Parallel spindles

Figure 2.3 All genetic interactions from the centromere to the first crossover are transmitted to offspring in gametes produced by a first division restitution mechanism such as parallel spindles.

In terms of evolutionary biology, the complex mitotic process of higher animals and plants has evolved through a progression of steps from simple prokaryotic fission sequences. In prokaryotic cells, the two copies of replicated chromosomes become attached to specialized regions of the cell membrane and are separated by the slow intrusion of the membrane between them. In many primitive eukaryotes, the nuclear membrane participates in a similar process and remains intact the spindle microtubules are extranuclear but may indent the nuclear membrane to form parallel channels. In yeasts and diatoms, the nuclear membrane also remains intact, an intranuclear polar spindle forms and attaches at each pole to the nuclear envelope, and a single kinetochore microtubule moves each chromosome to a pole. In the cells of higher animals and plants, the mitotic spindle starts to form outside of the nucleus, the nuclear envelope breaks down, and the spindle microtubules are captured by chromosomes (Kubai, 1975 Heath, 1980 Alberts et al., 1989). 

Chia I can t think of a good way of mislocalizing Pins. With Inscuteable, early on in embryogenesis it is expressed in a single domain and nowhere else. The cells give rise to some of the cells that become the larval brain. The spindle in this region forms parallel to the surface and reorients at 90°, perpendicular to the surface of the embryo. These cells which don t express Insc set up their spindle parallel and divide parallel to the surface. If you force Insc expression in these cells they will reorient. 

Chia This is hard to say. But probably not, because in Pins- embryos epithelial cells still orient their spindles parallel to the surface. 

For very small pulsation-free metering flows (e.g., 10 to 103 ml/h), hydraulic and mechanical (spindle) linear drives can be used for pressures up to several thousand bar. By operating two systems in parallel controlled by sensors, these can also be operated without essential interruption (Fig. 4.1-8a and b). By superposing two displacement pistons, or by controlling the angular velocity with a special cam drive, small metering flows with low pulsation are achieved up to a pressure of about 700 bar. This can even be done with leak-free hydraulic... 

Microtubules similar to those found in flagella are also present in the cytoplasm. Together with thinner microfilaments of several kinds they form an internal cytoskeleton that provides rigidity to cells.58 59 Microtubules also form the "spindle" of dividing cells. In nerve axons (Chapter 30) the microtubules run parallel to the length of the axons and are part of a mechanical transport system for cell constituents. 

Spindle/stem A part whose axial orientation is parallel to the travel of the disc/ seat. It may be used in one or more of the following functions ... 

Fibroblasts live in the spaces between other cells and secrete the proteins of the extracellular matrix, e.g. collagen. They do not associate tightly with one another or with other cell types, but they do readily attach themselves to a substratum. In dilute culture they are observed as individual spindle shaped cells which move around the surface of the culture vessel avoiding each other. As their density increases they tend to align themselves in parallel assays (Fig. 2.1). However, fibroblasts can become chondrocytes or adipocytes in the appropriate environment (Taylor and Jones, 1979) and on transformation ( 2.2) they readily lose their contact inhibition and pile up on top of one another (Fig. 2.1)... 

The reflex doctrine could not, however, help the pioneer sleep and dream scientists very much, because no link could be established between the activity of circuits of neurons (neuronal circuits) and the EEG. It had long been assumed that the EEG was the register of voltage changes in the brain (i.e. cerebral action potentials), although this could not explain the patterns of the EEG seen in sleep (e.g. spindles and slow waves), unless neuronal activity was continuous, i.e. spontaneous, as well as reflexive. Consequently, work at the cellular and EEG levels proceeded along entirely separate but parallel tracks, similar to those that Descartes thought God had used to set mind and body in perfect but independent motion. Cartesian duality dies slowly it is still alive and well in most of us because we cannot yet see how a physical object, the brain, can have subjective experience. This is the so-called hard problem of philosophy. 

Exploiting the fact that the spindle hbers are optically anisotropic, or birefringent, with different indices of refraction in different directions (i.e., parallel or perpendicular to the hber axis), Inoue (2) developed a sensitive polarized light microscope... 

The cortex forms the bulk of fine animal hairs and is derived from highly differentiated spindle-shaped cells that are densely packed with keratinous proteins. The long axes of the cortical cells are oriented parallel to the fiber length, and elongated cavities near the center of the cells are similarly oriented. These cavities are derived from the nuclei of the developing cells and contain debris usually referred to as nuclear remnants. Between cortical cells there is a layer 250-300 A in thickness which is similar to that found between cuticle cells this also is referred to sometimes as intercellular cement. Many nonkeratinous inclusions are found within the cortical cells and these are believed to be cytoplasmic debris. 

Mammillary calcite is very dense, with porosities much less than 1%. Pore spaces are of two different types. The first type consists of irregularly shaped pore spaces with fluid inclusions that are commonly oriented parallel with the crystallite boundaries. In traditional speleothems, spindle-shaped inclusions mark the sites where columnar crystals have coalesced (Kendall and Broughton, 1978). In mammillary calcite, the irregular inclusions probably mark... 

Fibrosarcoma is a mesenchymal tumour originating from fibroblasts it can therefore occur ubiquitously in the whole body. (12) It was first described by R.H. Jaefe in 1924. About 35 cases have been reported so far. This type of tumour has a firm consistency and contains cystic structures with focal necroses and haemorrhages. It possesses a fibrous pseudocapsule and consists of fascicu-larly arranged, spindle-like or fusiform tumour cells embedded in parallel collagen fibres. The non-epithelial stroma marker vimentin is overexpressed. These cells may exhibit marked polymorphism. Fibrosarcoma mainly occurs in men of advanced age. Therapy consists of tumour resection and adjuvant chemotherapy. (280,281)... 

The starting drift is the most difficult to make (Fig. 2) because the central hole which fits over the spindle is comparatively long and must be bored exactly parallel to the outside for Its entire length. 

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