Morphology and histology of the male reproductive system in two species of internally inseminating South American catfishes,Trachelyopterus lucenai andT. galeatus (Teleostei: Auchenipteridae)

Abstract

As part of an effort to characterize reproductive modifications in internally inseminating catfishes, ovaries and male reproductive systems were examined histologically in two species of auchenipterid catfishes, Trachelyopterus lucenai and T. galeatus, from southeastern Brazil. Internal insemination was documented in both species by the presence of sperm within ovaries. Although there is some variation in gross morphology of the male reproductive systems between the two species, both have four main regions: spermatogenic lobes, sperm storage regions, and secretory and storage regions of the seminal vesicle. In both species, the anterior portion of the reproductive system is spermatogenic and divided into numerous finger‐like lobes. Posterior to the spermatogenic area is the storage region of the seminal vesicle, a large median structure with a honeycomb‐like appearance. This region is consistently larger in T. lucenai. Attached to the storage region of the seminal vesicle in both species are secretory lobes comprised of tubules lined by secretory cells. These lobes in T. lucenai are small and located on the anterior aspect of the storage region of the seminal vesicle, whereas in T. galeatus the lobes are much larger and located laterally. The sperm storage regions of T. lucenai consist of two large lobes located ventral to the storage region of the seminal vesicle. Highly compact sperm packets (spermatozeugmata) fill the lumina of the ramifying tubules of these regions. Each spermatozeugma consists of elongate nuclei tightly arranged parallel to one another. In T. galeatus two distinct sperm storage regions are present. Just posterior to the spermatogenic lobes a series of small lobes serve as anterior sperm storage regions. Posterior to the secretory lobes of the seminal vesicle is a series of lobes, at the most posterior aspect of the reproductive tract, that serve as posterior sperm storage regions. Both are identical, histologically, to the sperm storage regions of T. lucenai. An absence of compact spermatozeugmata in the T. galeatus specimens may be related to variations in their sexual activity. The descriptions presented here allow for consistent terminology for comparison of regions of the male reproductive system based on presumed function. J. Morphol. 246:131–141, 2000 © 2000 Wiley‐Liss, Inc.

Phylogenetic relationships of the South American Doradoidea (Ostariophysi: Siluriformes)

“…This characteristic was recorded for several species of auchenipterids based on observations of reproduction in captivity (Burgess & Azuma, Franke, 1990), on studies of sperm morphology (Ihering, 1937;Burns et al, 2002;Parreira et al, 2009), morphology of the male reproductive tract (Mazzoldi et al, 2007;Meisner et al, 2009), and the presence of spermatozoa in the ovarian lumen found in some species (Parreira et al, 2009). Furthermore, reproduction by insemination is herein inferred to be present in all species of Auchenipteridae due to the fact that they all have the anal fin modified in mature males for insemination.…”

“…However, some auchenipterids, including Auchenipterichthys, Glanidium, Liosomadoras, Pseudauchenipterus, Pseudepapterus, Tetranematichthys, Tocantinsia, Trachelyichthys, Trachelyopterichthys, Trachelyopterus, and Trachycorystes, have the posterior testicular lobes modified into storage bags (Figs. 17d;Akama, 2004: #142;Mazzoldi et al, 2007;Meisner et al, 2009). The auchenipterids Ageneiosus and Auchenipterus lack the posterior testicular lobes (Fig.…”

Seminal vesicle and its role in the reproduction of teleosts

“…Such modifications have been reported in blennies, gobies, charids, pimelodids, and catfishes and are described variously as testicular glands, testicular blind pouches, and seminal vesicles or sperm duct glands (Colombo and Burighel 1974;Patzner and Seiwald 1987a, b;de Jonge et al 1989;Patzner 1987, 1989;Lahnsteiner et al , 1992aFishelson et al 1994;Joy and Singh 1998;Singh and Joy 1998a;Meisner et al 2000;Richtarski and Patzner 2000;Hamlett et al 2002;Reardon et al 2002;Cruz and Santos 2004). Various functions are attributed to these, such as differentiation of spermatids, storage and nutrition of spermatozoa, secretion of sialomucins, proteins and enzymes, storage of lipids and phospholipids, production of steroids and steroid conjugates, phagocytosis of residual germ cells, pheromonal function, and the enhancement of sperm motility and fertilization efficiency (Sundararaj and Nayyar 1969a;Lahnsteiner et al , 1992avan den Hurk and Resink 1992;Ohta et al 1997;Singh and Joy 1999;Chowdhury and Joy 2001a;Mansour et al 2004) (Fig.…”

“…They are found in some families of the Teleostei: Gobiidae, Heteropneustidae, Bagridae (Rastogi 1969;Sircar and Har 1980;Meisner et al 2000;Hamlett et al 2002;Mazzoldi et al 2005), Batrachoididae (Hoffmann 1963), Chaenopsidae (Patzner 1991), Ictaluridae (Sneed and Clemens 1963), Siluridae (Sircar 1970;van Tienhoven 1983;, Eleotridae (Hernandez-Saavedra et al 2004), Callichthyidae , and in some Blenniidae (Patzner 1984(Patzner , 1989. However, there is a lack of detailed information on the distribution of SV in all fish species.…”

“…The SV of various species show morphological variations with regard to the number, size, and shape of the lobes. In almost all catfish species, the male reproductive system possesses paired SV, which show great species variability with regard to the number of lobes and morphology (van Tienhoven 1983;Joy and Singh 1998;Meisner et al 2000), from a single pair in Heteropneustes fossilis to numerous SV as in Trachycorystes striatulus (van Tienhoven 1983) and Pangassius pangassius (Joy and Singh 1998). Also there is great intraspecific variation in the size of the SV, which determines their storage capacity for seminal fluid and spermatozoa.…”