Structural analysis of embryogenesis ofLeiarius marmoratus(Siluriformes: Pimelodidae)

Abstract

Embryological studies in fish species are useful to the understanding of their biology and systematics. The available biological data in Leiarius marmoratus are scarce and additional information about its reproductive biology is needed, mainly because this species has been commercially exploited and used in production of hybrid lineages. In order to evaluate the temporal-morphological embryonic modifications in L. marmoratus, samples of nearly 200 embryos were collected at random at different stages of development, starting from fecundation (time zero). Embryos were fixed in modified Karnovsk's solution and 2.5% glutaraldehyde, processed and analysed under optic and electron microscopy. The incubation period of L. marmoratus was equal to 14.42 h at a mean temperature of 28.3 ± 0.07°C. The following stages of embryonic development were established: zygote, cleavage, gastrula, organogenesis and hatching. These stages were divided into phases, as follows: cleavage - phases of 2, 4, 8, 16, 32 and 64 cells and morula; gastrula - phases of 25, 50, 75 and 90% of epiboly and blastopore closure; and organogenesis - neurula, segmentation and pre-larval phases. The embryogenesis of L. marmoratus was typical of neotropical teleosteans, with peculiarities in species development.

Morphological and histochemical features of the digestive tract ofLeiarius marmoratus(Gill, 1870)

“…This is reflected in the ease of handling it in captivity, and the species ability to assimilate pelleted food (Cruz-Casallas et al, 2010). According to Sánchez et al (2009), L. marmoratus has great gastronomic value because of the quality of its meat (light colour, mild flavour and the presence of few intramuscular bones), in addition to great commercial relevance, as it is a species widely used to obtain hybrids (Bernardes et al, 2016;Fortes-Silva et al, 2017;Oliveira-Almeida et al, 2015;Paulino et al, 2020). In the search for a better understanding of the digestive and nutritional characteristics of L. marmoratus, this work aims to describe the morphological and histochemical characteristics of the different segments of the digestive tract of L. marmoratus, because it is the mucosa layer that is in constant contact with the luminal contents.…”

Improved solution for vitrification ofProchilodus lineatusembryos based on the reduction in risk factors: Toxicity, osmotic responses and ice-nucleation

“…On the other hand, if we consider the use of the initial stages of development, other problems hinder the cryogenic processes. The existence of a blastoderm grouped in a cell mass, resting on a cellular syncytium (yolk syncytial layer) reduces the surface area in contact with medium, thus hindering the penetration of cryoprotectant to cells at the interior of the blastoderm, since the diffusion capacity of cryoprotectants is influenced by the contact area of medium (Adams, Zhang & Rawson, ; Hagedorn, Kleinhans, Artemov & Pilatus, ; Hagedorn, Kleinhans, Freitas, et al., ; Hagedorn, Kleinhans, Wildt, et al., ; Oliveira‐Almeida et al., ). Also, it has been verified that the adhesion between embryonic cells possibly becomes larger by the expression of Wnt11 genes, which regulates the production and location of integrin complexes during gastrulation (Puech et al., ), reducing the incidence of possible mechanical damage throughout the process.…”

Effects of cryoprotectants and low temperatures on hatching and abnormal embryo development of Prochilodus lineatus (Characiformes: Prochilodontidae)

“…It is considered a good biological model that reproduces in captivity and has some of the reproductive features common to most neotropical rheophilic fishes, such as prolificity, non-adhesive eggs, fast embryonic development, and a large yolk sac and perivitelline space (Ninhaus-Silveira et al, 2006;Oliveira-Almeida et al, 2014).…”