Comparative analysis of gonadal morphology in six fish species of the Incertae Sedis genera in Characidae of occurrence in the São Francisco River Basin, Brazil

Abstract

Martins, Y.S., Arantes, F.P., Sato, Y., dos Santos, J.E., Rizzo, E. and Bazzoli, N. 2012. Comparative analysis of gonadal morphology in six fish species of the Incertae Sedis genera in Characidae of occurrence in the São Francisco River Basin, Brazil. -Acta Zoologica (Stockholm) 93: 48-56.This study presents a comparative analysis aiming to show the remarkable differences found in gonad morphology between six fish species from the genera Incertae Sedis in the Characidae family. Maturing ovaries of Astyanax fasciatus presented grayish color whilst the other species' were yellowish in color. The cortical alveoli of the analyzed species are small (5.20 ± 1.44-8.28 ± 2.02 lm) and are formed by various discontinuous layers of vesicles except in the Bryconops affinis, where they are large (12.87 ± 2.41 lm) and form various continuous layers of vesicles. The pellucid zone is thin and varies from 2.44 ± 0.90 to 5.79 ± 1.90 lm and is thickest in B. affinis (10.57 ± 2.08 lm). Folds in the pellucid zone were observed in Astyanax bimaculatus, A. fasciatus, Hemigrammus marginatus, and Moenkhausia costae. The follicular cells of B. affinis are columnar (28.19 ± 13.71 lm), while they are squamous in other species (1.52 ± 0.64-2.12 ± 0.78 lm). This study showed that the morphologic and biometric characteristics of the B. affinis vitellogenic oocytes are statistically different than the analyzed other ones Incertae Sedis of the Characidae family. In advanced maturing testis of A. bimaculatus and A. fasciatus, the spermatozoa were embedded in acidophilic secretion which was gradually reabsorbed in the seminiferous tubules when males were partially spent.

Comparative morphology of gonads from six species of fish belonging to the family Anostomidae (Characiformes: Anostomidae)

“…In testis of this kind, the seminiferous tubules form anastomosis throughout the gonad, contrary to the neoteleostei which form anastomosis only in the seminiferous tubules located in the central region of the testis (Parenti & Grier, 2004). The main morphology characteristics here described, also has been reported for other Characidae (Grier, Linton, Leatherland, & deVlaming, 1980;Martins et al, 2011), reinforcing the fact that the testicular morphology is an important parameter in phylogenetic studies (Parenti & Grier 2004).…”

“…This assumption is reinforced by ultrastructure studies showing, in species with adhesive eggs, follicular cells with a large amount of organelles that synthesize mucosubstances that are transferred to the pellucid zone for a strong adhesiveness of the eggs to the substratum (Andrade, Bazzoli, Rizzo, & Sato, 2001;Rizzo et al, 2002;Santos et al, 2006). In vitellogenic oocytes of S. knerii, cubic follicular cells in the animal pole and prismatic ones on the vegetative pole were observed; similar to what has been registered for Cichlidae (Normando et al, 2009;Martins et al, 2011). The cubic cells synthesize proteins which are important for the micropyle region whereas prismatic cells are involved in the secretion of substances related to the eggs adhesiveness (Rizzo et al, 2002).…”

“…The morphologic characteristics of the testis showed a similar pattern to that of the majority of neotropical Charciformes, that have external fertilization, without possessing accessory structures in their gonads (Gonçalves, Bazzoli, & Brito, 2006;Carvalho, Paschoalini, Santos, Rizzo, & Bazzoli, 2009;Arantes et al, 2011;Martins et al, 2011). The species studied in our work presented spermatogonia throughout the length of the testis, which places them in the unrestricted spermatogonial type according to Grier (1981); a testicular organization that allows a potential germinative cell production (Schulz & Miura, 2002).…”

“…Gonad morphology has been used for the understanding of the reproduction and the phylogenetic relationships amongst fishes (Belova, 2008;Martins et al, 2011;Melo et al, 2011). Although some studies showed that species of the same family and sub-family usually present a common pattern of gonad morphology (Rizzo, Sato, Barreto, & Godinho, 2002;Martins et al, 2011;Melo et al, 2011), in specialized literature there are no studies comparing the gonad morphology of the Anostomidae family. In a review, Parenti and Grier (2004) observed an evolutionary net on the teleosts testis morphology, through the organization of the seminiferous tubules and the distribution of spermatogonia throughout the germinal epithelium.…”

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“…Usually, gonad development was monitored on the basis of their macroscopic and microscopic appearance (Wang et al, 2003;Martins et al, 2012). Testis of numerous teleosts showed general structures with a paired testis is either fused along the entire length or completely separated or fused posteriorly (Selman and Wallace, 2005).…”