bluuebunny/crossref_metadata_2025 huggingface dataset:
Microdissection by ultrasonication: Scanning electron microscopy of the epithelial basal lamina of the alimentary canal in the rat
Authors: Low Frank N. , McClugage Samuel G.
Published: February 2005

The epithelial basal lamina of the various parts of the alimentary canal of the rat was exposed by removal of the overlying epithelium. This was achieved by prolonged fixation in OsO4 or immersion in aqueous boric acid or both, followed by dehydration in acetone and exposure to ultrasonic vibration.

The surface of the esophageal basal lamina is undulating with smooth hills and valleys, the smallest of which model the basal surfaces of the germinal cells of the epithelium. The stomach presents a perforated appearance because of ostia formed by evaginations of the basal lamina to enclose glands. In the small intestine, clavate rather than cylindrical villous cores are separated by ostia of intestinal crypts. In the large intestine, ostia are separated by broad areas of basal lamina in the cecum but are close together in the colon. The complex contours of the basal lamina are largely determined by the basal surface of the overlying epithelium but may be affected by structures in the underlying interstitium. Subepithelial lymph nodes, for example, are covered by a conspicuously porous basal lamina. Each nodule may be surrounded by ostia of as many as 20 crypts of Lieberkühn. The basal lamina of the ileocecal valve displays gradual transition from ileum to cecum.
Quantitative determination of the intracellular fate of internalized plasma membrane in dissociated pituitary prolactin cells utilizing a radioiodinated cationic ferritin probe (CFI*) and electron microscopic autoradiography
Authors: Rosenzweig Lionel J. , Kanwar Yashpal S.
Published: February 2005

Dissociated anterior pituitary cells derived from estrogen‐treated female rats were incubated with radioiodinated cationic ferritin (CFI*) for 2 min and subsequently in the absence of CFI* for varying periods of time up to 3 hr in order to quantitate, using electron microscopic autoradiography, the distribution of retrieved plasma membrane in these cells. Following a 2‐min incubation with CFI*, autoradiographic grains were found to be associated almost exclusively with the plasma membrane. With increasing periods of incubation in the absence of CFI*, grain‐density analysis revealed increasing levels of CFI* in multiple intracellular organelles. The levels of CFI* were greatest for the lysosomes, intermediate for the mature secretory granules, and least for the Golgi cisternae and immature secretory granules. These findings are consistent with the idea that a portion of the retrieved plasma membrane is degraded in lysosomes and that the remainder is recycled to organelles comprising the secretory pathway to be reutilized in successive waves of the secretory cycle.
The morphology and hormonal responsiveness of developing skeletal elements in chick limb buds
Authors: Ballard Timothy A. , Biddulph David M.
Published: February 2005

While parathyroid hormone (PTH), calcitonin (CT), and certain prostaglandins (PGs) are known to regulate the metabolism of both osteogenic and osteolytic cells of the adult skeleton through an adenosine 3′,5′‐monophosphate‐dependent mechanism, little is known about the development of this hormonally mediated response in embryonic skeletal tissues. In the present study, the responsiveness of embryonic skeletal elements to PTH and PGE2 was examined during various stages of development utilizing cAMP concentrations as an indicator of hormone‐receptor interaction. The cytology of the limb skeletal system was examined also at each stage tested in order to compare the differentiated cellular phenotypes with their hormonal responsiveness. Prior to differentiation of cartilaginous elements in developing limb buds (stage 20–21), cells were responsive to PGE2 and epinephrine (EPI) but not to PTH. The first consistent response to PTH occurred coincident with the initial differentiation of the cartilage phenotype in limb buds (stage 24–25). A responsiveness to both PTH and PGE2 was progressively increased as maturation of cartilaginous and osteogenic elements occurred (stage 26–35). The initial response to CT was detected within cartilage rods in which osteogenic cells had differentiated (stage 33–35). The results of this study indicate that PGE2‐sensitive cells exist within the developing limb prior to cytodifferentiation. The development of PTH responsiveness within embryonic chick limb buds is correlated with the onset of both chondrogenesis and osteogenesis in vivo.
The early development of the hypoglossal nerve and occipital somites in staged human embryos
Authors: O'Rahilly Ronan , Müller Fabiola
Published: February 2005

Serial sections of 105 human embryos (including 20 silver preparations) from stage 11 (24 days) to stage 22 (54 days) were studied, and 23 graphic reconstructions were prepared. The hypoglossal nucleus is evident at stage 12 and becomes isolated from other efferent nuclei at stage 14. The first hypoglossal nerve fibers appear at stage 12. The roots unite at stage 14 and the main trunk arrives in the tongue at stage 15. Four occipital somites can be identified during stage 13, and the sclerotomic material forms two bilateral masses. The fourth sclerotome separates in stage 14 and develops like a vertebra. This and the remaining sclerotomic material form the basioccipital and exoccipital parts of the chondrocranium, which are the first to appear. Four occipital myotomes develop and grow towards the tongue as the “hypoglossal cord”, which arrives prior to the hypoglossal nerve. The developmental similarity in the hypoglossal region between birds and mammals, combined with experimental studies in birds, renders it extremely likely that the hypoglossal musculature in mammals also is derived from occipital somites. The present study is the first in which this conclusion is adequately supported in the human. This investigation aids in the interpretation and timing of origin of variations (e.g., bipartite hypoglossal canal) and anomalies (e.g., persistent hypoglossal artery).
Microvascular architecture of the pampiniform plexus‐testicular artery system in the rat: A scanning electron microscope study of corrosion casts
Authors: Ohtsuka Aiji
Published: February 2005

The vascular architecture of the rat pampiniform plexus was studied by scanning electron microscopy of vascular corrosion casts. The plexus consists of a thick bundle of many anastomosing veins that entirely and closely surround the convoluted segments of the testicular artery. This specially developed close contact of the pampiniform plexus with the testicular artery may allow heat exchange between the plexus and the artery to maintain the cooled condition of the testis. The epididymal arteries are also closely surrounded by the networks of the epididymal veins. It is likely that heat exchange may operate even between these epididymal vessels. The ductus deferens is provided with no vascular channels for such heat exchange. A loose or coarse capillary network is always observed between the testicular artery and the pampiniform plexus. This network is supplied by the epididymal arteries and drains into the pampiniform plexus.
Dimensional analysis and dynamic response characterization of mammalian peripheral vestibular structures
Authors: Ramprashad Fred , Landolt Jack P. , Money Kenneth E. , Laufer Jerry
Published: February 2005

Extensive morphometric measurements were made on the vestibular system of the rabbit (Oryctulagus cuniculus), the gerbil (Meriones unguiculatus), the chinchilla (Chinchilla laniger), and the squirrel monkey (Saimiri sciureus) from serial sections of temporal bones. Additionally, a more limited set of measurements were also completed on the owl monkey (Aotus trivirgatus), the Capuchin monkey (Cebus sp.), the harp seal (Pagophilus groenlandicus Erxleben, 1777), and the two‐toed sloth (Choloepus sp.). The following measurements were made: (1) radius of curvature (R) of each membranous semicircular canal (herein called semicircular duct—see nomenclature in Nomina Anatomica (1968)) (2) cross‐sectional diameter of the ducts and the osseous semicircular canals, and (3) some pertinent morphometrics of the cristae ampullares and the utricle. In all species studied (1) the radii of curvature of the three semicircular ducts are dissimilar, with that of the lateral duct being as small as, or smaller than, those of the anterior and posterior ducts; (2) R for the anterior duct is largest in the harp seal and the rabbit; (3) the canal and duct dimensions are largest in the Capuchin and squirrel monkeys, the two‐toed sloth, and the harp seal, and smallest in the gerbil; (4) the proportion of otic fluid “space” that is occupied by endolymph shows a ranking of gerbil > rabbit > two‐toed sloth > chinchilla = owl monkey > squirrel monkey > Capuchin monkey > harp seal; and (5) the gross ampullary and utricular dimensions are largest in the harp seal and smallest in the gerbil. These measurements were used for determining the time constants describing semicircular‐canal dynamics in the Steinhausen (1931, 1933) and Oman‐Marcus (1980) equations.
Enzyme histochemical differentiation of white adipose tissue in the rat
Authors: Hausman G. J. , Thomas G. B.
Published: February 2005

Subcutaneous adipose tissues from fetal and young rats were studied with enzyme histochemical techniques. Lipid staining and histological evaluation were also utilized to compare the development of a wide variety of enzyme activities to cytoplasmic lipid deposition and morphological differentiation of adipocytes. Three distinct stages of adipose‐tissue differentiation were postulated. In stage III, adipocytes were morphologically differentiated (rounded, basal‐lamina positive) and enzyme reactive for many enzymes. In stage II, however, adipocytes were reactive for some enzymes but were not morphologically differentiated. Stage I adipose tissue was histologically distinct from connective tissue but did not contain lipid‐laden cells or enzyme‐reactive cells. Stages I and II (95%) were predominant in fetuses, whereas stage III (90%) was predominant in young animals. Histochemical analysis of adipocytes in newborn rats established the metabolic competence of these cells despite their small size. These studies indicate that enzymatic differentiation of adipocytesclearly precedes morphological differentiation.
Arterial anatomy of chicken embryo and hatchling
Authors: Levinsohn E. Mark , Packard David S. , West Elizabeth M. , Hootnick David R.
Published: February 2005

The arterial pattern in chicken hatchlings was investigated by microangiography and microscopic analysis of cleared specimens. The hatchling arterial pattern was found to resemble strongly the pattern that has been described for the adult chicken. Several minor variations in this pattern were found which were probably due to species, strain, or age differences. We also investigated the arterial pattern in chicken embryos aged 4.5 to 21 days of incubation. The hatchling pattern was fully developed by approximately 8 days of incubation. Some similarities were found to exist between the embryonic pattern in the chicken embryo and that described for the human embryo.
Surface topography and distribution of cell types in the rat nasal respiratory epithelium: Scanning electron microscopic observations
Authors: Popp James A. , Martin Joseph T.
Published: February 2005

Several cell types were identified in the rat nasal respiratory epithelium using scanning electron microscopy. In addition to the previously described ciliated, nonciliated, and goblet cells, the nasal brush cell was identified based on its surface characteristics and its location between nonciliated epithelial cells. Scanning electron microscopy clearly showed the differences in distribution of cell types in the nasal mucosa. The ciliated cells increase in number from the anterior to the posterior areas of the respiratory epithelium with a corresponding decrease in nonciliated cells. However, even at a single cross‐sectional area of the nasal cavity, the various surfaces have different proportions of ciliated versus nonciliated cells, e.g., the medial surface of the nasal concha has more ciliated cells than other surfaces. Brush cells are distributed between nonciliated cells of the respiratory epithelium on most surfaces of the nasal cavity including the conchae and the lateral wall. Based on the available information, scanning electron microscopy will be useful in future studies to determine the effects that inhaled toxicants have on cells and on the location of lesions.
Lobular and cellular patterns of early hepatic glycogen deposition in the rat as observed by light and electron microscopic radioautography after injection of 3H‐galactose
Authors: Michaels John E. , Hung Julia T. , Garfield Sanford A. , Cardell Robert R.
Published: February 2005

Very low hepatic glycogen levels are achieved by overnight fasting of adrenalectomized (ADX) rats. Subsequent injection of dexamethasone (DEX), a synthetic glucocorticoid, stimulates marked increases in glycogen synthesis. Using this system and injecting 3H‐galactose as a glycogen precursor 1 hr prior to sacrifice, the intralobular and intracellular patterns of labeled glycogen deposition were studied by light (LM) and electron (EM) microscopic radioautography. LM radioautography revealed that 1 hr after DEX treatment, labeling patterns for both periportal and centrilobular hepatocytes resembled those in rats with no DEX treatment: 18% of the hepatocytes were unlabeled, and 82% showed light labeling. Two hours after treatment with DEX, 14% of the hepatocytes remained unlabeled, and 78% were lightly labeled; however, 8% of the cells, located randomly throughout the lobule, were intensely labeled. An increased number of heavily labeled cells (26%) appeared 3 hr after DEX treatment; and by 5 hr 91% of the hepatocytes were intensely labeled. Label over the periportal cells at this time was aggregated, whereas centrilobular cells displayed dispersed label. EM radioautographs showed that 2 to 3 hr after DEX injection initial labeling of hepatocytes, regardless of their intralobular location, occurred over foci of smooth endoplasmic reticulum (SER) and small electron‐dense particles of presumptive glycogen, and in areas of SER and distinct glycogen particles. After 5 hrs of treatment with DEX, the intracellular distribution of label reflected the glycogen patterns characteristic of periportal or centrilobular regions.
The cytoarchitecture of the wall and the innervation pattern of the microvessels in the rat mammary gland: A scanning electron microscopic observation
Authors: Fujiwara Takashi , Uehara Yasuo
Published: February 2005

This report describes the morphology of the smooth muscle cells, pericytes, and the perivascular autonomic nerve plexus of blood vessels in the rat mammary gland as visualized by scanning electron microscopy after removal of connective‐tissue components. From the differences in cellular morphology, eight vascular segments were identified: (1) terminal arterioles (10–30 μm in outer diameter), with a compact layer of spindle‐shaped and circularly oriented smooth muscle cells; (2) precapillary arterioles (6–12 μm), with a less compact layer of branched smooth muscle cells having circular processes; (3) arterial capillaries (4–7 μm), with “spidery” pericytes having mostly circularly oriented processes; (4) true capillaries (3–5 μm), with widely scattered pericytes having longitudinal and several circular processes; (5) venous capillaries (5–8 μm), with spidery pericytes having ramifying processes; (6) postcapillary venules (10–40 μm), with clustered spidery pericytes; (7) collecting venules (30–60 μm), with a discontinuous layer of circularly oriented and elongated stellate or branched spindle‐shaped cells which may represent primitive smooth muscle cells; and (8) muscular venules (over 60 μm), with a discontinuous layer of ribbon‐like smooth muscle cells having a series of small lateral projections. No focal precapillary sphincters were found.

The nerve plexus appears to innervate terminal arterioles densely and precapillary arterioles less densely. Fine nerve fibers are only occasionally associated with arterial capillaries. Venous microvessels in the rat mammary gland seemingly lack innervation.
Light‐ and electron‐microscopic observations of the tail bud of the larval lamprey (Lampetra japonica), with special reference to neural tube formation
Authors: Nakao Taisuke , Ishizawa Akimitsu
Published: February 2005

Serial transverse and horizontal sections of the tail of the 26‐day larval lamprey, Lampetra japonica, were observed by light and electron microscopy. The axial structures in the tail of the larval lamprey seem to differentiate from the prospective materials derived individually from the tail bud. The latter consists of two closely adjoined cell populations (C1 and C2). C1 is a small cell cluster located posterior to the other group (C2) and consists of loosely arranged polymorphous cells. The cell cluster extends cranially as a cell sheet on the ventral surface of C2; somites differentiate from this cell sheet. C2 is composed of cells elongated mediolaterally and stacked horizontally to form a compact cell mass which is covered on each lateral surface by a basal lamina. The upper one‐third of C2 seems to differentiate into the neural tube, anteceding other axial structures. The middle one‐third of C2 seems to develop into the notochord, and the lower one‐third into the subchord and the undefined cell cord. The central canal develops in the upper one‐third of C2 through the following events: (1) appearance of cilia and a small cavity between adjoining cells; (2) appearance of microvilli in the cavity, in addition to cilia; and (3) development of junctional complexes along the luminal borders of cells surrounding the cavity. Together with these events, cells surrounding the cavity increase in number, acquiring apicobasal polarity and radial arrangement. The cavity itself enlarges by incorporation of periciliary clefts and fusion of cavities with each other to establish the central canal. Near the caudal end of the neural tube, the central canal is directly confluent with the connective‐tissue space through an opening in the dorsal wall of the neural tube.
Relationship between chromaffin cells and blood vessels in the rat adrenal medulla: A transmission electron microscopic study combined with blood vessel reconstructions
Authors: Kikuta Akio , Murakami Takuro
Published: February 2005

The rat adrenal medulla architecture was examined using a combination of medullary blood vessel reconstructions and transmission electron microscopy. The peripheral radicles of the central vein and the medullary capillaries of the medullary arteries were thus precisely identified in the electron microscopic observations. The observations confirmed that the peripheral segments of the central vein were sinusoidal vessels with an attenuated and fenestrated endothelial wall. No ultrastructural differences were observed between segments lined by epinephrine‐storing cells and those lined by norepinephrine‐storing cells. The findings suggest that these peripheral segments of the adrenal central vein were sites of cortical hormonal effects on the adrenal medulla. The vessel structure does not support the hypothesis that medullary chromaffin‐cell development is controlled by selective distribution of adrenal blood vessels.
The effect of dietary consistency on gross and histologic morphology in the craniofacial region of young rats
Authors: Bouvier Marianne , Hylander William L.
Published: February 2005

Three groups of weanling rats and three groups of juvenile rats were fed diets which differed in physical consistency for periods of 5 and 8 weeks, respectively. In both the weanling and juvenile rats, one group was fed a soft diet, a second group was fed a hard diet, and a third group was initially fed the soft diet and then was switched to the hard diet for the remainder of the experimental period. The effects of these differences in dietary consistency on gross and histologic morphology of the craniofacial region were examined. Significant differences were found in the dimensions and morphology of the condyle and condylar cartilage as a result of the differences in dietary consistency in both the weanling and juvenile groups. Soft‐diet rats generally had smaller condyles and a thinner layer of condylar cartilage than either hard‐diet or soft/hard‐diet rats. Little change, however, was found in the overall dimensions of the mandible and maxilla in any of the groups of rats.
Genesis of B lymphocytes in the bone marrow: Extravascular and intravascular localization of surface IgM‐bearing cells in mouse bone marrow detected by electron‐microscope radioautography after in vivo perfusion of 125I anti‐IgM antibody
Authors: Osmond D. G. , Batten S. J.
Published: February 2005

The role of mammalian bone marrow in generating surface IgM (sIgM)‐bearing B lymphocytes is reviewed. Precursor cells in the marrow give rise to large, rapidly dividing cells bearing free cytoplasmic μ chains (cμ). The progeny of the large cμ+ cells form a population of small, nondividing cμ+ cells that mature into small lymphocytes, progressively expressing sIgM and other B‐cell surface membrane components. Newly formed sIgM+ cells soon migrate through the bloodstream to the spleen and other lymphoid tissues, where they may die after a short lifespan or be activated to produce antibody molecules. The large‐scale lymphocytopoiesis in the bone marrow thus maintains a population of rapidly renewed virgin B lymphocytes in the peripheral lymphoid tissues. This process continuously creates and selects B cell clones with the wide range of antibody specificites necessary to mediate primary humoral immune responses through postnatal life.

A technique for perfusing radiolabeled anti‐IgM antibodies in young mice has now permitted sIgM+ cells to be detected radioautographically in histological preparations of bone marrow under the electron microscope. Small sIgM+ lymphocytes are situated either singly or in small groups throughout the extravascular hemopoietic compartment of the bone marrow, often near sinusoid walls adjacent to late erythroblasts and reticular cells. Some regional concentrations of sIgM+ cells are apparent. sIgM+ cells also appear in transit through the sinusoidal endothelium and are markedly concentrated in the lumen of some sinusoids. Intrasinusoidal sIgM+ small lymphocytes have high densities of sIgM and long microvilli, on which sIgM molecules are concentrated. These studies reveal the localization and cell associations of specifically identified sIgM+ small lymphocytes in the extravascular marrow compartment and suggest that these cells may also undergo a transient intravascular storage and maturation phase. Use of this in vivo immunolabeling technique to detect other cell‐surface markers may further elucidate the microenvironmental basis of B lymphocyte genesis in the bone marrow.
Life history of cells mediating natural resistance to tumor cells and bone‐marrow transplants: The respective roles of cell lineage commitment and host environment in determining strain characteristics of natural resistance to foreign marrow grafts
Authors: Miller Sandra C.
Published: February 2005

A class of cells present in the blood and lymphoid tissues of mammals produces rapid cytolysis of tumor cells on first contact. Abundant evidence suggests that such natural killer (NK) cells play a role in tumor immunosurveillance in vivo. A similarly prompt and spontaneous activity can cause the rejection of foreign marrow transplants. These phenomena are known collectively as natural resistance. The cells mediating natural resistance are lymphoid in morphology, but are neither T nor B lymphocytes. Kinetically, NK cells and cells mediating natural resistance to foreign marrow grafts are themselves nondividing but are rapidly renewed from radiosensitive proliferating precursors in the bone marrow. They appear to have no long‐lived (memory) component. Newly formed NK cells have a short residence time in the spleen. Other general properties of the natural‐resistance cell lineage, including strain variation, ontogeny, and cell phenotype, are reviewed in this article. The present study aimed to examine the respective roles of cell lineage commitment and of the host environment in determining strain characteristics of natural resistance to foreign marrow grafts. Chimeras produced by inoculating mice of a strain that normally has little or no natural resistance with bone marrow from adult mice of a highly resistant strain develop resistance to a third‐party marrow allograft. Such chimeras do not develop the full rejection capacity of the high‐resistance strain, however; and chimeras created by inoculating marrow from infant mice develop less resistance than those reconstituted by bone marrow from adult mice. The results demonstrate that the ability to reject foreign marrow grafts develops as an intrinsic property of the natural‐resistance cell lineage. The host environment may provide an additional influence, however, particularly in the initial development of natural resistance in early postnatal life.
Tissue localization and retention of antigen in relation to the immune response
Authors: Tew J. G. , Mandel T. E. , Phipps R. P. , Szakal A. K.
Published: February 2005

Antigen persists for months or even years in lymphoid tissues of immune animals and this antigen is believed to participate in the induction and maintenance of B‐cell memory as well as in the maintenance of serum antibody levels. In the present report we describe the phenomenon of antigen localization and long‐term retention on mouse follicular dendritic cells (FDCs). The antigens used were injected in the hind footpads of immune mice and the popliteal lymph nodes were the lymphoid organs generally studied. In addition to presenting the morphological features of mouse FDCs, we report the results of a study of the mechanism of antigen migration from the site of initial localization in the lymph node subcapsular sinus to the regions of follicular retention in the cortex. The migration was followed by light and electron microscopy. The results support the concepts that immune complexes are trapped in the subcapsular sinus and are transported by a group of nonphagocytic cells to follicular regions. The mechanism of transport may involve either migration of pre‐FDCs with a concomitant maturation into FDCs, or cell‐to‐cell transport utilizing dendritic cell processes and membrane fluidity; or a combination of the two mechanisms may be in operation.
Cellular basis of graft‐versus‐host reactions
Authors: Clancy John
Published: February 2005

The biologic basis of Graft‐Versus‐Host Disease (GVHD) is presented as an extremely complex immunopathologic syndrome that involves interaction between many different donor and host cell types. A model of acute lethal GVHD was employed where adult unirradiated (DA X LEW)F1 rats were injected with LEW spleen and lymph node cells. Controls received the same dose of syngeneic cells. At intervals from 2 to 21 days after cell injection, GVHD and control animals were killed and nonadherent cell suspensions prepared from their lymph nodes, spleen and peripheral blood. Cell suspensions were treated with LEW‐anti‐DA‐alloantiserum or normal LEW serum and then analyzed for sIgM+ (B cells), W 3/13+ (T cells), and IgG‐Fc receptors (FcR). Evidence is discussed for the selective removal of host cells with the alloantiserum. In addition, the level of naturally cytolytic (NK/NC) cells was assessed by adding GVHD and control nonadherent lymphoid cells to heterologous lymphoma and sarcoma target cells. Evidence is presented that during acute GVHD, in this parental →F1 combination, there is an early increase within most compartments of donor as well as host W 3/13+ and W 3/13+FcR+ cells. NK/NC cells are increased as well at day 7. During middle stages of acute GVHD, host sIgM+ cells predominate. Late‐stage acute GVHD rats contain few donor and host W 3/13+FcR+, and NK/NC cells but many null cells most of which are FcR−. The importance of unraveling the nature of donor‐ and host‐cell interactions occurring during acute GVHD, which result in rats whose lymphoid tissues are severely depleted of all nonadherent lymphoid cells but FcR− null cells, is discussed.
Influence of colchicine and vinblastine on the intracellular migration of secretory and membrane glycoproteins: I. Inhibition of glycoprotein migration in various rat cell types as shown by light microscope radioautography after injection of 3H‐fucose
Authors: Bennett G. , Parsons S. , Carlet E.
Published: February 2005

Previous studies have shown that colchicine and vinblastine inhibit secretion in many cell types by interrupting the normal intracellular migration of secretory products. In the present work, radioautography has been used to study the effects of these drugs on migration of membrane and secretory glycoproteins in a variety of cell types. Young (40 gm) rats were given a single intravenous injection of colchicine (4.0 mg) or vinblastine (2.0 mg). At 10 min after colchicine and 30 min after vinblastine administration, the rats were injected with 3H‐fucose. Control rats received 3H‐fucose only. All rats were sacrificed 90 min after 3H‐fucose injection and their tissues processed for light microscope radioautography.

Examination of secretory cell types such as ameloblasts and thyroid follicular cells in control animals revealed reactions of approximately equal intensity over the Golgi region and over extracellular secretion products, while in drug‐treated rats most of the reaction was confined to the Golgi region. In a variety of other cell types, including endocrine cells (e.g., hepatocytes) and cells generally considered as nonsecretory (e.g., intestinal columnar cells), reaction in control animals occurred both over the Golgi region and over various portions of the cell surface. In drug‐treated animals, a strong Golgi reaction was present, but reaction over the cell surface was weak or absent.

These results indicate that in many cell types, colchicine and vinblastine inhibit migration out of the Golgi region not only of secretory glycoproteins, but also of membrane glycoproteins destined for the plasma membrane.
Development of elastic fibers of nuchal ligament, aorta, and lung of fetal and postnatal sheep: An ultrastructural and electron microscopic immunohistochemical study
Authors: Fukuda Yuh , Ferrans Victor J. , Crystal Ronald G.
Published: February 2005

The morphogenesis of elastic fibers of the nuchal ligament, aorta, and lung of sheep was studied by light microscopy, transmission electron microscopy, and immunohistochemical methods for the detection of elastin. The degree of maturation of the amorphous materials of elastic fibers was assessed morphologically in preparations stained by the tannic acid and periodic acid methenamine‐silver methods. With both of these methods, the amorphous components of mature fibers stained less intensely than did those of immature fibers. Elastic fibers in early stages of development consisted of many microfibrils and few, small, branching masses of immature amorphous material. Thicker fibers were formed by the coalescence of growing masses of amorphous materials. In late stages of formation of elastic fibers, the mature amorphous materials were associated with few microfibrils; and they were partially surrounded by immature amorphous materials associated with many microfibrils. Antielastin antibody reacted evenly with amorphous materials in very early stages of elastic‐fiber development, but reacted only with the other zones of amorphous materials in later stages; it also reacted with the microfibrils in all stages. These findings were interpreted as indicating that the microfibrils were associated with small amounts of elastin on their surfaces. This conclusion is in agreement with ultrastructural observations showing (1) that development of microfibrils precedes that of the amorphous material and (2) that the microfibrils adjacent to the immature amorphous materials are covered with small amounts of tannnic acid‐positive amorphous materials. These observations suggest that microfibrils serve as sites for elastin deposition, both in early elastogenesis and in subsequent growth of elastic fibers. However, the nature of the interaction between elastin and microfibrils remains unknown.
Functional anatomy of the peripheral olfactory system of the african lungfish Protopterus annectens owen: Development of the primary olfactory pathway during postembryonic growth
Authors: Derivot Jacques H.
Published: February 2005

Seven specimens of the African lungfish ranging in size from 4 to 350 gm were used for the study of changes in the olfactory nerve and bulb during postembryonic growth as expressed by the increasing number of lamellae of the olfactory organ. Serial semithin sections were used, and the data were studied mathematically. The number of axons of the olfactory nerve, the surface area of the bulb, and the number of mitral cells increase exponentially; the mitral cell density decreases exponentially; and the calculated average convergence (counted axons/counted mitral cells) of axons onto the cells of the bulbar relay increases exponentially. Convergence figures obtained are smaller than those cited by other authors; two factors might explain this: first the mode of calculation, and second the fact that every year this fish undergoes a 6‐month starvation stage marked by degeneration of the primary olfactory structure. A preliminary view of the primary olfactory pathway using serial‐section reconstructions is proposed: An orderly projection of the mucosa onto the bulb takes place after a 90° rotation of the system of two perpendicular axes which apply to both the olfactory organ and the olfactory bulb. This study suggests an original attempt at relating the postembryonic change in convergence and projection to the primary processing of the olfactory message.
Structure, development, and cytochemical properties of the nucleolus‐associated “round body” in rat spermatocytes and early spermatids
Authors: Schultz M. C. , Hermo L. , Leblond C. P.
Published: February 2005

The “round body,” a spherical structure typically associated with a nucleolus in male germ cells of the rat, has been examined in the electron microscope using routine and cytochemical methods to determine its structure, composition, and mode of development. Cytochemical analysis indicates that the round body includes neither nucleic acid nor lipid, but is composed of nonhistone protein which appears in the form of 1.6‐nm‐wide fibrils. Development begins in late leptotene, when a single round body appears in each spermatocyte as an irregular spheroid located along the inner surface of the nuclear envelope. During subsequent stages of the meiotic prophase, the round body leaves the nuclear envelope, becomes a regular sphere, and gradually enlarges from a diameter of 0.4 μm in leptotene to 1.6 μm in diplotene. Concurrently, lacunae appear within its substance and enlarge. At each maturation division, the amount of round‐body material is decreased by about half, presumably because the constituent proteins are dissociated at metaphase, distributed between the two daughter cells at telophase, and reconstituted into half‐sized round bodies. As spermiogenesis proceeds, the round body shrinks gradually and disappears at step 8.

Soon after its appearance at leptotene, the round body becomes associated with and is surrounded by the pars granulosa of one of the nucleoli. Moreover, 3H‐uridine incorporation into nucleolar RNA is high as long as the size of the round body increases, but is low or absent when it decreases. It is possible, therefore, that the round body exerts some control on nucleolar activity in meiotic cells.
Development of the vascular bed in the rabbit ear: Scanning electron microscopy of vascular corrosion casts
Authors: Morris Judith L. , Bevan Rosemary D.
Published: February 2005

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

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

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

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

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

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

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