ABSTRACT
This review compiles all the research done on gametes and fertilization in the rock shrimp, R. typus, and describes the sequence of events from the first gamete interaction to zygote formation and the first cleavage of the embryo, with light, fluorescence confocal and electron microscopes. Early studies showed that sperm from the vas deferens have a tack-shape with a "needle-like process" or rigid spike (RS) that extends from a semi-spherical body that contains the arms with chromatin and spines. Upon contact with seawater and by action of Na +, the arms and spines extend, producing an inverted umbrella form of the spermatozoa. The first sperm-oocyte interaction occurs between protein receptors type lectins of the sperm RS and oocyte chorion sperm ligands. These ligands contain residues of a-Glu, Man (a 1-3) Man, a and p-GlcNAc and a-GalNA terminal residues. It was found that a-Man and GlcNAc residues are the ligands that are directly related to the adhesion process and further penetration of sperm. After this first interaction, the RS enters the oocyte envelope by the action of a trypsin-like enzyme, rhynchocinecine, present in the acicular process. Later, arms and spines penetrate the oocyte cytoplasm, where the chromatin of the arms begin to migrate to the central area of the sperm, condensing in a cup-shaped structure near the connecting piece, which forms the male pronucleus.
Subject(s)
Animals , Female , Male , Decapoda/physiology , Fertilization in Vitro/veterinary , Sperm-Ovum Interactions/physiology , Decapoda/ultrastructure , Enzyme Activation , Fertilization in Vitro/methods , Microscopy, Electron, Scanning , Trypsin/metabolismABSTRACT
Se describe la citología axonal y la ultraestructura de las aperturas mielínicas (nudos de Ranvier) de las fibras mielinizadas no gigantes del camarón Penaeus, comparándolas con las características morfológicas de otros nudos de Ranvier en invertebrados y vertebrados