Immunohistochemical localization of riboflavin carrier protein in testicular cells of mammals

Using specific polyclonal antibodies against chicken riboflavin carrier protein (cRCP), immunocytochemical localization of riboflavin carrier protein was carried out in testicular sections and isolated cells of mammals. A positive reaction was observed in the developing germ cells of rat testis, especially in meiotic and post-meiotic germ cells such as pachytene spermatocytes, round spermatids and spermatozoa. In addition both the somatic cells of the testis, viz. Leydig and Sertoli cells with vital function in germ cell proliferation and differentiation, displayed a moderate to strong staining reaction. This was further confirmed using in utero X-irradiated rat testis devoid of germ cells. Different types of cells isolated from testis when subjected to immunostaining showed similar patterns of reaction as in the intact tissue. Mature spermatozoa from different mammals (rat, bull and monkey) exhibited strong staining reaction in their head regions localized mainly in acrosomal caps. It is suggested that the testicular riboflavin carrier protein has a role in cell to cell communication and may be crucial during development of germ cells especially at the meiotic and post-meiotic stages