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October, 2006
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Cell Differentiation: Progressive restriction of the developmental potential and increasing specialization of function that leads to the formation of specialized cells, tissues, and organs.

Cell Division- Concept

JoVE 10571

Cell division is fundamental to all living organisms and required for growth and development. As an essential means of reproduction for all living things, cell division allows organisms to transfer their genetic material to their offspring. For a unicellular organism, cellular division generates a completely new organism. For multicellular organisms, cellular division produces new cells for…

 Lab Bio

Embryonic Stem Cell Culture and Differentiation

JoVE 5332

Culturing embryonic stem (ES) cells requires conditions that maintain these cells in an undifferentiated state to preserve their capacity for self-renewal and pluripotency. Stem cell biologists are continuously optimizing methods to improve the efficiency of ES cell culture, and are simultaneously trying to direct the differentiation of ES cells into specific cell types that could be used in…

 Developmental Biology

Cell-mediated Immune Responses

JoVE 10896

The cell-mediated immune system is the host’s primary response against invasive bacteria and viruses that cause intracellular infections. It is also essential for fighting against and destroying cancer cells. Furthermore, the cell-mediated immune system plays a role in the rejection of organ transplants or graft tissue.

Phagocytic cells of the innate immune system, such as macrophages or dendritic cells, are the first to recognize a foreign particle. These cells engulf the foreign particle and digest it. Small molecules of the foreign particle, called antigens, remain intact and are presented at the surface of the phagocytic cell. The presentation is facilitated by proteins of the major histocompatibility complex (MHC), which binds the antigen and protrude from the cell. The phagocytic cell is therefore also called an antigen presenting cell (APC). The MHC-antigen complex activates cells of the adaptive immune system, which eventually fight the source of the foreign particle. T cells are a type of lymphocyte that are named after their location of maturation—the thymus. In the thymus, precursor T cells differentiate into two main types, CD4+ and CD8+ T cells. These cell types are named after the surface receptor that determines the cell’s function. All T cells carry T-cell receptors, but the coreceptor CD4

 Core: Biology

An Introduction to Stem Cell Biology

JoVE 5331

Cells that can differentiate into a variety of cell types, known as stem cells, are at the center of one of the most exciting fields of science today. Stem cell biologists are working to understand the basic mechanisms that regulate how these cells function. These researchers are also interested in harnessing the remarkable potential of stem cells to treat human diseases.


 Developmental Biology

Induced Pluripotent Stem Cells

JoVE 10812

Stem cells are undifferentiated cells that divide and produce different types of cells. Ordinarily, cells that have differentiated into a specific cell type are post-mitotic—that is, they no longer divide. However, scientists have found a way to reprogram these mature cells so that they “de-differentiate” and return to an unspecialized, proliferative state. These cells are also pluripotent like embryonic stem cells—able to produce all cell types—and are therefore called induced pluripotent stem cells (iPSCs). iPSCs are potentially valuable in medicine, because a patient who needs a particular cell type—for instance, someone with a damaged retina due to macular degeneration—could receive a transplant of the required cells, generated from another cell type in their own body. This is called autologous transplantation, and it reduces the risk of transplant rejection that can occur when tissues are transplanted between individuals. To create iPSCs, mature cells such as skin fibroblasts or blood cells from a person are grown in culture. Then, genes for multiple transcription factors are delivered into the cells using a viral vector, and the transcription factor proteins are expressed using the cell’s machinery. The transcription factors then turn on many other genes that are expressed by embryonic stem cells, re

 Core: Biology


JoVE 10912

During embryogenesis, cells become progressively committed to different fates through a two-step process: specification followed by determination. Specification is demonstrated by removing a segment of an early embryo, “neutrally” culturing the tissue in vitro—for example, in a petri dish with simple medium—and then observing the derivatives. If the cultured region gives rise to cell types that it would normally generate in the embryo, this means that it is specified. In contrast, determination occurs if a region of the embryo is removed and placed in a “non-neutral” environment—such as in a dish containing complex medium supplemented with a variety of proteins, or even a different area of the embryo itself—and it still generates the expected derivatives. Specification and determination are two sequential steps in the developmental pathway of a cell, which precede the final stage of differentiation, during which mature tissues with unique morphologies and functions are produced. To study specification, researchers must first understand the normal derivatives of different regions of an embryo. To accomplish this, fate maps are often used, which are generated by dyeing or labeling cells early in embryonic development, culturing whole embryos and monitoring where the marked cells end up. For example, such te

 Core: Biology


JoVE 11094

Plant morphogenesis—the development of a plant’s form and structure—involves several overlapping developmental processes, including growth and cell differentiation. Precursor cells differentiate into specific cell types, which are organized into the tissues and organ systems that make up the functional plant.

Plant growth and cell differentiation are under complex hormonal control. Plant hormones regulate gene expression, often in response to environmental stimuli. For example, many plants form flowers. Unlike stems and roots, flowers do not grow throughout a plant’s life. Flowering involves a change in the identity of meristems—regions of the plant containing actively-dividing cells that form new tissues. In addition to internal signals, environmental cues—such as temperature and day length—trigger the expression of meristem identity genes. Meristem identity genes enable the conversion of the shoot apical meristem into the inflorescence meristem, allowing the meristem to produce floral rather than vegetative structures. The inflorescence meristem produces the floral meristem. Cells in the floral meristem differentiate into one of the flower organs—sepals, petals, stamens, or carpels—according to their radial position, which dictates the expression of organ identity genes. The ABC hypo

 Core: Biology

Histotypic Tissue Culture

JoVE 5787

Although two-dimensional tissue culture has been common for some time, cells behave more realistically in a three-dimensional culture, and more closely mimics native tissue. This video introduces histotypic tissue culture, where the growth and propagation of one cell line is done in an engineered three-dimensional matrix to reach high cell density. Here, we show the…


Induced Pluripotency

JoVE 5333

Induced pluripotent stem cells (iPSCs) are somatic cells that have been genetically reprogrammed to form undifferentiated stem cells. Like embryonic stem cells, iPSCs can be grown in culture conditions that promote differentiation into different cell types. Thus, iPSCs may provide a potentially unlimited source of any human cell type, which is a major breakthrough in the field of regenerative…

 Developmental Biology
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