Immunocytochemical demonstration of mammalian lutropin-like material in the pituitary of the lungfish, Lepidosiren paradoxa.

The presence of lutropin (LH)-like material in the pituitary gland of the South-American lungfish, Lepidosiren paradoxa, has been demonstrated by means of the unlabeled antibody-enzyme method, by use of rabbit anti-ovine LH as first antibody. The LH-like substance was revealed in a single PAS-positive cell type primarily located in the anterior part of the distal lobe. Dot blot tests as well as conventional liquid-phase absorption experiments indicate that the anti-ovine LH antibodies possess specificity against the oLH beta subunit. These observations indicate that dipnoans (Lepidosiren) share a number of antigenic determinants with those of mammalian LH beta and support the concept that mammalian LH beta, or part of it, was established early in evolution. The exact nature and physiological function of the substance detected remains to be defined.