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It has already been accepted that the function and activity of the testis is regulated not only by gonadotrophins, but also by many locally produced factors and by cell-cell interactions. That is why the aim of our work was to determine whether macrophages and/or their products have an influence on Leydig cell steroidogenic activity. The source of Leydig cells and macrophages were male bank voles of spring and autumn generations, reared in 18 light:6 dark or 6 light:18 dark (18L:6D or 6L:18D) conditions for 7-8 weeks. The Leydig cells were growing in monocultures or in co-cultures with macrophages (testicular or peritoneal), either as control or hCG-stimulated ones. To some of the cultures 6 IU/ml of interleukin 1alpha (IL-1alpha) was added. After then the cells were analysed morphologically, histochemically, and radioimmunologically. In the present study we found many differences in morphology and steroidogenic activity of Leydig cells obtained from different photoperiods. Leydig cells from a long day formed monolayer contrary to the cells from a short one growing as single cells or in clusters. Moreover, Leydig cells from a long photoperiod produced more testosterone and were sensitive to the stimulatory effect of both testicular macrophages and testicular macrophage-conditioned medium. They were also more sensitive to the inhibitory influence of IL-1alpha.

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Porcine luteal cells were collected from corpora lutea in four different stages of the luteal phase and cultured as monolayers. Progesterone (P4) secretion was assayed using radioimmunoassays (Gregoraszczuk, 1991). Luteal cells cultured from porcine corpora lutea collected in the early luteal phase maintained steroidogenic capacity for 6 days in culture until the time comparable with midluteal corpora lutea. Luteal cells collected from mature and regressing corpora lutea did not dedifferentiate during 2 days of culture. After this time secretion of progesterone decreased to undetectable amounts characteristic of old corpora lutea. The regression in the culture progressed. The results demonstrate that the degree of the decline of progesterone depends on the type of corpus luteum, which is connected to particular time intervals of the luteal phase. Before starting experiments it is necessary to take into consideration the stage of the luteal phase from which the material is collected for culture. This study provides evidence that long term culture is useful for investigating a variety of aspects of luteal function only if cells are collected in the early luteal phase. Short term culture is suitable for investigation of cells collected from mid and late luteal phase. Regulation of luteal function is dependent on stage of the luteal phase.

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