The job content of academic posts should be kept under regular review to ensure that clinical service pressures do not inappropriately erode research time while also ensuring that postholders have adequate clinical training. Training programmes need flexibility to accommodate the needs of clinical academics in their progress through higher specialist training.

Summary Cell fusion has been used to analyse the genetic determinants of metastasis at the cellular level. Highly metastatic mouse melanoma cells were fused with diploid mouse lymphocytes and a range of hybrid clones isolated and tested for tumorigenicity and metastatic potential by s.c. injection into newborn, histocompatible, sublethally-irradiated mice. Although almost all clones tested were tumorigenic, most had considerably reduced metastatic potential. This suggests that tumorigenicity and metastasis are determined by different genetic elements. Histological examination of primary tumours produced by metastatic and nonmetastatic hybrid cell lines showed that an essential step in the production of metastases is the separation of tumour cells from the main tumour mass and their movement into the surrounding tissues. The primary tumours of a metastatic hybrid cell line showed local invasiveness whereas those of a non-metastatic cell line did not.

The catecholaminergic neurons of the nervous system have been studied histochemically with fluorescent derivatives of catecholamines and immunocytochemically using antibodies against their biosynthetic enzymes. The immunocytochemical techniques yield permanent preparations and make possible ultrastructural studies and combined applications with other procedures. In this report, we describe the production and application of a high-affinity mouse monoclonal antibody against the rate-limiting enzyme in I Supported by grants from the Wellcome Trust, Medical Research Council (UK and Canada),

Mouse antibodies are increasingly used as primary antibodies for immunocytochemistry as more mouse monoclonal antibodies are being produced. The localisation of these antibodies by the PAP technique requires mouse antiperoxidase antibody. A monoclonal antiperoxidase would obviate the limitations of production of a polyclonal mouse antiperoxidase. This paper describes the development of a mouse hybridoma producing such an antibody (MAP A6-2) and the use of this antibody to localise a number of mouse primary antibodies by the PAP technique for both light and electron microscopy. The antibodies localised include monoclonal antienkephalin and antityrosine hydroxylase. MAP A6-2 had a higher affinity in immuno-diffusion experiments and gives slightly better staining with an horse radish peroxidase of a different type from that used for immunisation. Staining was optimum with horse radish peroxidase type X whereas horse radish peroxidase type VI was used for immunisation. Also described is the production of a HAT sensitive variant cell line allowing the possibility of using this hybridoma as a parent cell line for the production of hybrid hybridomas secreting bi-specific antibodies.

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