A comparative electron microscope study was carried out on ultrathin sections of bone marrow, spleen, lymph nodes, and mediastinal tumors from eighteen rats with leukemia induced by mouse leukemia virus (Gross). In organs of all eighteen rats with leukemia, two types of particles were observed: one type, described as virus particles of 990 A average diameter, with an electron-dense center of 63...

Numerous, ongoing outbreaks in Brazilian swine herds have been characterized by vesicular lesions in sows and acute losses of neonatal piglets. The complete genome of Seneca Valley virus (SVV) was identified in vesicular fluid and sera of sows, providing evidence of association between SVV and vesicular disease and viraemia in affected animals.

Gross morphology and morphometry of the bowhead whale ovary, including ovulatory corpora, were investigated in 50 whales from the Chukchi and Beaufort seas off the coast of Alaska. Using the presence of ovarian corpora to define sexual maturity, 23 sexually immature whales (7.6-14.2 m total body length) and 27 sexually mature whales (14.2-17.7 m total body length) were identified. Ovary pair we...

Bovine virus diarrhoea virus (BVDV) has been (tentatively) identified by electron microscopy in purified virus preparations, in infected cell cultures and in tissues and cells from infected animals. These studies have revealed a spherical membrane-bound particle with a diameter of 40-60 nm. The membrane is smooth, bilaminar and surrounds a dense or semi-dense core of 20-25 nm. The core particle...

The terminal degeneration of retino-tectal fibres was studied electron microscopically in the pigeon Synaptic vesicles seem to undergo systematic changes which can best be observed in aldehyde-fixed material. Initially (i.e. within 12-24 h) the vesicles begin to swell. The enlargement is clearly visible after 4 days (40 % increase in diameter) and reaches a maximum at 14 days (100% increase). A...

The vitelline body in the mature oocyte of the spider Tegenaria parietina is composed of 4 different zones. 1. The central zone contains granular areas, vesicles, and a few lamellae. 2. The lamellar zone consists of numerous concentric lamellae. These sheets, 45 A in thickness, are stacked in groups. The fine structure and the regular arrangement recall those of myelin sheets, retinal rods, and...

In plants, newly synthesized fatty acids are either directly incorporated into glycerolipids in the plastid or exported and assembled into lipids at the endoplasmic reticulum (ER). ER-derived glycerolipids serve as building blocks for extraplastidic membranes. Alternatively, they can return to the plastid where their diacylglycerol backbone is incorporated into the glycerolipids of the photosyn...

In vitro synthesis of collagen by established mouse fibroblast lines has been examined by electron microscopy. During rapid growth (log phase), when collagen could not be detected in the cultures, the cells lacked a well developed granular ergastoplasm and Golgi system. Upon cessation of growth (stationary phase), collagen accumulated in the cultures and the cells demonstrated highly developed ...

Myoneural junctions in Anolis are characterized by the formation of troughs in the surface of the muscle fibers in which small branches of the terminal axon lie. The muscle surface membrane lining the troughs is thrown into complex branching and anastomosing folds, which compose the subneural apparatus of Couteaux. A compound membrane 500 to 700 A thick separates axoplasm from sarcoplasm at the...

Atomic force microscopy reveal pit-like structures typically containing three or four, approximately 150 nm in diameter depressions at the apical plasma membrane in live pancreatic acinar cells. Stimulation of secretion causes these depressions to dilate and return to their resting size following completion of the process. Exposure of acinar cells to cytochalasin B results in decreased depressi...