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Biomedical subjects

H Stephan

Publications and source records attributed to H Stephan.

At least 109 records · Page 6Linked to original sources
PubMed1980

Comparative investigations on hippocampus in insectivores and primates.

Quantitative investigations on the hippocampus and its components from insectivores through lower to higher primates show a marked enlargement of area CA 1 of the retrocommissural hippocampus. In man, the retrocommissural hippocampus as a whole has an allometric enlargement of 3.5 times that of the lower insectivores of equal body weight. The allometric enlargement of area CA 1 is much greater (6.6 times) than that of all other components (1.6 to 3.3 times). The marked enlargement of CA 1 is accompanied by clear histomorphological alterations, the most striking of which is an obvious migration of the CA 1 pyramidal cells into the stratum oriens in the direction of the alveus. This migration of cells is considered to be caused by neurobiotaxic influences from the afferent alvear system which thus appears to be more important in higher primates. In contrast, the small praecommissural hippocampus (0.5 to 7% of the total hippocampus) is reduced. The possible relationship of this structure to olfaction is discussed.

Animals↗
PubMed1979

A quantitative approach to cytoarchitectonics. IV. The areal pattern of the cortex of Galago demidovii (e. Geoffroy, 1796), (lorisidae, primates).

The boundaries of neo- and allocortical areas of Galago demidovii are analyzed with an automatic quantitative procedure using an image analyzer. The results are summarized in a cortical map and compared with a cortical map of Tupaia. Galago shows a highly differentiated temporal lobe and no homogeneous peristriate area comparable to the classical concept of Brodmann's Area 19. Primary motor, somatosensory, auditory, and visual areas are delineated and shown to be surrounded by distinct secondary areas.

Animals↗
PubMed1978

Transfer of bovine J-blood-group determinant onto erythrocytes: isolation and identification of a blocker.

The bovine J-blood-group determinant is transferred from a serum glycoprotein to an erythrocyte membrane lipid by incubation in vitro. This transfer is inhibited by a lipid (called 'blocker') occurring in bovine and human serum, in other bovine and human tissues, yeast and plant tissues. The blocker was isolated from bovine spleen and identified as phosphatidylserine. Moreover, phosphatidylinositol acts as a blocker, while a variety of other phospholipids, glycosphingolipids and neutral lipids have no function as blockers. Mild alkaline deacylation deletes the blocker activity of both phosphatidylserine and phosphatidylinositol. Methyl esters of these phospholipids, or exchange of the amino group for a hydroxyl group in phosphatidylserine or N-benzoylation of phosphatidylserine, do not affect the blocker function. The blocker function of phosphatidylinositol is lost after periodate oxidation. The blocker reacts with the J-containing serum protein, not with the erythrocyte membrane. After preincubation of the J-positive serum protein with the blocker and reextraction of excess blocker, the serum protein remains J-positive, but is then unable to transfer the J determinant to the erythrocyte membrane.

Animals↗
PubMed1977

Quantitative comparison of the amygdala in insectivores and primates.

Comparative architectonic studies have resulted in a classification of the amygdaloid complex which differs somewhat from the commonly used classification (first proposed by Humphrey, 1936) by separating the cortical amygdaloid nucleus from the centromedial group and assigning it to the basolateral group, which then forms a cortico-basolateral group. The size changes of these groups and of the nucleus of the lateral olfactory tract (belonging to the centromedial group) and the large-celled part of the basal nucleus (belonging to the corticobasolateral group) have been investigated in representatives of an ascending primate scale. In all structural complexes investigated so far, the small-celled part of the cortico-basolateral group is the most progressive. In descending order of progression there follow: the corticobasolateral group as a whole, the amygdala as a whole, and the large-celled basal nucleus. No clear changes were found in the centromedial group as a whole, whereas the size of the nucleus of the lateral olfactory tract, which represents a small component of this latter group, shows a strong reduction. These differences in the developmental trends point to increasing or decreasing capacities of the functional (limbic and olfactory) systems, to which these structures are related.

Amygdala↗
PubMed1976

[Comparative volumetry of brains from wild and captive tree shrews (Tupaia)].

The changes in brain weight and composition during captivity were investigated in two groups of tree-shrews (Tupaia). One group consisted of wild animals whose brains were dissected and weighed immediately after trapping in Thailand. The second group (F1) consisted of animals reared in captivity whose parents originated from the same populations of Thailand animals as the first group. Wild- and F1-animals showed no significanct differences in body weight; however, the brain weight was significantly greater in F1-animals. This is in clear contrast to the results of former investigations of other species, in which the brain size became reduced in captivity. Of the various brain parts, the absolute volumes of the cerebellum and the telencephalon, and, within the latter, those of the striatum, schizocortex, neocortex, and area striata were enlarged significantly in animals reared in captivity. A significant decrease was observed in the complex of paleocortex + amygdala, and a possible decrease in the hippocampus. An attempt to interpret the changes was made with regard to differences in age-composition between the two groups, different nutrition and motor activities, heterochronies in the ontogenetic development, and, finally, different environmental influences during ontogeny.

Age Factors↗