Studies of newt (Triturus or Diemictylus viridescens) erythropoietic cells showed that DNA synthesis and mitosis normally occur throughout most of the developmental process. Mitotic divisions were found in all immature precursor stages from the proerythroblast to the highly hemoglobinized reticulocyte. Mitoses were absent in mature erythrocytes. Radioautographic examination of thymidine-(3)H in...

Pollen, as the male gametophyte, plays a vital role in the reproduction of flowering plants. Mature pollen grains contain mRNAs that are the products of approximately 20,000 different genes, of which up to 4000 may be pollen specific (Mascarenhas, 1990). In recent years, severa1 pollen-specific genes have been isolated from different plants. Some of these genes encode proteins showing amino aci...

Neurogenesis occurs in the adult mammalian hippocampus, a region of the brain important for learning and memory. Hibernation in Siberian ground squirrels provides a natural model to study mitosis as the rapid fall in body temperature in 24 h (from 35-36°C to +4-6°C) permits accumulation of mitotic cells at different stages of the cell cycle. Histological methods used to study adult neurogenesis...

In angiosperms, mitosis and cytokinesis take place in the absence of structurally defined microtubule-organizing centers and the underlying mechanisms are largely unknown. In the spindle and phragmoplast, microtubule reorganization depends on microtubule-interacting factors like the γ-tubulin complex. Because of their critical functions in cell division, loss-of-function mutations in the corres...

In the previous paper (Wada, Nagao and Awasawa 1963), we have demonstrated the presence of spindle membrane in fixed preparations of root tip cells in Vicia faba and Allium cepa. These materials are most familiar in the laboratory for observations of mitosis in somatic cells and their mitotic figures are described in text-books of cytology as a standard type of somatic cell division. In this pa...

The molecular basis of recognition between plant cells is incompletely understood. Some principles established for recognition between animal cells may well apply to plant cell recognition, although, in contrast to animal cells, plant cells are encased by cell walls that play an active role in plant cell-cell recognition. The interaction that controls fertilization in flowering plants involves ...

In this study, microspore formation (microsporogenesis), gamete (microgametogenesis), and pollen features of Silene sangaria, a species endemic to Turkey, was examined cytoembryologically histochemically. The is distributed along the Black Sea coast Turkey. materials were collected from Igneada village (Kirklareli province). anthers, separated by size, passed through ethyl alcohol concentration...

The two sperm cells of common origin within the pollen tube of flowering plants are each involved in a fertilization event. It has long been recognized that preferential fusion of one sperm with the egg can occur in B chromosome-containing lines of maize. If the second pollen mitosis begins with a single B chromosome, nondisjunction will result in one sperm possessing two B chromosomes and the ...

The water and nutrient status of pollen is crucial to plant reproduction. Pollen grains of Arabidopsis (Arabidopsis thaliana) contain a large vegetative cell and two smaller sperm cells. Pollen grains express AtTIP1;3 and AtTIP5;1, two members of the Tonoplast Intrinsic Protein subfamily of aquaporins. To address the spatial and temporal expression pattern of the two homologs, C-terminal fusion...