Fig. 4. spe-38 sperm exhibit normal transfer and migratory behavior, but fail to penetrate oocytes. (A-E) Partial images of whole-mount DAPI-stained hermaphrodites or genetic females, in which the oviduct (left), spermatheca (large arrowheads) and uterus (right) are shown. In such DAPI-stained preparations, the small dense chromatin mass of mature spermatozoa distinguishes them from other somatic- and germ-cell types. (A) In an unmated wild-type hermaphrodite, numerous sperm (small bright spots) are present within the spermatheca. (B) An unmated fem-1 female lacks sperm within her spermatheca, and her uterus is filled with unfertilized, endomitotic (emo) oocytes (arrows). (C-E) Upon mating, sperm from either wild-type (C) or spe-38(eb44) males (D,E) populate the spermatheca of fem-1 females. (F) In a newly fertilized wild-type oocyte, the sperm chromatin remains as a single, highly condensed DNA mass, while the oocyte chromosomes are undergoing their meiotic divisions. (G,H) Sperm chromatin masses were never observed in either young (G) or older (H) emo oocytes from the uteri of unmated spe-38 hermaphrodites. (I,J) Young (I) and older (J) emo oocytes from the uteri of fog-2 females crossed with spe-38; him-5 males. (K) A series of developing embryos within the uterus of a spe-38 hermaphrodite mated to wild-type males. A condensed sperm chromatin mass is visible in the meiotic-stage embryo (far left). The broken lines outline the oocytes and embryos.