Embryology of dolphins. Staging and ageing of embryos and fetuses of some cetaceans.

Comparative embryology has been neglected in the past decades. In our opinion the decreased interest has been caused by the fact that the time factor has not sufficiently been respected. Therefore we used the Staging and Ageing Method (Sterba 1999) to determine the ontogenetic age of embryos and to state the time tables and time relations of various ontogenetic events. We examined 167 embryos and fetuses of four dolphin species (collection Dr. Senckenbergische Anatomie, Frankfurt am Main). The study of intrauterine development and growth while consistently respecting the time factor enabled us to determine the time course of organogenesis of all organ systems. The resulting comparison with other mammals detected the time lag in ossification, retardation of odontogeny, the time of the origin and development of the fluke, dorsal fin and flipper, etc. We believe the Staging and Ageing Method serves for a much more efficient evaluation of existing embryological collections which very often contain embryos of unknown age.

Sex chromosome abnormalities in natural populations of the common vole (Microtus arvalis).

Four specimens with an aberrant sex chromosome constitution were found in natural populations of the common vole (Microtus arvalis). Two females had an X0 sex chromosome constitution and single males were 2n = 47, XXY and 2n = 47, XYY, respectively. No apparent phenotypical anomalies were recorded in the sex chromosome aneuploids, but their fertility may have been impaired. The incidence of sex chromosome aneuploidy seems to be unusually high in natural populations of the common vole (1.5% of animals examined). Possible explanations for this are discussed.

Effect of a synthetic poly N-(2-hydroxypropyl)methacrylamide (Duxon) on haemopoiesis and graft-versus-host reaction.

A synthetic polymer, Duxon, was developed and tested as a substitute of blood plasma for transfusion purposes. Tests of this preparation included a test for its influence on the haemopoietic stem cells and the graft-versus-host reaction (GVHR). A single dose or repeated doses of Duxon did not reduce the number of pluripotent haemopoietic colonies (CFU-S) in mice and short-term incubation of cells from haemopoietic organs of mice with Duxon resulted in a slight, yet significant, increase in the number of CFU-S. Injection of Duxon non-significantly diminished the manifestations of the regional GVHR. Incubation of spleen cells with Duxon significantly reduced their GVH reactivity in the regional test. The systemic GVHR was moderately inhibited by repeated doses of Duxon in sublethally irradiated mice. A significant delay in deaths of animals from GVHR was seen in lethally irradiated mice receiving a single dose of Duxon on day 4 after GVHR induction. Survival of lethally and sublethally irradiated mice was prolonged following injection of cells incubated with Duxon. Possible uses of Duxon, a preparation with mild immunosuppressive properties, not impairing haemopoiesis, are discussed.

Immunosuppressive effects of a synthetic polymer poly N-(2-hydroxypropyl)methacrylamide (Duxon).

Poly N-(2-hydroxypropyl)methacrylamide (Duxon) was studied as a substitute of blood plasma and was found to prolong significantly the survival of semiallogeneic skin grafts in mice and rats and to reduce MLC reactions of human lymphocytes. It did not inhibit the growth of lymphocytes and the growth of the fibroblast-like (diploid) or epithelioid (heteroploid) cell lines in tissue culture.

New types of synthetic infusion solutions. III. Elimination and retention of poly-[N-(2-hydroxypropyl)methacrylamide] in a test organism.

The elimination and retention of a new, fully synthetic plasma prosthesis of Czechoslovak origin under the working name of Duxon (poly[N-(2-hydroxypropyl)methacrylamide]) was investigated in experiments on rabbits by using a 14C-labeled polymer. Results published earlier on elimination have been confirmed and extended. Retention was examined after repeated application. The effect of molecular weight prevailed both in elimination and in retention. Polymers of lower molecular weights, which possess a good therapeutical effect, are not permanently deposited in the organism.