In vitro culture & growth of organs or parts thereof in which their various tissue components, eg parenchyma & stroma, are preserved both in terms of their structure & functions so that the culture organs resemble closely the concerned organs in vivo is called organ culture
- New growth occurs in form of differentiated structures. e.g.- glandular structure is retained in glands.
- Cultured organ retains its physiological features. e.g.- hormone dependent organ continue to be dependent.
- Morphogenesis in cultured fetal tissues ia more or less comparable to that in vivo.
- Outgrowth of isolated cells from periphery of explants can be minimized by manipulating the culture. conditions
- Explant remain comparable to the in vivo organs both in structure & function,developmental of fetal organ is comparable,
- It provides information on the pattern s of growth, differentiation, & development of an organ.
- In some cases, it can replace whole animals in experimentation as the results from are easier to interpret.
Results from organ cultures are often not comparable to those from whole animals studies, e.g. in studies on drug action, since the drug are metabolized in vivo but not in vitro
TECHNIQUES OF ORGAN CULTURE:
Plasma Clot Method:- The explant is culture on the surface of a clot consisting of chick (or other) plasma & chick embryo extract contained in a watch glass. The watch glass may or may not be closed with a glass lid & sealed with paraffin wax. This has been the classical technique for studying the morphogenesis in embryonic organ rudiments. It has been also modified to study the action of hormones, vitamins carcinogens etc on the adult mammalian tissues.
Raft Method:- The explant is placed on to a raft of lens paper or rayon acetate, which is floated on a serum in a watch glass. Rayon acetate rafts were made to float on the serum by treating their 4 corners by silicone. Similarly, the floatability of lens paper is enhanced by treating with silicone. on each raft 4 or more explants are placed. In a combination of raft and clot techniques, the explant are first placed on a suitable raft, which is then kept on a plasma clot. This modification makes media changes easy& prevents the sinking into the liquefied plasma.
Agar Gel Method:- The medium( consisting of suitable salt solution, serum, chick embryo extract or a mixture of certain amino acids & vitamins) is gelled with 1% agar. This method avoids the immersion of explants into the medium & permits the use of defined media. generally the explants need to be subculutured on fresh agar gels every 5-7 days. The agar gels are generally kept in embryological watch glasses & sealed with paraffin wax. This method is used to study many developmental aspects of normal organs as well as tumors.
Grid Method:- Devised by trowell in 1954, this method utilizes 25 mm X 25 mm pieces of suitable wiremesh or pwerforated stainless steelsheet whose edges are bent to form4 legs of about 4 mm height. Skeletal tissues are generally placed directly on the grid but softer tissues like glandsor skin are vfirst placed on rafts, which are then kept on the grids. the grid themselves are then placed on a culturechamber filled with fluid medium upto the grid; the chamber is supplied witth a mixture of O2 & Co2 to meet the high O2 requirement of adult mammalian organs.