bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrastructure of mouse olfactory mucosa
Authors: Frisch Donald 
Published: February 2005

AbstractThe fine structure of the olfactory mucosa has been investigated with particular reference to those aspects of the morphology which may be significant in chemoreception. Morphology of the supporting cells of the epithelium indicate that they function in mucus production or regulation. Bowman's glands were found to consist of two cell types, both of which also seem to contribute to mucus production. Olfactory receptor cells were found to be completely covered by the mucus including the atypical olfactory cell cilia that project above the surface of the epithelium. The potential role of these cilia in initial reception is discussed. Lack of intervening cytoplasm between adjacent olfactory cell cytoplasm has been noted with the consequent possibility that electrical interaction between cells may occur. This may be significant in subsequent evaluations of electrical potentials recorded from the mucosa.
The relationship between the dimensions of the fibres and the number of nuclei during normal growth of skeletal muscle in the domestic fowl
Authors: Moss F. P. 
Published: February 2005

AbstractBetween 0 and 266 days of age the weight of the pectoral and gastrocnemius muscles of chickens increased 300–600‐ and 40–90‐fold respectively depending on the breed and sex. In both muscles the mean cross‐sectional area of the fibres and the total number of nuclei (estimated from DNA determination) maintained a constant ratio during growth. This suggests that for individual fibres the cross‐sectional area increased in proportion to the number of nuclei. This phenomenon is discussed in relation to current knowledge concerning the mode of growth and multinucleation of skeletal muscle fibres.In the pectoral muscle, between 0 and 266 days, the cross‐sectional area of the fibres increased in proportion to the two‐thirds power of the muscle weight, which suggests that the length and diameter of the fibres maintained a constant ratio. The same relationship existed for the gastrocnemius for two months, after which the fibre cross‐sectional area increased in proportion to the muscle weight, which suggests that the fibre length was then constant.
Involution and regeneration of the thymus in mice, induced by bacterial endotoxin and studied by quantitative histology and electron microscopy
Authors: Gad Palle , Clark Sam L. 
Published: February 2005

AbstractLipopolysaccharide from S. typhosa, injected intraperitoneally into Swiss albino mice, produced acute thymic involution—maximal at 48 hours after injection, followed by regeneration that was complete within 5 to 7 days. Using tissues fixed and embedded for electron microscopy, cell counts were made with the light microscope and cytological details were examined in electron micrographs. The cellular events of involution and regeneration were similar to those produced by injection of adrenal glucocorticoids, but it remains to be determined whether or not endotoxin acts on the thymus by inciting adrenal cortical secretion.Involution appeared to be the result of both the death of small lymphocytes and reduced lymphopoiesis in the thymus. Within 48 hours, macrophages had cleared away the cellular debris and medullary epithelial cells showed signs of hypertrophy and increased putative secretory activity. Subsequently, large lymphocytes proliferated at an accelerated rate in the subcapsular cortex, the cortex grew in width by the accumulation of small lymphocytes, and regeneration ceased when the thymus had reached its former size.These observations provide circumstantial evidence for the hypothesis that in regeneration, medullary epithelial cells increase their production of a lymphopoietic hormone which stimulates mitotic proliferaton of cortical lymphocytes.
Morphogenesis of the placenta and fetal membranes of the tree shrews (family tupaiidae)
Authors: Luckett Winter Patrick 
Published: February 2005

AbstractThe paucity of information on the early developmental stages and the necessity for re‐evaluation of the phylogenetic implications of the tupaiid fetal membranes have stimulated the present study.Neonatal tupaiids possess prominent bilateral endometrial pads that run the length of each uterine horn. These gland‐free pads are the sites of implantation and placentation in adults. Implantation is bilateral and superficial. Multinucleated giant cells differentiate from the cytotrophoblast of the attachment sites; they facilitate the marginal expansion of the placental disc by detaching the paraplacental epithelium from its basement membrane.Prominent bilateral chorio‐vitelline placentae develop and remain functional through early limb bud stages. Decidual cells fuse to form “decidual knots” during this period.The bilateral chorio‐allantoic placentae are labyrinthine endotheliochorial. The trophoblast of the labyrinth is entirely syntrophoblastic, similar to the condition in the armadillo placenta. Epithelioid mesenchymal cells in the labyrinth are strikingly similar to those of the shrew placenta. The large allantoic vesicle and free vascular yolk sac persist. Amniogenesis occurs by folding.Uterine glands remain secretory throughout pregnancy; iron is probably supplied to the fetus in this manner.
The development of the extracellular space in neonatal rat inferior colliculus: An electron microscopic study,
Authors: Pysh Joseph John 
Published: February 2005

AbstractRat inferior colliculi were fixed by intracardiac perfusion of 4% methanol‐free formalin in an isotonic phosphate‐sucrose buffer, dehydrated in ethanol and studied during the first two weeks of postnatal life. The extracellular space during the first week was made up of intercellular gaps about 100–150 Å wide and large intercellular lakes (1–3 μ long) which diminished in size and number as maturation proceeded. Similar intercellular lakes were found in tissue fixed by immersion in glutaraldehyde containing ruthenium red. In these tissues an intense ruthenium red reaction product, distributed extracellularly, suggested an intercellular substance comparable to that described in adult brain. Intercellular lakes were also found in tissue dehydrated in acetone. Morphometric estimations indicated the extracellular space of neuropil during the first week to be about twice that of the adult, which was approached progressively.
Cytological studies of muscle dedifferentiation and differentiation during limb regeneration of the newt Triturus
Authors: Lentz Thomas L. 
Published: February 2005

AbstractDuring limb regeneration of the newt Triturus, muscle first dedifferentiates giving rise to mesenchymal cells which, subsequently, differentiate to reform normal muscle. In dedifferentiating muscle, myofibrils and elements of the sarcoplasmic reticulum decrease gradually in number. Myofilaments become less distinct and seem to be supplanted by zones of amorphous material. Large masses of glycogen accumulate in dedifferentiating cells and mitochondria show a transient enlargement. In the later stages of dedifferentiation, glycogen decreases in amount while cytoplasmic ribosomes and cisternae of rough‐surfaced endoplasmic reticulum appear. Mesenchymal cells are formed by disappearance of all traces of myofilaments, by further elaboration of rough endoplasmic reticulum, and increase in number of Golgi complexes.During the earliest stages of differentiation, muscle has less endoplasmic reticulum and many more free ribosomes which occur in clusters or linear chains. Thin (−70 A) and thick (−135 A) filaments appear in the cytoplasm, often in association with ribosomal olusters, and shortly thereafter aggregate into small fibrils. In early fibrils, the thin filaments overlap the thick to produce I and A bands and the free ends of the thin filaments converge and cross to mark the site of the Z line. Fibrils enlarge by addition of filaments along their sides and at their ends. In larger fibrils, the H band and M line are apparent. Initially, the transverse tubular system develops by the confluence of vesicular inpocketings of the surface plasma membrane. The smooth sarcoplasmic reticulum is continuous with rough‐surfaced membranous cisternae. Some of the smooth tubules, probably sarcoplasmic reticulum, contain intracisternal masses of dense granular material and are situated adjacent to the Z line. When dense material occurs in the membranous structures, material of similar density and texture appears within the adjacent Z line. Normal muscle fibers are formed by fusion of myoblasts, increase in number and size of myofibrils, organization of transverse tubules and sarcoplasmic reticulum into triads, loss of ribosomes, and appearance of glycogen.
Relation of types of dietary fat to cardiovascular damage in mice
Authors: Wicks Mark S. , Ball Carroll R. , Williams W. Lane 
Published: February 2005

AbstractNine edible oils or fats (hydrogenated coconut, cod liver, Wesson, linseed, olive, butter, lard, corn and cocoa‐butter) were fed for 50–90 days to study the relation of saturation, chain length and essential fatty acid content to production of cardiovascular lesions. The specific oil or fat (selected for ranges in the above variables) was used as the dietary lipid in a high‐fat (28%), low‐protein (8%), hypolipotropic diet. Half of the animals received identical diets containing choline chloride (2 gm/100 gm of diet) as a lipotropic supplement.Atrial mural thrombosis and ventricular myocardial necrosis and calcification developed in all dietary groups. Atrial thrombosis was the most frequent lesion. The greatest incidence of atrial thrombosis occurred in mice fed the choline‐deficient, butter‐containing diet (92%) and the lowest incidence with the supplemented cod liver oil diet (20%). The diet containing unsupplemented hydrogenated coconut oil produced the greatest incidence of ventricular necrosis (79%) and that with choline‐supplemented cocoa‐butter the lowest (8%). Ventricular calcification was most extensive within the unsupplemented cod liver oil group (83%), most limited in the supplemented lard group (5%). In general, choline‐supplemented diets produced a lower incidence of cardiac damage. Little correlation existed between the composition and characteristics of specific fats and their activity in producing the specific cardiac lesions observed here.
Fine structure of the developing trout erythrocytes and thrombocytes with special reference to the marginal band and the cytoplasmic organelles
Authors: Sekhon Sant S. , Beams H. W. 
Published: February 2005

AbstractThe cytological changes accompanying the development of red blood cells of trout were studied. These changes appear to parallel closely those seen in the maturation of red blood cells of mammals. Immature erythrocytes of the trout contain mitochondria, Golgi complex, rough and smooth endoplasmic reticulum, centrioles, bundles of microtubules and numerous ribosomes in their cytoplasm. With progressive differentiation and maturation such cells appear to shrink in size, acquire a biconvex ellipsoid form, lose most of their cytoplasmic organelles and concomitantly increase their hemoglobin content. Mitochondrial degradation begins early in the process of maturation and usually consists of the following sequence of morphological changes within them: the appearance of small dense bodies, degeneration of the cristae and the formation of lamellar bodies. Degenerating mitochondria are often observed bulging from the surface of the cell, suggesting that they are in the process of being extruded from it. However, this observation does not preclude the possibility that mitochondria may also be disposed of in situ through the action of lysosomal enzymes. It is suggested that the disappearance of mitochondria and other cytoplasmic organelles contributes to the volumetric shrinkage which accompanies the maturation of trout red blood cells. The existence of an equatorially oriented “marginal band” of microtubules has been confirmed in this material in agreement with studies on other species. A band of microtubules was also observed in trout thrombocytes. It is concluded that the marginal band plays an important role in the maintenance of the flat ellipsoidal shape of these cells as has been suggested by other investigators studying other vertebrate forms.
Development of the lateral musculature in the teleost, Brachydanio rerio: A fine structural study
Authors: Waterman Robert Earle 
Published: February 2005

AbstractThe lateral musculature in the midbody region of the teleost, Brachydanio rerio, was examined by light and electron microscopy in the adult and six developmental stages. Two main divisions of the adult lateral musculature are described: (1) a superficial portion composed of small, dark fibers with high fat content and succinic dehydrogenase (SDH) activity; and (2) a deep portion composed principally of larger, pale, “deep fibers” showing little SDH activity and containing little fat. Some “intermediate fibers” are also present in the deep portion near the horizontal septum. Myofibrils of all cell types appear ultrastructurally similar.A general outline of myotomal differentiation has been established for the midbody somites. Myogenesis begins at the medial surface of the somite between the 20‐ and 25‐somite stages and progresses laterally. Shortly before hatching, the myotome contains two structurally dissimilar types of young muscle cells. The appearance of these two muscle cell populations in larvae and fry supports the hypothesis that they develop into the superficial and deep portions of the adult lateral musculature. The intermediate fiber population is present by 2 1/2 months. The most lateral cells of the somite form a layer of flattened cells covering the lateral myotomal surface in the 33‐somite embryo, and are considered to form the dermatome in this species.
The development of the baboon (Papio sp.) placenta during the fetal period of gestation
Authors: Houston Marshall L. 
Published: February 2005

AbstractBaboon placentae ranging in age from 45 to 175 days were studied for progressive changes in their morphology. The baboon embryo implants superficially and develops a single, discoid, villous hemochorial placenta. The remainder of the chorion is membranous and a true decidua capsularis is not formed. A lobular structure is developed during the fetal period. At 45 days the amnion only partially fills the chorionic cavity but by 60 days has expanded and the two membranes are directly contiguous. Trophoblastic tissue is of two types: cytotrophoblast and syncytiotrophoblast. Cytotrophoblast is found primarily in the chorionic plate and cytotrophoblastic shell. The chorionic villi are originally composed of a double layer of trophoblast; cytotrophoblast internally and syncytiotrophoblast externally. The cellular layer gradually disappears so that by full‐term the villous walls are formed by a single layer of syncytiotrophoblast. Hofbauer cells are common within the villous cores, diminishing in number toward term. Large amounts of collagenous connective tissue develop in the chorionic plate and in the villi, and fibrin and fibrinoid materials accumulate in the basal plate and anchoring villi. The endometrium is decidualized to its greatest extent by the beginning of the fetal period and undergoes only minor cytological alteration throughout the remainder of gestation.
Two classes of spermatogonial stem cells in the monkey (Cercopithecus aethiops)
Authors: Clermont Yves 
Published: February 2005

AbstractTo analyze the behavior of spermatogonia in the monkey, the cytological features, topographical arrangement and frequency of the two classes of type A (A1, A2) and the four classes of type B (B1–B4) spermatogonia were determined in dissected tubules, fixed in Carnoy, stained with hematoxylin and mounted “in toto.” The capacity of spermatogonia to divide was also analyzed in radioautographed testicular sections from an animal injected with tritiated thymidine.The type A1 spermatogonia, characterized by nuclei containing deeply stained, finely granulated chromatin, were found to be non‐dividing elements. The type A2 spermatogonia, characterized by nuclei showing palely stained, coarsely granular chromatin, all divided in stages IX–X of the cycle of the seminiferous epithelium to yield equal numbers of new type A2 cells and type B1 spermatogonia. The type B1, as the other type B cells, were characterized by nuclei containing granules or flakes of deeply stained chromatin. While the type A2 spermatogonia remained dormant until stage IX of the following cycle, the type B1 cells all divided during stage XII to yield twice their number of type B2 spermatogonia. These, in stage II, divided to give twice as many type B3, which, in stage IV, divided to produce twice as many type B4 spermatogonia. Lastly, in stage VI, the latter elements all divided to yield spermatocytes.Thus, the type A1 spermatogonia, did not appear to be actively involved in the production of spermatocytes and were tentatively considered as “reserve stem cells;” the type A2 spermatogonia, were identified as “renewing stem cells.”
Cyclic changes in ovarian morphology during the menstrual cycle in Macaca mulatta
Authors: Koering Marilyn J. 
Published: February 2005

AbstractTwenty‐seven mature female macaques were ovariectomized at various times during the menstrual cycle. The ovaries were sectioned serially and each vesicular follicle was measured and classified according to size and developmental state. Also noted was the presence of differentiated and undifferentiated glandular tissue.The data showed that when the corpus luteum was active the largest follicle in each animal was not less than 1 mm in diameter, and that when the corpus luteum began to degenerate follicular enlargement commenced. Most follicles became atretic when under 1 mm in diameter, except for a few in the late follicular stage. The maximal diameter for an atretic follicle was 3.1 mm and for a developing follicle 6.3 mm.Interstitial gland tissue (theca interna of atretic follicles) was noted in large amounts just before ovulation while minimal amounts were present throughout the rest of the cycle.Other glandular types occasionally seen were aberrant and accessory corpora lutea, cords of cells in the stroma and adrenal rests.
The role of the parafollicular cell of the thyroid gland in the pathogenesis of congenital osteopetrosis in mice
Authors: Marks Sandy C. , Walker Donald G. 
Published: February 2005

AbstractCongenital osteopetrosis as manifested in the grey‐lethal, microphthalmic and osteosclerotic stocks of the house mouse is characterized by an increased rate of bone matrix formation, hyperplasia of the parafollicular cell population of the thyroid gland and hypocalcemia. Osteopetrotic mice were abnormally resistant to the tendencies of parathyroid extract to promote hypercalcemia and to depress osteogenesis. The results of this investigation suggest that the parafollicular cell is the source of an osteoblast‐stimulating factor and that an excess of this factor results in osteopetrosis.
Features of trigeminal mesencephalic nucleus structure and organization. I. Light microscopy
Authors: Hinrichsen Colin F. L. , Larramendi Luis M. H. 
Published: February 2005

AbstractThe morphology and distribution of cells in the trigeminal mesencephalic nucleus were compared in newborn and adult mice, and in adult rats and cats. No gross morphological differences indicated a somatotypic subdivision of the nucleus. Changes in cell morphology in the adult mouse as compared with the newborn, are possibly related to the relatively late innervation of muscle spindles. Cell counts indicated that cell number increased not only with growth of the animal but also with increasing complexity of the jaw musculature. Analysis of the trigeminal motor root in the adult mouse showed a unimodal distribution of myelinated fibers that numericaly could not encompass both motor and mesencephalic fibers. No provision for the Y motor system appeared to be present. A substantial proportion (1:7) of cells were in soma‐soma contact. The possible functional implications of these cell clusters were discussed.
The opisthonephric kidney of the sea lamprey of the great lakes, Petromyzon marinus L. II. Neck and proximal segments of the tubular nephron
Authors: Youson John H. , McMillan Donald B. 
Published: February 2005

AbstractThe spatial arrangement of the five basic segments of the tubular nephron of the sea lamprey is reversed between ammocoetes and adults due to differences in the position of the glomus. The initial segment, the ciliated neck segment, resembles the pronephric nephrostome. The proximal segment is divided into two distinct regions, the pars convoluta followed by the pars recta, and has a brush border which reacts positively with the periodic acid‐Schiff stain.Ultrastructurally the cells of the proximal segment resemble the corresponding cells of other vertebrates except that they lack the usual infoldings of the basal plasma membrane and they often show intercellular spaces. The mitochondria of these cells often contain filamentous and crystalline material and are usually associated with “flocculent bodies” resembling “non‐nucleoid” renal microbodies.The structure of the cells of the proximal segment suggest that they are involved in endocytosis.
An ultrastructural study of human eosinophil granules: Maturational stages and pyroantimonate reactive cation
Authors: Hardin J. H. , Spicer S. S. 
Published: February 2005

AbstractFor ultrastructural study of the formation and maturation of human eosinophil granules, bone marrow and buffy coat specimens were fixed with an aqueous solution of potassium pyroantimonate and osmium tetroxide and by conventional methods. The antimonate‐osmium tetroxide method of fixation, which is thought to permit ultrastructural localization of sodium or other cations, offered an advantage over routine methods in that it permitted recognition of four rather than two varieties of cytoplasmic granules in human eosinophils at various stages of cell development. These four granule varieties, designated A, B, C, and D, differed primarily in distribution and content of crystalloids and antimonate deposits: A granules lacked antimonate deposits and cystalloids; B granules contained a rim of deposits but lacked crystalloids; C granules possessed deposits that were present in the peripheral matrices but not in the central crystalloids; and D granules lacked deposits but contained crystalloids. Evidence is provided that these four varieties of granules represent progressive stages in the maturation of a single granule type and that granules without crystalloids are transformed into granules with crystalloids. The results also provide evidence for the presence of an as yet unidentified pyroantimonate precipitable cation in human eosinophil granules.