bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructural localization of defined sequences of viral RNA and DNA by in situ hybridization of biotinylated DNA probes on sections of herpes simplex virus type 1 infected cells
Authors: Puvion‐Dutilleul Francine , Puvion Edmond
Published: February 2005

The influence of fixation and enzymatic digestions on the ability of a denatured double‐stranded DNA probe to bind specifically to related sequences of RNA and DNA in sections of Lowicryl embedded cells was investigated. Specificity of the hybridization was assessed using a biotinylated cloned subgenomic herpes simplex virus type 1 DNA fragment to localize viral nucleic acids in sections of infected cells. The probe was detected by anti‐biotin antibodies and indirect immunogold labeling. Controls indicated that protease digestion of proteins from the section eliminated non‐specific binding of the probe and labeling of endogenous biotin.

Both formaldehyde and glutaraldehyde fixation retained viral RNA in protease digested sections. Its labeling was randomly and sparsely distributed over the fibrillo‐granular network of the infected nucleus and over the ribosome‐rich regions of cytoplasm.

Labeling of single‐stranded portions of viral DNA in protease‐RNase digested sections was infrequent. It was located precisely over nucleoids of a few viral nucleocapsids whatever their location in the cell and their stage of maturation.

Labeling of double‐stranded viral DNA by denaturation of the DNA in the sections of Lowicryl embedded cells was possible after fixation with formaldehyde but not glutaraldehyde. Among several denaturation protocols, 0.5 N NaOH treatment was best for hybridization of both nonencapsidated and encapsidated viral DNA in protease‐RNase digested sections. Free viral genomes were detected exclusively within the virus‐replicating region of infected nuclei. Labeling of viral nucleoids was independent of their location in the cell. The high percentage of labeled viral nucleoids suggests that the related viral DNA sequence is not aggregated in the nucleoid but is extended and therefore numerous portions of this defined DNA sequence are accessible at the surface of the section for the binding of the probe.
Computer reconstruction of nucleolar architecture by interactive three‐dimensional color display
Authors: Geraud G. , Soyer A. , Hernandez‐Verdun D.
Published: February 2005

The first complete three dimensional ultrastructural reconstruction of pancreatic cell nucleoli, was done using EM and computer 3D‐assisted reconstruction of serial sections with interactive 3D back‐to‐front and color display methods based on voxel representation. The purpose of the study was to depict the architecture of the nucleolar components. We obtained information about the location of the nucleolus within the nuclear volume and about the shape and polarity of the 3 main nucleolar territories.
Cryo‐electron microscopy of vitrified specimens: An approach to the study of bulk specimens
Authors: Erk I. , Delacroix H. , Nicolas G. , Ranck J.‐L. , Lepault J.
Published: February 2005

We are using and developing cryo‐electron microscopy of vitrified specimens. Our main interests concern the structure of muscle and muscular components. Micrographs which generally contain periodic features are analyzed by numerical image processing methods. To detect artifacts induced by the electron microscopy techniques, we correlate our results to those obtained by X‐ray diffraction. In this paper, we describe our approach to the study of bulk specimens. Vitrification of such specimens is assessed by cryo‐X‐ray diffraction. Microscopy is done on cryo‐substituted specimens.
X‐ray microanalysis of cell nuclei
Authors: Quintana Carmen
Published: February 2005

The principal component analysis, a multivariate statistical analysis of data, has been used to process X‐ray microanalytical data from cell nuclei. Sixty‐seven measurements from different areas of chromatin, nucleoli of rat follicular cells, and nucleoli of rat oocyte cells in their antral stage have been studied. The variables are the X‐ray characteristic signals for P, S, Al, Fe, Cu, and Zn. This method demonstrates four distinct groups, the chromatin area, which is associated with a higher concentration of P; the compact mass of oocyte nucleolus which possesses the highest content in S, Al, and Zn, and two groups of nucleolar areas. The fibrillar component is richer in S, Al, and Zn than the granular component. The high degree of correlation between these three elements proves the chemical affinity of metals for the proteins (S being the signature for proteins).

Cryoembedding in Lowicryl resin at even lower temperatures (213° K in K11M) after quick cryofixation and cryosubstitution in the absence of chemical fixatives gives good ultrastructural preservation and the possibility of simultaneously performing X‐ray microanalysis and immuno‐cytochemistry.
Biological applications of electron probe microanalysis in france
Authors: Quintana Carmen , Nicaise Ghislain
Published: February 2005

The contribution of French science to the field of biological X‐ray microanalysis is reviewed. The main analytical microscopy centers are listed, and their methods and main results are summarized.
A computer program for many‐beam image simulation of amplitude‐contrast images
Authors: René Rasmussen D. , Barry Carter C.
Published: February 2005

A computer program for the simulation of amplitude‐contrast electron micrographs is described. The program is based on the n‐beam dynamical theory of diffraction contrast as described by Howie and Whelan (see Howie, A., and Whelan, M.J. (1961) Proc. R. Soc. Lond. [Biol]). The displacement fields associated with crystal lattice defects are calculated using linear anisotropic elasticity. The program can be used to simulate images of crystals containing line or planar defects or combinations of these defects. The line defects can be oriented freely within the foil, and are not restricted to being mutually parallel, but must be straight. Different techniques available for solving the diffraction problem, with or without the column approximation, are discussed.
Effects of drugs on pituitary fine structure in laboratory animals
Authors: Stefaneanu Lucia , Kovacs Kalman
Published: February 2005

Although an increasing number of chemicals are reported to affect endocrine glands, only a few studies are dealing with their toxic effect on pituitary. The drugs can induce lesions acting directly on endocrine cells or indirectly by interfering with the regulation of their endocrine activities. Some drugs stimulate pituitary cell proliferation leading to hyperplasia and tumor formation; other chemicals have an inhibitory effect on adenohypophysial cells; and only one drug, hexadimethrine bromide, has been found to induce pituitary necrosis.

Although complex toxicologic studies have been carried out on many chemicals, the mechanism of action of most drugs is not completely elucidated and further studies are necessary to establish structure function correlations.
Preparation of (InGa)As/GaAs materials for TEM by one side non‐rotation ion beam thinning
Authors: Yao J. Y. , Dunlop G. L.
Published: February 2005

A technique is described for the preparation of thin specimens for transmission electron microscopy (TEM) of (InGa)As/GaAs multilayered materials. In this technique, a shielding method is used for selective‐area perforation by ion beam thinning. Thin cross‐sectional specimen slices are mechanically pre‐thinned to about 30 μm and then thinned by ion sputtering from one side of the specimen at a time without rotation of the specimen stage. No direct ion sputtering occurs at the growth surface of the specimen so that a specimen with thin areas containing the desired near‐surface structures can be obtained. The recipe for this technique is given in detail. A patterning method for increasing the size of the thin area for TEM investigation is also described. It is shown that a smooth surface can be obtained by sputtering without rotating the stage if obstacles that produce redeposits onto the sputtered surface are removed.
Testicular differentiation in mammals under normal and experimental conditions
Authors: Merchant‐Larios Horacio , Taketo Teruko
Published: February 2005

Gonadal differentiation begins with the establishment of a sexually undifferentiated gonad, in which gonadal cords are formed by condensation of somatic cells and deposition of basal laminar components around the cluster of epithelial‐like cells. The first event of sexual differentiation is the invasion of mesenchymal and endothelial cells into the genital ridge in the XY gonad. As a consequence of this event, the gonadal cords become conspicuous, recognized as seminiferous cords (or testis cords). Cytological differentiation of Sertoli cells follows these stromal changes. In the XX gonad, by contrast, the invasion of the mesenchyme is absent and gonadal cords remain associated with the surface epithelium. In the B6.YDOM XY ovotestis, seminiferous cords and ovarian gonadal cords are often enveloped by common basal laminae, confirming that both structures share the embryonic origin. It has been recently reported that seminiferous‐like cords are formed after loss of oocytes in the rat XX ovary cultured in the presence of Müllerian inhibiting substance or after long‐term culture in the basic medium alone. These results are comparable with our observation on the persistent gonadal cords in the ovary of busulphan‐treated rats or W/WV mutant mice, in which oogonia are absent or scarce. Ultrastructural evidence for Sertoli cell differentiation from XX cells has been presented, so far, only in the fetal mouse ovary that has been grafted beneath the kidney capsule of adult male mice. Possible mechanism of gonadal sex determination is discussed based on these morphological studies.
Sertoli cells and testicular differentiation in the rat fetus
Authors: Magre Solange , Jost Alfred
Published: February 2005

The fetal testis is not merely a precursor of the adult organ: it is indeed an endocrine gland whose function is the masculinization of the fetus. It differs physiologically and morphologically from the adult testis. In this paper, the first stages of testicular differentiation in the rat are described, with special emphasis on the ultrastructural aspects. At the stage of 13.5 days after fertilization, the first Sertoli cells differentiate; they are characterized by a voluminous and little electron dense cytoplasm, a well‐developed RER formed by vesicles and short cisternae filled with a flocculent material. Progressively, they polarize and adhere to one another by adherens‐like junctions and cytoplasmic interdigitations to form the differentiating seminiferous cords. In the basal part of the Sertoli cells, a mat of microfilaments differentiates under the plasmalemma, while cytoplasmic blebs protruding in the extracellular space tend to disappear. A continuous basal lamina delineating the seminiferous cords begins to appear on day 14.5 and becomes widespread on day 15.5. These observations, when compared with other data from the literature, emphasize the fact that the differentiation of the Sertoli cells is the first morphological event during testicular differentiation. A possible role of the Sertoli cells in the subsequent organogenesis of the testis is suggested.
High‐Resolution scanning electron micrographs of freeze‐cracked cells in testes from normal and irradiated rats at different stages of gonadal development
Authors: Burdzy Krystyna , Tung Pierre S. , Fritz Irving B.
Published: February 2005

Newly developed techniques in high‐resolution scanning electron microscopy (SEM) and for tissue‐processing procedures have been applied to an investigation of structures of various cells in rat testes at different stages of gonadal maturation. A series of high‐resolution SEM micrographs are presented which survey the surfaces of different types of testis cells during normal development, and which also illustrate ultrastructural features of some of their intracellular organelles. In addition, a series of high‐resolution SEM micrographs are presented which compare the structural features of Sertoli cells in normal testes with those in germ‐cell‐depleted testes obtained from rats killed at varying times after having been irradiated in utero. We describe our observations on the structural properties of surfaces and intracellular organelles in Sertoli cells, Leydig cells, peritubular myoid cells, and some classes of germinal cells. We also consider the possible role of Sertoli cell apical cytoplasmic processes in lumen formation. Similarities are pointed out between the structure of germ‐cell‐depleted testes, resulting from irradiation in utero, and the structure of germ‐cell‐depleted testes in seasonal breeders during periods of involution. Finally, we discuss advantages and disadvantages of methods employed to reveal the fine structure of intracellular organelles in cells of the testis.
Formation of a functional endothelium on vascular grafts
Authors: Williams Stuart K. , Schneider Timothy , Kapelan Barbara , Jarrell Bruce E.
Published: February 2005

The lack of a functional endothelial cell lining on artificial polymeric vascular grafts severely reduces their effectiveness in replacing small caliber (< 6 mm) blood vessels. Techniques have now been developed to transplant autologous endothelial cells from one site in the body onto the surface of grafts prior to implantation. Pre‐clinical animal trials provide evidence that grafts sodded with autologous, fat‐derived, microvessel endothelial cells exhibit a stable, antithrombogenic lining of endothelium. The new endothelial cell lining exhibits morphologies identical with endothelium on native blood vessels. The effectiveness of endothelial cell sodding techniques in pre‐clinical animal trials provides support for expanded clinical trials.
Cross‐sectional transmission electron microscopy of x‐ray multilayer thin film structures
Authors: Nguyen Tai D. , Gronsky Ronald , Kortright Jeffrey B.
Published: February 2005

A simple method for preparing cross‐sectional transmission electron microscopy specimens and discussions of possible artifacts from specimen preparation and observation of x‐ray multilayer thin film structures are presented. The specimen preparation method employs mechanical grinding and polishing to approximately 20 μm, followed by ion milling, without dimpling. Artifacts such as preferential ion milling and crystallization under the electron beam, as well as effects of Fresnel fringes at interfaces, are important factors in interpretation of the images. Care in identifying them is required to avoid erroneous results in studies of morphology and microstructures within the layers and at their interfaces. Example high‐resolution TEM results of cross‐sectional W/C, Ru/C, and Mo/Si multilayers are presented.
An alkali digestion method to expose connective tissue fibers: A scanning electron microscopy study of rat lung
Authors: O'Donnell M. D. , McGeeney K. F.
Published: February 2005

Alkali digestion has been used to remove cellular elements of tissues thus exposing the underlying connective tissue framework. We studied the action of this severe alkali treatment on the delicate tissues of rat lung. The lungs of male Sprague‐Dawley rats were perfused with saline to remove blood and then inflated by fixation through the airways at 20 cm pressure. Sections of lung 2 × 5 × 5 mm were immersed in 2.5 M NaOH at 25°C for 6 h, 16 h, 24 h, 48 h, and 72 h. The alkali was changed daily. Tissues were washed to neutral with water (24 h), treated with tannic acid (1%, 3h), post‐fixed with osmic acid (1%, 3 h) and processed for SEM. At 6 h, epithelial cells started to peel off the alveolar surface. At 16 h the digestion process was well advanced. At 48 h the cells were completely removed revealing the lattice network of connective tissue fibers within the alveolar surface. The method allows the complete removal of cellular elements of the lung while retaining the very fine 3D structure of the connective tissue matrix.
Clasmatosis of skin mast cells as affected by moccasin venom
Authors: Zahl Paul A. , Nowak Andrew
Published: February 2005

Moccasin venom injected intradermally into mouse skin induces an almost immediate clasmatosis of mast cells, followed by dissolution or loss of staining reaction of the released granules, a condition from which there is no observable recovery for at least 25 days. The possible significance of this reaction is discussed.
An autoradiographic study of RNA synthesis in isolated salivary glands of Drosophila hydei. I. Autoradiographic studies
Authors: Arnold Gail
Published: February 2005

RNA synthesis in isolated Drosophila salivary glands was studied by autoradiography. The dry mass of cellular structures was determined by interference microscopy; a correction which compensates for self‐absorption of β‐particles, and consequent lowered grain counts, is discussed. The correction factors are 12.0 for nucleolus, 5.0 for nucleoplasm and 8.8 for cytoplasm.

After 15 seconds in uridine‐H3, label was localized over the nucleolus; after one minute, nucleoplasm RNA became labeled also. In situ synthesis of some nucleolar RNA is indicated.

Comparisons of uridine‐H3 and cytidine‐H3 incorporation were made in glands exposed briefly to isotope, followed by transfer to unlabeled nucleoside solutions. The data suggest two RNA fractions in nucleoli. Rapid turnover and higher uridine incorporation characterized one fraction, which resembled RNA of nucleoplasm metabolically. The second nucleolar RNA incorporated less uridine, remained longer in the nucleolus, and resembled cytoplasmic RNA in precursor incorporation pattern.

Preincubation in Actinomycin D before uridine‐H3 labeling resulted in 80% inhibition of RNA synthesis in both nucleolus and nucleoplasm. Longer isotope exposures produced some increase in labeling. Actinomycin treatment delayed appearance of label in cytoplasmic RNA.

After HCl extraction of uridine‐H3‐labeled RNA, some activity, presumed to be incorporated in DNA, remained. This non‐extractable label appeared earliest over nucleoli, and subsequently over chromatin. Actinomycin treatment abolished incorporation of non‐extractable label into nucleoli.
Histochemistry of the developing chick esophagus and trachea. I. Alkaline phosphatase
Authors: Hinsch Gertrude W. , Buxbaum Susan K.
Published: February 2005

Tissues of White Leghorn embryos of stages 17–45, and chicks of one day, two days, and three weeks of age were frozen or fixed in 85% ethanol. Alkaline phosphatase was identified using the azo‐dye or Gomori techniques.

Alkaline phosphatase activity is found in the ventral mesenchyme of the esophagus surrounding the epithelium to stage 34. At stage 38 activity appears in the basal layers of the epithelium and is subsequently lost in the mesenchymal tissues. This activity persists in the epithelium throughout development and following hatching. At 16 days the mucous glands arise as solid buds of epithelium projecting into the tunica propria. These buds are highly positive for alkaline phosphatase. As differentiation of the glands becomes complete they and their ducts lose their positive phosphatase reaction.

On the fourth day of development the trachea is found lying ventral to the esophagus. Mesenchyme has condensed around the tracheal epithelium by the fifth day, at stage 37 (11 days) the first cartilaginous rings appear, and by stage 38 (12 days) all are completely formed. During the third week of development the trachea increases in size. Pseudo‐stratified columnar ciliated epithelium begins to appear at 15 days. Alkaline phosphatase is highly reactive in the mesenchyme surrounding the epithelium prior to cartilage formation. After the cartilages have formed the reaction diminishes and in late stages of development phosphatase is found only in the epithelium.
Development of intracranial arterial patterns in turtles
Authors: Burda Doris J.
Published: February 2005

Observations on chelonian intracranial arteries are based primarily on the adult condition in Pseudemys scripta and on a series of Chrysemys marginata embryos. Those vessels which show major modifications are the anterior cerebral, posterior cerebral, cerebellar, and internal auditory arteries. The distal portion of the embryonic anterior cerebral is acquired by more medial vessels; from the proximal portion develops the middle cerebral which becomes the major source of supply for the lateral surface of the adult cerebral hemisphere. The posterior cerebral appears early in development and eventually supplies branches to the epiphysis, posterior portions of the hemisphere, olfactory regions, anterior face of the optic lobe, and choroid plexus of the third and lateral ventricles. The cerebellar and internal auditory arteries show similarities in development, each initially supplying the area immediately surrounding a nerve root and then acquiring larger areas of distribution by means of anastomoses with nearby medullary vessels.
Chick cephalogenesis. The normal development of the cephalic region of stages 3 through 11 chick embryos
Authors: Hillman Nina W. , Hillman Ralph
Published: February 2005

The cephalogenesis of chick embryos was studied at stages 3 through 11 inclusive. Ten embryos were examined at each stage. Particular attention was paid to the time of appearance of the prechordal plate mesoderm and cephalic notochord. It was found that the presumptive neural ectoderm begins to differentiate to form medullary plate as soon as it becomes associated with the chordamesoderm. Histological studies revealed the similarity of the notochord underlying the presumptive forebrain and midbrain regions, and the differences between this notochord and that associated with the hindbrain. These differences included the notochord histology and time of separation of the notochord from entoderm and neural ectoderm.
The phenomena of amphibian metamorphosis. IV. The development of the median eminence
Authors: Etkin William
Published: February 2005

The development of the median eminence of several species of American anurans was studied in correlation with the progress of metamorphosis. Before metamorphosis the hypothalamic arteries break up into a plexus of capillaries lying in the extensive area of contact between the anterior lobe and the floor of the hypothalamus. During prometamorphosis the neural tissue of this area is converted into the median eminence. The neural tissue becomes thicker and shorter as the capillaries on its surface sink inward. The anterior lobe separates from the neural tissue except at its anterior tip where the residual capillaries have enlarged to form the pituitary portal veins. These changes are largely but not completely accomplished by the be‐ beginning of metamorphic climax. No significant alterations were found in the neurosecretory cells or their fibers during metamorphosis. The morphological data are interpreted in terms of the changing level of activity of the pituitary‐ thyroid axis during metamorphosis and its dependence upon a thyrotropin‐ releasing factor from the brain.
A reinvestigation of the segmentation of the crayfish abdomen and thorax, based on a study of the deep flexor muscles and their relation to the skeleton and innervation. I. The skeleton and intersegmental membranes
Authors: Rayner M. D.
Published: February 2005

Recent physiological studies on the crayfish Procambarus clarki (Girard), Astacura, Decapoda, have suggested the existence of certain anomalies between the classical interpretation of the segmentation of the crayfish and the more recently established segmental innervation patterns. An extensive reinvestigation of the skeletal segmentation has been undertaken, based on the dissection of both fresh and fixed specimens of this and two other crayfish species, to decide to what extent misinterpretation of the skeletal structure might provide an explanation of these apparent anomalies.

As a result of this attempt to provide a self‐ consistent analysis of the crayfish skeleton, it has been necessary to conclude that the epimeral plate is tergal rather than pleural in origin, that the basal segment of the thoracic legs contains a subcoxal element, that this subcoxa exists as a free leg segment in the last thoracic legs and that the abdominal pleural folds are in part homologous with the subcoxae of the thorax. On the other hand it has not been necessary to diverge from the classical account of the segmentation, except to recognize the existence of a seventh abdominal segment (segment XXI) posterior to the uropod segment.
The lymphatic system of Dasypus novemcinctus and Dasypus sexcinctus
Authors: Azzali Giacomo , Didio Liberato J. A.
Published: February 2005

The lymphatic system of 40 specimens of Dasypus novemcinctus and 5 of Dasypus sexcinctus, both found in Brazil, were injected with Prussian blue suspension, neoprene latex (followed by partial corrosion). Lymphangioradiographic study was also made. The data concern the lymph nodes, the lymphatic networks, vessels and main trunks. The main features are the following: a few lymph nodes were missing (popliteal, subpubic and ischial); the superficial jugular ll.nn. predominate on the deep ones; the dorsal mediastinal ll.nn. are well developed; a mesentericocolic plexus is formed by the many anastomoses among the mesenteric and cecocolic ll.nn.; at regular intervals there is a concentration of vessels in the submucous network of the small intestine; the submucous network of the colon shows parallel lamellar lymphatic vessels; the mucous‐submucous networks are usually independent from the subserous‐muscular ones; there are two types of lymphatic networks alternating along the duodenum; folliculi lymphatici aggregati are absent; the lymphatic vessels run in the mesentery independently from the blood vessels; the mesenteric lymphatic vessels present many valves; the vessels from the diaphragm terminate directly in the cisterna chyli; there is a multipolarity of the abdominal lymphatic circulation, i.e., each organ has its own lymphatic tr.
The poison gland of the cottonmouth moccasin, Ancistrodon P. piscivorus, as observed with the electron microscope
Authors: Odor D. Louise
Published: February 2005

The structure of the poison gland of the cottonmouth moccasin has been studied with the electron microscope. This gland is divided functionally and structurally into a posterior and an anterior portion. In the posterior gland the columnar principal cells are considered to be responsible for the production of the secretory material, including the toxic substances in the venom. This cell is characterized by numerous dilated membrane pairs of the granular endoplasmic reticulum and by a large Golgi complex. Four other types of cells are observed within the epithelial layer of the posterior part of the gland, but their function is unknown.

The majority of the cells of the anterior part of the gland are mucous‐secreting goblet cells. Some possible stages in their secretory cycle are described. Granular endoplasmic reticulum is present in the basal areas of the cell. The accumulation of recognizable secretory material appears first in structures considered to be a part of the Golgi complex.
Nerves and muscles of the pregenital abdominal segments of the American cockroach, Periplaneta americana (L.)
Authors: Shankland D. L.
Published: February 2005

The muscles and motor and sensory nerves of the pregenital abdominal segments were described and discussed in relation to the nerves and muscles of the thorax, as described by other workers. Each of the integumental muscles was named and described with regard to its location, function and innervation. Differences among segments of the same sex and between sexes were noted.

A description of a longitudinal muscle, named here the hyperneural muscle, was included. The muscle overlies the abdominal portion of the nerve cord and may be derived from the ventral diaphragm. The most notable features of its structure are chiasmata of fibers which occur at points along its length and which show consistent relationships to the nerve cord and median nerve.

A previously undescribed organ, located ventrally at the intersegmental fold, having dual innervation and showing stretch receptor function was described.
The development of the ovary of the sea lamprey (Petromyzon marinus L.)
Authors: Lewis J. C. , McMillan D. B.
Published: February 2005

This investigation is a histological study of the development of the ovary of the sea lamprey from south‐western Ontario, Canada. Development is described from the first appearance of primordial oögonia at the site of the ovary up to ovulation. After mitotic proliferation, oögonia enter meiotic prophase and become oöcytes which enlarge and acquire basophilic cytoplasm.

During metamorphosis all oöcytes are at a uniform stage of development and no oögonia remain in the ovary.

The follicular layer in the early adult produces nurse cells which are incorporated into the oöcyte and increase its mass of RNA‐rich cytoplasm. As the oöcyte enlarges, proteid yolk platelets are laid down in the cytoplasm. Vacuolation of the nucleolus, indicative of protein synthesis, is extensive during period of rapid growth and yolk formation.

Immediately prior to spawning there is an accumulation of fluid under the follicular layer and the oöcyte emerges through a mound of follicular cells.

Atresia of oöcytes occurs throughout the adult stages and following spawning. It is characterized by an enzymic dissolution of the yolk followed by phagocytic invasion. The phagocytes arise from the follicle in the early adult stages and from an unidentified source in the spawning‐phase adult.
Reversal of primary embryonic induction by cold, and the “fixation” of induction in cells activated by lithium chloride
Authors: Ansevin Krystyna D.
Published: February 2005

The effects of low temperature on embryonic induction were investigated. Presumptive epidermis cells of Rana pipiens were either pretreated with cold (4°C) and then treated with lithium chloride at the same temperature, or activated by lithium chloride at 22°C, then rapidly chilled to 4° and kept at this temperature for a period of time. Cultures were made from the treated cells.

It was found that induction at low temperature could occur, although it did not proceed beyond determining neuralization. When, on the other hand, the cells were first induced with LiCl to the point at which they should have been determined to differentiate into melanophores, but were then rapidly chilled and kept in the cold for some time, the effects of induction were suppressed and the cells differentiated into ciliated epithelium. A 15–60 minute lag in time between induction and chilling (during which the cells were kept in the culture medium at room temperature) allowed neural induction to be gradually “fixed,” and a 120–180 minute lag was sufficient for melanphore induction to become insensitive to the subsequent treatment with cold.

It is speculated from these results that induction occurs very slowly at low temperature and that the inductive stimulus activates a sequence of reactions, one or several of which are strongly repressed by the cold. In this case, when no products result from these reactions, the sequence is assumed to stop and possible feed‐back mechanisms switch the whole system to its initial condition.
Ultrastructural studies of normal and alloxan‐treated islet cells of the pancreas of the lizard, Eumeces fasciatus
Authors: Burton Paul R. , Vensel William H.
Published: February 2005

Alpha and beta cells can be distinguished by differences in mitochondrial and secretion granule structure. Many mitochondria of alpha cells possess “tubular” or prismatic cristae oriented longitudinally and having triangular profiles in cross‐section. The matrix is particulate, with the roughly spherical particles measuring about 100 A in diameter. Evidence is presented indicating that alpha and beta granules are sequestrated in association with Golgi elements. Fully‐condensed beta granules, assumed to be insulin, appear homogeneously dense and crystalline. Recurrent profiles of crystalline beta granules suggest that they possess an octahedral configuration. Alpha cell granules also appear homogeneously dense but have round profiles.

Many acinar cell nuclei in both normal and alloxan‐treated pancreata display masses of moderately dense fibrils oriented roughly parallel to each other. These fibrils are about 200 A across and their terminal portions are rebranched and often appear to be continuous with the finely granular or filamentous component of the nucleoplasm. Not infrequently the fibrils show evidence of periodicity.

Alloxan has a specific destructive effect on beta cells. An initial effect seems to be the disruption and coalescence of the bounding membranes of beta granules. Lysosome‐like bodies are often seen in beta cell cytoplasm, which ultimately becomes degranulated and necrotic following prolonged administration of large doses of alloxan.
The fine structure of myocytes in the sponges Microciona prolifera (Ellis and Solander) and Tedania ignis (Duchassaing and Michelotti)
Authors: Bagby Roland M.
Published: February 2005

Myocytes are long, fusiform cells found in the osculum and other contractile areas of many sponges. Myocytes in the oscular sphincter of Tedania ignis and the osculum and dermal membrane of Microciona prolifera were studied with light‐ and electron‐microscopes to compare their structure to that of muscles. Salient points of similarity between myocytes and smooth muscles were their long, fusiform shape, their red color after staining with Mallory's triple stain, and the presence of filaments running longitudinally in the cytoplasm.

Microciona myocytes have thick filaments of 150–250 Å diameter and thin filament of 50–70 Å diameter, and in transverse sections the thin filaments occasionally appear as a ring of dots around a thick filament. Longitudinal sections of Tedania myocytes show only one type of filament, which varies from 100 Å to 200–300 Å diameter in thick regions of the filament. Although transverse sections show light material around the dense filaments, a distinct pattern of thick and thin filaments is not seen in Tedania.

Due to infrequent contacts between cells, the large extra‐cellular space observed with the electron microscope (49% in Tedania, 57% in Microciona), and the absence of nerves, each myocyte probably acts as an independent contractile unit.
The effects of thiourea and cortisone acetate on duodenal length and diameter and on morphogenesis of duodenal villi in chick embryos
Authors: Stocum David L.
Published: February 2005

Subnormal growth in length and diameter of the duodenum is encountered both in chick embryos injected with thiourea at 11 days of incubation, and in embryos injected with cortisone acetate at 14 days of incubation. Morphogenesis of previllous ridges and villi is retarded in thiourea‐treated embryos. Morphogenesis of previllous ridges and villi in cortisone acetate‐treated embryos at first seems to be slightly accelerated over that of controls, but the acceleration does not appear to be maintained, and the hormone may actually be inhibitory to normal morphogenesis of villi by 19 days of incubation. The results indicate that normal levels of endogenous thyroxine are necessary for normal growth in length and diameter of the duodenum and for normal morphogenesis of previllous ridges and villi. The possibility that adrenocorticoids may also play a role in the normal development of these parameters is indicated, although the evidence is inconclusive.
The post‐ovulatory follicles of blackbirds (Agelaius)
Authors: Payne Robert B.
Published: February 2005

Post‐ovulatory follicles of tricolored blackbirds (Agelaius tricolor) and redwinged blackbirds (A. phoeniceus) regress from 6.0 to 3.0 mm in length by two days after ovulation and remain less than 3.0 mm during incubation. The follicles of females feeding young average less than 1.0 mm. Serial sections of ovaries of birds in all stages of the nesting cycle show distinct post‐ovulatory follicles up to 25 days after ovulation.

Lymphocytes, granular polymorphonuclear leucocytes, macrophages, and fibroblasts invade the sloughed granulosa and the hemorrhaged theca interna after ovulation. Granulosa cells, epithelioid cells in the theca interna, and connective tissue cells in the theca externa are lipoidal and cholesterol‐positive for at least ten days after ovulation. The rapid regression and histological evidence of degenerating tissue and the invasion of cell types characteristic of the inflammatory response suggest that the ovulated follicles are degenerating rather than secretory organs.
Lipid of normal and regenerating limb tissues of the adult newt, Diemictylus viridescens: Acidic and non‐acidic lipids, phospholipids, and cholesterol
Authors: Schmidt Anthony J.
Published: February 2005

Cryostat‐cut sections of unamputated and amputated‐regenerating limbs of the adult newt were examined following the Nile blue test for acidic and non‐acidic lipids, the acid hematein and plasmal tests for phospholipids, and a Schultz test for cholesterol.

Triglycerides (Nile blue test) are prominent in dermis and macrophages: triglyceride droplets are scattered in epidermis, wound epithelium, and regeneration blastema. Fatty acids (Nile blue test) are present in all tissues of the normal and regenerating limb: nerve myelin contains relatively little free fatty acid, while macrophages appear to contain the least amount of this lipidic substance.

Plasmalogens (plasmal test) are prominent in the myelin of nerves, and macrophages: a weak cytoplasmic reaction obtains in the epidermis, subcutaneous glands, striated muscle, tunics of blood vessels, wound epithelium, blastema cells, chondrocytes, perichondrium and periosteum.

Mitochondria responding for cephalin, lecithin, and sphingomyelin (acid hematein test) are ubiquitously distributed among the cells and tissues of the normal and regenerating limb. These phosphatides are prominent in nerve myelin, macrophages, and in dermal droplets: a variable response obtains from the myofibrils of striated muscle.

Cholesterol (Schultz test) was demonstrated only in nerve myelin and in macrophages associated with injured nerves.

Particular attention was paid to the lipid responses of the regeneration blastema, and the conclusion was reached that not all of the lipid previously demonstrated with sudan dyes was characterized by the current series of lipid tests.

A modified Nile blue sulfate test that promises greater specificity in distinguishing between acidic and non‐acidic lipids is introduced.
Fine structure of supporting cells in the lateral‐line canal‐organ of Fundulus
Authors: Petraitis Ruth
Published: February 2005

Phase and electron microscopic studies have revealed that the supporting cells of the lateral‐line canal‐organ of Fundulus heteroclitus have a fine structure characterized by (1) mitochondria and vacuoles in the apical zone, (2) granular endoplasmic reticulum surrounding a core of Golgi complex in the middle zone, and (3) an indented nucleus in the basal zone. In the middle and basal zones, wide intercellular spaces separate the adjacent supporting cells, whose plasma membranes form long flap‐like interdigitations across the intercellular spaces. Secretion of subcupular fluid and cupula, metabolic regulation through the intercellular spaces, and rigid support for the organ are discussed as possible metabolic and mechanical functions of the supporting cells essential for the lateral‐line canal‐organ.
Polyploidy and reproductive patterns in the root‐knot nematode Meloidogyne hapla
Authors: Triantaphyllou A. C.
Published: February 2005

A total of 32 populations and egg mass isolates of Meloidogyne hapla obtained from various geographical areas were studied cytologically and with respect to their mode of reproduction. In 29, maturation of oocytes is by regular meiosis. The reduced chromosome number at metaphase I is 17 in 18 populations, 16 in 8, and 15 in 3 populations. Reproduction in all these populations is by cross‐fertilization, although nonfertilized eggs can develop by parthenogenesis. In the latter case, the two groups of telophase chromosomes of the second maturation division become enclosed in the same pronucleus, thus reestablishing the somatic chromosome number. Maturation of spermatocytes in three populations studied is by regular meiosis and the reduced chromosome number appears to be equal to that of the oocytes. In the remaining three populations, no synapsis takes place and the somatic number of 45 chromosomes is observed at metaphase of the single maturation division of both oocytes and spermatocytes. Reproduction is by obligatory mitotic parthenogensis. It is postulated that the basic chromosome number for the genus is nine and that the facultatively parthenogenetic populations are tetraploid, whereas, the obligatorily parthenogenetic populations are pentaploid. A preliminary scheme of the phylogeny in the family Heteroderidae is given.
A study of regression and budding in Perophora viridis
Authors: Barth Lester G. , Barth Lucena J.
Published: February 2005

1. A method has been devised for studying the regression of the zooid of Perophora into a stolon and the subsequent differentiation of a new zooid from this stolon.

2. Circulatory cells of the stolon resulting from regression will aggregate into masses larger than the minimal size necessary for differentiation of a zooid, but fail to differentiate into a zooid.

3. The cells of a zooid after staining with neutral red appear in the stolon during regression and finally come to lie in the newly formed zooid.

4. During the cycle of adult zooid to stolon to newly formed zooid, there is no evidence for cell division from studies with tritiated thymidine.

5. It is concluded that under conditions of starvation, an adult zooid furnishes all the cells for the formation of a stolon and the subsequent zooids without cell division.
Early secretory activity in the hypothalamic nuclei and neurohypophysis in the rat; determined by selective staining
Authors: Dawson Alden B.
Published: February 2005

Visualization of stainable material in the neural lobe of the rat provided the most reliable index of the age at which secretory activity can first be recognized, though preceded by both hypothalamic synthesis and axonal transportation. A problem of interpretation was encountered in the neural lobes of fetal and infant animals, due to different staining responses obtained during this age period, to the two methods of staining employed; chrome alum hematoxylin‐phloxin and aldehyde fuchsin after oxidation by either acidified potassium permanganate or performic acid. With aldehyde fuchsin the material of the neural lobe is stainable selectively from the eighteenth day of fetal life to adulthood. With hematoxylin phloxine the first staining response also occurred in the posterior lobe but much later, at the end of the first postnatal week.

The staining situation in the pars neuralis has its counterpart in the differentiating hypothalamic nuclei; complicated by the differentiation of the supraoptic nuclei some days in advance of the paraventricular nuclei. After aldehyde fuchsin staining, evidences of neurosecretory activity were present in the perikarya of the supraoptic nuclei at birth, but mature neurons were rarely seen in the paraventricularis until at least 24 hours later. Nuclei of fetal hypothalami were not studied, but the demonstration of stainable material in the fetal neural lobes constitutes circumstantial evidence of functional competence of some neurons of either one or both types of nucleus, most likely the supraoptic.
A new intranuclear inclusion body in the frog renal adenocarcinoma
Authors: Lunger Philip D.
Published: February 2005

The morphology and possible functional significance of a new intranuclear inclusion body associated with the frog renal adenocarcinoma is described. The inclusion consists of particles, 40 to 50 mμ in diameter, arranged in an orderly pattern suggestive of a crystalline array. Individual particles eventually appear to be involved in the production of “doughnut” type virions characteristically associated with this malignancy.
Neurosecretory cells in the central nervous system of the adult blowfly Phormia regina meigen (diptera: Calliphoridae)
Authors: Hsiao Catherine , Fraenkel G.
Published: February 2005

Neurosecretary cells in the central nervous system of the adult blowfly, Phormia regina Meig., have been examined histologically using the parparaldehyde‐fuchsin and Gomori's staining method. Six groups of the neurosecretory cells occur in each hemisphere of the brain, the medial, frontal, lateral A, lateral B, posterior I and posterior II groups. In the subesophageal ganglion, four B‐cells and two A‐cells are present. In the thoracico‐abdominal ganglion, ten A‐cells are found in the thoracic region and a total of about 50 A‐ and B‐cells in the hind part of the abdominal region.

A comparison with the neurosecretory system of two other species of blowfly, Calliphora erythrocephala Meig., Sarcophaga bullata Parker, and the housefly, Musca domestica L., showed similar arrangements and grouping.

Neurosecretory granules have been observed along the axons originating from the medial neurosecretory cells of the brain, and the thoracico‐abdominal ganglion. The granules originating from the medial groups can be traced directly to the corpus cardiacum from which they move to the aorta, crop duct and cardia through axons.

There is with advancing age a gradual increase in the size of cell bodies and nuclei of the median neurosecretory cells in both females and males of Phormia regina, and also a decrease in stainable granules. This increase in size is dependent on nutrition, with no increase in water alone, a slight increase on sugar, and a maximum increase on sugar and liver. Corresponding increases in size occur in the ovaries in connection with feeding the same substances.
The gastric argentaffin cell population of the rat
Authors: Gregg Robert V.
Published: February 2005

The distribution and morphology of the argentaffin cell population within the stomach of the albino rat has been investigated histologically. The argentaffin cell's situation is restricted to and evenly distributed over the antrum, lying usually in the basal third of the mucosa among mucous cells. A band of mucosa, less than a millimeter wide, containing argentaffin cells, extends from the antrum and encircles the stomach just caudal to the forestomach. The argentaffin cell population is found in less than three‐tenths of the total stomach by weight, a point for consideration in serotonin assay.
A study of a hereditary cataract in the mouse
Authors: Davidorf Frederick , Eglitis Irma
Published: February 2005

This report presents a study of cataracts seen in a random‐bred strain of Swiss mice with Balb/c mice used as a control group. The embryonic development, and histological and slit lamp observations of the lenses in the two groups of animals are contrasted.

The cataract is dominant in its inheritance (Tissot, '62). It appears either unilaterally or bilaterally as a dense white opacity in the lens substance. The earliest sign of abnormal formation occurs at 14 days of embryonic development. This is associated with a defect in the primary lens fibers formation. Progressive degeneration of these fibers occurs until they are reduced to a mass of cellular debris seen at the last day of gestation. The secondary fibers are also laid down in an abnormal manner. The normal lamellar arrangement of the secondary fibers is not seen in cataractous lenses.

The abnormal lens fiber development leads to progressive vacuolization.

The mature cataract seen in the adult is filled with many vacuoles, the largest ones occurring at the equatorial region. The nuclear region consists of a clumpy eosinophilic mass with scattered calcified areas. The rate of growth of the secondary fibers is different from that of the normal group. Most of the mature cataracts in the adult contain a vascularized epithelium.

There are three possible areas of primary involvement which may lead to the development of the cataract. This are: (1) A defect in the development of the primary lens fibers; (2) A defect in the development of the secondary lens fibers; (3) An abnormal lens epithelium which may interfere with nutrition of the lens and thus initiate cataract formation.