title: An ultrastructural study of germ plasm in spermatogenesis of Xenopus laevis.
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002466:Cell Nucleolus / Q000648:ultrastructure; D002467:Cell Nucleus / Q000648:ultrastructure; D003593:Cytoplasm / Q000648:ultrastructure; D005854:Germ Cells / Q000648:ultrastructure*; D008297:Male; D008540:Meiosis; D008854:Microscopy, Electron; D008928:Mitochondria / Q000648:ultrastructure; D013091:Spermatogenesis; D013094:Spermatozoa / Q000648:ultrastructure*; D013737:Testis / Q000166:cytology / Q000648:ultrastructure; D014981:Xenopus / Q000196:embryology*