The camp analogue, dbcAMP can stimulate rabbit reproductive functions: I. Effect on ovarian folliculogenesis, ovulation and embryo production

The aim of our study was to examine the influence of administration of N6,2’-dibutyryladenosine 3’5’-cyclic monophosphate (dbcAMP), a cAMP agonist, on ovarian folliculogenesis and atresia, as well as on reproductive efficiency in rabbits, whose ovarian cycle and ovulation was induced by gonadotropins. Ovarian cycle and ovulation of control rabbits were induced by 20 IU/kg PMSG followed by 35 IU/kg hCG administration. Experimental animals received PMSG and hCG together with dbcAMP (at 5, 25 or 50 μg/animal). After ovulation and insemination, the animals were sacrificed. Ovaries were weighted, histological sections of ovaries were prepared, and the presence of ovulated and not ovulated follicles and different stages of atresia was evaluated by light microscopy. The eggs were flushed from the oviducts after insemination and cultured up to blastocyst cell stage. Numbers of ovarian Corpora lutea, ovulated oocytes and oocyte-derived zygotes and embryos reaching hatched blastocyst stage were determined. Administration of dbcAMP (at doses 25 or 50 μg/animal, but not at 5 μg/animal) was able to increase the proportion of follicles with cystic and luteinization-related atresia. Furthermore, dbcAMP (50 μg/animal, but not lower doses) increased the ovarian mass, number of Corpora lutea, number of harvested oocytes, zygotes and embryos at blastocyst stage derived from these zygotes after culture. These data demonstrate that dbcAMP can stimulate rabbit ovarian follicle atresia, ovulation, oocyte, zygote and embryo yield and development. Furthermore, they confirm in the involvement of cyclic nucleotide-dependent intracellular mechanisms in the control of rabbit reproductive functions and potential practical usefulness of dbcAMP in improving animal reproduction and fertility

Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

Undesired electrode-electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries.ope

The fate and role of macromolecules synthesized during mammalian oocyte meiotic maturation. I. Autoradiographic topography of newly synthesized RNA and protein in the germinal vesicle of the pig and rabbit

International audienc

Nucleogenesis in the cleaving bovine embryo : immunocytochemical aspects

International audienc

Ultrastructure of Granulosa Cells of Bovine Ovarian Antral Follicles in Relation to Atresia

The aim of this study was to describe the most common forms of ovarian follicle atresia in large antral follicles of cows and quantify the occurrence of different cell structures in each form. Atresia of antral follicles in ovaries was determined on the basis of ultrastructural images acquired by electron microscopy of ultrathin sections contrasted with uranyl acetate and lead citrate to visualize cell organelles. All forms of atresia in large follicles are accompanied by regressive changes of the granulosa cells. The initial form of atresia is characterized by enlarged intercellular spaces after the disruption of the gap junctions and desmosomes. Small collapsed cells with pyknotic nuclei, substantially reduced the cytoplasm and a higher incidence of lysosomes are located on the surface of the granulosa layer. The stratum granulosum wall collapses and the basal membrane is swollen with a rupture of the lamina basalis. Obliterative atresia is characterized by a multiplied loose connective tissue consisting of collagen fibers, fibroblasts, histiocytes, blood capillaries and sporadically granulocytes. The cystic form of atresia is characterized by small collapsed, pyknotic granulosa cells settled in one or two layers. In luteinization-associated atresia, granulosa cells are hypertrophied, their cytoplasm contains smooth endoplasmic reticulum and mitochondria with tubules. In conclusion, the initial atresia of large antral ovarian follicles is associated with processes of cell death, followed by multiplication of the loose connective tissue cells, its dystrophy and hyalinization of the collagen fibers. Ultrastructural examination could be used as a complementary method to improve histopathological diagnostics of cow reproductive organs in veterinary practice

Autoradiography of 3

International audienc