Mongolian gerbils exposed to relatively short (7 or 15 min) unilateral or bilateral occlusions of the common carotid artery develop, 20 h after release of the clipping, characteristic morphologic changes in the H3 sector of the hippocampus. Ultrastructural study of these changes revealed an eccentric shift of the nuclei associated with chromatolytic perikarya which showed a dense accumulation of lysosomes and mitochondria in their central parts. The Golgi apparatus was recognizable only by clusters of vesicles, and this change was associated with a negative thiamine pyrophosphatase reaction.

Animals↗

PubMed1976

Isolation of brain capillaries: a simplified technique.

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Animals↗

PubMed1976

Late changes in human sural nerves in Minamata disease and in nerves of rats with experimental organic mercury poisoning.

The sural nerves of 2 human cases with Minamata disease and poisoned rats were examined histopathologically. Both showed similar findings: the myelinated nerve fibres were decreased in number, but small myelinated nerve fibres were increased: The latter were irregular in shape and their Schwann cells showed regressive changes, with high electron density of the cytoplasms and many glycogen granules. Onion bulb formation was not found. According to fibre diameter histograms, the ratio of small myelinated nerve fibres of 2-5 mum showed a high percentage. A large number of the small myelinated nerve fibres were presumed to be regenerated nerve fibres. These findings are different from other peripheral neuropathies and may be characteristics of the late changes of the sural nerve induced by organic mercury compound.

Adolescent↗

PubMed1976

The origin, migration and morphology of the primordial germ cells in the chick embryo.

Chick primordial germ cells (PGCs) which separated from the "germinal crescent" entoderm in the period from stages 4 to 8 circulated mostly through the developing blood vessels from stage 10 onward and finally migrated into the gonad. The PGCs making their appearance up to this stage were generally spherical in profile, about 14 mum in diameter. Some of the PGCs in contrast, did not enter the blood vessels but remained in the tissue (mesenchyme) of the embryo proper (tissue PGCs) and possessed pseudopodial processes, suggesting their migration by means of amoeboid movements. The circulating PGCs emerged from blood vessels in the vicinity of developing gonads by three days (gonadal PGCs). The principal mechanism responsible for the subsequent migration of gonadal PGCs is assumed to be amoeboid movements as in the case of tissue PGCs. Notable amounts of PAS-positive glycogen were demonstrated in the cytoplasm of PGCs in all stages obsreved. They also contained yolk and lipids intracytoplasmically, the former dissipating in relatively early stages of development. Electron microscopic observation revealed the electron-opaque, "fragmented nucleolus" in the large nucleus (8 mum in diameter), which represented another prominent feature of chick PGCs. PGCs contained a well-developed Golgi complex and endoplasmic reticulum.

Aged↗

PubMed1976