Notes Ghar

Placenta Placenta :-  Placenta is a temporary intimate  mechanical and physiological connection between foetal and maternal tissues for the nutrition, respiration and excretion etc.   The placenta is the passage that unites the fetus to the mother. The placenta facilitates the exchange of nutrients and oxygen to the fetus. It is also responsible for collecting carbon dioxide and waste materials from the fetus. In appearance, the placenta is disk-shaped and measures up to 22 cm in length. The placenta is also rich in blood vessels. The placenta is exclusive to mammals. The umbilical cord connects the foetus to the placenta, facilitating the transfer of materials. The placenta is usually attached at the top, bottom, side, front or back of the uterus. In extreme cases, the placenta gets attached to the lower part of the uterus resulting in a condition known as placenta previa. In human meta-distal placenta is present The placenta  is fully formed in 10 weeks and last throughout the pregna

 Application of Cell lineage (in C.elegans ) Observe which cells in blastula develop into a cell of a particular tissue or organ of the Embryo. During gastrulation these cells migrate from the existing position to the prospective position Understanding – Gastrulation Classical developmental biology : insight into development process of C. elegans  and dorsophilla these organism display in vibrant patterns of cell division in which is specification of cell determination and and highly reproducible and cell -cell interactions. Mutation in cell lineage help us understand mechanisms of fate specification and control of cell proliferation. Stem cell research - provides information about how the behaves in context of intact tissue as opposed to isolation ,  transplantation and invito– culture. Modelling heterogeneity in cancer Can be performed with prior  knowledgeable of what the genes are expressed by cell of  interest.

 Cell Lineage CellLineage of an organism is the pattern of cell division during its development  In lineage tracing, a single cell is marked in such a way that the mark is transmitted to the cell’s progeny , resulting in a set of labelled clones. Provides information about number of progeny of the founder cell, their location and their differentiation status. Applied to stem cell research and in modelling cellular heterogeneity in cancer. Began with Whitman’s description of cleavage patterns in leech embryos. Later lineage were described in nematodes, sea urchins and ascidians. Why Caenorhabditis elegans ? Small, relatively simple and precisely structured organism. Anatomy has been described in detail and one can map out the exact lineage of every cell in the body. Development is highly determinant , and cell fate decisions are autonomous from the surroundings. Number of somatic cell is highly limited . Make the analyses straight forward and accurate. Fate of every cell in the embryo