H. -J. Merker

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In vitro experiments using whole rat embryo cultures show that all -trans retinoic acid (all- trans RA) administered at low concentrations (30 ng/ml culture medium) is 10 times more active than 13-cis retinoic acid (13-cis RA) and 3 times more active when administered at high concentrations (1000 ng/ml culture medium). Morphological investigation of the(More)
Light and electron microscopic as well as immunohistochemical investigations were performed on the basement membrane (BM) of the nasal mucosa from the inferior nasal conchae of 20 patients, aged 15–50 years. Two of the patients served as controls. Clinical disorders requiring the turbinectomies were hyperplastic nasal inferior conchae (17 patients) and(More)
The influence of follicle-stimulating hormone, forskolin, insulin-like growth factor type I, epidermal growth factor, and 12-tetradecanoyl-phorbol-13-acetate on marmoset granulosa cell communication via gap junctions was investigated by morphological means and microinjection of carboxyfluorescein. Gap junctions between neighbouring granulosa cells were(More)
Das vomeronasale oder Jacobson-Organ (VNO) ist bei den meisten Mammalia unentbehrlich für die Reaktion auf Pheromone und das Paarungsverhalten. Beim Menschen wurde das VNO als winziger, paariger Blindschlauch an der vorderen Nasenscheidewand ohne dokumentierte Funktion beschrieben. Wir untersuchten mit dem Transmissionselektronenmikroskop die Feinstruktur(More)
An oral dose of 700 mg/kg salicylic acid was given to normal and Zn-deficient rats at day 16 of gestation. Maternal and fetal kidneys were studied at day 19 of gestation. Zn-deficiency did not cause any lesions detectable by semi-thin section light microscopy, electron microscopy, enzyme histochemistry and immunohistochemistry. Salicylate may lead only to(More)
In order to get insight into the synthesis rates occuring in mammalian embryos during the phase of differentiation, wet and dry weight as well as DNA-, RNA-, and nitrogen content of the whole implantation site (day 7 to 10 of gestation) and of the embryos (day 11 to 14) have been determined. Growth of the whole implantation site (day 7 to 10) proceeds(More)
A number of organs from adult female mice were investigated after continuous application of the anticonvulsant drug valproic acid (VPA) by enzyme cytochemistry, light and electron microscopy, pharmacokinetics and clinical chemistry. VPA plasma levels were maintained between 55 μg/ml and 67 μg/ml for three days following subcutaneous implantation of drug(More)
Pregnant rats were treated with an oral dose of 40.0 mg benzo(α) pyrene (BP) per kg body weight and were sacrificed 24 h later. Maternal liver, placenta, and fetus were assayed for BP-hydroxylase activity. The enzyme activity was measured from day 13 to day 18 of gestation. Pretreatment of rats with BP results in an approximately 15-fold increase of(More)
The placenta of marmosets (Callithrix jacchus) differs from that of other species in two respects: marmosets have (a) haemopoetic foci in the connective tissue of the placental trabeculae (Jollie et aI., 1975), and (b) blood vessels which open into the intratrabecular spaces. They are presumed to be arterioles of maternal origin (Hill, 1932; Wislocki &(More)