Induction of DNA synthesis or apoptosis in mammalian nuclei by Xenopus egg extracts that fail to support the replication of sperm chromatin.

Cell-free extracts of Xenopus eggs are widely used to study DNA replication in higher eukaryotes. However, with Xenopus sperm chromatin as template, it is a common experience that the efficiency of replication varies from extract to extract, for reasons that are unclear. Here we show that the majority of extracts unable to support sperm replication are nevertheless able to induce DNA synthesis in intact mammalian nuclei.

Description of primordial germ cells, oogonia, oocytes and embryo-like growth in squash preparations of tissues from hematological malignancies.

This study evidences the presence of primordial germ cells, in tissue squash preparations and sections from hematological malignancies. Primordial germ cells were identified by their morphology, the intense PAS, PAS-D reaction and presence of calcium-activated neutral proteinase. Primordial germ cells gave rise to nuclear vlimata.

Meiosis in hematological malignancies. In situ cytogenetic morphology.

This is the first study on the in situ cytogenetic morphology and analysis of malignant bone marrow cells, growing attached on a culture vessel surface. It was documented that bone marrow cells, in different types of hematological malignancies, divide by meiosis giving rise to a non-repetitive aneuploidy. Male and female gametes are formed by meiosis and fertilization occurs in a life cycle of: [sequence see text] Immature and mature somatic oocytes were evidenced by prophase stages of the first and diploid or hypodiploid or haploid metaphases identical to those of the second human, ovarian oocytic meiotic division, showing "XX" or "XY" sex chromosomes in female or male patients respectively.

Nuclear vlimata and aneuploidy in embryonic cells is caused by meiosis. Behaviour and properties of meiotic cells.

This study demonstrates that human embryonic cells divide by meiosis. The use of trophoblastic tissue cells (early embryo) and amniotic cells (late embryo) exhibited the following characteristic events of meiosis: nuclear (NVs) and nucleolar (NuVs) vlimata formation; NV invasion in host cells; extrusion of chromosomes; nuclear fusion; metaphase fusion; hybrid cell formation; nuclear, nucleolar and cytoplasmic bridges, chromosomal transfer, variable-sized nuclei; nuclear fragmentation; condensed meiotic chromosomes; "O" chromosome; and aneuploidy. Two types of nuclear bridges (NBs) were identified and defined as communicative tubules through which chromosomal transfer among cells is achieved.

The inhibitor of calcium activated neutral proteinase is an anti-meiotic agent. The spermicidal and anti-viral action.

In situ cytogenetic morphology and analysis showed that Epstein-Barr Virus (EBV)-infected Raji and EBV-producing P3HR-1 cells divide by meiosis and follow the life cycle of malignant cells in vitro. Meiosis was documented by the presence of condensed chromosomes, "o" chromosome, nuclear vlimata (NVs), NV invasion, extrusion of chromosomes, chromosomal transfer, metaphase fusion and aneuploidy. EBV-Raji, EBV-producing P3HR, HIV1-infected MOLT-4 cells (dividing by meiosis) and human spermatozoa (cellular products of meiosis) were highly sensitive to the endogenous inhibitor (CANP-I) of calcium-activated neutral proteinase (CANP).