bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on uterine mast cells during early pregnancy in the vole, Microtus agrestis
Authors: Brandon Janet M. , Evans Janet E. 
Published: February 2005

AbstractThe vole, Microtus agrestis, was chosen for this study of mast cells during early pregnancy because this species does not show spontaneous estrous cycles. Mast cell numbers in the uterus are known to vary during the estrous cycle in some species (rat, cow, Syrian hamster). Mast cell changes during early pregnancy in the vole could not reflect hormonal changes which had occurred during a preceding estrous cycle. Mast cells in the uterus (myometrium, endometrium, and mesometrial triangle) and ear skin were examined at 0 hours (virgin, estrus) and at 24, 48, 72 and 96 hours postcoitum (p.c.). The stain used was 0.06% toluidine blue in 0.12 M Michaelis's veronal acetatehydrochloric acid buffer at pH 4.5. The number of mast of cells observed in the uterus was not significantly affected when the nondehydrating fixative used routinely (Helly's solution) was substituted by a dehydrating fixative (Carnoy's solution without chloroform). The number of mast cells in the myometrium decreased from 0 to 72 hours p.c. and increased from 72 to 96 hours p.c. There was no significant variation in mast cell numbers in the endometrium. The number of mast cells in ear skin and in the mesometrial triangle decreased from 0 to 48 hours p.c. An increase occurred from 48 to 96 hours p.c. in ear skin and from 72 to 96 hours p.c. in the mesometrium.
Tridimensional study of the deep cortex of the rat lymph node: VIII. The deep cortex units of the athymic nude rat
Authors: Sainte‐Marie G. , Peng F.‐S. , Pritchard D. 
Published: February 2005

AbstractThe deep cortex of the lymph node of various species actually consists of hemispherical structures, termed deep cortex “units.” Each unit is centered under an opening of an afferent lymphatic and comprises a center and a periphery. In a recent work on the nude mouse, we found that the congenital athymic state inhibits the development of the lymphocyte population in the center of the units as well as in a related area of peripheral cortex, and that it also modifies other nodal components. In the present work, we wanted to compare the effects of the athymic state on the rat nodes. Therefore, nodes from various anatomical locations in 8‐week‐old nude rats were submitted to a tridimensional analysis. The overall effects of the congenital athymic state were found to be comparable in rats and mice. However, marked differences were noticed in the modifications of the node histology, in both species of nude animals. Their significance is discussed together with new findings.
Microvasculature of the mouse epididymis, with special reference to fenestrated capillaries localized in the initial segment
Authors: Abe Kazuhiro , Takano Hiroko , Ito Takashi 
Published: February 2005

AbstractThe blood supply, microvasculature, and ultrastructure of the capillaries in the epididymis in adult mice were regionally examined. The epididymal duct of the initial segment is surrounded with a dense network of fenestrated capillaries running just under the epithelium. The other segments have loose networks of nonfenestrated capillaries running in the interductal connective tissue. The fenestration of capillaries in the initial segment was markedly reduced in frequency immediately after cutting the efferent duct. In adult mice which were subjected to cutting of the efferent duct neonatally, the dense capillary network did not develop, and fenestrated capillaries were absent in the initial segment. We interpret our results to indicate that the fenestrated capillaries in the initial segment provide for absorption of the testicular fluid and that their development is dependent upon the testicular fluid entering the epididymal duct.
Descriptive studies of occlusion and reopening of the spinal canal of the early chick embryo
Authors: Schoenwolf Gary C. , Desmond Mary E. 
Published: February 2005

AbstractOcclusion and reopening of the lumen of the spinal cord, two processes believed to be involved in early brain enlargement, were examined in chick embryos to determine what morphological features characterize these events. Occlusion begins at a particular craniocaudal level near the time that the neural folds become apposed in the dorsal midline and blocklike somites form from the segmental plates. During occlusion, the apical sides of the lateral walls of the neural tube are in close apposition. Interdigitating apical surface protrusions, cross‐luminal intercellular junctions, and abundant cell‐surface materials are lacking. Reopening has occurred by about stage 20 throughout most of the craniocaudal extent of the spinal cord. A lumen suddenly appears during this process, but correlated structural changes that might account for such a dramatic change in morphology were undetectable. Reopening involves the release of the forces that previously maintained occlusion, or the generation of new forces that overcome those causing occlusion, but what these forces are remains to be determined. Observations suggest that forces generated outside of the neural tube might be largely responsible for occlusion, and experiments are in progress to test this possibility.
Ovulation of ovarian implants in unilaterally ovariectomized rats
Authors: Quattropani Steven L. 
Published: February 2005

AbstractSubcutaneous autografts of ovarian tissue were made in unilaterally ovariectomized adult rats and were examined by light microscopy at various times after implantation. The implants were surrounded by a dense connective tissue capsule. They were well vascularized and contained follicles in varying stages of development as well as in different stages of atresia. Oocytes and fresh corpora lutea indicated that grafts ovulated in the presence of the in situ ovary but that the number of ovulations and their frequency were reduced when compared to normal ovaries or ovaries grafted in bilaterally castrated animals. Ovulation results in the formation of a cyst that contains follicular fluid, the oocyte, and cumulus in the ovarian stroma. Macrophages are associated with the oocyte‐cumulus complex but are not prominent in association with the fluid in the cyst. It is suggested that follicular fluid is retained owing to inefficient resorption mechanisms and that this coupled with occasional ovulations results in the formation and maintenance of the large cysts.
The effects of simulated increases in body weight for 60 days on robusticity and mineral content of limb bones of hypophysectomized rats
Authors: Simon Mark R. , Holmes Kenneth R. , Olsen Aart M. 
Published: February 2005

AbstractThe purpose of this investigation was to subject separate male and female groups of weanling hypophysectomized rats each to a specific 10% simulated increase in body weight using constant centrifugation, ranging from 1.1G to 2.0G, to study changes in bone robusticity and bone mineral content. (In this paper, “G” is the acceleration due to gravity.) After 60 days of centrifugation at 24 rpm, the rats were killed and the humerus, radius, ulna, femur, and tibia were removed, cleared of soft tissues, weighed, measured, decalcified with EDTA, and reweighed. Bone robusticity was determined using the ponderal index: P.I. = bone length ÷ \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt[3]{{{\rm bone}\,{\rm weight}}} $\end{document}; and bone mineral content (BMC) was determined using the formula: BMC = [(Wu – Wd) ÷ Wu] × 100. Tukey's Studentized Multiple Range T Test was used. The data suggest that, for both male and female hypophysectomized rats, bone robusticity is decreased with simulated increases in body weight; also, for males, a bimodal curve describing the relationship between BMC and simulated increases in body weight is suggested.
A method for the preparation of large intact sheets of intestinal mucosa: Application to the study of mouse aggregation chimeras
Authors: Schmidt Günter H. , Wilkinson Maureen M. , Ponder B. A. J. 
Published: February 2005

AbstractA technique for the preparation of entire intestinal mucosal sheets is described that renders the population of crypts accessible for two‐dimensional study. We have applied the technique to demonstrate the mosaic crypt populations in the intestinal epithelium of mouse aggregation chimeras, using the lectin Dolichos biflorus agglutinin (DBA) as a strain‐specific histochemical marker.
Further evidence of inactivity of hypothalamo‐pituitary‐thyroid axis in snell dwarf mice
Authors: Lewiński Andrzej , Bartke Andrzej , Kovacs Kalman , Richardson Lyn , Smith Nancy K. R. 
Published: February 2005

AbstractThe effects of hemithyroidectomy (hemiTX) and complete thyroidectomy (TX) on the cellular composition and the mitotic activity of the anterior pituitary gland were examined in genetically thyrotropin (TSH)‐deficient female Snell dwarf mice (dw/dw) and in phenotypically normal female mice (?/+) from the same strain. In normal (nondwarf) mice, both hemiTX and TX reduced the percentage of acidophilic (orange G‐positive) cells and increased the percentage of thyrotropic (aldehyde fuchsin [AF]‐positive) cells, whereas the percentage of gonadotrophs (PAS‐positive cells) and chromophobes (unstained cells) was not affected. Both interventions increased the mean mitotic activity rate (MMAR) of the anterior pituitary lobe. This effect was related to the enhancement of the MMAR of acidophilic cells and, particularly, thyrotropic cells. The MMAR of thyrotrophs in thyroidectomized normal mice was significantly higher than that in sham‐TX controls or in hemithyroidectomized animals.In Snell dwarf mice, neither hemiTX nor TX affected the percentage of the various cell categories (PAS‐positive, unstained, and extremely rare AF‐positive cells) in the anterior pituitary lobe. Furthermore, neither hemiTX nor TX substantially influenced the MMAR of the gland. No mitotic figures were found in the AF‐positive cells. Since the AF‐positive cells in the anterior pituitary of dwarf mice completely failed to respond to hemiTX or TX, we believe they are not true thyrotropic cells.Using electron microscopy, we confirmed a lack of somatotrophs, mammotrophs, and normal thyrotrophs in the anterior pituitary of Snell dwarf mice. The results provide morphological evidence of inactivity of the hypothalamo‐pituitary‐thyroid axis in Snell dwarf mice.
Resistance vessels supplying the median eminence of the rabbit, rat, and cat
Authors: Page Robert B. , Dovey‐Hartman Barbara J. 
Published: February 2005

AbstractThe ultrastructure of arterioles supplying the median eminence of eight rats, eight rabbits, and two cats was studied after vascular perfusion with phosphate buffered aldehyde fixatives. There were terminal arterioles with a lumen diameter of 50–70 μm within the pars tuberalis. Smaller arterioles (precapillary sphincters and metarterioles) with a lumen diameter of 15–20 μm were present on the surface of the median eminence. Arterioles were not observed to penetrate the neuropil but were seen to supply the external capillary plexus of the median eminence. Direct innervation of arterioles supplying the median eminence was not present and hence regulation of median eminence blood flow by peripheral sympathetic mechanisms appears unlikely. Resistance vessels were found to be closely related to axon terminals on the surface of the median eminence and to fenestrated capillaries of the external plexus. In addition, the endothelial cells of arterioles were characterized by the presence of pits and vesicles which may play a role in transendothelial transport. These findings suggest two mechanisms by which blood flow into the median eminence can be regulated: (a) by central catecholaminergic systems terminating in the median eminence and (b) by catecholamine secretions from the adrenal medulla.
Distribution of lectin binding sites in rabbit oviduct
Authors: Menghi Giovanna , Maria Bondi Anna , Materazzi Giovanni 
Published: February 2005

AbstractThe carbohydrate histochemistry of the rabbit oviduct has been examined by the use of four lectins conjugated with horseradish peroxidase as histochemical reagents. Each lectin gave a very distinct typical pattern of binding, but for each lectin there was no difference between the distribution of binding sites in ampulla and isthmus. Wheat germ lectin bound exclusively with the connective tissue of the oviduct folds; winged pea lectin was detected only in the ciliated cells; peanut lectin binding sites were visualized in the secretory cells; the binding reactivity of soybean lectin was limited to the basal part of the cilia. Although it is very difficult at present to correlate the distribution of lectin binding sites with the function of the positive cells, some hypotheses have been advanced.
Effects of hormones and gonadal status on the midventral gland of the grasshopper mouse Onychomys leucogaster
Authors: Pinter Aelita J. 
Published: February 2005

AbstractA midventrally located fusiform sebaceous gland is found in the northern grasshopper mouse Onychomys leucogaster. Microscopically, the gland consists of numerous multilobular units. Copious secretory material collects in the central duct of each unit and is extruded to the outside. The gland is larger in the male than in the female. Castration causes an involution of the gland in both sexes. Testosterone propionate (1.0 mg/0.1 cc olive oil, subcutaneously every other day for 4 weeks) restores the gland to full activity in castrates of both sexes. Estradiol benzoate (0.1 mg/0.1 cc olive oil, subcutaneously every other day for 4 weeks) has no effect on the midventral gland of ovariectomized females. A long photoperiod (18 L/6 D) leads to the development of testes, ovaries, and uteri that are significantly heavier than those of animals from a short photoperiod (6 L/18 D) regime. Midventral glands in animals of both sexes from the long photoperiod are larger and more active than glands of animals from the short photoperiod. The secretions of the midventral gland of Onychomys are probably used for communications such as territorial marking, advertisement of gonadal status, or pup identification.
Epidermal and papillary dermal characteristics of the bowhead whale (balaena mysticetus)
Authors: Haldiman Jerrold T. , Henk William G. , Henry Robert W. , Albert Thomas F. , Abdelbaki Yahya Z. , Duffield Dennis W. 
Published: February 2005

AbstractSkin samples from most body regions of the bowhead whale were examined. The epidermis is 2.7 to 50 times thicker than that reported in other cetaceans with both regional and individual variations in thickness. The thinnest areas examined (1 mm) occur on the eyelid margins and the thickest (25 mm) occur on the lower jaw. A distinctive parakeratotic stratuim corneum with a thick underlying stratum spinosum (without a stratum granulosum) extgends over the entire body surface. From a few dozen to several hundred epidermal lesions are present on all whales studied. A typical stratum basale of germinative keratinocytes (with melanocytes in pigmented areas) rests upon a well‐defined basal lamina. Epidermal rod arrays arise from the basal keratinocytes which cover highly elongated dermal papillae and extend to the epidermal surface through the distal stratum spinosum and the stratum corneum. At least four diatom genera occur on and in the stratum corneum and lesion areas of different whales. The superficial dermis consists of a papillary layer with long (up to 13 mm) dermal papillae interdigitating with the epidermis from a basal area that is 2–4 mm in thickness. The number of dermal papillae per mm2 varies inversely with the thickness of the epidermis. Large diameter, sensory papillae packed with tortuous, highly elongated, encapsulated nerve end organs also interdigitate with the thin epidermal areas of the ventral surface of the rostrum, the upper and lower lip margins, and the upper and lower eyelid margins. Scattered, single, stiff hairs emerge from the skin only in specific, pigmented regions of the head.
Light and electron microscopy of the new born sagittal suture
Authors: Decker Jay D. , Hall Stanton H. 
Published: February 2005

AbstractMorphogenesis and maturation of the sagittal suture in newborn C57B1/6J strain mice were studied using light and electron microscopy. Morphodifferentiation of the murine parietal bones progresses radially with the interposed sagittal suture, assuming a greater level of maturity at birth at a midpoint along its length. The presumptive suture develops in a sulcus, deeper posteriorly, more shallow anteriorly. Cells at the osteogenic front (OF) are distinguished from the surrounding fibrocytic cells by a number of distinctive characteristics: 1. increased cytoplasmic density; 2. extensive endoplasmic reticulum; 3. dispersed nuclear chromatin aggregates; 4. extensive surface projections; 5. close approximation.Mineralization of the developing parietal bone occurs extracellularly with the initial deposits of apatite crystals exhibiting no oriented relationship to either cellular or extracellular fibrillar elements.The majority of collagen fibers lie superior and inferior to the presumptive suture, oriented anteroposteriorly with their long axes parallel to the ectocranial surface. Other fiber bundles more intimately associated with the developing suture display a more random orientation.
1,25‐dihydroxyvitamin D3 in teeth of rats and humans: Receptors and nuclear localization
Authors: Clark S. A. , Dame M. C. , Kim Y. S. , Stumpf W. E. , DeLuca H. F. 
Published: February 2005

AbstractAutoradiographic and biochemical studies were used to demonstrate 1,25 (OH)2 vitamin D3 target cells in teeth. Incisor pulp of rats and molar pulp of humans were incubated in vitro with 3H‐1,25 (OH)2 vitamin D3. Subsequent frozen‐section autoradiography revealed a large population of cells in the pulp of both incisors and molars which selectively concentrated radioactivity in their nuclei. Extracts of incisor pulp from mature rats were found to bind 3H‐1,25 (OH)2 vitamin D3 and this binding was displaceable with excess 1,25 (OH)2 vitamin D3. Sucrose density analysis revealed that the protein in tooth pulp which binds 1,25 (OH)2 vitamin D3 sediments at 3.2–3.5S. The 1,25 (OH)2 vitamin D3 receptor of intestine and kidney also sediments in this region, indicating that the 1,25 (OH)2 vitamin D3 binding protein of tooth pulp is similar to that found in other target organs. These autoradiographic and biochemical data indicate that pulpal cells of mature rat and human teeth contain receptors for 1,25 (OH)2 vitamin D3.
Mitochondrial alterations in embryos exposed to B‐hydroxybutyrate in whole embryo culture
Authors: Horton W. E. , Sadler T. W. 
Published: February 2005

AbstractThe ketone body B‐hydroxybutyrate (B‐OHB) produces malformations and ultrastructural alterations in mitochondria of mouse embryos exposed for 24 hours to the compound in whole embryo culture. The present study was conducted to establish the time‐course of the mitochondrial changes to determine whether the changes are reversible, and to relate these changes to the malformations produced by the compound. Since mitochondria also play a key role in the metabolism of ketone bodies, the capacity of the early somite embryo to metabolize B‐OHB was investigated in an effort to link the morphological alterations in the mitochondria to a biochemical process. Early somite embryos were cultured 4, 8, or 24 hours in the presence of 32 mM DL‐B‐OHB and then cultured for an additional 24 hours in control serum. Finally, embryonic tissue during the teratogenic period was assessed for its capability to oxidize B‐OHB using D‐(3‐14C)‐B‐OHB. The treated embryos showed progressive alterations in the mitochondria, beginning at 4 hours with a loss of matrix density and culminating at 24 hours with high‐amplitude swelling, complete loss of matrix density, and disappearance of cristae. These alterations were reversible following removal of the embryos after 24 hours of exposure to B‐OHB and culturing for an additional 24 hours in control serum. Metabolism studies demonstrated that the early somite embryo possesses a limited capacity to oxidatively metabolize B‐OHB. The biochemical implications of these findings are discussed with respect to the possible role of ketone bodies in the mechanism of diabetes‐induced congenital malformations.
Bone lining cells and hematopoiesis: An electron microscopic study of canine bone marrow
Authors: Deldar Ahmed , Weiss Leon , Lewis Hugh 
Published: February 2005

AbstractHematopoietic bone marrow in the dog is enclosed by a nearly complete and rather complex layer of endosteum, consisting of a diverse group of cells collectively called bone lining cells (BLC). Cell types comprising BLC include osteoblasts and osteoclasts, and other cell types, among which are elongated, flat cells with a spindle‐shaped nucleus, and small cytoplasmic vesicles. The composition and thickness of the layer of BLC varies along the perimeter of the marrow. The layer may be simple or stratified. Occasionally a zone of tightly packed regularly arranged collagenous fibers lies between the bone lining cells and bone. Hematopoiesis, particularly neutrophilic, often occurs in the bone marrow next to the BLC. Cytoplasmic processes of BLC occasionally extend into the hematopoietic spaces and stromal cells in the hematopoietic compartment may extend processes to the layer of BLC. Occasionally cells of the BLC are similar in appearance to stromal cells within the marrow. Our observations together with the experimental findings of others (that fibroblastic stromal cells contribute to the hematopoietic inductive microenvironment, that hematopoietic stem cells are concentrated subosteally, that cells responsible for regeneration of the marrow stroma are derived from the endosteal layer, and that high concentrations of hematopoietic colony‐stimulating factors are produced there) indicate that the hematopoietic capacities of bone marrow may be regulated by BLC.
Morphometric analysis of the nucleolus during the life cycle of human odontoblasts
Authors: Couve Eduardo 
Published: February 2005

AbstractDeveloping first premolars were used as a model system to obtain information on the nucleolar structure of human odontoblasts at several stages of their life cycle. Four stages were defined by their location within the tooth: (a) preodontoblasts were located at the growing tip of the root; (b) secretory odontoblasts in the apical region; (c) transitional odontoblasts in the middle region; and (d) aged odontoblasts in the coronal region. Preodontoblasts have a small nucleolus (0.55 μm2) with few strands of dense fibrillar material radiating from the fibrillar center. Secretory odontoblasts are characterized by a large (1.24 μm2), irregular, and reticulated nucleolus. The fibrillogranular material, the largest component in all nucleoli, reaches maximal size at this stage (0.88 μm2). Fibrillar centers occupy about the same area (0.1 μm2) throughout the odontoblast's life cycle. As the formation of primary dentin is completed, the nucleolus of transitional odontoblasts is reduced in size (0.54 μm2). Finally, the aged odontoblasts have a small, compact nucleolus (0.39 μm2), with segregated components. Morphologic analysis and quantification of size and component areas of nucleoli obtained with an image analyzer indicated that secretory odontoblasts had the most active, and aged odontoblasts the least active, nucleolus.