PMC

Early embryogenesis of Bursaphelenchus okinawaensis through four-cell stage. (A–E) Pronuclear migration and fusion. (F) Asymmetric first cleavage. (G) Two-cell stage. (H) Four-cell stage. Scale bar represents 10 μm.

The number of self-produced sperm and progeny in Bursaphelenchus okinawaensis. The numbers presented are mean values of eight biological replicates. Error bars represent SD.

Distribution of spermatid cross-sectional areas in hermaphrodites and males in Bursaphelenchus okinawaensis. The cross-sectional area of spherical spermatids was measured using ImageJ software. A total of 100 sperm from 80 hermaphrodites and 126 sperm from 24 males were measured.

Stereomicroscope images of wild-type and mutant strains of Bursaphelenchus okinawaensis. (A and B) WT, wild-type. (C and D) Dpy, Dumpy. (E and F) Rol, Roller. (G and H) Unc, Uncoordinated. Scale bar represents 200 μm.

Spermatogenesis in L4 hermaphrodite of Bursaphelenchus okinawaensis. (A and B) Spermatogenesis in the proximal gonad. (C and D) Transition from spermatogenesis to oogenesis. (E and F) The spermatids are pushed into the spermatheca by the first oocyte during the first ovulation. Vu, vulva; Sp, spermatid; Rb, residual body; Spc, spermatocyte; Spt, spermatheca. Scale bar represents 10 μm.

Chromosome behavior and polar body extrusion of Bursaphelenchus okinawaensis during early embryogenesis. (A) First polar body extrusion. (B) Second polar body extrusion. (C) Emergence of two pronuclei. (D–F) Pronuclear migration. (G) Pronuclear fusion. (H–J) First cleavage. Sp, sperm pronucleus; Op, oocyte pronucleus; Pb, polar body. Scale bar represents 10 μm.

The germ line of Bursaphelenchus okinawaensis. (A, B) Confocal images showing DAPI staining of a gonad dissected from an adult hermaphrodite. The oocyte stored in the proximal gonad is boxed in (A) and shown at higher magnification in (B). (C and D) Differential interference contrast images of the reproductive system of a gravid adult hermaphrodite. The egg in the uterus is boxed in (C) and shown at higher magnification in (D). Vu, vulva; Spt, spermatheca. Scale bar represents 10 μm.