Hadron Beams

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Light and electron-microscope studies on dragonfly ovarioles reveal evidence that the precursor vitelline membrane and chorion secretions are synthesized within the follicle cells. It is suggested that the sequence of synthesis and deposition of the vitelline membrane occurs as follows. The vitelline membrane presecretion appears to be synthesized by the(More)
Early diplotene oocytes from Necturus maculosus ranging from ∼ 0.2 to 0.5 mm in diameter were examined by electron microscopy. In the smallest oocytes of this range, the cytoplasm is largely devoid of membranes, but contains primarily ribosomes and mitochondria. In slightly larger oocytes, smooth-surfaced cytomembranes first appear in the perinuclear(More)
The endoplasmic reticulum is composed, in places, of stacks of parallel cisternae which are limited by membranes having great numbers of ribosomes attached to their outer surface. These are connected with other cisternae of similar structure but with fewer ribosomes and without preferred orientation. The latter extend in all directions from the stacked(More)
Ultracentrifugation of living cells from the liver of the mouse, rat, dog, frog, Necturus, follicle cells, of grasshopper testis, and meristem of the onion root tip shows evidence that the interphase chromatin is attached to the nuclear envelope. Because of its relatively high density, the bulk of the interphase chromatin, and often the nucleoli, are(More)
The test cell in the ovary of the tunicate Styela contains a large and robust Golgi complex which demonstrates a regional structural differentiation. In one of the regions, branching of the lamellae occurs resulting in a honeycomb or lattice-type arrangement. Small, dense granules or homogeneous material of moderate density may be present within certain of(More)