contrast, LIMP 2 (64–71 K) was present in all cells of the epidiyms, except clear cells. LIMPs 4 and 5 (93 K and 93 K) were detected in all epididymal cells, including the clear cells. Finally, whereas the regional and cell type distribution of LIMP 3 (74 K) in the epididymis was identical to that of LIMPs 4 and 5, the nature of the vesicles immunostained was distinct. In cultured cells, the general immunostaining patterns observed in vivo were maintained during the duration of the primary cultures for all five LIMPs. Our results begin to address the molecular heterogeneity of the lysosomal system along the lenght of the epidiymis, and may suggest in part a basis for underlying structural and functional characteristics of the epididymis leading to the sequential maturation of sperm.
Pathways of lymph flow through intestinal lymph nodes in the horse
Authors: Nikles Stephen A. , Heath Trevor J.
Published: May 2005

In the horse, several thousand lymph nodes receive lymph from the intestine, part of which is very large and contains microorganisms that enable the animal to utilize refractory dietary constituents such as cellulose. The aim of this study was to describe the pathways by which lymph is delivered into, traverses, and is drained from these lymph nodes. These pathways were studied with either Microfil or methacrylate casting materials and with light and electron microscopy.

The afferent lymphatic vessel delivering lymph into one of the nodes divides over the capsular surface and within trabeculae into terminal branches, and these are continuous with the subcapsular and trabecular sinuses through rounded holes up to 30 μm across.

Lymph is conveyed from the subcapsular and trabecular sinuses through the cortex by four types of sinuses: trabecular sinuses, cortical tubular sinuses, tubulelike sinuses with a network of stellate cell processes, and sinuses between cortical cords. It is conveyed through the medulla by sinuses both within and between medullary cords.

Lymph is drained from these sinuses by initial efferent lymphatics of three types: those between medullary cords, those within the subcapsular sinus overlying medullary or cortical cords, and those within trabeculae. All three types are continuous with surrounding sinuses through holes 5–30 μm across. These three alternative routes for lymph drainage may ensure adequate lymph flow during different intranodal conditions that may exist when the node is responding to microcrganisms or other foreign materials.
Basement membrane and fibronectin matrix are distinct entities in the developing mouse blastocyst
Authors: Thorsteinsdóttir Sólveig
Published: May 2005

Immunocytochemical techniques were used to study the distribution of fibronectin, type IV collagen (collagen‐IV), and laminin in four different stages of mouse blastocyst development. Immunoreactivity for collagen‐IV and laminin is present in a granular pattern inside the inner cell mass (ICM) cells in stage 1 blastocysts, while these blastocysts are negative for fibronectin. Fibronectin immunoreactivity appears extracellularly under the trophectoderm (TE) in stage 2 blastocysts, in the form of homogeneously distributed dots, and/or fibrils located preferentially close to cell boundaries. It is followed by the appearance of both collagen‐IV and laminin immunoreactivity in patches on the basal side of the TE in stage 3 blastocysts. These patches are initially localized under the central region of TE cells, thus in a location clearly different from that of fibronectinpositive fibrils. As development proceeds the collagen‐IV‐ and laminin‐positive patches become larger, covering, by stage 4, an extensive portion of the inner lining of the blastocoel. Fibronectin‐positive material is still present in a fibrillar form in stage 3 blastocysts, but is generally reduced to thin strands by stage 4. These results indicate that fibronectin is independent of the mouse blastocyst basement membrane, but may play a transient role in cell adhesion during its deposition. In addition, the results suggest that the ICM plays a major role in the production of collagen‐IV and laminin, while the basal surface of TE cells is the primary site of basement membrane assembly.
Anatomical evidence for a countercurrent heat exchanger associated with dolphin testes
Authors: Rommel Sentiel A. , Pabst D. Ann , McLellan William A. , Mead James G. , Potter Charles W.
Published: May 2005

Cetaceans possess cryptic testes that lie within the abdominal cavity, that are surrounded by primary locomotor muscles, and that are presumably exposed to core or above core body temperatures. It has remained a question as to how cetaceans produce and store viable sperm at these high temperatures. We offer anatomical evidence for a two layer arterio‐venous countercurrent heat exchanger at the cetacean testis. Subcutaneous veins from the peripheral surfaces of the dorsal fin and flukes carry cool blood from the fins to the lumbo‐caudal venous plexus. The lumbo‐caudal venous plexus is juxtaposed to the spermatic arterial plexus, which supplies the testis. Venous plexus flow is from the ventro‐lateral margins of the visceral cavity towards the vena cava. Arterial plexus flow is from the aorta towards the ventro‐lateral margins of the visceral cavity and into the testis. The existence of a countercurrent heat exchanger suggests that cetaceans potentially compensate for detrimental effects of core temperatures on sperm viability and storage by regulating the temperature of blood flow to the testis.
Use of biplanar radiographs for estimating cross‐sectional geometric properties of mandibles
Authors: Biknevicius Audrone R. , Ruff Christopher B.
Published: May 2005

Several radiographic techniques for estimating bone cross‐sectional geometric properties of mandibular corpora are compared. A hollow symmetrical model significantly improves estimates compared to solid or hollow symmetrical models that have been used in previous studies. Using this model, biplanar radiographs can give sufficiently accurate information of the amount and distribution of cortical bone in a section given relatively regular subperiosteal and endosteal perimeters.
Human evolution
Authors: Wood Bernard
Published: May 2005

The common ancestor of modern humans and the great apes is estimated to have lived between 5 and 8 Myrs ago, but the earliest evidence in the human, or hominid, fossil record is Ardipithecus ramidus, from a 4.5 Myr Ethiopian site. This genus was succeeded by Australopithecus, within which four species are presently recognised. All combine a relatively primitive postcranial skeleton, a dentition with expanded chewing teeth and a small brain. The most primitive species in our own genus, Homo habilis and Homo rudolfensis, are little advanced over the australopithecines and with hindsight their inclusion in Homo may not be appropriate. The first species to share a substantial number of features with later Homo is Homo ergaster, or ‘early African Homo erectus’, which appears in the fossil record around 2.0 Myr. Outside Africa, fossil hominids appear as Homo erectus‐like hominids, in mainland Asia and in Indonesia close to 2 Myr ago; the earliest good evidence of ‘archaic Homo’ in Europe is dated at between 600–700 Kyr before the present. Anatomically modern human, or Homo sapiens, fossils are seen first in the fossil record in Africa around 150 Kyr ago. Taken together with molecular evidence on the extent of DNA variation, this suggests that the transition from ‘archiac’ to ‘modern’ Homo may have taken place in Africa.
Analysing human developmental abnormalities
Authors: Winter Robin M.
Published: May 2005

About one in forty babies is born with a recognisable congenital anomaly at birth. Rapid progress is being made in recognising the genetic contribution to these defects. From over 2000 likely single gene malformation syndromes in humans the gene has been isolated or mapped in about 10%. Despite the availability of animal models, the study of malformations in humans continues to reveal novel genes and unpredicted functions for known genes. The importance of the study of clinical malformations to the understanding of embryological development in humans and other organisms is discussed and reviewed.