engleski

Neuroendocrine properties of human fetal Leydig cells

Introduction. Few studies have been devoted to Leydig cells of fetal human testis. Moreover, limited number of studies have dealt with the neuroendocrine nature of adult Leydig cells, while the data on the expression of ‘ neuroendocrine markers’ in human fetal Leydig cells are still extremely meagre. Materials and methods. Qualitative morphological morphometric (stereological) and immunohistochemical analysis of human foetal testicular tissue (in the developmental stage between the 15th and 36th gestational week) has been performed. The material for analysis originated from the archives of paraffin blocks at the Institute of Histology and Embryology, Medical School University of Zagreb. Bioptic samples of adult testis with the histological picture of normal spermatogenesis were used as control tissue. Immediately after the section, testes were weighed on precision laboratory scales to establish their mass, i.e. volume, and then they were subjected to a standard sequence of histological procedures. The obtained sections were stained by hemalaun eosin, and were used for morphometric and immunohistochemical analysis. Results. This research has shown that fetal Leydig cells are dynamic population of cells within the interstitum of human testes in the period between the 15th and 36th gestational weeks. The above mentioned cells have 2 basic shapes: round/oval or elongated, having an on- or off-centre nucleus with loose chromatin. In certain gestational weeks, fetal Leydig cells become ‘ passive’ , with flat shape and relatively meagre cytoplasm, and in this way they are similar to their mesenchymal progenitors. According to the results of this research, the total number of Leydig cells of human fetal testes changes through different stages of gestation by means of a ‘ pulsatile’ dynamics (most likely by following the variable level of gonadotrophins). Oscillations in the number of Leydig cells are noticeable from week to week of foetal development, but the trend curve shows a clear and steady growth of the Leydig cells population. At the early stages of development (15th-17th gestational week) immunohistochemical reaction to the expression of neuron specific enolase (NSE) is positive within the sex cords and between them, in the interstitum. Prospermatogonia within the sex cords are positive, as well as the elongated spindle-shaped cells within the interstitum. In the later stages of development (28th-36th week), apart from the prospermatogonia, the interstitial Leydig cells are also positive. The expression of NSE in the prospermatogonia indicates the pluripotent features of these cells and the possibility of differentiation in various directions, including the cells of central/peripheral nervous system. Application of antibodies to protein S 100 in the analysed samples of human foetal testes (15th-17th gestational week) did not show immunohistochemically positive cells ; immunohistochemical reaction to the expression of glial fibrillar acidic protein (GFAP) was negative on the sections of foetal testes ; so was the immunohistochemical reaction to the expression of chromogranin and synaptophysin. Conclusion. The results of immunohistochemical analysis (the expression of NSE) confirm the hypothesis of neuroendocrine nature of human foetal Leydig cells.

Leydig cells; fetus; human; neuroendocrine system

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