摘要：Spermiogenesis in the relict deep-sea cephalopodVampyroteuthis infernalis Chun is examined using transmission electron microscopy (TEM), and the results compared with available data on other cephalopods. Early spermatids ofVampyroteuthis exhibit an ovoid nucleus (with dense irregular patches), numerous mitochondria and a pair of triplet substructure centrioles (arranged parallel to each other). Subsequently, the following morphological changes take place: (1) nuclear contents condense into a fibrous reticulum, then into thick fibres; (2) the acrosomal vesicle (presumably Golgi-derived) positions itself in a shallow depression at the nuclear apex; (3) the flagellum forms from one of the two centrioles; (4) mitochondria cluster around the flagellum at the base of the nucleus; (5) a dense, fibrous plug forms within the basal invagination of the nucleus. Microtubules surround the acrosome and condensing nucleus of spermatids. The dense plug is of special systematic importance since it also occurs in spermatids and spermatozoa ofOctopus spp., but not in any investigated species of the Sepiida, Sepiolida or Teuthida. Late spermatids and mature spermatozoa ofVampyroteuthis strongly resemble developing spermatids ofOctopus, suggesting a close phylogenetic relationship betweenVampyroteuthis (and the Vampyromorpha) and octopods.
关键词：Transmission Electron Microscopy;Mature Spermatozoon;Close Phylogenetic Relationship;Shallow Depression;Numerous Mitochondrion
