bluuebunny/crossref_metadata_2025 huggingface dataset:
The ciliary pattern of the parietal layer of Bowman's capsule
Authors: Webber W. A. , Lee J.
Published: February 2005

The parietal layer of Bowman's capsule in man and rat has been examined by transmission and scanning electron microscopy. In both species, cilia were found to be present in a regular pattern occurring one per cell. The cilia differed in length between the immature and mature human kidney, but were consistently located near the edge of the cell nucleus. Since they are not numerous enough to have a significant propulsive role, we have postulated that they may have some other specific function. In addition to the cilia, microvilli were regularly observed on the surface of the parietal cells. They tended to be more numerous along the margins of the epithelial cells and, in contrast to the cilia, their pattern was highly variable. This variability probably indicates that they are transitory structures which can be increased or decreased in response to as yet unknown stimuli.
Electron microscopic studies of the state of myosin aggregation in the vertebrate smooth muscle cell
Authors: Bois Richard M. , Pease Daniel C.
Published: February 2005

Glycol dehydration followed by rehydration prior to conventional fixation appears to demonstrate the essential identity of the thick filaments observed in unfixed, glycol dehydrated and conventionally fixed smooth muscle. Observed differences in the solubilities of actin and myosin filaments also suggest that the thick filaments of smooth muscle are not formed by the apposition of actin filaments or by the deposition of myosin upon actin filaments. Evidence that the thick filaments of smooth muscle are not formed by an unnatural aggregation of smaller myosin aggregates or by the dissociation of myosin “ribbons” during tissue preparation is also reported. Examinations of smooth muscle contracted or relaxed by pharmacological agents appear to indicate that the myosin content of smooth muscle is aggregated into filaments in both the contracted and relaxed cell.
Correlation of serum gonadotropins, ovarian and uterine histology in immature and prepubertal rats
Authors: Knudsen J. F. , Costoff A. , Mahesh V. B.
Published: February 2005

Ovarian and uterine morphological changes were examined in the maturing Holtzman rat, ages 22–40 days, using routine histological procedures. These findings were then correlated with serum follicle stimulating hormone (FSH) and luteinizing hormone (LH), in an effort to trace the sequence of events involved in the onset of puberty (i.e., the initiation of cyclicity) which occurred most consistently in our rats at 38 days of age. Ovaries exhibited no significant weight increases prior to day 36. However, microscopic changes became apparent as early as day 30, and continued to day 38, the day of the gonadotropin surge. During this time interval, the proportion of large type 6‐7 (potentially estrogen secreting follicles) increased dramatically relative to non‐antrum containing follicles. An increasingly hypertrophied and well differentiated theca interna of the larger follicles was also characteristic of this age interval. Closely paralleling the sequence of follicular maturation, quantitative and qualitative increases in all layers of the uterus occurred. As early as day 32, the luminal epithelium had increased some three to four‐fold over earlier age groups. Similarly, the stromal endometrium and myometrium increased significantly at this time. Further increments occurred through day 34, with a leveling off at this time.

Serum FSH showed no significant increases prior to day 38, at which time levels increased some two‐fold over previously existing levels. In contrast, LH remained tonic until days 34 and 36, at which time subthreshold elevations occurred. On day 38, LH rose some 40‐fold over pre‐existing levels. Serum prolactin followed a similar pattern; levels became detectable at 33 days of age with marked elevations seen on day 35 and on day 38 of age.

From quantitative and qualitative analysis of ovarian and uterine morphology with subsequent correlations to serum gonadotropins over the maturing process, we conclude that the ovary possibly acts as a “Zeitgeber” for the gonadotropin surge and ovulation.
Human muscle spindles: Microfilaments in the group IA sensory nerve endings
Authors: Kennedy William R. , Def. Webster Henry , Yoon Kwon Sang , Jean Dou H.
Published: February 2005

The fine structure of the group IA sensory nerve endings from normal human muscle spindles was studied in transverse and longitudinal sections. Two arrangements of microfilaments, approximately 75 Å in diameter, were found in each of ten spindles examined. The first was a central aggregate of densely packed filaments. The aggregates were partly surrounded by mitochondria, and were oriented parallel to the longitudinal axis of the sensory ending as it encircled the intrafusal muscle fiber. Individual aggregate filaments of glycerinated endings appeared to react with heavy meromyosin. The second arrangement was a filamentous network in the periphery of the sensory ending profiles. These microfilaments approached and appeared to merge with the surface membrane. They resembled the microfilaments that others have described in growth cones of cultured neurons. Both types of microfilaments are thought to be involved in changing the shape of the sensory endings during stretch and relaxation of the spindle.
The effect of proteolytic enzymes and hyaluronidase on the intracellular β‐ and γ‐metachromatic granules and the matrix of rat epiphyseal cartilage
Authors: Hirschman Albert , McCabe Dorothy M.
Published: February 2005

The effects of trypsin, chymotrypsin, papain, pronase, cartilage protease and hyaluronidase on the staining of fresh epiphyseal cartilage in 0.01% toluidine blue at pH 4 was studied. Treatment with these enzymes resulted in a loss of the β‐ and γ‐metachromatic granules in the cells, and an intensification of the staining in the matrix of the lower hypertrophic zone. Treatment with collagenase also resulted in a loss of the β‐ and γ‐metachromatic granules, but did not appreciably intensify the staining of the matrix. Carboxypeptidase A, ribonuclease and bovine serum albumin, globulins, and globin had little or no effect.
The effect of ruthenium red and concanavalin A on the vitelline surface of fertilized and unfertilized rabbit ova
Authors: Gordon Mildred , Fraser Lynn R. , Dandekar Pramila V.
Published: February 2005

Fertilized and unfertilized rabbit ova were exposed to ruthenium red with the zona intact or after machanical removal, for the demonstration of mucopolysaccharides on the surface coat. Ova were also exposed to Concanavalin A. Ruthenium red bound strongly to elements of the zona and increased the opacity of the plasmalemma. There was no notable change in staining of the vitellus following fertilization. Although there were ruthenium red stained bodies resembling cortical granules in crypts in the plasmalemma, there was no evidence for cortical granule extrusion of mucopolysaccharides. The Concanavalin reaction was seen over both unfertilized and fertilized ova, demonstrating receptors for terminal α‐D‐mannopyranosyl, α‐D‐glycopyranosyl, β‐D‐fructofuranyosyl residues. The deposit on the fertilized egg surface was enormously enhanced indicating a change in the distribution of receptor sites.
Immunochemical staining of the rat adenohypophysis in organ culture
Authors: Pakurar Alice S. , Kahn Raymond H. , Conklin James L.
Published: February 2005

Rat anterior pituitaries were cytologically studied following cultivation in organ culture, with and without the addition of hypothalamic and cortical extracts. Although five distinct cell types could be identified with classical stains in the uncultivated glands, the peroxidase‐labeled antibody technique (using antibodies against STH, LTH, FSH, LH and TSH) showed that not all of the immune‐specific cell types were being identified with the classical stains. This discrepancy was magnified following culture as chromophilic cells seen with classic stains decreased in number with an increase in culture time. The peroxidase technique, however, revealed that all cells remained constant in type and number regardless of time in culture. While the addition of either hypothalamic or cortical extract to the culture medium produced cytological alterations demonstrated by the classical dyes, the antibody technique showed no such alterations. Such a comparison of staining techniques emphasizes the hazards of relying solely on histological procedures to reveal the hormonal activity of the pituitary gland.
Reciprocal synapses between cholinergic axons and small granule‐containing cells in the rat cardiac ganglion
Authors: Yamauchi Akio , Yokota Reiko , Fujimaki Yoko
Published: February 2005

Electron microscopy of the rat cardiac ganglion shows occurence of small granule‐containing cells that form reciprocal synaptic junctions with cholinergic terminals. At the synaptic junctions which are from axon to granule‐containing cell, the intraaxonal vesicles are clustered against the junctional axolemma, but dense‐cored vesicles in the postynaptic cell do not cluster towards the membrane densities in these synapses. By contrast, the synaptic zone polarized in the opposite direction shows an absence of axonal vesicles in close proximity to the postsynaptic axolemma, but there is a marked aggregation of dense‐cored vesicles towards the presynaptic specializations of granule‐containing cells. The synaptic zones are multifocal rather than bifocal, and the minimal distance separating each synaptic zone is about 0.3 μ. These findings may indicate that cholinergic excitation of some or all granule‐containing cells causes a reciprocal inhibition of one or more cholinergic terminals.
SEM preparation and observations of the hen's oviduct
Authors: Bakst M. , Howarth B.
Published: February 2005

The surface patterns of the oviduct of Gallus domesticus were examined by scanning electron microscopy (SEM) using several preparatory techniques. Ciliated epithelial cells predominate throughout the oviduct with nonciliated cells approaching an equal proportion in the magnum and isthmus. Short, randomly oriented mucosal folds which characterize the infundibulum increase in height and longitudinal orientation as they approach the magnum. Here and in the isthmus they broaden and become dimpled with glandular apertures. The folds narrow again in the uterus and vagina. Cryofracture followed by SEM demonstrate the deeper mucosal folds and submucosal tubular system.
Intestinal mucosa of the platypus, Ornithorhynchus anatinus
Authors: Krause William J.
Published: February 2005

The intestinal mucosa of the platypus takes the form of numerous transverse surface folds. These folds are made up of a lamina propria covered by pseudostratified epithelium which lies on a thick modified basement membrane. The cells of the intestinal epithelium consist of columnar cells which generally resemble typical intestinal epithelium and cuboidal cells, which are undifferentiated in appearance, show few organelles and possess an electron lucent cytoplasm. Numerous desmosomes are found between the adjacent cell membranes of both cell types. Villi are absent and appear to be represented by the large surface folds.

Intestinal glands are composed of columnar epithelium similar to that found in the intestinal glands of other mammalian species. Groups of these glands drain into common tubular ducts which follow a tortuous course and empty into the intestinal lumen between the surface folds.

The peculiar morphological features of the platypus intestinal mucosa raise questions concerning traditional concepts of intestinal gland formation as well as the origin and migration of intestinal epithelium with regard to this particular species.
Pathways of clearance in mouse lungs exposed to iron oxide aerosols
Authors: Sorokin Sergei P. , Brain Joseph D.
Published: February 2005

The history of particle clearance was studied in lungs of mice serially sacrificed at intervals up to 14 months following single exposures to an aerosol of submicronic, particulate, iron oxide used as a similitude for atmospheric dust. Clearance was followed by light microscopy in unstained and Prussian blue stained frozen and plastic embedded sections, as well as by electron microscopy, where iron oxide can be recognized by its form. Related problems were investigated through histochemical demonstration of acid phosphatase activity in pulmonary lysosomes and Prussian blue staining of various tissues after administration of iron compounds by gastrointestinal and vascular routes.

The iron particles settle extensively but not uniformly on pulmonary alveolar surfaces. Clearance is centripetal and involves two mechanisms, an extracellular mechanism fed by fluid currents sweeping across the surface, and a cellular mechanism principally involving alveolar macrophages. In the early post exposure period both actively remove deposited particles predominantly through the pulmonary airways. By 24 hours uncleared residues have become ingested and clearance thereafter results mainly from cellular action. Macrophages enter bronchial passages where they sometimes continue to pursue normal activities. A chronic phase of clearance begins when deposited particles become sequestered in macrophages of pulmonary connective tissues. These cells are reached by several routes, not least by crossing the bronchial epithelium. Particle clearance from these macrophages is very slow, and residue‐containing cells eventually congregate in lymphoid tissues surrounding major bronchi. These findings are discussed as they help to develop an overall picture of clearance from the lungs and as they bear on related topics, such as functional roles of alveolar and pulmonary connective tissue macrophages and the pathogenesis of chronic bronchial disease.
Adrenergic innervation of cat adrenal medulla
Authors: Prentice F. David , Wood Joe G.
Published: February 2005

Cat adrenal medulla was studied to determine whether or not an adrenergic nerve supply was available to medullary cells. The techniques used were those of routine electron microscopy, injection and uptake of “false” transmitter substance (5‐hydroxydopamine), injection of 6‐hydroxydopamine, which selectively destroys postganglionic adrenergic elements and a specific cytochemical method using glutaraldehyde and heavy metal techniques for cytochemical localization of biogenic amines. Each method consistently demonstrated adrenergic fibers and terminals in the adrenal medulla; these adrenergic elements contain dense, large core and small core vesicles which are not of the “dense cored” cholinergic type. Localization of adrenergic fibers and terminals is deemed significant since the latter had the bouton en passage configuration immediately adjacent to norepinephrine cells; adrenergic elements were not seen in close relationship to epinephrine cells. Consistency of the findings from the three techniques point to the fact that the norepinephrine cells of the adrenal medulla have a dual innervation, both cholinergic and adrenergic. This type of innervation pattern is not unique for the autonomic nervous system, but it has not been reported previously for adrenal medullary cells. It is believed that such an innervation pattern has functional and pharmacologic significance.
The fine structure of the myoneural junctions in the body wall muscles in Branchiobdella pentodonta whit. (Annelida, oligochaeta)
Authors: Farnesi Rosalba Maria , Vagnetti Daniela
Published: February 2005

The ultrastructure of the myoneural junctions in the body wall muscles has been studied in Branchiobdella pentodonta Whit. A single junctional type has been found. Within the terminal axon there are two types of vesicles, which differ in number, size and electron opacity. The junctional gap contains the basement membrane. The post‐junctional membrane displays concave patches on which slender projections arising from the outer lamina of the sarcolemma extend into the junctional gap. These concave patches overlie a cytoplasmic lamina made up of electron dense material.
A region of mitochondrial division in the epithelium of the small intestine of the rat
Authors: Jeynes B. J. , Altmann G. G.
Published: February 2005

Electron microscopic examination of samples from various regions of the rat small intestine was carried out. The number of mitochondria in the epithelial cells was estimated. The counts were made in sections of cells cut along their longitudinal central plane. The errors involved in extrapolating these counts to the whole cells were also estimated.

The average mitochondrial number per cell section was 21 in the lower third of the crypts, it gradually increased in the mid and upper thirds and reached about double, 42, at the villus base. The known forms of dividing mitochondria were identified in the mid and upper third of the crypts. The counts remained around 42 along the epithelium of the villi.

Crypt cells are continually produced in the lower crypt; these cells migrate to the villi while differentiating into nonproliferative absorptive cells. After inhibiting mitosis by methotrexate, this migration continued (Altmann, 1974) and mitochondrial division persisted. In segments of the jejunum isolated surgically from the functional intestine for three weeks, mitosis and cell migration continued, but no evidence of mitochondrial duplication was found.

Each mitochondrion probably undergoes a division as the crypt cells migrate from the mid‐crypts to the villus. As a result, the villus epithelial cells contain double numbers of mitochondria. It appears that the mitochondrial division is not directly related to mitosis and is elicited by a stimulus present only in the functional intestine.
The development of various generations of nephrons during postnatal ontogenesis in the rat
Authors: Goncharevskaya Olga A. , Dlouhá Helena
Published: February 2005

The structural development of individual nephrons has been investigated in the kidneys of young rats by microdissection.

Superficial, intercortical and juxtamedullary nephrons in Wistar‐Konárovice rats aged 2 to 60 days have been followed. At two and five days of age the superficial nephrons were in an early stage of anatomical development. At this time intercortical and juxtamedullary nephrons were more developed, and basically resembled similar structures in adult animals with the exception that the loops of Henle did not have a thin ascending limb.

At ten days of age all three types of nephrons were differentiated with the exception that the intercortical nephrons did not possess a thin ascending limb of Henle's loop.

At selected stages of development there appears to be a direct relation between the length of the superficial nephrons and the weight of the kidney. Since individual segments of these nephrons do not grow at the same proportional rate, this relationship does not hold when compared to kidney weight.
Characteristics of bovine lung as observed by scanning electron microscopy
Authors: Mariassy A. T. , Plopper C. G. , Dungworth D. L.
Published: February 2005

The surface characteristics of the intrapulmonary airways and alveoli of the lungs from 12 young adult cattle examined by the scanning electron microscope are described. When compared with similar studies of the lungs of various other mammalian species, the bovine lung gneerally resmebles that of other mammals except for several important features: (1) Alveolar pores of Kohn are small and extremely rare; (2) Alveolar macrophages are seldom seen in alveolar air spaces; (3) Interlobular septa completely separate the lung into distinct lobules.
An unusual modification of endoplasmic reticulum in epithelial cells of the mouse ascending colon
Authors: Michaels John E.
Published: February 2005

A rarely occurring structure that is apparently a modification of endoplasmic reticulum was observed in the epithelial cells of the ascending colon of the mouse. The structure consists of a stack of 3 to 15 parallel cisterna‐like elements separated by about 67 nm. The stacked cisternae usually are located adjacent to the basal end of the nucleus or in the region between nucleus and basal cell membrane. Top and bottom cisternae of many of the stacks have patent lumens and their outer membranes are lined by ribosomes. Most frequently, middle cisternae have attenuated lumens in their central regions. In some instances the width of the cisternal lumens is similar throughout. Closely apposed pairs of cisternae also occur. Some stacks have a concentric configuration. The intercisternal space contains tightly packed vesicles (38 nm) arranged in a hexagonal array. Many of the vesicles are connected to the membranes of the cisternae by stalk‐like projections. The vesicles also occur between the nuclear envelope and the adjacent parallel cistenae. Mitochondria are situated close to each stack.
Regeneration in free grafts of normal and denervated muscles in the rat: Morphology and histochemistry
Authors: Carlson Bruce M. , Gutmann Ernest
Published: February 2005

Intact soleus and extensor digitorum longus muscles in the rat were freely grafted to the contralateral leg after either no preliminary tretment or 14 days prior denervation. Normal muscle grafts during the first week were characterized by a central zone of degenerating original muscle fibers (disappearing by 7–9 days) and a peripheral zone, containing regenerating muscle as well as small numbers of surviving original muscle fibers. A radial gradient of regeneration was established, with more mature muscle at the periphery and less mature muscle toward the center. Denervated grafts were characterized by rapid degeneration (within 2–3 days ) of original muscle fibers in the central area, rapid appearance of regenerating muscle fibers (e.g., cross striations by 5 days) with uniform levels of differentiation throughout the graft and larger numbers of surviving original muscle fibers at the periphery. During the first week, stages of muscle differentiation in denervated grafts were attained 1–2 days earlier than comparable stages in normal grafts. Later stages of muscle differentiation were similar in both types of grafts. Histochemical studies revealed a loss of enzyme activity (phosphorylase, ATPase and SDH) in the center of early (2–4‐day) normal and denervated grafts. Denervated grafts, however, possessed a thicker peripheral rim of enzymatically active surviving muscle fibers than normal grafts. In both types of grafts the old muscle fibers in the center were replaced by enzymatically active regenerating muscle fibers which stained uniformly (ATPase) until 30 days. By 60 days a mixed fiber pattern had developed. Muscle spindles were found within the grafts.
Life span of small lymphocytes in the thymolymphatic tissues of normal and thymus‐deprived BALB/C mice
Authors: Röpke C. , Everett N. B.
Published: February 2005

Autoradiography and scintillation counting have been used after various schedules of 3H‐thymidine injections to evaluate lymphocyte kinetics in normal and thymus‐deprived BALB/C mice. The thymus was found to be an active production site of small lymphocytes, the majority of these cells having thymic residence times of three to five days. Peripheral lymphoid tissues – including spleen, lymph nodes and Peyer's patches – were dominated by long‐lived lymphocytes and produced very few small lymphocytes. Nearly identical percentages of long‐lived lymphocytes with comparable grain counts were found in the peripheral tissues. In adult thymectomized animals, and in mice thymectomized and reconstituted with bone marrow cells following total body irradiation, percentages and lifespan of long‐lived lymphocytes were found to be of the same order as in normal or sham‐operated controls. It is concluded that T cells in the peripheral long‐lived pool can be formed outside the thymus and that the bone marrow probably produces long‐lived B lymphocytes.
Electron microscopy of endothelial microvilli of large arteries
Authors: Fujimoto Sunao , Yamamoto Koji , Takeshige Yoshio
Published: February 2005

Scanning electron microscopic investigations by others have revealed “hair‐like” projections from the endothelial surface of the rabbit aorta. We have confirmed by transmission electron microscopy that endothelial microvilli are found, in a limited number of areas in the aortic arch, particularly at the presumed site of fetal origin of the ductus arteriosus and near the origin of the subclavian artery.

The microvilli are almost uniform in diameter (about 0.1 μm) and are as long as 3 μm in length. The outer leaflet of the limiting membrane shows a fuzzy appearance, and thin filaments are recognized in their interiors.

A profuse array of endothelial microvilli was also found over the entire surface of the large arteries of human fetuses. The possible hemodynamic significance of these processes is discussed.
The sertoli cell junctional specializations and their relationship to the germinal epithelium as observed after efferent ductule ligation
Authors: Ross Michael H. , Dobler Johanna
Published: February 2005

Seminiferous tubules from testes of normal and efferent ductule ligated mice were examined with the electron microscope. The tubules in the ligated animals were markedly distended and at most stages of the seminiferous cycle the epithelium exhibited a series of circumferentially‐oriented ridges. Cross‐sectional profiles of these ridges were studied with particular emphasis on the Sertoli cell junctional specializations and their relationship to the germinal cells.

In the ligated specimen the basal cytoplasm of the Sertoli cells is highly attenuated, often appearing as a thin process resting on the basement lamina. Where the cytoplasm of one Sertoli cell ends, it meets in apposition with the cytoplasm of an adjoining Sertoli cell, and at these sites, junctional specializations are present. The ridges are comprised of a stalk of apical Sertoli cell cytoplasm, often appearing like an inverted cone, with young spermatids aligned along the lateral surfaces and the more mature spermatid population embedded within the apical cytoplasm. Junctional specializations were observed along these lateral Sertoli cell surfaces. In some instances, they formed a free surface, but usually early spermatids were in contact with the junctional specializations. With respect to the more mature spermatids, the acrosomal component was typically found in relation to a junctional specialization. Germ cells at the spermatocyte stage were also noted in relation to the Sertoli cell junctional specializations.

The findings suggest that spermatocytes cross the Sertoli cell barrier and gain access to the adluminal compartment of the seminiferous tubule through the disengagement of the inter‐Sertoli cell junctional complex. It is proposed that when the inter‐Sertoli cell junctional specializations separate, the spermatocytes come in apposition with the newly freed junctional surfaces and remain in relation with them through the ensuing divisions. It appears that at some point, firm adhesion between germ cells and the junctional specializations occurs; the spermatid progeny may thus maintain contact with the original inter‐Sertoli cell junctional specializations until their release into the tubule lumen.
Observations on the fine structure of propylthiouracil‐induced “brown degeneration” in the zona reticularis of mouse adrenal cortex
Authors: Moore N. A. , Callas Gerald
Published: February 2005

Propylthiouracil (6‐propyl‐2‐thiouracil), an anti‐thyroid agent, was fed to mice in a concentration equal to 0.1% of their diet for periods of 10 and 15 weeks. The cells of the inner zone of the adrenal cortex were examined with the electron microscope. In animals receiving propylthiouracil for ten weeks mitochondria were altered and the smooth endoplasmic reticulum (SER) showed a marked focal proliferation. In contrast to control animals rough endoplasmic reticulum was abundant and was frequently associated with the hyperplastic SER. After 15 weeks these alterations were no longer present but had been replaced by a spectrum of “brown degeneration.” The less affected cells were characterized by increased numbers of liposomes and lysosomes and the more affected cells by liposomal and mitochondrial degeneration. These observations emphasize that “brown degeneration” is a true degenerative process and not a spontaneous proliferation of ceroid pigment. It is suggested that the changes described may be directly related to an alteration in cholesterol metabolism.
Chondroitin sulfate and electron lucent bodies in the pericellular rim about unshrunken hypertrophied chondrocytes of chick long bone
Authors: Kashiwa Herbert K. , Luchtel Daniel L. , Park Han Z.
Published: February 2005

Direct observation of unstained, 1 mm thick blocks of fresh epiphyseal cartilage from tibia of 15‐ and 18‐day‐old chick embryos revealed shrunken chondrocytes on its cut surfaces but unshrunken chondrocytes deep within the tissue blocks. The unshrunken hypertrophied chondrocytes are rimmed with refractile substance identified as chondroitin sulfate removable with hyaluronidase. This substance is stained metachromatically red with toluidine blue, and is stained with ruthenium red and with ruthenium red‐OsO4. The latter, observed with the electron microscope, is present as an electron dense rim, specifically about the unshrunken, hypertrophied chondrocytes between the plasma membrane and lacunar wall. By rendering the chondroitin sulfate electron dense with RR‐OsO4, electron lucent bodies (ELB) were revealed specifically about the hypertrophied chondrocytes. The ELB contain an electron dense core with radiating fibrils. The content and source of ELB, also found in the intercellular matrix, are not known. The 0.1% toluidine blue solution containing 0.2 m MgCl2 or 0.4% NaCl or KCl stained juxtanuclear clusters of granules metachromatically red. The location of intracellular granules was believed to represent a cluster of Golgi‐derived vesicles. The pericellular metachromatic, RR‐OsO4‐positive rim is believed to be an accumulation of externalized juxtanuclear metachromatic granules. The possibility that the ELB may also be externalized content of Golgi vesicles was entertained.
Transmission and scanning electron microscope studies of calcified cartilage resorption
Authors: Savostin‐Asling Irene , Asling C. Willet
Published: February 2005

The authors' previous report (Savostin‐Asling and Asling, 1973) demonstrated that Meckel's cartilage is a favorable site for study of calcified cartilage resorption. In the present study the ultrastructural features at this resorption front have been examined by transmission and scanning electron microscopes (19‐day rat fetus). Multinucleated giant cells (chondroclasts) dominated the erosion front. The many features which they showed in common with osteoclasts included abundant mitochondria, vacuolation, lysosomes, sparsity of roughsurfaced endoplasmic reticulum, and deep infoldings at loci of contact with calcified matrix. Crumbling of matrix (with mineral crystals penetrating between these foldings) and fragmentation of collagen fibrils were also seen. The propensity of chondroclasts for spanning several opened lacunae provided special opportunity to demonstrate cell surface modifications in presence or absence of matrix contact. Ameboid processes extending into lacunae were seen by both transmission and scanning procedures; they were sometimes tipped with a veil of filamentous processes as small as 0.3 μm in diameter. Most hypertrophic chondrocytes, when released from lacunae, appeared to be disintegrating. However, in accord with previous evidence of their possible merger with chondroclasts (in light microscopic studies) there was also evidence for breakdown of cell walls between a chondroclast and a chondrocyte in intimate contact, with possibility of cytoplasmic continuity.
An angiographic study of the fox testis in various stages of sexual activity
Authors: Joffre M. , Kormano M.
Published: February 2005

The arteries and veins of the fox testis were studied using an angiographic technique. The postnatal development of the testis involved only minor modification of the vasculature. In the non‐breeding season both the arteries and veins of the adult fox testis undergo extensive spiralization which completaly disappears during the breeding season. When the sequence of morphological changes in blood vessels are related to available data on changes in testicular size, blood flow and connective tissue content, it is obvious that the vascular spiralization is passive and related to shrinkage of the organ and does not primarily influence the testicular blood flow.
Appearance and disappearance of multiply ciliated follicular cells during development of the dog's thyroid gland
Authors: Nunez Eladio A. , Gershon Michael D.
Published: February 2005

Multiply ciliated follicular cells have been observed in developing thyroid glands in dogs. These cells are prominent three weeks prior to the expected date of birth but become progressively less common as development proceeds. After birth only rare isolated cilia remain. No evidence of removal of cilia by autophagy or loss into colloid was found. It is concluded that cilia are probably no longer formed by mature cells and that those already present are diluted out by progressive division of mature follicular cells.
The use of ultraviolet light to induce melanogenesis in the epidermis of the rhesus monkey: An ultrastructural and biochemical study
Authors: Erickson Kent L.
Published: February 2005

The general body epidermis of the rhesus monkey (Macaca mulatta) contains no discernible melanocytes, but after repeated ultraviolet irradiation DOPA‐positive melanocytes appear and increase numerically up to 30 exposures. With continued irradiation, however, the number again declines.

Experiments to determine how melanogenic activity, assayed by the incorporation of labeled DOPA or tyrosine, is related to DOPA positivity indicated that biochemical activity corresponded to the histochemical pattern. Ultrastructural studies demonstrated that after the exposure to ultraviolet light, a pool of indeterminate cells in the skin of rhesus monkeys developed into melanocytes. The melanosomes formed by these cells, however, differed from the eumelanin melanosomes described in other species; they had no internal filamentous matrix with periodicity but appeared similar to phaeomelanin melanosomes. Long term ultraviolet light irradiation may damage keratinocytes and render them incapable of phagocytizing melanosomes.
Kinetics of intraepithelial lymphocytes in the small intestine of thymus‐deprived mice and antigen‐deprived mice
Authors: Röpke C. , Everett N. B.
Published: February 2005

The kinetics of lymphoid cells within the epithelium of the small gut has been studied in various thymus‐deprived mice and in antigen‐deprived mice by the use of 3H‐thymidine injections and radioautography. In thymusdeprived mice —including adult thymectomized, thymectomized and irradiated, neonatally thymectomized, and nude mice —and in germ‐free mice decreased numbers of intraepithelial lymphocytes (IL) were found. On the other hand, the radioautographic results indicated that the remaining IL populations included both newly formed and long‐lived lymphoid cells in the same percentages as found in sham‐operated controls and normal mice. It is concluded that although the presence of the thymus and the antigen content of the gut is of importance to the maintenance of the numbers of cells in the lymphoid populations of the intestinal wall, the basic kinetics of these cell populations are preserved in deprived mice.
A study of germ cell morphology and duration of spermatogenic cycle in the baboon, Papio anubis
Authors: Chowdhury A. K. , Steinberger E.
Published: February 2005

Biopsy and orchiectomy specimens were collected from two adult baboons (Papio anubis) at different intervals after intratesticular injection of H3‐thymidine. Zenker‐formol or Bouin's fixed materials were stained with PASWeigert‐Hematoxylin and radioautographed using the H.S.R. (Harleco Synthetic Resin) coating technique. Morphological features of most germ cells appeared similar to those of other monkeys, except that the spermatids in steps 9 to 11 showed a spike‐like projection of the acrosome. Also, the type A spermatogonia showed some resemblance to the human type A spermatogonia. The cell associations consisted of 12 stages and a large number of tubular cross sections showed the presence of two or more stages. In Papio anubis, the zygotene spermatocytes are formed in stage VIII, and spermatozoa are released during stages V and VI.

H3‐thymidine labeling of germ cells indicated that one cycle of spermatogenesis in this species takes approximately 11 days, and complete spermatogenesis occupies 3.8 cycles, or approximately 42 days. The presence of labeled B type spermatogonia 35 days after H3‐thymidine injection indicated the existence of some stem cells. The presence of some labeled Ad spermatogonia in these specimens could not be explained. The data indicated that spermatogenesis in this monkey is somewhat different from that in other monkey species described.
Light microscopic and ultrastructural observations of the calcifying zone of the mandibular condyle in the rat
Authors: Larsson Åke
Published: February 2005

The hypertrophic stage of development of the rat mandibular condyle was investigated in 16 and 26‐day‐old rats by electron microscopy. Interest was focused on the zone of mineralization and erosion. It was observed that capillaries invaded the lower level of the hypertrophic zone, without any previous chondroclastic resorption of calcified partitions. The partitions surrounding the hypertrophic chondrocytes were not mineralized around their entire circumference at the level of capillary penetration. The capillaries were accompanied by perivascular cells but these showed no similarities to chondroclasts. Multinucleated chondro‐ or osteoclasts were however present at a lower level of the subchondral area. It is suggested that there are no inherent differences with respect to the pattern of mineralization and erosion between the epiphyseal growth plate and the developing mandibular condyle.
Numerical density of nuclei in the sheep placenta
Authors: Teasdale François
Published: February 2005

A method is described for estimating the number of nuclei of different cell types in the sheep placenta. The method was applied to the study of six placentas of different ages and the results have been correlated with data on the chemical composition and the physiology of the ovine placenta. In agreement with studies of placental DNA content, there is no demonstrable increase in the total number of placental nuclei in the last two months of gestation. However, the number of fetal mesenchymal nuclei decreases and there is a concomitant increase of fetal endothelial nuclei from 80 days to term. These changes correlate with a decrease in volume of the core of the placental villi and increase in umbilical blood flow.
Astrocytic gap junctions in the rat lateral hypothalamic area
Authors: Sipe Jack C. , Moore Robert Y.
Published: February 2005

An extensive system of gap or nexus junctions has been found between astrocytic processes in the neuropil of the lateral hypothalamic area in the albino rat. These specialized interastrocytic junctions occur in regions of high synaptic density where neural processes are separated by the interconnected glial system. In this study, 90% of the gap junctions observed in the lateral hypothalamic neuropil are in the immediate proximity of synaptic terminals. The close morphological relationship of these glial gap junctions with synaptic contacts suggests that they may play a significant role in the process of synaptic transmission.
Lanthanum hydroxide labelling of gap junctions in the odontoblast layer
Authors: Holland G. R.
Published: February 2005

Earlier work has suggested that terminal nerve fibers in the periphery of the dental pulp are linked to one another and to odontoblasts by gap junctions although positive identification of the junctions was lacking. In this study, the lanthanum hydroxide tracer technique has been used to demonstrate that the junctions in this area do have the characteristic features of gap junctions, a wide dark intermediate line in transverse section, stippling in oblique section and a globular arrangement of sub‐units in tangential section. Other studies have shown these junctions to be of low electrical resistance although the functional importance of this characteristic in this situation has not been determined.
The hematopoietic microenvironment of the bone marrow: An ultrastructural study of the stroma in rats
Authors: Weiss Leon
Published: February 2005

The bone marrow contains branching vascular sinuses lying in a fibroblastic stroma which supports hematopoiesis. This paper describes the stroma and vascular sinuses by scanning and transmission electron microscopy and in freeze‐fracture etch replicas in normal rat femoral marrow and in rats made eosinophilic by larvae of trichinella spiralis.

The stroma consists primarily of reticular cells which ensheath sinuses as adventitial cells and branch into the surrounding hematopoietic space. They form a spongework on which hematopoietic cells are arranged. Erythroblasts, clustered into islets, and megakaryocytes lie just outside sinuses. Granulocytes, until the metamyelocyte stage, lie in the midst of the hematopoietic cords. Lymphocytes, monocytes and likely stem cells, are clustered about arterial vessels. Macrophages occur throughout the marrow. Fat cells occur adventitial to vascular sinuses and appear to be reticular cells which accumulate fat.

Processes of reticular cells closely envelope hematopoietic cells or protrude into them. Reticular cells contain rough ER and are likely fibroblastic. The argyrophilic reticular fibers of the marrow are, however, slender and scanty. Reticular cells are rich in filaments and they may contain many microtubules. They are not phagocytic and possess few lysosomes. The reticular cell cover of a vascular sinus is lifted away as maturing hematopoietic cells approach the sinus, preparatory to crossing the endothelium and entering the circulation. Maturing granulocytes often show microvilli on reaching the basal endothelial surface.

The level of eosinophils in the marrow may increase from approximately four to more than 20% after injection of trichinella larvae. Close distinctive association of reticular cells and eosinophils are marked.

Reticular cells provide a physical spongework on which hematopoietic cells are supported. But I postulate that they also trap and induce differentiation of hematopoietic stem cells, and sort the differentiating hematopoietic cells into characteristic locations in their spongework.
Distribution of growth hormone‐release‐inhibiting hormone (somatostatin) in the rat brain as observed with immunocytochemistry
Authors: Baker Burton L. , Yu Ya‐Yen
Published: February 2005

The objective was to determine the distribution of growth hormone‐release‐inhibiting hormone (somatostatin) in the rat brain using the peroxidase‐antiperoxidase immunocytochemical method with antisera prepared against unconjugated, synthetic somatostatin. Somatostatin occurred in low quantity in the organum vasculosum of the lamina terminalis. It was present throughout the full length of the median eminence and occupied the entire width between the tuberoinfundibular sulci. Most somatostatin was located in the dorsal portion of the external lamina, and the amount varied according to the mediolateral position. The bodies labeled for somatostatin were most often granules; occasionally they appeared as clusters of granules that seemed to be membrane‐enclosed. Some of these bodies appeared to be portions of axons. Many of the larger bodies were arranged alongside tanycytes, but no label was distributed generally in tanycyte cytoplasm. Somatostatin was highly concentrated in the proximal one‐quarter of the infundibular stem and appeared in lower concentration throughout the distal portion of the stem. It was absent from the pars nervosa and pars intermedia of the pituitary gland. The distribution of somatostatin in the median eminence differed considerably from that of gonadotropinreleasing hormone.

Somatostatin was identified in the ventromedial and/or dorsomedial hypothalamic nuclei of only two animals. Here it was probably located in axons that terminated on neuronal cell bodies but also may have been present in a restricted portion of the perikaryonal cytoplasm.
Morphological changes in the midpiece of wooly opossum spermatozoa during epididymal transit
Authors: Olson Gary E. , Hamilton David W.
Published: February 2005

Several ultrastructural changes were found to occur in the midpiece region of wooly opossum spermatozoa during epididymal maturation. The changes include alterations in mitochondrial morphology, development of structural specializations of the plasma membrane, and acquisition of a prominent extracellular coating. The lamellar membrane network which is wound about the periphery of the mitochondria becomes more densely packed during sperm development and the reticular network of membranes noted in the center of the mitochondria of immature sperm disappears leaving a homogeneous electron dense central zone. During epididymal transit the plasma membrane over the sperm midpiece region shows extensive structural modification. In cross sections of paired spermatozoa the plasma membrane of the midpiece regions shows a very regular, repetitive scalloping. Inlongitudinal sections the scalloping is observed as continuous parallel ridges which extend slightly obliquely to the flagellar long axis. Each ridge appears to be greater in density than the interridge areas. In theepididymis a prominent extracellular coating of dense material is reposited over the midpiece surface; thismaterial is similar in appearance to dense material seen in restricted areas of the epididymal lumen. At the proximal and distal ends of the midpiece the plasma membrane comes into intimate contact with underlying structural specializations and it is suggested that these zones of fusion may serve to preserve regional differences in membrane composition.
Ultrastructural studies of the female breast. I. 9+0 Cilia In myoepithelial cells
Authors: Stirling John W. , Chandler John A.
Published: February 2005

9+0 cilia associated with diplosomes were observed in myoepithelial cells of the ductal system in the undiseased, resting, adult female breast. Ciliary diameter was 250 nm, and the longest found was 830 nm. The centrioles comprising the diplosome were 500 nm in length and 160 to 200 nm in diameter. Satellite bodies were associated with the diplosome but there was no rootlet system. Evidence suggested that all myoepithelial cells bear a cilium. The possible functions of the cilia in a sensory role as chemo‐ or mechanoreceptors related to myoepithelial and epithelial activities are discussed.
Actin‐like filaments in the Sertoli cell junctional specializations in the swine and mouse testis
Authors: Toyama Yoshiro
Published: February 2005

Microfilaments at the junctional specializations between adjacent Sertoli cells and between the Sertoli cell and the late spermatid of the mouse and swine testes bind HMM and form arrowhead complexes with a periodicity of about 35 nm. The arrowhead formation is inhibited when the tissues are treated with HMM in the presence of ATP. These observations show that the microfilaments are actin‐like in nature. The functional significance of these filaments in the Sertoli cell is discussed.