Microtubular Network of the Gelatinous Egg Envelope Within the Egg Ribbon of European Perch, <I>Perca Fluviatilis</I> L.

Abstract

Formicki K., Smaruj I., Szulc J., Winnicki A. 2009. Microtubular network of the gelatinous egg envelope within the egg ribbon of European perch, Perca fluviatilis L. Acta Ichthyol. Piscat. 39 (2): 147-151.Background. After their deposition in water, eggs of perch form characteristic, long gelatinous ribbons (strands) floating within the water column. The ultrastructure of the external gelatinious egg envelope of members of the family Percidae was believed to be amorphous. The aim of the presently reported study was to describe the ultrastructure and function of the gelatinous egg envelope composing the perch egg ribbon. Materials and Methods. Fresh eggs of European perch, Perca fluviatilis L., were collected, in the form of egg ribbons, from females caught at the spawning grounds on the Odra River side canal Dziewoklicz, within the city limits of Szczecin, Poland. After fertilization eggs were fixed in 4% formaldehyde. In the laboratory, the commonly accepted techniques (dehydration, critical-point drying, sputter coating) were used to prepare samples for examination with a scanning electron microscope (SEM). The observations were photographically documented.Results. Closely below the surface of the gelatinous egg ribbon we observed a network of microtubules. These microtubules opened at the egg ribbon surface in the form of ring-like or nozzle-like pores. Conclusion.The gelatinous egg envelope of perch is a complex microtubular network that likely performs a skeletal role for the egg ribbon. Our results also suggest that the regular surface openings of the aforementioned network may play an attachment function (micro-suckers) reciprocally between eggs and between eggs and other objects, thereby facilitating the fastening the eggs to underwater vegetation.

Early ontogenesis of the angelfish, Pterophyllum scalare Schultze, 1823 (Cichlidae)

“…cyprinids such as tench, rudd, bleak, the eggs of which show 70% of the volume being taken by the perivitelline space (Winnicki & Korzelecka, 1997;Bonislawska et al, 1999). Despite the relatively small perivitelline space, the angelfish show no quasi-peristaltic movements of the ectoplasm similar to those reported in pike (Tañski et al, 2000) or stickleback ; in those species, there is an ectoplasm wave movement along the yolk sphere surface, which mixes the perivitelline space and effectively enhances oxygen transport to the respiratory surfaces of the embryo (Bonislawska et al, 1999;Formicki et al, 2009). Regular aeration of water at the egg surface, brought about by the parental fish fin movement, ensures that despite high ambient temperature, the embryos receive a sufficient oxygen supply; a quasi-peristaltic movement would in this membrane seem an unnecessary loss of energy.…”

An alternative developmental table to describe non-model fish species embryogenesis: application to the description of the Eurasian perch (Perca fluviatilis L. 1758) development

“…2b, arrowhead) and a large gelatinous envelope (or jelly coat) organized with tubular structures (Fig. 2c) called zona radiata externa as previously described by Formicki et al [14]. It allows maintaining the eggs together and forming a ribbon (Fig.…”

“…Indeed, while it is commonly admitted that the starting point of the embryogenesis corresponds to the egg activation occurring at the ova releasing in the water [9, 12], the end of the embryogenesis is defined either by the hatching or the first oral feeding depending on the authors [for review 9, 12, 13]. From a general point of view, the first definition of an embryo corresponds to a specific period of the development during which individuals are protected by an envelope [12, 13] or a gelatinous layer surrounding the embryo that is called gangue [14]. In the meantime, larva mainly defines the developmental period elapsing from the hatching to the juvenile stage often characterized by the metamorphosis.…”

Effect of different activating solutions on the fertilization ability of Eurasian perch, Perca fluviatilis L., eggs

“…Dabrowski et al, 1994). Subsequently, the eggs [which are situated within a large, cylindrical gelatinous strand in the perch called ribbons (e.g., Probst et al, 2009;Formicki et al, 2009)] were washed with clean water several times and placed in incubation devices. However, the embryo survival rate varied when this method was applied in the European perch, even if the highest-quality eggs were used for fertilisation (Kucharczyk et al, 1996;Żarski et al, 2011).…”