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Zusammenfassung Bei den in vitro-Versuchen wurde die Inkorporation und Elution des radioaktiven Chromats51Cr bei Rattenerythrozyten, die durch Erwärmen im Wasserbad bei _49,5°C während 30 min geschädigt worden waren, verfolgt. Die geschädigten Erythrozyten wurden mit51Cr 30 min lang bei Zimmertemperatur inkubiert und der Prozentsatz der51Cr-Utilisierung in die roten Blutkörperchen untersucht. In allen Versuchen trat eine geringe Inkorporationszunahme auf, welche jedoch in Versuchsanordnung nicht signifikant war. Nach einer 90 min langen Inkubation der markierten und wärmegeschädigten Erythrozyten in nicht radioaktivem Plasma bei physiologischer Temperatur von +37°C wurde ein kleiner, jedoch statistisch signifikanter Anstieg der51Cr- und Hämoglobinspiegel im Plasma beobachtet.

The diuresis and the urinary excretion of ions by rats with hereditary and with lesion-induced hypothalamic diabetes insipidus and the change in these parameters in response to lysine vasopressin have been found to be practically identical. The time course of the antidiuretic response can be followed in detail over long periods; it has been found to be sensitive to the nature of the antidiuretic hormone preparation and to the dose level. It is concluded that rats with hypothalamic diabetes insipidus are useful models for studying the time course of the antidiuretic response, in particular to long-acting preparations.

Forty eight hours after unilateral nephrectomy, both in non-castrated and in castrated male mice the relative dry weight of the remaining kidney increased significantly.This compensatory hypertrophy was significantly stimulated as early as 96 hours after operation by the treatment with 19-nortestosterone phenylpropionate (= NPP) at the time of operation. The percentual increase of the kidney weight was approximately the same in non-castrated as in castrated mice. The absolute initial values as well as the resulting values 96 hours after operation were higher in non-castrated male mice than in castrated animals.The number of cells and the DNA concentration per g tissue decreased during the period of non-stimulated compensatory hypertrophy in both groups of animals. NPP caused a still further decrease. The concentration of DNA per cell did not change.Following non-stimulated compensatory hypertrophy, there was no change in the RNA concentration per g tissue or per cell in castrated mice. In non-castrated mice the concentration increased. NPP caused approximately the same percentual increase of RNA concentration in non-castrated as in castrated animals during the period of compensatory hypertrophy. The difference between both groups of mice in the RNA concentration in the remaining kidney following stimulation of the compensatory hypertrophy by NPP was statistically significant.

ACCORDING to the present view, the forces responsible for the closure of the neural tube reside in the neural plate itself. On this view, the disproportion between the surface area and the volume of the neural plate is the real mechanical cause of neurulation movements. This disproportion can arise either by a diminution of the surface area, or by an increase in volume, or, occasionally, by a combination of both processes. In all these cases the neural plate cells must be firmly anchored in the developing internal limiting membrane system1,2. The first possibility has been generally conceded as the theory of active contraction3–6, which presupposes the existence of a contractile system settled either extra- or intra-cellularly at the level of the internal limiting membrane. Volume increase of the neural plate may occur either as a result of cell multiplication (proliferation hypothesis), or by an augmentation in size of particular cells (hydration hypothesis7). The active part of proliferation has generally been overlooked, in spite of the fact that only one research worker7denies the existence of mitoses in the neural plate.

ON July 30, 1965, in the course of the archaeological investigation of the Kůlna Cave in the Moravian Karst, the right part of the upper jaw of a Neanderthal man was found. The Kůlna Cave is situated about 45 km to the north of Brno. Moravia is probably one of the richest palaeolithic regions in Europe. Apart from rich finds of the skeletal remains of Upper Palaeolithic man, it has also provided the well known find of the neanderthaloid jaw from the Šipka Cave, and of the “Ochoz jaw” from the Švédůvstůl Cave1. The new find from the Kůlna Cave has, however, the best stratigraphic dating and is substantiated by a wealth of archaeological and palaeontological evidence. It is thus important not only for the solution of questions relating to the palaeolithic populations of Central Europe, but also for the explanation of the origin and formation of modern man Homo sapiens.

F. SAUER1, referring to mitosis in the neural tube, wrote: “The attachment of the neural tube cells to each other at the surface bordering the lumen appears to play an important part in the mechanics of the development of the neural tube”. Having been preceded in general conception by other authors2–4, he stated that elements of neural epithelium were attached to each other at the surface bordering the lumen by a terminal bar net, and that there was “no internal limiting membrane other than the cytoplasmic membrane of cells”. In spite of this statement, the old conception of His5describing the internal limiting membrane as a felt-work of fibrils into which passed the cytoplasmic fibrils of the spongioblasts had been generally accepted. Later on, Sauer's suggestion was revived by further authors6–11; but none of them elaborated the minute structure of internal limiting membrane or considered its possible significance in ontogenesis.

<$O_ST_ABS>Authors synopsis<$C_ST_ABS>Kidney weight, renal renin content, and blood pressure were measured in rats with different degrees of renal ischaemia induced either by means of a clip on one renal artery or by stenosing the aorta between the origins of the two renal arteries, the ureter of the ischaemic kidney left free or being ligated. Renal ischaemia was more pronounced after aortic constriction than after clamping the renal artery, and renin production was more stimulated in the first case. In the ischaemic kidney a negative correlation between renal mass and renin content was found, but renin content of the kidneys was not correlated with the degree of hypertension .

TESTS of teratogenicity using tissue culture, laboratory rodents or primates may not yield results applicable to man1. Different species and even strains differ in their response to teratogens. In mice, the percentage induction of cleft palate after administration of corticoids varies from strain to strain2; in rats, the effect cannot be found at all3–5. The relative influences of maternal metabolism on the one hand, and of specificity of the morphogenetic processes in the embryo on the other, remain unknown. The development of a test for the teratogenic effect of drugs depends on the solution of this problem: strict species specificity of the embryonic morphogenetic mechanisms would absolutely preclude extrapolation from laboratory animals to humans.