Body weights, absolute and relative organ weights by maturation and ageing (with sexual differences), and their importance as measures of reference for metabolic investigations.

In this contribution, several organs important, especially for geronto-pharmacological not only out of theoretical but especially for practical clinical reasons, to the development of absolute and relative organ weights of rats are examined, as related to a) body weight that is exhibited during the life span, and b) to the weight of the brain. This examination deals with male and female albino rats of the Sprague-Dawley-inbred strain, Sut : SDT ( Chbb : SPF) of both sexes that were two months old at the beginning of the experiment. The experiment results are given in monthly intervals and should be reference figures for metabolism and performance analyses of the examined organs during the course of life into old age (in continuation of corresponding earlier studies, also with humans). Since the following results are obviously of great importance to human medicine, the corresponding age groups for comparison are given and verified. The findings also show that pharmacokinetic experiments in extended test series concerning development during the course of life, therefore concerning all age groups, with the use of the here tested parameters, are better to conduct with female rats than with male. Along with this, the relative organ weights in relation to the brain weight are better to use than the (until now, usual) relative organ weights in relation to body weight. Further shown by the results of these studies is that, during the often necessarily large series, it can be preferable to use the absolute organ weights rather than the relative organ weights (as related to body weight).(ABSTRACT TRUNCATED AT 250 WORDS)

[Contribution to wet and dry weights of mesenchymal and parenchymatous organs of humans and rats during the course of life (author's transl)]. / Beitrag zur Frages des Wassergehaltes (mit Untersuchungen von Frisch- und Trockengewicht) mesenchymaler und parenchymatöser Organe von Mensch und Ratte im Lebensablauf.

The wet and dry weights of parenchymatous (lung, heart, liver, kidney) and of mesenchymal organs (aorta, skin, xiphoid cartilage) of humans and rats (both sexes) were investigated during the course of life. Furthermore, these investigations were done on the following rat organs: brain (divided in cerebrum as well as in cerebellum plus pons), spleen, rib cartilage, testis and ovar. The water content of these tissues and organs of both species was calculated by means of their wet and dry weights. The dry weights of the investigated parenchymal and mesenchymal organs of both species remain constant during the whole course of life (pastly until the high senile age)--using freeze-drying. The same is true for the water content: constancy without significant decrease during the investigated life periods and without sex dependent differences.

[Studies on DNA content of tissues and organs. 2nd communication: findings on DNA content in various rat organs 1. during maturation and aging and 2. during experimental pathological models and their therapy (author's transl)]. / Untersuchungen zum DNS-Gehalt von Geweben und Organen. 2. Mitt.: Ergebnisse über den DNS-Gehalt verschiedener Organe der Ratte 1. während Reifung und Alterung und 2. während experimenteller Modelle menschlicher Erkrankungen und ihrer Behandlung.

In this paper the DNA content as a quantitative parameter of the cell content was analyzed on selected rat organs. Aging changes in parenchymatous and connective tissue (= mesenchymal) organs were examined. Further, some pilot studies on experimental animal models of human diseases (experimental shock and liver fibrosis) and their therapy were carried out. In these simulations of human diseases only some preliminary indications about changes in cell or DNA content, resp., of the various organs could be obtained. The results show that these pilot studies justify intensified continuation (in larger series).

[Age-dependent DNA-content of brain, testis and ovar in men and rats (author's transl)]. / Alternveränderungen des DNA-Gehaltes (sowie von Gewicht und Wasserhaushalt) des Gehirnes von Mensch und Ratte, sowie DNA-Analysen von Testes und Ovarien der Ratte.

The DNA-content of brain, testis and ovar of Wistar rats (inbred strain) was quantitatively analysed. We observed no significant differences between the several parts of the cerebrum, but between the cerebrum and the cerebellum. Furthermore we demonstrated alterations (with increase and decrease) of the DNA content of all brain parts as well as of testis and ovar during the course of life of this Wistar rat strain. These results and further investigations of the water content as well as of the absolute and of the relative weight of brains of these rats (in comparison to humans) extend the data and our knowledge about these subjects. It is possible to differentiate growth phases (by means of the DNA assays, which correlate with the morphologically well defined growth phases. Finally these results are fundamentals and presuppositions for investigations of the production metabolism of these organs because the DNA content is a better parameter (reference or relation figure, resp.) than the dry or wet weights and the protein or the nitrogen contents.

[Studies on DNA content of tissues and organs. 1st communication: changes in cell content of some mesenchymal and parenchymatous rat organs during development, maturation, and in part aging (determinations of DNA) (author's transl)]. / Untersuchungen zum DNS-Gehalt von Geweben und Organen. 1. Mitt.: Veränderungen des Zellgehaltes einiger bindegewebiger und parenchymatöser Organe der Ratte während Entwicklung und Reifung, zum Teil auch bei Alterung (DNS-Bestimmungen).

In this study the cell content was analyzed by means of the DNA content of certain mesenchymal and parenchymal organs of the rat. The main aspects were the postnatal stages of development and maturation. Their correlation to aging was examined only on examples, so was their correlation to the prenatal development (on 2 examples: liver and skin). One important result of this research is that a gradual reduction in the exponential growth takes place with increasing maturation and development. The "growth by production" prevails over the "growth by division" (of cells). This is the explanation for the "relative" (= apparent) decrease in the cell content of the tissues and organs analyzed during the decisive postnatal development and maturation phases. In this period the complete differentiation of the cytoplasmic structures and of the differentiation products of the tissues and organs here analyzed occurs. This leads to a shift in their relative amounts to the disadvantage of the cell nuclei, which prevailed in the total weight of tissues and organs during the early phases of development. This concerns determinations of the DNA content related to wet weight even more than such of the DNA content related to dry weight. As already shown clearly, the different tissues and organs of the mammalian organism (here on the example of the rat) grow, mature and age differently. During growth different phases can be distinguished, too, by analysis of the DNA content which partly correlate with phases of growth which were differentiated morphologically. Determinations of DNA contents are necessary as parameters for determinations of the production metabolism (e.g. activities of enzymes, products of formation and differentiation) of the different tissues and organs during their development, maturation and aging.