FIG. 3.
Epididymal spermatozoa. a, c and e are phase contrast and b, d and f are fluorescence photomicrographs. a, b Normal mouse spermatozoa, with short, thick, sickle-shaped head. c, d Normal rat spermatozoa, with long, thin head, and tail that is longer and thicker than mouse. e, f Spermatozoa from epididymides of recipient mouse 767, with distinct rat and mouse morphologies. Ratio was 1 rat to 39 mouse spermatozoa in this animal.
METHODS. To examine and count spermatozoa, epididymides were placed in phosphate-buffered saline and cut in several places20. Mouse and rat spermatozoa were distinguished by their characteristic head morphology and tail size. For fluorescence photography, the spermatozoa solution was treated with 20 μg per ml Hoecsht 33258 dye20. Scale bar, 25μm.