a direct reaction.
This technique can be modified by attaching the peroxidase to an anti-? globulin antibody (the most prevalent antibodies are of the ?-globulin type, and these are usually the ones harvested when antibodies are raised in animals)(8). This secondary antibody binds to the first antibody, which further amplifies the (indirect) reaction, making it easier to visualize. The end product of the peroxidase reaction is also readily visible in the electron microscope, so this is a useful reaction to consider if wishing to localize the antigen at both a cellular and subcellular level. Monoclonal antibodies conjugated to gold or ferritin can be used as the primary antibody in this reaction so that fine localization of the antigen is possible under the electron microscope, which is superior to when polyclonal antibodies are used.
The use of secondary antibodies is useful in that a single secondary antibody can be used to localize the tissue-specific and intercellular binding of several different primary antibodies (8). In fluorescence microscopy, the secondary antibody can be conjugated with different fluorescent dyes so that multiple labels can be seen in the same tissue section or cell.
The integration of the short-term meal-related signal cholecystokinin (CCK) with the long-term adipose signaling is hypothesized to involve descending projections of the hypothalamus into areas of the caudal brain stem (CBS) to regulate the amount of food consumed during a single meal (Blevins, Eakin, Murphy, Schwarz and Baskin 30-41). One of these projections extends from the cell bodies in the hypothalamic paraventricular nucleus (PVN) to the nucleus tractus solitarius (NTS), which is the area where cells which respond to peripheral cholecystokinin (CCK) are located. Cell types which may comprise this PVN-NTS system include those which express corticotropin-releasing hormone (CRH) or oxytocin. These researchers used immun...