The goal of the histochemistry core is to provide technical expertise, help with experimental design, assistance with anatomical image analysis, and training opportunities in modern histochemical methodology. Histochemistry methods are an important part of projects 1-4 of this program project. A core laboratory will provide facilities and technical assistance in the histological and histochemical processing of animal tissues and obviate the purchasing of expensive equipment required for these procedures by each laboratory. The core will also provide the necessary expertise in trouble-shooting histochemical experiments, as well assist with the analysis and quantification of the results. By Centralizing the tissue processing and coordinating experimental protocols used by each laboratory this core will facilitate progress toward the stated goals of each project and enhance the process of interrelating results across projects. Dr. Chinkers (Project 1) will utilize the histochemistry core to evaluate the distribution of natriuretic peptides in the hypothalamus and study their possible co- expression in CRF neurons, as well as define the expression pattern of receptors for these peptides in the hypothalamus and pituitary. Dr. Low (Project 2) will need free access to the core facilities to characterize the development and adult organization of key aspects of hypothalamic and pituitary components of the HPA axis in transgenic mice that lack beta- endorphin. Dr. Thomas (Project 3) proposes studies that will required access to the histochemistry core for processing pituitary tissue from transgenic animals for immunohistochemistry and in situ hybridization. Dr. Cone (project 4) will require extensive use of the core facilities to study the expression pattern of novel melanocortin receptors in the brain of adult and developing normal and transgenic animals. In support of these projects the histochemistry core will: 1) Provide equipment, supplies and technical assistance for the acquisition of frozen tissue sections using both cryostat and sliding microtomes; 2) Store frozen tissue samples (-cT) and slide-mounted sections until they can be processed for histochemistry; 3) Supply detailed protocols for immunohistochemical (both double fluorescence and ABC staining) and in situ hybridization (using both non- and isotopically-labeled cRNA probes) histochemical techniques, as well as assist in the optimization of procedures for specific applications; 4) Assist in the experimental design and interpretation of all histochemical experiments; and 5) Provide image analysis facilities and assistance with anatomical and quantitative analysis of histochemical experiments.