bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereological analysis of normal rabbit pancreatic islets
Authors: Sato Tamiko , Herman Lawrence 
Published: February 2005

AbstractStereological methods were applied to obtain morphometric data related to pancreatic islets of Langerhans in the normal rabbit. By light microscopy, it was found that 1 mm3 of pancreatic parenchyma contained 47.7 islets, constituting 2.2% of its volume. Approximately 69% of the islets had diameters less than 80 μm; 31% were greater than 80 μm. The former group of islets, however, composed only 13% of the volume of the endocrine pancreas and the latter group, 87%. Using electron microscopy, a unit volume of islet tissue was observed to consist of 86% beta cells, 7.7% alpha cells, and 2.2% delta cells. The average beta‐cell volume was 1260 μm3 and its cytoplasm consisted of 52.6% matrix, 12.7% rough endoplasmic reticulum, 10.2% secretory granules, 7.8% mitochondria, and 3.3% Golgi apparatus. A typical beta cell contained 662 mitochondria, intermediate (10‐nm) filaments whose length totalled 50 mm, and 9,200 secretory granules with a ratio of four mature granules to each immature or “pale” granule. Within alpha and beta cells, three parameters were used for the quantitation of organelles or their component parts: (1) volume; (2) surface; and (3) numerical densities. In the beta cell, the surface densities of rough endoplasmic reticulum and Golgi membranes exceeded, by two‐ or threefold, their counterparts in alpha cells. Similarly, the number of beta‐cell mitochondria exceeded by 30% that of alpha cells; but beta‐cell mitochondrial volume was twice that of the alpha cell, as were surface densities of both inner and outer mitochondrial membranes. Volume and surface densities of secretory granules within beta cells were half the values obtained for alpha cells. An alpha cell contained three times the number of granules present in a beta cell.
Innervation of the thymus gland by brain stem and spinal cord in mouse and rat
Authors: Bulloch Karen , Moore Robert Y. 
Published: February 2005

AbstractCentral nervous system (CNS) projections to the thymus were studied in the mouse and rat using the horseradish peroxidase (HRP)‐retrograde transport method. With discrete HRP injections localized to the thymus, labeled neurons are evident in both medulla and spinal cord. In the medulla the largest population of labeled neurons is present in the retrofacial nucleus. Within this cytoarchitectonically distinct nucleus, the majority of neurons are labeled with large HRP injections in the thymus. In addition to retrofacial nucleus, scattered labeled neurons are found throughout the rostrocaudal extent of the nucleus ambiguus and in the dorsal medullary tegmentum adjacent to the dorsal motor vagus nucleus. With HRP injections restricted to thymus parenchyma, no labeled neurons are evident in the dorsal motor vagus nucleus. Three groups of spinal cord neurons are labeled. In segments C2–C4, neurons localized to the ventral horn are labeled in two distinct columns, one located lying laterally in the ventral horn and the other located medially. Labeling of neurons in these segments is distinct from that of large motor neurons located medially in the ventral horn extending from the level of the decussation of the pyramids through the C1 segment. The location and sizes of neurons labeled in these areas following HRP injection in the thymus are identical in the mouse and rat. These observations provide evidence for previously unknown projections from spinal cord and brain stem to the thymus which may play an important role in the regulation of thymic function.
Morphological evidence of reduced bone resorption in osteopetrotic (op) mice
Authors: Marks Sandy C. 
Published: February 2005

AbstractOsteopetrosis, a metabolic bone disease in which a generalized accumulation of bone mass reduces or obliterates marrow cavities, is inherited as an autosomal recessive in several mammalian species. A recently discovered mutation in mice, the osteopetrosic (op) mutation, exhibits an elevation in bone matrix synthesis and a resistance to the hypercalcemic effects of exogenous parathyroid extract when young mutants are compared with normal littermates.This investigation examined the number, cytology, and ultrastructure of osteoclasts and the structure of bone surfaces in op mice in a morphologic assessment of bone resorption. Compared with normal littermates, op mice have a severe deficiency of osteoclasts, which also contain unusual toluidine blue‐positive and electron‐dense cytoplasmic inclusions and hypertrophy of clear zones and ruffled borders. Marrow spaces in op mice contained large numbers of megakaryocytes and large lipoid masses. Bone surfaces exhibiting evidence of resorption by scanning electron microscopy in normal littermates showed no evidence of resorption in op mice. Instead, these areas were characterized by morphologic features of bone formation.These data offer morphologic evidence of a reduction of bone resorption in this mutation. They are interpreted to mean (1) that op mice have a severe reduction in numbers or proliferative capacity of osteoclast precursors, which may be related to the cellular inclusions in the osteoclast population, and (2) that hypertrophy of the ruffled borders and clear zones of op osteoclasts is a compensatory attempt to increase bone resorption.
Functional morphology of lingual protrusion in marine toads (Bufo marinus)
Authors: Gans Carl , Gorniak Gerard C. 
Published: February 2005

AbstractBufo marinus catches its prey by stiffening the intrinsic muscles of the tongue, rapidly flipping the tongue out of the mouth. High‐speed cinematography synchronized with computer‐analyzed electromyograms (EMGs) shows that during the flip the tongue is supported by the M. genioglossus medialis and that this muscle stiffens into a rod when stimulated. Coincident stiffening of the transversely arranged M. genioglossus basalis provides a wedge under the anterior tip of this rod. Stiffening of the M. submentalis depresses the mandibular symphysis and brings the dentary tips together. The M. submentalis also acts on the wedge of the basalis to raise and rotate the rigid rod of the medialis over the symphysial attachment. The tip of this lingual rod carries along the pad and soft tissues of the tongue. The lingual pad, positioned in the posterodorsal portion of the resting tongue, rotates during eversion so that its dorsal surface impacts onto the prey object. Retraction starts by contraction of the elongate, parallel fibers of the M. hyoglossus; this retracts the medial sulcus of the pad and holds the prey by a suction cup‐like effect. The extensibility of the buccal membranes allows the pad to be retracted first; it reaches the posterior portion of the buccal cavity before the still‐rigid, backward rotating M. genioglossus has reached the level of the symphysis.Protraction of the hyoid facilitates the extension of the M. hyoglossus. The M. sternohyoideus only retracts the hyoid and stabilizes it when the tongue starts to pull posteriorly; it does not assist tongue protrusion. The Mm. petrohyoideus and omohyoideus show only incidental activity, and the M. depressor mandibulae participates in mouth opening but is not otherwise involved in the flip.Previous hypotheses of the flipping mechanism are reviewed and evaluated.
Temporal patterns of neurogenesis in avian cranial sensory and autonomic ganglia
Authors: D'amico‐Martel Adele 
Published: February 2005

AbstractAvian cranial sensory ganglia are embryonically derived from neural crest and epidermal placodes. Cells from these two populations interact with each other and with other components of their environment to influence the complex structural and functional organization of the ganglia. To help understand these processes, the times of terminal mitosis of cranial sensory neuroblasts were established. Birthdate patterns within each ganglion are described with particular attention given to the structural organization of the VII‐VIII ganglionic complex. Birthdate information on cranial autonomic ganglia is also included.Chick embryos ranging in age from 1 to 8 days of incubation were treated with 3H‐thymidine and sacrificed on embryonic day 8, 10, or 18. Large, placode‐derived neurons are generated between days 2 and 5 of incubation. Embryonically smaller, neural crest‐derived cells leave the proliferative pool between days 4 and 7. Neurons of the acoustic ganglion cease their mitotic activity in an apical to basal fashion and are the only placodal neurons to form later than day 5. Of the cranial autonomic ganglia, the period of neuron production is best defined for the ciliary ganglion, where it is 2.5–5.5 days of incubation. Most later‐dividing neuroblasts in the ciliary ganglion belong to the choroid cell population.Temporal patterns of neurogenesis are discussed in relationship to other aspects of sensory gangliogenesis including embryonic origin of neurons, condensation of ganglionic anlagen, cell degeneration, and cytological characteristics of mature ganglia.
Developmental alterations associated with spontaneous cleft lip and palate in CL/Fr mice
Authors: Millicovsky Guillermo , Ambrose L. Jeannie H. , Johnston Malcolm C. 
Published: February 2005

AbstractCleft lip with or without associated cleft palate [CL(P)], one of the most common human malformations, is believed to be caused by a combination of genetic and environmental factors. To study the morphological manifestations of genetic factors in this interaction, we compared the embryonic development of the CL/Fr mouse strain (with a mean incidence of 36% spontaneous CL(P) in our colony) with that of the C57B1/6J mouse strain (with no CL(P) in our colony). Results from our scanning electron microscopic study demonstrated that, when compared with C57B1/6J embryos, CL/Fr embryos have several developmental differences including: (1) altered facial geometry, (2) depressed ability of the surface epithelium of primary‐palate primordia to participate in the fusion process, and (3) variable hypoplasia of the lateral nasal prominences. We suggest that all of these alterations may contribute to the pathogenesis of CL(P) in the CL/Fr mouse strain.
Division of the mouse gastric mucosa into zymogenic and mucous regions on the basis of gland features
Authors: Lee E. R. , Trasler J. , Dwivedi S. , Leblond C. P. 
Published: February 2005

AbstractThe stomachs of adult CD1 mice were investigated by anatomical examination and light microscopy. Serial sections were prepared of entire stomachs; the various types of gastric glands were characterized; and, using every 30th or 60th serial section, maps of gland distribution were obtained through point‐plotting serial reconstruction.Gross examination shows that the cephalic third of the stomach consists of a thin‐walled, domelike structure, the forestomach. The rest of the organ, or stomach proper, is subdivided into two parts, the thick‐walled corpus, which approximately occupies the middle third, and the less vascular pyloric antrum which forms the remaining caudal third of the organ.Histologically, glands are absent from the forestomach mucosa but are numerous throughout the stomach proper. They are of two main types, namely, zymogenic glands, which contain, among others, zymogenic cells, and mucous glands, which lack these cells but contain mucous cells. Both gland types show a few enteroendocrine cells. Moreover, some of the mucous glands include parietal cells (mucoparietal glands), while others do not (pure mucous glands).Mucosal maps reveal that the glands of each type are located in distinct areas of the mucosa. Thus a compact zymogenic region may be defined, occupying 56% of the glandular mucosa and containing only zymogenic glands. The mucous region, on the other hand, composed only of mucous glands, is extensive and divided into a narrow cephalic band (5.2% of the glandular mucosa) and a large caudal part (38.8%). Along the lesser curvature these parts are continuous, and together they encapsulate the zymogenic region. In proximity to the border of this region, and only there, do the mucous glands include parietal cells.A comparison of mucosal maps and gross features indicates that the corpus includes both the zymogenic region and the cephalic band of mucous glands, whereas the antrum is composed entirely of the mucous glands of the caudal part.
The establishment of a somitomeric pattern in the mesoderm of the gastrulating mouse embryo
Authors: Tam Patrick P. L. , Meier Stephen 
Published: February 2005

AbstractMesoderm formation in the mouse embryo begins at 6.5–6.75 days p.c. (postcoitum) when a primitive streak is formed along the posterior side of the egg cylinder. Epiblast cells in a localized region separate from one another and spread laterally between the primitive endoderm and the rest of the epiblast. The newly formed mesoderm contributes to both embryonic and extraembryonic regions. When the endoderm is removed, a definitive somitomeric pattern is first observed in the lateral wings of mesoderm of the mid‐primitive‐streak‐stage embryo. The sequential appearance and the placement of somitomeres in the gastrulating mouse embryo are closely related to the general changes in physical dimensions and to the pattern of tissue growth which occur during the maturation of the egg cylinder. By the late‐primitive‐streak stage, about four somitomeres are present in the paraxial mesoderm on either side of the embryonic axis. These somitomeres will undergo morphogenesis and give rise to the cranial segments and head mesenchyme of neurulating embryos (Meier and Tam, 1982). The midline or axial mesoderm, consisting of prechordal plate and notochord, is derived from the head process mesoderm originating from the anterior end of the primitive streak. Cells of the head process are compact and adherent to the endoderm. The early presence of a somitomeric pattern which persists and is added to throughout subsequent phases of mesoderm formation suggests that spreading mesodermal cells have relatively stable neighbor relationships. This morphological evidence supports the idea that the expansion of the mesoderm during gastrulation results from tissue growth and progressive deposition of cells from the primitive streak. Cell migration may be limited principally to nonsomitomeric mesodermal cells found in the leading edge of the spreading lateral wings.
Ultrastructure of mucocartilage in the larval anadromous sea lamprey, Petromyzon marinus L.
Authors: Wright Glenda M. , Youson John H. 
Published: February 2005

AbstractThe fine structure of mucocartilage, a tissue unique to larval lampreys, was examined in Petromyzon marinus L. This tissue is surrounded by a perichondrium of vascularized, dense connective tissue composed of fibroblasts, collagen fibrils, and elastic‐like microfibrils, but it is avascular itself and consists of elastic‐like microfibrils, ground substance, and a few diffusely scattered fibroblasts. Fibroblasts possess rough endoplasmic reticulum, many free ribosomes, a well‐developed Golgi apparatus, a tubulo‐vesicular network, and a number of secondary lysosomes containing crystalline material. The appearance of the organelles suggests the involvement of the cell in the synthesis and secretion of the ground substance and microfibrils. Tubular microfibrils, 11–13 nm in diameter, comprise the major portion of the matrix, and they are similar to those described in developing mammalian elastic tissue (Ross and Bornstein, 1969). The retention of the microfibrils may represent either a primitive form of elastic fiber in this “primitive” vertebrate or reflect the larval condition of the lampreys under examination. Scattered spherical to polyhedral‐shaped matrix granules and inter‐granular filaments make up the remainder of the matrix. It was concluded that mucocartilage in larval lampreys is not a conventional type of vertebrate connective tissue.
Ultrastructural visualization of complex carbohydrates in eosinophilic leukocytes
Authors: Parmley Richard T. , Takagi Minoru , Spicer Samuel S. , Thrasher Albert , Denys Francis R. 
Published: February 2005

AbstractComplex carbohydrates in eosinophils from human, rabbit, and rat marrow were identified and localized by cytochemical and radioautographic methods. The high iron diamine‐thiocarbohydrazide‐silver proteinate (HID‐TCH‐SP), low iron diamine (LID)‐TCH‐SP, and periodate (PA)‐TCH‐SP methods were used for the localization of sulfate, sulfate and carboxyl, and vicinal glycol‐containing complex carbohydrates, respectively. Golgi vesicles and small precursor granules (0.2–0.4 μm in diameter) demonstrated strong HID‐TCH‐SP staining and labeled intensely after a 10‐minute pulse with 35 SO42−. Crystalloid‐free or immature specific granules (0.5–0.9 μm in diameter) labeled heavily after a 60‐minute incubation and 60‐minute chase with 35SO42−. Immature granules were graded according to their HID‐TCH‐SP staining: Type 1 granules demonstrated strong rim staining and similar or somewhat less central staining, whereas type 2 granules only demonstrated rim staining, and type 3 granules lacked staining. Fully mature crystalloid‐containing granules lacked staining. LID‐TCH‐SP similarly stained the HID‐positive sulfated material in cytoplasmic granules. PA‐TCH‐SP stained some Golgi vesicles and diffusely stained all precursor granules and type 1 granules. Weaker staining was observed in type 2 granules and staining was very weak or absent in type 3 and crystalloid‐containing granules. In early eosinophils, tubulovesicular structures (TVS) were observed rosetting and contacting precursor and type 1 granules. These TVS contained material with strong PA‐TCH‐SP staining but lacked HID‐TCH‐SP or LID‐TCH‐SP‐reactive acidic glycoconjugates. Flattened Golgi saccules of early eosinophils stained weakly or not at all with the PA‐TCH‐SP method. Small granules and TVS in late (bilobed) eosinophils displayed PA‐TCH‐SP reactivity and lacked HID‐TCH‐SP staining but differed from TVS in early eosinophils in that they were not associated as rosettes with specific granules. These results indicate that sulfated and vicinal glycol‐containing complex carbohydrates are differently distributed in immature specific granules of eosinophils and presumably become masked to staining as the granule matures.
Nuclear size as a cell‐kinetic marker for osteoblast differentiation
Authors: Roberts W. Eugene , Mozsary Peter G. , Klingler Eliane 
Published: February 2005

AbstractA nuclear morphometic assay for preosteoblasts is introduced as a cell‐kinetic technique, applicable to routine histological preparations of mineralized tissue. Because this method is a morphological marker for osteoblast precursor cell differentiation, it provides a new dimension for determining the mechanism of osteoblast histogenesis. Osteoblast precursors of the periodontal ligament are a mixed population of progenitors, kinetically separable into two distinct groups according to nuclear size. Preosteoblasts, the immediate proliferating precursors of osteoblasts, have large nuclei (>170 μm3) and are derived from relatively undifferentiated fibroblastlike cells, which have smaller nuclei (<80 μm3). Increase in nuclear volume, during G 1 phase of the cell cycle, is apparently a morphological manifestation of change in genomic expression. This key event in preosteoblast differentiation is related to mechanical stress/strain and may be an important rate‐limiting step in osteoblast histogenesis.
Histochemical and biochemical studies of carbonic anhydrase activity in the opercular epithelium of the euryhaline teleost, Fundulus heteroclitus
Authors: Lacy Eric R. 
Published: February 2005

AbstractCarbonic anhydrase (CAH) activity was biochemically measured and histochemically localized (at both the light and electron microscope levels) in isolated opercular membranes from teleost fish, Fundulus heteroclitus, adapted to freshwater (FW), seawater (SW), and double‐strength seawater (2 × SW). The normal morphology of this membrane showed that its epithelial portion consisted of five cell types: (1) chloride cells, which have been previously implicated as responsible for the active chloride transport across the epithelium; (2) mucous cells; (3) pavement cells, which formed the major portion of the free epithelial surface; (4) supportive cells, which had an abundance of intermediate (10 nm)‐type filaments suggesting a structural role for these cells; and (5) vesicular cells, which were characterized by various types of membrane‐bound vesicles, including lysosomes, and numerous free ribosomes. Vesicular cells may be stem cells and/or endocrine cells. Hansson's histochemical method for CAH revealed cobalt sulfide reaction product confined to the following structures in fish from each environment: (1) chloride cells: throughout the cytoplasm and some nuclear staining; (2) mucous cells: throughout the cytoplasm, some nuclear staining, and some in mucous granules; (3) vesicular cells: confined to lysosomes, some of the vesicles, and nucleoli; (4) a small portion of the intracellular space between adjacent vesicular cells and supportive cells; and (5) supportive cells: in nucleoli and occasionally in larger membrane‐bound lysosomelike structures. Acetazolamide (10−5 M) and potassium cyanate (KCNO) (10−1 M) in Hansson's incubation medium completely inhibited the formation of reaction product. Biochemical determination of CAH activity on vascularly perfused, isolated opercular membranes showed no statistically significant difference in enzyme activity between environmental groups. The following units of activity/mg opercular membrane protein were measured: FW: 0.63 ± 0.02; SW: 0.43 ± 0.08; 2 × SW: 0.64 ± 0.09.
Observations on Graafian follicles and their oocytes during lactation and after the removal of pouch young in the marsupials Isoodon macrourus and Perameles nasuta
Authors: Lyne A. G. , Hollis D. E. 
Published: February 2005

AbstractOvaries from 63 bandicoots (Isoodon macrourus and Perameles nasuta) were collected in order to obtain Graafian follicles close to ovulation for light and electron microscopy. During the first 42 days of lactation (lactation c. 60 days), the follicles were less than 1.0 mm in diameter, whereas from 43 to 52 days, some animals had follicles up to 2.0 mm in diameter, or ovulation had occurred and new corpora lutea were present. This ovulation was associated with the lactation estrus that occurred in some animals.In general, the largest Graafian follicles of the bandicoots were morphologically similar and resembled those of many other mammals. These follicles protruded from the surface of the ovary and revealed a conspicuous theca interna. The granulosa cells exhibited an unusual feature in that they contained masses of glycogen, often associated with lipid droplets and filaments.The oocytes were similar in size (diameter c. 150 μm) to those of some other marsupials and were surrounded by a zona pellucida and cumulus cells attached to the granulosa layer. The cumulus cells did not form a corona radiata as in eutherian mammals. The oocyte nuclei were somewhat flattened, peripherally located and similar in size (c. 40 × 19 μm) to those in other marsupials. These nuclei, which stained lightly with Azure A and were electron‐lucent and homogeneous, were unusually irregular in contour. The nuclei were unique in that nucleoli were always absent. Small cytoplasmic bodies which may have been extruded nucleoli were found in the oocytes of I. macrourus, but not in P. nasuta.The cytoplasm in the bandicoot oocytes resembled that of other marsupials and some eutherians in that it was highly vacuolated with most of the organelles concentrated peripherally. Within the central region of the bandicoot oocytes there were crystalloids which were similar to those in oocytes of primordial follicles and in unilaminar blastocysts of I. macrourus.