bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of alveolar macrophages and pulmonary surfactant(?) Obtained from the lungs of human smokers and nonsmokers by endobronchial lavage
Authors: Pratt Susan A. , Finley Theodore N. , Smith Morris H. , Ladman Aaron J.
Published: February 2005

Endobronchial lavage was performed on eight smokers and eight nonsmokers. Centrifugation of lavage fluid produces a sediment consisting of two layers, a lower compact brown layer containing cells and an upper flocculent white layer. The brown layers from the smokers were greater in volume than those from the nonsmokers. Macrophages constituted about 93% of the cells from the smokers and about 63% of the cells from the nonsmokers. These data suggest that more free macrophages occur in the lungs of smokers than nonsmokers. In addition, many of the macrophages obtained from the smokers were filled with cytoplasmic inclusions. The volumes of white layers from the smokers were smaller than those from the non‐smokers. One white layer obtained from a nonsmoker was examined in a Wilhelmy balance and proved to be surface‐active. This may suggest that surface‐active material, pulmonary surfactant, is reduced in lavage fluids from smokers.
Fine structure of the resorptive cells in the teeth of frogs
Authors: Yaeger James A. , Kraucunas Eugenia
Published: February 2005

Teeth undergoing resorption were dissected from the maxillae of frogs and prepared for electron microscopy using standard methods and methods designed to minimize demineralization. The resorptive cells overlapped one another, forming palisades. A central ruffled border was surrounded by a relatively structureless cytoplasmic “seal.” Crystals of mineral were present in the folds of the ruffled borders, and demineralized collagen fibrils were seen in the adjacent matrix in sections treated to prevent demineralization. The surfaces of the cells opposite the ruffled borders displayed numerous small villi.

The cytoplasm of the resorptive cells contained a variety of lysosomes in various stages of development, mitochondria, scattered vesicles of endoplasmic reticulum and free ribosomes. Well developed Golgi zones were frequently seen, and occasional sections passed through centrioles. Two centrioles were commonly seen in such sections, but never more. Occasional patches of cytoplasm contained mitochondria and rough‐surfaced endoplasmic reticulum, resembling “blast” cell cytoplasm.

We concluded that the resorptive cells of several mineralized tissues of various vertebrates are morphologically, indistinguishable.
The subarachnoid angle: An area of transition in peripheral nerve
Authors: McCabe John S. , Low Frank N.
Published: February 2005

The lateral limit of the subarachnoid space, where nerve roots enter and leave, forms the subarachnoid angle. This is an important site of transition for nerve sheaths. Here the perineurium of peripheral nerve leaves the surface of the nerve and extends between the dura mater and the arachnoid. The perineurium is therefore open‐ended with respect to the subarachnoid space. The central perineurial extension is histologically the same as perineurium in some areas but in others forms a layer of hydrated cells without basement membranes. These lie in close apposition with the outermost cells of the arachnoid membrane. At the subarachnoid angle the arachnoid membrane may either reflect onto the root sheath or be attached to it by punctate junctions. The root sheath covers the nerve roots as they pass through the subarachnoid space. It is composed of loosely arranged cells bound by punctate junctions. Its intercellular spaces may contain connective tissue fibrils. A single basement membrane separates it from the endoneurium. The histological structure in the region of the subarachnoid angle is consistent with clinical evidence implicating the endoneurium of nerve trunks as a pathway for the transmission of infection from the periphery to the central nervous system.
The paranucleolar structure, accessory body of cajal, sex chromatin, and related structures in nuclei of rat trigeminal neurons: A cytochemical and ultrastructural study
Authors: Hardin James H. , Spicer Samuel S. , Greene William B.
Published: February 2005

Comparative light and electron microscopic study of nuclei in rat trigeminal neurons identified two structures which are the ultrastructural equivalent of the paranucloelar structure and the accessory body of Cajal, two nucleoplasmic structures previously demonstrated in other neurons by light microscope silver staining methods. Ultrastructural evidence indicates that the dense component of the nucleolus is converted into the paranucleolar structure, which then detaches from the nucleolar surface to lie free in the nucleoplasm as the accessory body of Cajal. The cytochemistry, ultrastructure, and antimonate reactivity of the paranucleolar structure and accessory body were identical. Both structures lacked cytochemically demonstrable DNA, RNA, or basic protein.

The neuronal nuclei also contained Feulgen‐positive sex chromatin bodies that adhered to the nucleolus, the nuclear membrane, or to both of these structures in specimens of female but not male rats. The ultrastructure and antimonate reactivity of these bodies closely resembled that of heterochromatin clumps but differed markedly from that of the paranucleolar structures and accessory bodies.

Additional structures characterized ultrastructurally included patches, granular bodies, and flakes. These structures, like the paranucleolar structure and the accessory body of Cajal, are apparently unique to nuclei of neurons. Cytochemical methods showed that the patches contained basic protein but no nucleic acid.
The fine structure and development of the neck region of the mammalian spermatozoon
Authors: Fawcett Don W. , Phillips David M.
Published: February 2005

The cross‐striated connecting‐piece in the neck region of the mammalian spermatozoon develops from material that seems to arise between the triplets in the wall of both proximal and distal centrioles. The precursor material extends radially from the centrioles and polymerizes around them to form the connecting piece. This is not composed of “segments” or “lamellae” as usually described but is a cross‐striated fibrous protein with a major period of 665 A and a complex pattern of intraperiod bands. It is considered to be homologous with the striated rootlets of cilia.

During differentiation of this region, the proximal centriole develops at one end, a cylindrical prolongation which is similar in its structure but not identical with the centriole proper. This centriolar adjunct is a transient structure. The proximal centriole persists in the mature spermatozoon, but the distal centriole disintegrates during formation of the connecting‐piece.

The outer dense fibers of the flagellum and the cross‐striated columns of the connecting piece are distinct components which arise separately and secondarily become continuous. The dense fibers originate as ridge‐like radial outgrowths from the wall of the corresponding doublets in the axonemal complex. As they enlarge they separate from the doublets throughout most of their length but they remain continuous with them at their distal ends.
The primitive erythropoietic series in the chick embryo, studied with the electron microscope
Authors: Ceresa‐Castellani Lucia , Leone Vincenzo G.
Published: February 2005

The ultrastructural aspects of the chick embryo primitive erythrocytic cell series are described. There are two points of particular interest: the appearance of ferritin in erythroblast cytoplasm in 20 somite stage embryos and the behaviour of ribosomes during the red cell maturation period, both with regard to their progressive diminution and how they are grouped in polyribosomes. Ribosomes are still present in primitive series erythrocytes, although fewer than in the immature cells, and they are mainly in group form.

A morphological comparison of the primitive red series erythrocytes with those of the definitive red series has also been made.
Influence of body weight, age, diet and sex on fat depots in rats
Authors: Schemmel Rachel , Mickelsen Olaf , Mostosky Ulreh
Published: February 2005

Weanling male and female littermate Osborne Mendel rats were randomly separated into two groups. The control group was fed a grain ration. The second group was fed a high fat ration which ultimately produced obesity. Male and female rats were killed at weaning (body weight, 50–60 gm). Thereafter rats from both diet groups were killed after an initial weight gain of about 100 gm and subsequent gains of about 150 gm. The inguinal, forelimb (axillary), interscapular perirenal, genital, xiphoid, and mesenteric and omental fat depots were removed, weighed, and weights recorded. Fat depots usually increased in weight more rapidly than overall body weight. This was typical of younger rats from both diet groups, but more pronounced in rats fed the high fat ration. The perirenal depots increased in weight more rapidly than body weight throughout the 450+ days of the study. In both sexes and diet groups, from weaning through sexual maturity, the weight of the genital fat depots increased proportionately more rapidly than body weight. Thereafter, the weight gain more nearly paralleled the body weight gain. In both diet groups, with the exception of the interscapular depot, the subcutaneous depots increased rapidly in weight during the first 100 days of life. The weight gain of these depots maintained a close relationship to body weight gain after 100 days of age. The interscapular depot in obese females increased at a very rapid rate as the animals approached 900 gm of body weight.
The time lag in the development of bronchial arteries
Authors: Boyden Edward A.
Published: February 2005

Reconstruction of the pulmonary and aortic trunks, together with adjacent structures in a 41 mm human embryo of the Carnegie Collection, demonstrates that as late as the ninth week after ovulation the bronchial artery is still a tiny vessel, arising ventrolaterally from the descending aorta at the level of the third pair of dorsal aortic‐intercostal arteries, and that any extension of it along the bronchial tree must still be of capillary calibre since no visible branches can be followed into the root of the lung. In sum, bronchial arteries arise later, more slowly and from a lower position than has hitherto been assumed. By contrast, the anomalous systemic pulmonary artery that supplies the right posterior basal bronchopulmonary segment in this fetus and which now arises from the aorta just above the celiac artery, is a robust vessel. Such systemic pulmonary arteries must arise very early, at the level of the definitive pulmonary arteries, and keep pace with them in growth, whether or not their stems descend along the aorta with the migrating celiac artery.
Development of adrenergic innervation in the puppy kidney
Authors: McKenna Olivia C. , Angelakos Evangelos T.
Published: February 2005

The development of the adrenergic innervation of the puppy kidney from birth to two months of age was studied with the fluorescence histochemical method of Falck and Hillarp in conjunction with chemical analyses for catechol‐amines in the cortex and medulla of the kidney. At birth adrenergic fibers were found entering the kidney with the renal arteries and following the arterial supply into the inner cortex. In this area the fibers were found in association with the interlobular arteries and afferent arterioles. Fibers were also seen in the neogenic zone of the cortex until the fourteenth day after birth when this area disappeared. From the fourteenth to fifty‐sixth day the adrenergic fibers were found extending to the interlobular arteries and afferent arterioles of the developing cortex. The levels of norepinephrine measured in the cortex during the first two months after birth reflected the increasing number of adrenergic nerves. In the medulla vasa recta were present at birth; norepinephrine and fluorescent fibers, however, were not found until 21 days. At this time nerves were found emerging in bundles from the arcuate connective tissue sheath and joining the vasa recta in the outer medulla. At subsequent ages the number of fibers in each bundle and the norepinephrine levels increased.
Morphology of alveolar lining layer
Authors: Kikkawa Yutaka
Published: February 2005

The extracellular alveolar lining layer (ALL), composed of both surface film and hypophase, is described under different conditions and fixatives.

With primary osmium fixation of small blocks the ALL is not preserved. Lamellar and homogeneous osmiophilic bodies are scattered at random within alveoli. Occasionally the surface film remains within an alveolus but the hypophase is not seen. Poor preservation of the ALL is thought to be due to the limited ability of osmium to cross link proteins and to the mechanical deformation of the alveoli which inevitably accompanies the cutting of fresh lung into small blocks. This leads to the escape of alveolar air and a loss of the air‐liquid interface.

With primary glutaraldehyde fixation of the whole lung, the ALL is well preserved in many alveoli. The hypophase is mostly homogeneous but occasionally contains osmiophilic bodies and lattices. There are no lamellar and homogeneous osmiophilic bodies within the air space of the alveoli when the ALL is preserved, which suggests that primary osmium fixation of tissue leads to the dislodgement of these osmiophilic bodies from the hypophase.

The electron densities of the surface film, the hypophase and the capillary fluid are alike in a given preparation but vary considerably with the concentration of the glutaraldehyde solution and the buffer vehicles used. It is pointed out that in phosphate‐buffered preparations the hypophase, the basement membrane and the capillary fluid are highly electron‐dense which makes difficult the localization of an electrondense tracers.
Fine structural study of rat molar cementum
Authors: Jande Sohan S. , Bélanger Leonard F.
Published: February 2005

In cementum of rat molars, the cementoblasts were found to differ from pre‐cementoblasts in having an increased granular endoplasmic reticulum, greater number of polyribosomes and denser material in the cisternae of granular E. R. as well as in the general cytoplasm. The cementocytes with maturation showed a gradual decrease in the size of the Golgi complex and the granular endoplasmic reticulum. On the other hand, an increase in the number of lysosomes was observed. Parallel with these intracellular changes, the pericullular space became irregular in width, its fibrillar material became replaced by a flocculent material. Ocasionally, structurally different matrix was seen. At the cemento‐dentinal junction the cementocytes showed degenerative changes indicative of degeneration and death. The epithelial cells, remnants of Hertwig's root‐sheath, some of which get enclosed in the cementum, accumulated filamentous material as well as spheres of amorphous substance. These cells eventually degenerated, leaving their debris in the lacunae. The degeneration of epithelial cells did not seem to affect the cementum matrix in their immediate vicinity. Some collagen fibrils of the cementum, seemed to differ structurally from those of the periodontal membrane. Thin fibrils, about 160 Å in diameter, were also observed in the cementum.
The microcirculation of the bone marrow
Authors: De Bruyn Peter P. H. , Breen Philip C. , Thomas Thurlo B.
Published: February 2005

The microcirculation in the bone marrow has been studied in the femur, tibia, and humerus of guinea pigs, rats, and rabbits. Used were whole mounts of bone with bone marrow in situ, perfused and not perfused with India ink, thick sections (0.5 to 1.0 mm) of the same material, and also serially cut histological sections. It is concluded that the major blood supply to the bone marrow is transosteal. Direct intramyeloid connections of the arborizations of the nutrient artery with the sinusoids are rare. The great majority of the terminal capillaries of the nutrient artery enter the bone, where they anastomose with the intraosteal vessels which in turn connect with the sinusoidal network at the osteomyeloid junction. In addition, numerous direct links exist between the periosteal vessels and the vessels in the osteal canals.
The dog pancreatic X cell: A light and electron microscopic study
Authors: Lazarus Sydney S. , Shapiro Stanley H.
Published: February 2005

A light and electron microscopic study was conducted on the X cell of the normal dog pancreas. These cells were identified by their acidophilic cytoplasmic granules which do not stain with iron or phosphotungstic acid hematoxylin and also show a distinctive multilobate nucleus. They were found to be neither argyrophilic nor argentaffinic. Ultrastructurally, when fixed in osmium alone, the X cell cytoplasm contained numerous rounded, smooth membrane bound secretory granules with content of low electron density. However, after double fixation in glutaraldehyde and osmium the granules appeared irregularly round, ovoid or kidney shaped with content which may vary from electron lucent to homogeneously electron dense with gradations between. The functional significance of the X cell is unknown. However, its structure showed it to be a distinct, active secretory element, independent of other pancreatic exocrine and endocrine cell types.
Cell replication of mesenchymal elements in adult tissues. I. The replication and migration of mesenchymal cells in the adult rabbit dermis
Authors: Kaye Gordon I. , Siegel Linda F. , Pascal Robert R.
Published: February 2005

Autoradiographic determination of the number and distribution of replicating mesenchymal cells in rabbit dermis was carried out using animals sacrificed between two hours and 21 days after a multiple‐dose‐pulse of 3H‐thymidine. Initial labeling of mesenchymal cells occurred principally in a zone immediately subjacent to the germinative epithelium. This was confirmed by in vitro studies of the uptake of 3H‐Tdr by rabbit skin during one hour of incubation. Five days after the in vitro pulse of 3H‐Tdr there was a fifteen‐fold increase in the number of labeled cells, considerable dilution of label and migration of labeled cells so that they were evenly distributed throughout the full thickness of the dermis. At 21 days the number of labeled cells was similar to that found at five days, but there was further migration of labeled cells toward the deep dermis.

This tissue provides an example of appositional replication and divergent migration of an epithelial‐mesenchymal system.
Microvascular organization of the adult human testis
Authors: Kormano Martti , Suoranta Hannu
Published: February 2005

The microvascular architecture of the adult human testis was studied from autopsy material using microangiography. The intratesticular arterial vessels show peculiar coiling independent of the age of the subject. These arteries run in either a centripetal or a centrifugal direction and give rise to inter‐tubular and peritubular capillary networks which are basically similar to those of the rodent testis. Venous drainage is directed either towards the surface of the testis or towards the rete testis. Some capillaries in the vicinity of the seminiferous tubules penetrate some of the layers of the tunica propria. The rete testis has a completely different and rather sparse microvascular architecture, and both the rete and the tunica albuginea receive blood from extratesticular sources as well as from the testis.
Development of the amphibian pineal organ; Fine structure during maturation
Authors: Hendrickson Anita E. , Kelly Douglas E.
Published: February 2005

The pineal organ of the West Coast newt Taricha torosa has been examined electron microscopically one, two and five years after metamorphosis. Although the organ has flattened with concomitant reduction of the lumen, the basic larval organization of the pineal photoreceptors and supportive cells is retained. Photoreceptors demonstrate both basal synaptic regions and outer segments, although the latter are disorganized as compared to the larva. Supportive cells, which increase in volume with age, contain membranous debris suggesting a sequence of phagocytosis of outer segments. Tubular vesticular membrane complexes enclosing 450 Å tubules are found in supportive cell processes adjacent to the basal lamina near blood vessels. Despite these changes the adult pineal organ retains the morphological entities thought to be necessary for photoreceptive function.
A phase and electron microscopic study of vasculogenesis and erythropoiesis in the yolk sac of the mouse
Authors: Haar Jack L. , Ackerman G. Adolph
Published: February 2005

By seven days of gestation, the yolk sac of the mouse has a sheet of mesoderm adjacent to the basement membrane separating it from the endodermal epithelium. Localized proliferations of this mesoderm produces thickened cellular regions which transform into the angioblastic cords; all of these developmental cells are attached by tight junctions and desmosomes. By eight and onehalf days, lumina appear within the angioblastic cords; the peripheral cells become attenuated and form endothelial cells which will line the primitive vessels while the more central cells become the primitive erythroblasts of the blood island.

The process of vasculogenesis and lumenization occurs between eight and onehalf and nine days of gestation and has been correlated with the reduction of cellular junctions between angioblasts and fixed primitive erythroblasts, a loss of the visceral basement membrane and the formation of wide intercellular channels between endodermal epithelial cells. The primitive erythroblasts comprising the blood islands have abundant polysomes, sparse rough endoplasmic reticulum and possess coated vesicles and ferritin aggregates in their cytoplasm and coated invaginations of their plasma membrane. By nine days of gestation, the primitive erythroblasts lose their attachments and become free in the vitelline vessels. Mitochondria of the primitive and free erythroblasts are slightly enlarged and have lighter matrices than angioblasts and mesodermal cells. By 10 to 11 days of gestation, as differentiation proceeds, coated vesicles and invaginations become more numerous and the developing erythroblasts gradually decrease in both cell and nuclear size. Concomitant with these changes is the decrease in the number and size of the mitochondria, a decrease in polysomal numbers and an increase in hemoglobin and cytoplasmic density.
Ruthenium red and violet. I. Chemistry, purification, methods of use for electron microscopy and mechanism of action
Authors: Luft John H.
Published: February 2005

The properties of the inorganic dye ruthenium red are presented with emphasis upon its use for electron microscopy of cells and tissues. Although commercial ruthenium red often can be used directly, it always contains various impurities and by‐products. One of these, termed ruthenium violet, can be isolated and is useful by itself. Absorption spectra of the ruthenium dyes and common impurities are given so that an assay is possible for any sample. Convenient fixative recipes containing ruthenium red or violet are provided together with constraints necessary for a reliable reaction to label extracellular acidic mucosubstances. Perfusion was not successful. The specificity of the ruthenium red reaction was evaluated by spot testing with 57 substances, and by titration with chemically defined pectins. The results indicate that ruthenium red, as a hexavalent cation, precipitates a large variety of polyanions by ionic interaction, and that its classical reaction with pectin is typical rather than specific. New data are presented regarding its reaction with phospholipids. For electron microscopy, a further reaction with OsO4 amplifies the feeble electron density, which is the counterpart of its intense optical labeling, to a practical level resulting in strong contrast. An hypothesis is presented for the mechanism underlying this intensification.
Autoradiographic studies of intramedullary schwann cells in irradiated spinal cords of immature rats
Authors: Gilmore Shirley Ann
Published: February 2005

This investigation examined the development of intramedullary Schwann cells. The presence of these cells in spinal cords of rats irradiated when three days old and examined 15 or more days later had been noted previously in this laboratory. The present study is an autoradiographic evaluation of spinal cords from groups of rats receiving a single injection of tritiated thymidine at an interval from 7 to 15 days after irradiation (3 days of age) and killed four hours to seven days following injection. The earliest post‐irradiation interval at which the intramedullary Schwann cells were present was at nine days in only one animal. These cells were seen in approximately half of the rats injected and killed 11 days after irradiation and in all in the 15‐day‐group. In all of these cases the animals were killed four hours after injection of tritiated thymidine and a portion of this cell population was labeled. When the time between injection and autopsy was delayed for three or seven days, a decrease in intensity of the labeling was apparent and many cells were lightly labeled, indicating that cell proliferation had occurred. Although the evidence was not conclusive, the results suggested that the intramedullary Schwann cells were probably progeny of cells derived from the dorsal roots, the latter cells having been stimulated to migrate into and to divide within the spinal cord.
Neuro‐epithelial bodies (neuroreceptor or Secretory Organs?) in Human Infant Bronchial and Bronchiolar Epithelium
Authors: Lauweryns Joseph M. , Peuskens Joseph C.
Published: February 2005

Tissue sections of 15 lungs from human infants were taken immediately after death. In each case, routine staining methods and Jabonero's silver impregnation, modified by Van Campenhout, were performed. Cathecholamines were traced according to Falck's method. Each of these techniques revealed in the bronchial and bronchiolar mucosa spherical to ovoid groups of cells, which are distinct, from the surrounding epithelium by their light optical and their histochemical properties and which have been named “Neuroepithelial Bodies.”

The Neuroepithelial Body bulges into the corium and is built up of cells with a clear cytoplasm and a rounded nucleus. Its apical part protrudes into the bronchial and bronchiolar lumen mostly above the level of the ciliated cell lining and consists of small non‐ciliated cuboidal cells. After silver impregnation, they display a granular silver deposit, especially in the basal cells and appear to be innervated. The technique of Falck reveals a white to yellow fluorescence, especially in the basal area where also the argyrophilia is most marked.

The functions of these corpuscular, argyrophilic, innervated and fluorescent bronchial and bronchiolar Neuroepithelial Bodies remain unsettled. Though a separate entity, they seem to be related to the recently reported bronchial Argyrophil, Fluorescent and Granulated AFG (peptide and amine producing?) cells. They might be involved in mucosal bronchial and bronchiolar neurosecretory processes; most probably, however, they are chemo‐, stretch‐, and/or tactile neuro‐receptor organs.
The development of the periodontium: The origin of alveolar bone
Authors: Tencate A. R. , Mills C.
Published: February 2005

First molar tooth germs consisting of dental organ, dental papilla and dental follicle were dissected from one‐day old mice and transplanted subcutaneously into young adult animals of the same strain. Three to four weeks after implantation the host animals were sacrificed and the transplants harvested. The transplants were prepared for either routine histological examination or for electron microscopy. Forty tooth germs continued development with the formation of a periodontium consisting of cement, periodontal ligament and bone. Electron microscopical examination of this material demonstrated the presence of lymphocytes in association with the subcutaneous bone and thereby suggested the origin of the bone from donor tissue.
Presence of fenestrated capillaries in the skin
Authors: Takada Mitsuya , Hattori Shizuko
Published: February 2005

Capillaries of the skin have been thought to be of a nonfenestrated type according to studies of previous investigators. However, the present study revealed that fenestrations exist in the endothelium of cutaneous vessels. Capillary fenestrations are numerous in the human finger and the mouse sole and are moderately frequent in the guinea pig sole and ear. In the skin of the human chest, however, they are rarely encountered. Sometimes, endothelial fenestrations are encountered in venules as well.
Evidence of cell damage in rat salivary glands after isoproterenol
Authors: Simson J. A. V.
Published: February 2005

Isoproterenol, which stimulates cell replication in rat salivary gland acinar cells also produces cytoplasmic disruption in these cells, although there is apparently little resultant cell death. Evidence of cell damage includes loss of cytoplasmic density, vesiculation of endoplasmic reticulum, appearance of large lipid droplets within cells, and invasion of the epithelium by lymphoid elements.
A study of hematic barriers in peripheral nerves of albino rabbits
Authors: Aker F. David
Published: February 2005

Hematic barriers were studied in femoral and sciatic nerves and their peripheral branches in male albino rabbits by means of fluorescence microscopy and ultra‐freezing and drying technics. The fluorescent tracer used was a diaminoacridine, acriflavine neutral, which is non‐toxic at the 20 mg/kg dose administered intravenously, has a low molecular weight (259.7), and has a unique quality of chemically binding in vivo with nuclear DNA and RNA. This latter property of acriflavine neutral permitted the observation of fluorescent nuclei where the substance penetrated and no fluorescence where it did not penetrate. The interface between the two regions was identified as a locus of a hematic barrier.

Three hematic barrier loci were observed in spinal nerves and their branches: (1) in the plasma membranes of the cells forming inner lamellae of the “perineurial epithelium,” (2) in the luminal face of the plasma membrane of endothelialcellsforming the wall of endoneurial capillaries, and (3) in the “perineurial epithelial” sheath which surrounds endoneurial precapillaries. These barriers appeared to be dependent on normal living physiologic processes for their proper maintenance. In addition, they were very similar to some of the hematic barriers associated with the central nervous system.
The fine structure of the monkey (Macaca) sertoli cell and its role in maintaining the blood‐testis barrier
Authors: Dym Martin
Published: February 2005

The monkey Sertoli cell, a tall columnar cell, extends from the basement membrane of the seminiferous epithelium to the tubule lumen. Its nucleus occupies a basal position and reveals extensive nuclear envelope infoldings. A zone of fine filaments, approximately 0.5 μ in thickness, invests the nucleus and appears to prevent other cell organelles from approaching it. The basal cytoplasm is characterized by numerous mitochondria and abundant smooth endoplasmic reticulum. Lipid droplets, 3 to 4 μ in diameter, membrane‐limited dense bodies of various shapes and densities, Golgi cisternae, scattered free ribosomes and parallel profiles of rough endoplasmic reticulum are common. The more apical portions of the cell contain longitudinally oriented microtubules and rod‐shaped mitochondria, but other organelles are rare.

The seminiferous tubules of monkeys are surrounded by three to five circumferentially arranged cells that overlap each other but are separated by intercellular spaces of at least 300 to 400 Å. Tracers such as horseradish peroxidase and lanthanum nitrate injected intravascularly readily pass between the peritubular cells and enter the germinal epithelium. Within the epithelium the tracers outline the spermatogonia and early spermatocytes by permeating the surrounding intercellular spaces. Further penetration toward the tubule lumen is effectively prevented by the occluding tight junctions joining adjacent Sertoli cells. Thus, in monkeys the peritubular epithelioid cells do not impede vascularly introduced tracers from penetrating into the germinal epithelium. The only morphological component of the blood‐testis barrier in the macaque appears to be the Sertoli‐Sertoli occluding junction.
Ultrastructural morphology of the normal nasal respiratory epithelium of the mouse
Authors: Matulionis Daniel H. , Parks Harold F.
Published: February 2005

The nasal respiratory epithelium of the mouse has been studied at the ultrastructural level. The tissue was found to be a rather typical pseudostratified columnar ciliated epithelium, superficially different but basically similar to tracheal and bronchial epithelium in the same species, and clearly similar in most respects to that of other mammals. Four cell types were distinguished: ciliated columnar, secretory (goblet), intermediate, and basal.

The ciliated cells, which exhibited typical surface cilia and microvilli, were characterized by a distinct stratification in the arrangement of subcellular components in their supranuclear cytoplasm. Beginning at the apical end and proceeding basally, the following strata were seen: an ectoplasmic region relatively free of organelles; an area rich in vesicular and tubular membrane profiles; a mitochondrial zone; a layer rich in ribosomes and polyribosomes; and a stratum of Golgi complexes.

Secretory (goblet) cells were observed at various stages of secretion droplet accumulation. Cells in the earliest stage, characterized by a dense content of sER in the supranuclear cytoplasm, were similar to the “non‐ciliated” cells of the mouse's lower respiratory tract. Some of the secretory cells contained dilated cisternae of rER which were engorged with a relatively electron‐dense material. The possible significance of these inclusions is discussed.

Unlike the other cell types, intermediate and basal cells displayed no features indicative of specialized function.
Studies of human adipose tissue in culture. II. Effects of insulin and of medium glucose on lipolysis and cell size
Authors: Smith Ulf , Jacobsson Bo
Published: February 2005

Explants of human adipose tissue were maintained for one week in vitro and the effect of iodoacetate, insulin and of the medium glucose concentration on cell size determined. In the presence of iodoacetate the mean cell size remained unaltered indicating that the morphologic changes reflect the cellular rates of metabolism. Addition of insulin did not prevent a decrease in mean cell size of explants with a large initial mean offering indirect, morphologic evidence for the insulin resistance in large adipocytes. The data support our previous suggestion that the cellular insulin sensitivity is an important parameter to control adipocyte size and, hence, enlargement of the adipose tissue.
Alterations in the epithelial surface of A/Jax mouse palatal shelves prior to and during palatal fusion: A scanning electron microscopic study
Authors: Waterman Robert Earle , Ross Lawrence M. , Meller Samuel M.
Published: February 2005

The surfaces of palatal shelves from carefully staged A/Jax mouse embryos were examined with the scanning electron microscope prior to and during palatal fusion. No change was observed in the appearance of cells covering the oral and nasal surfaces of the shelves. A change was observed, however, in the region of presumptive fusion, and was detectable on vertical shelves just prior to transposition. This change initially involved surface cells along the future medial edge of the shelf at the level of the second to third rugae. It was characterized by a loss of distinct cellular boundaries, the appearance of intercellular gaps caused by apparent retraction of adjacent cells, and a progressive accumulation of filamentous material at the surface. These alterations spread posteriorly along the medial edge of the shelf during transposition and fusion. While it was impossible to determine the precise nature of the surface change from S.E.M. data alone, the fact that it both preceded closure and was restricted to the region of subsequent contact and fusion between the shelves suggests it may be a prerequisite for normal palatal fusion and may represent an expression of the acquisition of a potential to fuse similar to that proposed for palatal fusion in vitro.
Release and restoration of the secretory granules in the convoluted granular tubules of the rat submandibular gland
Authors: Cutler Leslie S. , Chaudhry Anand P.
Published: February 2005

Morphological changes in the secretory cells of the convoluted granular tubules of the rat submandibular gland were studied following the stimulation of salivary secretion with pilocarpine nitrate. The mechanism of synthesis of secretory protein by these cells is controversial and this study was undertaken to help elucidate this mechanism. It was found that the cells expelled the contents of their secretory granules in the typical exocrine fashion. Shortly after secretion, increased volumes of rough endoplasmic reticulum appeared in the cytoplasm. The endoplasmic reticulum underwent a sequence of morphologic changes and disappeared from the cytoplasm as the secretory products were restored. Additionally, the Golgi complex showed changes. The results of this study indicate that the secretory cells of these tubules follow the accepted exocrine pattern of secretory production and discharge and that they synthesize exportable proteins at a rate far below that of other exocrine systems. The relationship of these findings to the observation that under non‐stimulated conditions the cytoplasm of these cells lacks some of the organelles which are normally associated with exocrine type protein production is discussed.
Quantitative analysis of the synaptogenic period in the trigeminal mesencephalic nucleus
Authors: Alley Keith E.
Published: February 2005

The morphogenesis of chemical synapses in the trigeminal mesencephalic nucleus of the hamster was examined in the electron microscope. The relatively small complement of synapses and the simple geometry of these neurons facilitates quantitative analyses of synaptic development. Emphasis focused on the chronology of synaptic maturation and the length of the synaptogenic period in this nucleus. Synaptic endings first appear on the soma at three or four days after birth. These early terminals form desmosome‐like junctions without any synaptic vesicles. The surface density of terminals (synapses/100 μm of perimeter) increases rapidly from 5 to 15 days when it is approximately equivalent to the adult. However, calculations that also take into account the expansion in cell surface area suggest that the actual number of terminals continues to increase as the cells grow. This indicates that these neurons may retain their synaptic capacity and continue to add new synaptic sites for a longer period than proposed for other systems. Structural characteristics of these synapses in the adult suggest they may be inhibitory in nature and thus regulate the interaction of electronically coupled clusters of neurons.
Chronological and cytological details of fertilization and early embryonic development in the domestic pig, Sus scrofa
Authors: Hunter R. H. F.
Published: February 2005

The sequence of cytological events from sperm penetration of the oocyte until emergence of the blastocyst from the zona pellucida was studied in 1441 eggs from 134 animals in which the time of ovulation had been controlled precisely by gonadotrophin injection. Observations were also made on the rate of egg passage through the Fallopian tubes, on the process of denudation, and on the increase in numbers of spermatozoa associated with the zona pellucida.

Eggs may be penetrated and activated within three hours of mating or insemination close to the time of induced ovulation. A decondensation and swelling of the chromatin is seen very soon after incorporation of the sperm head into the vitellus, and central apposition of the pronuclei occurs three to five hours later. The male pronucleus is slightly larger than the female, and a portion of the flagellum is frequently closely associated with it until late syngamy. Cleaved embryos can be recovered within 14 to 16 hours of sperm penetration, but the two‐celled stage lasts only six to eight hours compared with 20 to 24 hours for the four‐celled stage. Embryos enter the uterus at the latter stage approximately 46 hours after ovulation. Morulae of 16 to 32 cells can occasionally be observed late on the third day of development, and blastocysts are present on the fifth day. However, the zona pellucida is not shed until the sixth day, after which the trophoblast commences the massive elongation characteristic of this ungulate blastocyst.
Cell population changes during acinus formation in the postnatal rat submandibular gland
Authors: Chang W. W. L.
Published: February 2005

The postnatal differentiation of acini in the submandibular glands of 2–42 day old rats given 3H‐thymidine was studied by using radioautographs prepared from Epon‐embedded, PAS and iron hematoxylin stained sections. The changes in morphology, population size and proliferative activity of various cell types in the gland were analyzed. At two days of age, rudimentary secretory units, designated as terminal tubules, were located at the end of the duct system and consisted of three cell types: (1) terminal tubule cells (30.7%) with darkly‐stained granules, (2) proacinar cells (23.6%) with large, lightly‐stained granules, and (3) acinar cells (1.6%) with PAS‐positive granules. The proacinar cells, which underwent mitosis, disappeared within the first two weeks of life. The terminal tubule cells increased in number between 2 and 14 days of age, but became less numerous thereafter and disappeared by six weeks. Concomitantly, the number of acinar cells increased linearly with age and at a much greater rate than that of intercalated duct cells. Yet the rate of proliferation of acinar cells was comparable to that of intercalated duct cells. The overall proliferative activity in the gland decreased with age, and was inversely correlated with the relative frequency of acinar cells in the gland. On the basis of above data, it is postulated that, during the formation of acini from terminal tubules, acinar cells have a dual origin: they arise from proacinar cells during the first one to two weeks and from terminal tubule cells between two and six weeks of age.
Muscle satellite cells: A validated technique for light microscopic identification and a quantitative study of changes in their population following denervation
Authors: Ontell Marcia
Published: February 2005

A staining technique, in which basic fuchsin, methylene blue, and Azure II is applied to 0.5 μ sections of striated rat muscle embedded in epoxy resin, has given sufficient differentiation of five nuclear types found in the muscle fascicle to warrant its use as a valid method for identifying satellite cells with the light microscope. The validity of this technique was assessed by studying serial thin and thick sections of denervated rat hind limb muscles. Nuclei “typed” light microscopically were examined under the electron microscope to determine the type of cell in which they were located. This stain technique was then applied to determine the effect of denervation on the satellite cell population of the tibialis anterior and extensor digitorum longus. In control muscle of 200 gm rats, satellite cells represented 2% of the total nuclear population. Two and three weeks after denervation they accounted for 6% and 12%, respectively. In 800 gm rats, satellite cells accounted for 0.7% of the total nuclei found in the normal muscle. Denervation increased the percentage to 3% (at 2 weeks) and 5% (at 3 weeks). Paired satellite cells were infrequently observed; however, in 0.5 μ sections a significant number of satellite cells were found to be less than 0.7 μ from a myonucleus of the same fiber. A model is proposed to explain the increase in satellite cells following denervation.
Patterns of degeneration in the caudal cochlear nucleus of the cat after cochlear ablation
Authors: Kane Eileen Cohen
Published: February 2005

Study of the caudal cochlear nucleus of the cat confirms the cochlear origin of synaptic terminals, identified in correlated rapid Golgi and electron microscopic preparations of the octopus cell area (OCA) and the dorsal cochlear nucleus (DCN) in normal cats. Type 1 and type 2 endings on octopus cell somas and basal dendrites, as well as type 1 and type 1a endings of the outer DCN, degenerate following complete ipsilateral cochlear ablations and short survival periods (12, 24, 48, 96 hours). Two distinct patterns of synaptic degeneration occur after short survival times; “dense degeneration” occurs in type 1 endings on octopus cells and several endings of the DCN. Dense terminals that contain tightly packed, but intact vesicles, occur most frequently after a 48‐hour survival period. A second type of degeneration, called “flocculent degeneration” occurs in type 1 and type 2 endings of the OCA and in type 1 and type 1a DCN terminals. Between 12 and 48 hours after ablation, the flocculent degeneration involves a continuous breakdown of organelles. Evidence for transneuronal degeneration of octopus cells and DCN granule cells is presented.
Ultrastructural organization of the sensory fibers innervating the Golgi tendon organ
Authors: Schoultz Ture W. , Swett John E.
Published: February 2005

The organization of the sensory innervation of Golgi tendon organs (GTO) from E. carpi ulnaris of the cat is described. The large Ib afferent fiber gives rise to small myelinated branches which become oriented longitudinally in a neural compartment of the GTO capsule lumen. The latter give rise to smaller, unmyelinated branches which further arborize among loosely packed collagen bundles. The unmyelinated fibers form numerous varicosities and small terminal branches which have portions of the axolemma covered only by basal lamina which intervenes between the collagen bundles and the axolemma. In places, the axon's surface may lack all investments and nerve and collagen come into intimate association. The large unmyelinated branches and their varicosities have different axoplasmic characteristics compared with the small unmyelinated terminal portions. The latter contain few or no mitochondria, vesicles, neurotubules, and neurofilaments. In addition to the description of the terminals, the similarities and differences of the innervation of the GTO, compared with other mechanoreceptors, are discussed.
Epithelial cell proliferation during organogenesis of rat colon
Authors: Eastwood Gregory L. , Trier Jerry S.
Published: February 2005

Between the 16th to the 20th day of gestation, the mucosa of the colon of fetal rats changes from a simple tube with a tiny lumen lined by stratified epithelium to a much more complex structure with a large lumen and well‐developed crypts lined by a single layer of columnar epithelium. Autoradiographic studies with 3H‐thymidine show that cell proliferation is present throughout the stratified epithelium but becomes confined to the lower half of colonic crypts immediately on their formation. The number of epithelial cells shown to be proliferating after exposure to a single pulse of 3H‐thymidine is high during this period of organogenesis but decreases rapidly after the 20th day of gestation once the adult mucosal pattern has formed.