Embryonic Coat of the Grass Shrimp Palaemonetes pugio

Abstract

The embryo of the grass shrimp, Palaemonetes pugio, is surrounded during development by a protective extracellular coat designated as the embryonic coat (EC). At hatching, this EC is composed of four embryonic envelopes (EE), each of which is composed of multiple layers. The outermost layer of the EC, the outer investment coat (OIC), is derived primarily, if not completely, from pleopods of the female. The first envelope (EE1) forms as a bilayered envelope, EE1a and EE1b, immediately after oviposition. The OIC becomes closely associated with EE1 and remains in close contact with EE1 until hatching occurs. An additional layer, EE1c, is added to the inner side of EE1 between 3 and 5 d after oviposition. Three more embryonic envelopes, EE2, EE3, and EE4, are formed between the embryo and EE1 by 7 d after oviposition. Formation of embryonic envelopes continues until 10 d after oviposition; by this time each envelope is morphologically distinct in composition, with "outer" and "inner" sides clearly identifiable. All but the innermost embryonic envelope (EE4) are shed by the embryo about 6 h before hatching. Permeability of the EC during the 12-d incubation period is found to decrease between 0 and 5 d after oviposition, and then increase until hatching. Fluorescently labeled lectins react positively with the OIC, indicating the presence of glucose and N-acetylglucosamine residues. Thus, the palaemonid EC is a dynamic structure throughout embryonic development.

Embryonic development of four species of palaemonid prawns (Crustacea, Decapoda): pre-naupliar, naupliar and post-naupliar periods

“…The characterized stages of embryonic development in palaemonids followed the general pattern of embryogenesis described for other species that have centrolecithal eggs, as Palaemonetes varians (Leach, 1814) (WEYGOLDT 1961), Macrobrachium carcinus (Linnaeus, 1758) (MÜLLER 1984), Palaemonetes pugio (GLAS et al 1997), Macrobrachium acanthurus (Wiegman, 1836) (BRESSAN & MÜLLER 1999).…”

Exoskeletal cuticle differentiation during intramarsupial development of Porcellio scaber (Crustacea: Isopoda)

“…Embryonic cuticles and embryonic molt cycles were observed by light microscopy in intact and unfixed embryos, for example in the decapod Homarus americanus (Helluy and Beltz, 1991) and in the branchiopod Eulimnadia antlei (Belk, 1987). However, ultrastructural studies, probing the cuticle in embryos and larvae are scarce, although some early studies were made on the ultrastructure of embryonic surface matrices in the branchiopod Artemia salina (Morris and Afzelius, 1967), in the isopod Hemioniscus balani (Goudeau, 1976) and in the decapods Carcinus maenas (Goudeau and Lachaise, 1983) and Palaemonetes pugio (Glas et al, 1997). An ultrastructural study of the embryo cuticle was performed recently in the aquatic amphipod Parhyale hawaiensis (Havemann et al, 2008).…”

Embryonic Development of the Palaemonid Prawn Macrobrachium idella idella (Hilgendorf, 1898)

“…This pattern is observed in most malacostracans in which the hatching form is the zoea [36]. The embryonic development in M. idella idella followed the general pattern of embroyogenesis described for other species that have centrolecithal eggs, as P. varians [41], M. carcinus [42], P. pugio [43] and M. acanthurus [44]. The formation of the zoea structures follows the organization of the basic body plan observed in the development of oligolecitic species eggs [45] where first larval phases correspond to the embryonized post-zoea in the meroblastic pattern [46].…”