A nuclear jamming transition in vertebrate organogenesis.

Jamming of cell collectives and associated rigidity transitions have been shown to play a key role in tissue dynamics, structure and morphogenesis. Cellular jamming is controlled by cellular density and the mechanics of cell-cell contacts. However, the contribution of subcellular organelles to the physical state of the emergent tissue is unclear.

Amoeboid-like migration ensures correct horizontal cell layer formation in the developing vertebrate retina.

Migration of cells in the developing brain is integral for the establishment of neural circuits and function of the central nervous system. While migration modes during which neurons employ predetermined directional guidance of either preexisting neuronal processes or underlying cells have been well explored, less is known about how cells featuring multipolar morphology migrate in the dense environment of the developing brain. To address this, we here investigated multipolar migration of horizontal cells in the zebrafish retina.

A hydraulic instability drives the cell death decision in the nematode germline.

Oocytes are large cells that develop into an embryo upon fertilization. As interconnected germ cells mature into oocytes, some of them grow-typically at the expense of others that undergo cell death. We present evidence that in the nematode , this cell-fate decision is mechanical and related to tissue hydraulics.

Stochastic single cell migration leads to robust horizontal cell layer formation in the vertebrate retina.

Developmental programs that arrange cells and tissues into patterned organs are remarkably robust. In the developing vertebrate retina, for example, neurons reproducibly assemble into distinct layers giving the mature organ its overall structured appearance. This stereotypic neuronal arrangement, termed lamination, is important for efficient neuronal connectivity.

Neuronal Migration and Lamination in the Vertebrate Retina.

In the retina, like in most other brain regions, developing neurons are arranged into distinct layers giving the mature tissue its stratified appearance. This process needs to be highly controlled and orchestrated, as neuronal layering defects lead to impaired retinal function. To achieve successful neuronal layering and lamination in the retina and beyond, three main developmental steps need to be executed: First, the correct type of neuron has to be generated at a precise developmental time.

Actomyosin contractility regulators stabilize the cytoplasmic bridge between the two primordial germ cells during embryogenesis.

Stable cytoplasmic bridges arise from failed cytokinesis, the last step of cell division, and a key feature of syncytial architectures in the germline of most metazoans. Whereas the germline is syncytial, its formation remains poorly understood. We found that the germline precursor blastomere, , fails cytokinesis, leaving a stable cytoplasmic bridge between the daughter cells, Z and Z Depletion of several regulators of actomyosin contractility resulted in a regression of the membrane partition between Z and Z, indicating that they required to stabilize the cytoplasmic bridge.

Liquid base cytology in evaluation of thyroid nodules.

Background: Palpable thyroid nodules are present in 4-7% of general population and Fine Needle Aspiration (FNA) is now accepted by endocrinologists and thyroid surgeons as a safe, simple and cost effective procedure for evaluating a thyroid nodule. The obtained sample can be spread directly on slides, processed as cell block preparations or prepared as liquid base smears. Liquid base method has been recently accepted due to its shorter preparation time and better preservation of nuclear details.

C. elegans Anillin proteins regulate intercellular bridge stability and germline syncytial organization.

Cytokinesis generally produces two separate daughter cells, but in some tissues daughter nuclei remain connected to a shared cytoplasm, or syncytium, through incomplete cytokinesis. How syncytia form remains poorly understood. We studied syncytial formation in the Caenorhabditis elegans germline, in which germ cells connect to a shared cytoplasm core (the rachis) via intercellular bridges.

Establishment of national laboratory standards in public and private hospital laboratories.

In September 2007 national standard manual was finalized and officially announced as the minimal quality requirements for all medical laboratories in the country. Apart from auditing laboratories, Reference Health Laboratory has performed benchmarking auditing of medical laboratory network (surveys) in provinces. 12(th) benchmarks performed in Tehran and Alborz provinces, Iran in 2010 in three stages.

Live imaging for studying asymmetric cell division in the C. elegans embryo.

Asymmetric cell division is essential during development to generate cell diversity and throughout adult life to maintain tissue homeostasis. For instance, many types of stem cells must divide asymmetrically to maintain their self-renewal capacities. Furthermore, recent studies suggest that the loss of asymmetric division could be used by cancer stem cells to trigger excessive proliferation of undifferentiated cells during tumorigenesis.

Influence of nitric oxide on morphine-induced amnesia and interactions with dopaminergic receptor agents.

The interactions of dopaminergic receptors and nitric oxide (NO) with morphine-induced memory of passive avoidance have been investigated in mice. Pre-training administration of morphine (1, 3 and 5 mg/kg, s.c.