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Biomedical subjects

H J Kretschmann

Publications and source records attributed to H J Kretschmann.

At least 37 records · Page 2Linked to original sources
PubMed1987

A quantitative study of Australian aboriginal and Caucasian brains.

The brain volumes of 8 male Australian Aborigines and 11 male Caucasians were determined. Total brain volume was significantly smaller for Aborigines (1199 +/- 84 ml) compared to Caucasians (1386 +/- 98 ml). Significantly smaller volumes were also found for cerebellum, prosencephalon-mesencephalon unit, cerebral cortex, frontal cortex, parieto-occipitotemporal cortex, and hippocampus. Volumes of ponsmedulla oblongata unit (21 +/- 3 ml for Aborigines and 22 +/- 3 ml for Caucasians) and visual cortex (14.9 ml +/- 2.6 ml and 14.6 +/- 2.2 ml, respectively) did not differ significantly. The striate cortex extended further onto the lateral surface of the occipital lobe in Aboriginal brains. The frontal portion of cerebral cortex was larger in Aboriginal than in Caucasian brains. According to the specific growth periods for the areas studied, these differences could be explained by the higher incidence of malnutrition and infectious diseases for Aboriginals during the development of the brain in early childhood, especially after the 6th postnatal month. However, genetic influences cannot be excluded. The results for the visual cortex of Aborigines might represent an adaptation to living conditions in the bush and desert regions of Australia.

Adult↗
PubMed1986

A quantitative study of the cerebral cortex in Alzheimer's disease and senile dementia using an automatic image analyzing system.

The gray level index method was used in order to quantitatively differentiate the histological characteristics of a pathological population (n = 14) from those of a normal population (n = 14). An automatic image analysis system compared the laminar patterns in the straight gyrus of the cerebral cortex of deceased normal patients with those who died with Alzheimer's disease and senile dementia. In comparison to the normal control group, the cases with Alzheimer's disease and senile dementia show a significant decrease in the gray level index of lamina III.

Aged↗
PubMed1986

Brain growth in man.

25 male brains meeting the criteria for normativity and available in serial sections suitable for morphometric studies were selected from the Yakovlev Collection. Growth parameters were calculated based on the generalized logistic function. The ideal weight is 1,313 g (SD = 41), with a half value time of 387 (SD = 26) ontogenetic days and a growth factor of 4.0 (SD = 0.5). Comparison of growth parameters derived from a sample of 161 normative male brains collected at the Department of Neuroanatomy of the Medical School in Hannover revealed an ideal weight of 1,353 g (SD = 14), a half value time of 401 (SD = 10) ontogenetic days and a growth factor of 4.0 (SD = 0.2). The minor discrepancies in the corresponding parameters reflect the small sample size and a considerable lack of developmental data of the three first postnatal decades in the material derived from the Yakovlev Collection. It was, therefore, deemed necessary to analyze these data in combination with data derived from other sources of human material. A comparison of human with animal growth parameters derived from mice, cats and tree shrews reveals differences in brain development. Histological shrinkage of the 25 male brains of the Yakovlev Collection related to fixation, embedding, and staining was assessed. Fetal brains shrank by about 75%, and adult brains by about 50%. The degree of shrinkage was inversely proportional to the age of the brain and was also characterized by individual variations of up to 20%. Therefore, shrinkage had to be corrected on an individual basis in order to determine the true growth of brain regions as reflected by morphometric analysis of histological serial sections.

Adolescent↗
PubMed1986

Growth of the hippocampal formation in man.

The fresh volumes of the cortical area of the hippocampal formation were determined in 29 male, normative human brains ranging in age from 137 to 36,221 ontogenetic days inclusive of mid-gestation to the 99th postnatal year. The data were fitted by the 3-, 4-, and 5-parametric logistic functions. The ideal value P1 of the left hippocampal formation is 3 ml (SD = 0.1), the half-value time is 306 (SD = 32) ontogenetic days and the growth factor is 2.5 (SD = 0.4). The maximal daily growth rate of 8 mm3 occurs at approximately the half value time. According to the theory of Dobbing and Sands [1979], this period of rapid growth of the hippocampal formation with other brain regions suggests the existence of heterochronous development.

Adolescent↗
PubMed1986

Volumetric development of the fetal telencephalon, cerebral cortex, diencephalon, and rhombencephalon including the cerebellum in man.

Fresh volumes of the human telencephalon, cerebral cortex, diencephalon, and of the rhombencephalon including cerebellum were determined in a series of 10 normal specimens ranging in age from 63 to 176 days after conception. The volumetric growth of these parts shows a nonlinear dependence on age with a smaller increase during the 3d ontogenetic month and a stronger increase from the 4th month on. These data were analyzed together with previous measurements of 28 brains taken from the Yakovlev Collection in Washington, D.C., and the Vogt Collection in Düsseldorf. These brains range in age from 137 to 22,900 days after conception. These samples were reproduced in a model using sigmoid logistic functions. The entire brain and all analyzed parts show a monotonous growth. The individual regions develop heterochronously. The diencephalon is the first part to reach its ideal volume, with a main growth spurt between 100 and 420 days after conception. The rhombencephalon including the cerebellum is the last, with its main growth spurt between 240 and 650 days after conception. The growth of the entire brain is determined to a great extent by that of the telencephalon, having a main growth spurt between 175 and 580 days after conception. The prenatal growth is described separately with the asymmetric sigmoid function according to Gompertz. This yields a better approximation of the data collected from the early prenatal period.

Cerebellum↗
PubMed1985

A new embedding and sectioning technique (macrovibratome) for macroscopic and morphometric examinations especially of the human brain.

The macrovibratome is a newly developed sectioning apparatus designed especially for the preparation of human brain material subject to macroscopic and morphometric examinations. The brain is embedded in an aqueous agar solution and cut into slices with a minimum thickness of 2 mm. Using a 20% or 40% gelatin solution as the embedding material results in an average shrinkage of the tissue blocks of 9.8 or 31.7% in volume, respectively. With a 3% agar solution the volume shrinkage lies on the average at 1.0% for smaller brain pieces and 4.5% for cerebra.

Agar↗
PubMed1982

Different volume changes of cerebral cortex and white matter during histological preparation.

In quantitative neuroanatomy and neuropathology, large neuronal systems are frequently analyzed on the basis of small tissue blocks thus assuming that the volume changes of the various compartments of the tissue block can be corrected by an overall factor. 228 blocks of cerebral cortex and white matter of the frontal lobe, thalamus, and striatum were prepared from 13 human brains and embedded in paraffin. The mean shrinkage in the paraffin sections was found to be 51% for the cerebral cortex and 42% for the white matter. Therefore, an overall correction factor tissue blocks both with cerebral cortex and white matter results in an underestimation of cerebral cortex and an overestimation of white matter.

Adult↗
PubMed1979

The Yakovlev Collection. A pilot study of its suitability for the morphometric documentation of the human brain.

A pilot study on the Yakovlev Collection in Washington, D.C. was carried out in September/October, 1977, to determine its suitability for morphometric documentation of the growth of the human brain and its structural components. The Yakovlev Collection contains complete serial sections of approximately 800 human brains which are practically unexplored with morphometric methods. The extent and quality of the Collection present a unique opportunity for enlarging into a multinational data bank for morphometric brain research.

Brain↗
PubMed1979

Human brain growth in the 19th and 20th century.

Data of 2399 brain weights and ages from populations before 1880, 1885 to 1900 and 1966 to 1976 were obtained from German anatomical and pathological institutes, analyzed with non-linear and multiple linear regression analyses and the results compared. The influence of the absolute age (sample period) on brain weights of adults (age of at least 10 years of ontogenesis) could not be verified. Different averages in the different samples seem to be stipulated by inhomogeneities of the age distributions. Sex differences were confirmed for the different periods. There is an accelerated degree of maturity of brain weights between the population sampled from 1966 to 1976 and the two older populations. The growth rate of the degree of maturity reveals the same fact, i.e., the growth rate is more rapid than 100 years ago. These differences may be explained by changed causes of death in the autopsy samples, but it is possible that they are at least partly caused by an acceleration of brain development in the early postnatal period. In all populations analyzed brain weights in females develop faster than in males. The development of the brain weight in 6 more samples is compared with the results for the Medical School Hannover sample.

Adolescent↗
PubMed1978

Automatic morphometric analysis of retrograde changes in the nucleus n. facialis at different ontogenetic stages in the rat.

The grey level index (= GLI) and the fresh voluem were determined with the image analyser Micro-Videomat for the nucl. n. facialis after axotomy of the left n. facialis. The experiments were performed on 10 rats in different stages of ontogenesis. The GLI is a quantitative parameter which could be quickly obtained and which demonstrated quantitative changes during retrograde reaction in the respective centres. A decrease in the fresh volumes of the affected nucl. n. facialis could also be demonstrated. The meaning of GLI is discussed.

Age Factors↗
PubMed1976

Semiautomatic morphometric analysis of the nucleolar development in the nucl. n. oculomotorii of Tupaia belangeri during ontogenesis.

The development during ontogenesis of the nuclear and nucleolar diameters and of the numbers of nucleoli per nucleus in the nucl. n. oculomotorii of 32 male Tupaia belangeri are described. The measurements of the nucleolar diameters were done automatically using the Micro-Videomat (Zeiss, Oberkochen). Increase of the nuclear and nucleolar diameters yielded a nearly sigmoid-shaped curve, which was fitted using the logistic growth function. The "ideal" value of the nucleolar diameter is 3.7 mum with a half value time of 22 days of ontogenesis and an enlargement factor of 1.53. The respective parameters for the nucleus are 12.2 mum, 28 days and 1.27. The ratio of the nuclear to nucleolar diameters decreases exponentially during ontogenesis to a value of 3.3. The validity of these easily determinable morphologic parameters for the RNA-synthesis is discussed. The number of nuclei with 2 or 3 nucleoli decreases during ontogenesis. The relevance of this fact for cell counting is also discussed.

Animals↗