The progression of spermatogenesis in the developing rat testis followed by 31P MR spectroscopy

To evaluate the use of human testicular 31P MR spectroscopy as a diagnostic tool to differentiate between several stages of male infertility, we have studied the testicular levels of several phosphorus containing compounds in the rat in relation to the condition of spermatogenesis and the cell types present in the seminiferous tubules of the testis. During testicular maturation several characteristic changes occur in the 31P MR spectrum of the testis of male Wistar rats. The phosphomonoester/adenosine triphosphate (PM/ATP) ratio shows a decline from 1.61 to 1.02 between the age of 3 and 12 weeks, whereas the phosphodiester (PD)/ATP ratio increases from 0 to 0.72. The testicular pH increases in the same time from 7.06 to 7.32. Testicular MR data obtained after 12 weeks of age onward do not show significant change anymore. The high PM/ATP ratio is associated by a relative high amount of proliferating spermatogonia and spermatocytes during meiosis in the testis, whereas the PD peak seems to be correlated with the release and maintenance of spermatozoa. The MR spectra show a specific fingerprint in all developmental stages of the rat testis as a result of the different cell types in the testis.