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R G KESSEL

Publications and source records attributed to R G KESSEL.

13 recordsLinked to original sources
PubMed1965

AN UNUSUAL CONFIGURATION OF THE GOLGI COMPLEX IN PIGMENT-PRODUCING "TEST" CELLS OF THE OVARY OF THE TUNICATE, STYELA.

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 the Golgi cisternae. The close association, or continuity in some cases, between elements of the Golgi complex and immature forms of pigment suggests that the Golgi complex in these cells is involved in pigment formation. These relationships are shown and discussed in terms of possible functional significance.

Animals↗
PubMed1963

ELECTRON MICROSCOPE STUDIES ON DEVELOPING CRAYFISH OOCYTES WITH SPECIAL REFERENCE TO THE ORIGIN OF YOLK.

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 cisternae, branching and anastomosing freely so that the entire system of membrane-limited cisternae appears interconnected; a morphological condition suitable to serve as the basis for an active transport system. Within the stacked cisternae appear granules about 40 to 60 mmicro in diameter. These are thought to represent the precursors of proteinaceous yolk, and the hypothesis is advanced that most of the intracisternal granules are synthesized here, possibly under the influence of the ribosomes. They then "flow" into and along the unoriented cisternae to regions where they collect, expand the cisternae, and undergo transformation into finely granular, relatively large proteinaceous yolk bodies. The mitochondria are somewhat pleomorphic, often show atypical cristae, and frequently contain a few dense granules. Lipid is abundant. Other cytoplasmic components are illustrated.

Animals↗
PubMed1963

ELECTRON MICROSCOPE STUDIES ON THE ORIGIN OF ANNULATE LAMELLAE IN OOCYTES OF NECTURUS.

Developing oocytes, ranging from approximately 0.1 to 1.0 mm in diameter, in Necturus were studied with the electron microscope. The outer layer of the nuclear envelope is actively engaged in the formation of vesicular elements along most of its surface, especially in smaller oocytes. Groups of vesicles appear to be released into the ooplasm at about the same time, resulting in long chains of individual vesicles immediately adjacent to the nuclear membrane. This process is repeated so that chains of vesicles grouped in rather ordered ranks extend progressively into the surrounding cytoplasm. Eventually, the cytoplasm becomes more concentrated with chains of vesicles and the distance between the individual rows becomes less. Very soon after a chain of vesicles has been budded off from the nuclear membrane, fine intervesicular connections appear between certain of the vesicles comprising the rows. Several of the vesicles in a row may then fuse, forming short, flattened cisternae. Fusion of vesicles continues, individual rows of vesicles become more closely packed and, finally, regions appear in the cytoplasm which have the appearance of annulate lamellae. Further growth of the lamellae appears to occur by the progressive fusion of vesicles at the ends of those lamellae already present, as well as by the addition of other fusing rows of vesicles.

Animals↗