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M J MOSES

Publications and source records attributed to M J MOSES.

14 recordsLinked to original sources
PubMed1964

DNA AND THE FINE STRUCTURE OF SYNAPTIC CHROMOSOMES IN THE DOMESTIC ROOSTER (GALLUS DOMESTICUS).

The indium trichloride method of Watson and Aldridge (38) for staining nucleic acids for electron microscopy was employed to study the relationship of DNA to the structure of the synaptinemal complex in meiotic prophase chromosomes of the domestic rooster. The selectivity of the method was demonstrated in untreated and DNase-digested testis material by comparing the distribution of indium staining in the electron microscope to Feulgen staining and ultraviolet absorption in thicker sections seen with the light microscope. Following staining by indium, DNA was found mainly in the microfibril component of the synaptinemal complex. When DNA was known to have been removed from aldehyde-fixed material by digestion with DNase, indium stainability was also lost. However, staining of the digested material with non-selective heavy metal techniques demonstrated the presence of material other than DNA in the microfibrils and showed that little alteration in appearance of the chromosome resulted from DNA removal. The two dense lateral axial elements of the synaptinemal complex, but not the central one to any extent, also contained DNA, together with non-DNA material.

Animals↗
PubMed1961

Microtubulation of the inner membrane of the nuclear envelope.

In the course of a light and electron microscopy study of spermatogenesis in the European crayfish, Astacus fluviatilis, spermatocytes of abnormal appearance were observed in two instances in individuals that had passed the mating period. The electron microscope showed that the inner membrane of the nuclear envelope of these cells was erupting into a mass of microtubules, 15 to 18 mmicro in diameter and 0.5 micro or more in length, while the outer membrane transformed into cytoplasmic vesicles. Stages in the formation of these novel processes were followed. The plasma membrane of the affected cells was seen in some cases to erupt into similar although shorter microtubules. It is concluded that the phenomenon is part of a degenerative process in which the spermatocytes are being absorbed by sustentacular cells. It is suggested that the observations provide further evidence for a fundamental functional as well as a morphological similarity between the membranes bounding the nucleus and the plasma membrane.

Cell Membrane↗
PubMed1961

Spermiogenesis in the crayfish (Procambarus clarkii) II. Description of stages.

The sperm of the crayfish, Procambarus clarkii, is relatively simple among decapod sperm and was described in the first paper of this series (28). The present paper details the development of this sperm as followed with the light and electron microscopes. The process is divided into six stages for purposes of description. The main points of interest discussed are the absence of mitochondria or mitochondrial derivatives in the mature sperm, the development of a complex acrosome in the absence of highly organized characteristic Golgi apparatus but in the presence of small stacks of annulate lamellae, and the changes in the nucleus. Of the latter, the elaborate convoluted sheets of membrane that are extensions of the nuclear envelope are unique. The nucleus undergoes unusual changes in size and shape that are accompanied by several phases of organization of the chromatin. In the mature sperm the nucleus is empty-appearing and notably lacking in any apparent high degree of order. The entire development of the sperm is consonant with the idea that the fate of the mitochondria and centrioles, structures that figure prominently in the elaborate architecture of flagellate sperm, is associated with the lack of a flagellum.

Acrosome↗
PubMed1958

The relation between the axial complex of meiotic prophase chromosomes and chromosome pairing in a salamander (Plethodon cinereus).

An investigation of the structure of meiotic chromosomes from primary spermatocytes of two salamanders, Plethodon cinereus and Desmognathus fusca, has been made using correlated light and electron microscopy. Feulgen squashes were compared with stained sections and these related to adjacent thin sections in the electron microscope. A transition from the familiar cytological preparation to the electron image was thus effected. A linear complex consisting of three parallel strands has been observed with the electron microscope, passing along the central axis of primary spermatocyte chromosomes. The complex is similar to that found in comparable chromosomes from at least a dozen animal species. The structure in Plethodon is described in detail. Synapsis has been positively identified as the stage of meiotic prophase at which the complex occurs. Thus the complex is a part of bivalent chromosomes. It has not been seen in other stages or other divisions and is thus thought to be exclusively of synaptic occurrence. The term synaptinemal complex is suggested for the entire structure. By virtue of the material condensed around it, the complex is also seen in the light microscope where it appears as a fine, densely Feulgen-positive central core along the chromosome. The complex is thus closely associated with DNA, if not at least in part, composed of it. In the stages studied, homologous chromosomes are not always completely paired. The lateral elements of the complex separate and follow the single chromosome axes at these points. The central element disappears and thus may be a phenomenon of pairing. It is concluded that the lateral elements of the synaptinemal complex may more correctly be a "core" of the single meiotic prophase chromosome, possibly being concerned with its linear organization.

Animals↗
PubMed1957

The Nissl substance of living and fixed spinal ganglion cells. II. An ultraviolet absorption study.

Living chick spinal ganglion neurons grown for 19 to 25 days in vitro were photographed with a color-translating ultraviolet microscope (UV-91) at 265, 287, and 310 mmicro. This instrument was unique in permitting rapid accumulation of ultraviolet information with minimal damage to the cell. In the photographs taken at 265 mmicro of the living neurons, discrete ultraviolet-absorbing cytoplasmic masses were observed which were found to be virtually unchanged in appearance after formalin fixation. These were identical with the Nissl bodies of the same cells seen after staining with basic dyes. The correlation of ultraviolet absorption, ribonuclease extraction, and staining experiments with acid and basic dyes confirmed the ribonucleoprotein nature of these Nissl bodies in the living and fixed cells. No change in distribution or concentration of ultraviolet-absorbing substance was observed in the first 12 ultraviolet photographs of a neuron, and it is concluded that the cells had not been subjected to significant ultraviolet damage during the period of photography. On the basis of these observations, as well as previous findings with phase contrast microscopy, it is concluded that Nissl bodies preexist in the living neuron as discrete aggregates containing high concentrations of nucleoprotein.

Cytoplasm↗
PubMed1956

Studies on nuclei using correlated cytochemical, light, and electron microscope techniques.

In this paper, a procedure for correlating electron microscope and light microscope cytochemical studies using immediately adjacent serial thin and thick sections has been described and discussed. This technique, combined with the Feulgen reaction for DNA, has been of particular value in framing and answering both general and specific questions about the nucleus. The results may be summarized as follows:- Apparent nuclear homogeneity in the electron microscope is not due to loss of DNA as evidenced by positive Feulgen reactions in such nuclei. Arrangement of Feulgen-positive material in chromosomes, heterochromatin, perinuclear and perinucleolar chromatin, etc., is similar to that customarily observed in the light microscope but this is not necessarily reflected in a cursory survey of the electron image. Careful comparison of light and electron images shows that fine differences in structure are associated with chromatin localization. Primary spermatocyte prophase chromosomes of crayfish have been positively identified by their Feulgen-positive nature. Core-like axial structures in such chromosomes have been observed (9) and are described further. A remarkable feature of spermiogenesis in the crayfish is an elaboration of the nuclear envelope of the spermatid accompanying the formation of what becomes a mass of convoluted membranes in the sperm. In the spermatid, perinuclear chromatin follows outpocketings of the nuclear envelope into the cytoplasm. In the early sperm, on the other hand, although the nuclear envelope is continuous with the system of convoluted membranes, the chromatin is distinct from it and is retained in the nucleus proper by some mechanism independent of the nuclear envelope. None of the above observations was apparent from the electron microscope images alone; they were possible only by virtue of the correlated cytochemical and electron microscope study of adjacent sections. The successful use of other cytochemical tests, such as the PAS reaction for certain carbohydrates, in such correlated studies is also described.

Cell Nucleus↗
PubMed1954

Cellular mechanisms of protein metabolism in the nephron. II. The histochemical characteristics of protein absorption droplets.

Histochemical methods show not only the presence of absorbed protein in the cellular droplet, but also the general identity of its constituent substances with those of the mitochondrial rodlets. Both contain considerable amounts of phospholipid and probably some PNA. The reactivity of the cytoplasmic constituents in droplet and in rodlet are different, however, since in the droplet these substances stain more intensely. As judged by variations observed in this intensity during the evolution of the droplet, these constituents and the absorbed protein vary in their proportions and amount. The droplet would appear to be a highly active center of protein metabolism.

Cytoplasm↗