INVESTIGATION OF EPIDIDYMAL SPERM MATURATION IN THE GOLDEN-HAMSTER, (VOL 17, PG 256, 1994)

During passage of hamster spermatozoa through the epididymis their mat uration is shown to involve changes in the sperm head, midpiece (mitoc hondria) and tail. The sum of these changes results in a dramatic incr ease in the fertilizing potential of the spermatozoa. When comparable numbers of spermatozoa from the caput or corpus epididymis were inject ed into one uterine horn of mature females, following ovulation induct ion, and spermatozoa from the cauda epididymis were injected into the contralateral horn, no fertilization was observed with caput epididyma l spermatozoa, 1.7% of oocytes were fertilized by corpus epididymal sp ermatozoa, whereas 79.5% fertilization was obtained with cauda epididy mal spermatozoa. Total sperm numbers increased from caput to corpus to cauda [28.3 +/- 12.2, 40.6 +/- 20.8, 144 +/- 62 million, respectively ]. The percentage of progressively motile spermatozoa increased from 2 7.9 +/- 6.4 to 33.8 +/- 4.8 to 70 +/- 10.7 during this passage. Viabil ity, measured by exclusion of the dye, propidium iodide, was significa ntly less in spermatozoa from the cauda than from the proximal or mid- caput epididymis. The percentage of the live cells that were stained i ntensely by rhodamine-123 (a measure of mitochondrial membrane potenti al) increased during epididymal passage from 22.8 +/- 7.8% in the prox imal caput epididymis to 57.2 +/- 16.5% in-the cauda epididymis. Stain ing with acridine orange (a measure of DNA packaging in the sperm head ) indicated an increase in chromatin condensation in cauda epididymal spermatozoa, when compared to those obtained from the caput or corpus.