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H H MOLLENHAUER

Publications and source records attributed to H H MOLLENHAUER.

13 recordsLinked to original sources
PubMed1964

ISOLATION OF THE GOLGI APPARATUS FROM PLANT CELLS.

A method for the isolation of the Golgi apparatus from stem tissues of onion is described. Preparations that consisted mainly of morphologically identifiable Golgi apparatus have been obtained. The best preparations were obtained from tissue homogenized under conditions of minimum shear, and in the presence of sucrose and certain additives which aid in preservation of the integrity of the Golgi membranes. Those additives, which had a pronounced stabilizing effect on the isolated apparatus, included both monovalent and divalent ions (sodium and calcium) and dextran. A large portion of the Golgi apparatus did not appear to change microscopic appearance upon isolation, but were observed to fuse into large aggregate structures not unlike those occurring naturally in certain animal or insect cells (12). Fusion occurred both at the edges of the cisternae and in register, but the integrity of the individual cisternae was not destroyed. The major contaminants of the Golgi apparatus fraction were numerous small and large spherical vesicles. At least some of these vesicles appeared to have been derived from the Golgi apparatus; others may have been fragments of the cell membrane, the endoplasmic reticulum, or other cell debris. By utilizing this procedure, it has been possible to obtain fractions of Golgi apparatus from plant tissues other than onion stem. However, at the present time it is only with onion that the Golgi apparatus has been isolated in a form that would warrant further purification for biochemical analysis.

Animals↗
PubMed1960

Electron microscopic observations on mitochondria of rat testes fixed in potassium permanganate.

A morphological investigation of mitochondria within the seminal epithelial cells of rat testes fixed in potassium permanganate reveals differences in electron opacity between the internal mitochondrial membranes of spermatogenic cells and those of Sertoli cells. Some interpretations of the apparent density differences are briefly discussed. It is concluded that the different effects of permanganate fixation upon the mitochondria of these cell types may reflect a significant structural difference between them.

Animals↗
PubMed1960

Some observations on the nuclear envelope.

In maize root meristem cells, fixed in KMnO(4), embedded in epoxy resin, ultrathin sectioned, and studied with an electron microscope, the nuclear envelope is demonstrated to be a double membrane structure. In the nuclear envelope there are: pores of the sort reported in many species of animals and plants; different types of openings associated with extensions of both nuclear membranes into the cytoplasm; and also, often, large discontinuities. The nuclear envelope is a component of the general vesicular reticulum. The reticula of neighboring cells including the nuclear envelopes make up, at certain stages at least, a "systemic" structure. The status of the nuclear envelope as a component of the general cellular reticulum is recognized to change during differentiation. The existence of several types of discontinuities in the nuclear envelope and the extent of nuclear-cytoplasmic surface relationships indicated suggests alteration in concepts of transport and exchanges between nucleus and cytoplasm.

Animals↗
PubMed1960

Permanganate fixation of the Golgi complex and other cytoplasmic structures of mammalian tests.

Observations on the fine structure of KMnO(4)-fixed testes of small mammals (guinea pig, rat, and mouse) reveal certain morphological differences between the spermatogenic and Sertoli cells which have not been demonstrated in the same tissue fixed with OsO(4). Aggregates of minute circular profiles, much smaller than the spherical Golgi vesicles, are described in close association with the Golgi complex of developing spermatids. Groups of dense flattened vesicles, individually surrounded by a membrane of different dimensions than that which bounds most of the other cell organelles, appear dispersed within the cytoplasm of some spermatogenic cells. Flattened vesicles of greater density than those belonging to the Golgi complex are reported confined to the inner Golgi zone of developing guinea pig spermatids between the Golgi cisternae and the head cap. The profiles of endoplasmic reticulum within spermatocytes appear shorter, wider, and more tortuous than those of Sertoli cells. Minute cytoplasmic particles approximately 300 A in diameter and of high electron opacity appear randomly disposed in some Sertoli cells. Groups of irregular-shaped ovoid bodies within the developing spermatids are described as resembling portions of cytoplasm from closely adjacent spermatids. Interpretation is presented regarding the fine structure of KMnO(4)-fixed testes in view of what has already been reported for mammalian testes fixed in OsO(4).

Animals↗
PubMed1959

The endoplasmic reticulum and the Golgi structures in maize root cells.

Maize root tips were fixed in potassium permanganate, embedded in epoxy resin, sectioned to show silver interference color, and studied with the electron microscope. All the cells were seen to contain an endoplasmic reticulum and apparently independent Golgi structures. The endoplasmic reticulum is demonstrated as a membrane-bounded, vesicular structure comparable in many aspects to that of several types of animal cells. With the treatment used here the membranes appear smooth surfaced. The endoplasmic reticulum is continuous with the nuclear envelope and, by contact at least, with structures passing through the cell wall. The nuclear envelope is characterized by discontinuities, as previously reported for animal cells. The reticula of adjacent cells seem to be in contact at or through the plasmodesmata. Because of these contacts the endoplasmic reticulum of a given cell appears to be part of an intercellular system. The Golgi structures appear as stacks of platelet-vesicles which apparently may, under certain conditions, produce small vesicles around their edges. Their form changes markedly with development of the cell.

Animals↗
PubMed1959

Permanganate fixation of plant cells.

In an evaluation of procedures explored to circumvent some of the problems of osmium tetroxide-fixation and methacrylate embedding of plant materials, excised segments of root tips of Zea mays were fixed for electron microscopy in potassium permanganate in the following treatment variations: unbuffered and veronal-acetate buffered solutions of 0.6, 2.0, and 5.0 per cent KMnO(4) at pH 5.0, 6.0, 6.7, and 7.5, and temperatures of 2-4 degrees C. and 22 degrees C. After fixation the segments were dehydrated, embedded in epoxy resin, sectioned, and observed or photographed. The cells of the central region of the rootcap are described. The fixation procedures employing unbuffered solutions containing 2.0 to 5.0 per cent KMnO(4) at a temperature of 22 degrees C. gave particularly good preservation of cell structure and all membrane systems. Similar results were obtained using a solution containing 2.0 per cent KMnO(4), buffered with veronal-acetate to pH 6.0, and a fixation time of 2 hours at 22 degrees C. The fixation procedure utilizing veronal-acetate buffered, 0.6 per cent KMnO(4) at 2-4 degrees C. and pH 6.7 also gave relatively good preservation of most cellular constituents. However, preservation of the plasma membrane was not so good, nor was the intensity of staining so great, as that with the group of fixatives containing greater concentrations of KMnO(4). The other fixation procedures did not give satisfactory preservation of fine structure. A comparison is made of cell structures as fixed in KMnO(4) or OsO(4).

Cell Membrane↗