Ultrastructure of spermatozoa of the Atlantic cod Gadus morhua L. observed by scanning and transmission electron microscopy (original) (raw)
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Scanning and transmission electron microscopy were used to investigate the fine structure of the sperm of the sparid fish Sparus aurata L. The mature spermatozoon of gilthead sea bream belongs, like that of the other sparid fish, to a "type I" as defined by Mattei (1970). It has a spherical head which lacks an acrosome, a short, irregularly-shaped midpiece and a long cylindrical tail. The nucleus reveals a deep invagination (nuclear fossa) in which the centriolar complex is located. The two centrioles are approximately perpendicular to each other and show a conventional "9+0" pattern. The proximal centriole is associated with a cross-striated cylindrical body lying inside a peculiar satellite nuclear notch which appears as a narrow invagination of the nuclear fossa. The distal centriole is attached to the nuclear envelope by means of a lateral plate and radial fibres made of an electron-dense material. The short midpiece houses one mitochondrion. The flagellum is...
The spermatozoa and eggs of the cardinal fish
Journal of Fish Biology, 2003
The gametes of the cardinal fish Apogon imberbis had the following characteristic: the semen contained both biflagellate (c. 20% in the investigated samples) and monoflagellate (c. 80%) spermatozoa. The spermatozoa were acrosomless, had an ovoid head, and a cylindrical midpiece. The midpiece contained a high number of mitochondria (seven^10). The distal centriole was fastened to the nucleus via electron-dense material. The proximal centriole was completely reduced. The eggs were spherical, had a smooth surface and one micropyle consisting of the micropylar channel, the vestibulum and a ring-like convulsion bordering the vestibulum. The zona radiata was formed out of four layers which could be distinguished by their fine structural and histochemical features. It was only c. 1Á5 mm thick and therefore much thinner than in other marine teleosts. The internal organization of the eggs (homogenous protein yolk containing cortical granules and lipid droplets) as well as the qualitative and quantitative biochemical composition of proteins, lipids and carbohydrates was similar to that of the pelagic eggs of other marine species.
Tissue and Cell, 2004
Mature spermatozoa of two perciform teleost fishes, Paraupeneus spilurus (Mullidae) and Siganus fuscescens (Siganidae) from Taiwan were examined using transmission and scanning electron microscopy. Despite the fact that spermatozoa of both species are of the primitive type, the results of the present study highlight the potential application of spermatozoal morphology in studies of fish phylogenetic relationships. To our knowledge, the flattened nucleus observed in P. spilurus spermatozoa is reported for the first time. Several features common to Sigandae spermatozoa-the unusual almost parallel situation of the centrioles, the arrangement of mitochondria and the near absence of shallow nuclear fossa-are significantly different from other common teleost sperm types. These unique features may be synapomorphies for the Siganidae and Mullidae and evidently contribute to the study of phylogenetic relationships in teleosts.
African Journal of Biotechnology, 2012
The current study was designed to study the ultrastructure of the spermatogenic stages of the protandrous hermaphrodite sparid Diplodus cervinus cervinus. Although, it is a useful tool to enhance understanding of germ cells differentiation in this economic species, none of the available references paid attention to the studied species. The testis of the studied specie is tubular in shape and the germ cells are arranged in cysts or clusters within the seminiferous lobules. Spermatogenesis occurs in several places along the length of each lobule and induced by the action of the somatic steroidogenic secretory cells which are known as Leydig cells. Such cells contained four main morphological structural characteristics a vesicular nucleus, ovoid and elongated mitochondria with tubular cristae, a number of smooth endoplasmic reticula, and a considerable amount lipid droplets in the cytoplasm. Spermatogenic cyst displays round shaped cells with large nuclei containing clumps of heterogenic dense chromatin and reduced cytoplasm known as primary spermatogonia. They undergo a series of mitotic divisions to reach the secondary spermatogonia stage; such cells irreversibly divide meiotically to form primary and secondary spermatocytes.
Tissue and Cell, 2004
Mature spermatozoa of two perciform teleost fishes, Paraupeneus spilurus (Mullidae) and Siganus fuscescens (Siganidae) from Taiwan were examined using transmission and scanning electron microscopy. Despite the fact that spermatozoa of both species are of the primitive type, the results of the present study highlight the potential application of spermatozoal morphology in studies of fish phylogenetic relationships. To our knowledge, the flattened nucleus observed in P. spilurus spermatozoa is reported for the first time. Several features common to Sigandae spermatozoa-the unusual almost parallel situation of the centrioles, the arrangement of mitochondria and the near absence of shallow nuclear fossa-are significantly different from other common teleost sperm types. These unique features may be synapomorphies for the Siganidae and Mullidae and evidently contribute to the study of phylogenetic relationships in teleosts.
In this work we provide the ultrastructural study of the spermiogenesis of the lanternfish Lampanyctus crocodilus (Myctophiformes, Myctophidae) with special emphasis on the condensation of chromatin and the biochemical characterization of its sperm nuclear basic proteins (SNBPs). The round head of the early spermatid of L. crocodilus develops into a curved conical-shaped head in the spermatozoon. Two flagella, already present in the spermatid, are inserted laterally at the convex side of the sperm head. Both flagella possess a 9+0 axoneme instead of the typical 9+2 axonemal structure. Mitochondria undergo a characteristic redistribution during spermiogenesis. A reduced number of them are present away from the centrioles at both ends of the concave side of the sperm head. In the process of chromatin condensation during spermiogenesis, fibrogranular structures with granules of 25±5 nm and 50±5 nm can be observed in the early spermatid, which develop into larger granules of about 150±50 nm in the middle spermatid. The later coalesce during the transition to advanced spermatid and spermatozoon giving rise to a highly condensed chromatin organization in the sperm cell. Protamines are the main SNBPs associated with this chromatin; however, they are unusually large and correspond to the largest protamines described in fish to date. Small stoichiometric amounts of histones as well as other basic proteins coexist with these protamines in the spermatozoon.
IOSR Journal of Pharmacy and Biological Sciences, 2014
Transmission and scanning electron microscopy were used to investigate the ultrastructure of spermatogenesis of the Sparid fish Rhabdosargus sarba. The testis is lobular in shape and spermatogensis is of unrestricted type. Spermatogonia occur isolated or in clusters within the seminiferous lobules. The germ cells are found in cysts formed by sertoli cell processes. Cells within cysts are found in the same developmental stage. Spermiogenesis is characterized by chromatin condensation, movement of the centrioles, flagellum development, nuclear rotation, nuclear indentation and nuclear fossa formation, reduction of the cytoplasm and differentiation of the flagellar complex. Ultrastructurally the spermatozoa of R. sarb belonges, like that of other sparid fish, to the teleosean "type 1" spermatozoan with the flagellum axis perpendicular to the nuclear fossa. It has an ovoidal head, a short, cylindrically shaped midpiece and a long tail region. The nucleus reveals a deep invagination (nuclear fossa) in which the centrriolar complex is located, and a satellite nuclear noch shaped like a bell. The centriolar complex lies inside the nuclear fossa and is composed of a proximal and a distal centriole. The two centerioles are perpendicular to each other. The distal centriole is traversed by a conspicuous basal plate in its base. At the neck of the flagellum the necklace is observed. A nuclear noch is located above the proximal centeriol. The short midpiece houses two spherical mitochondria. The flagellum is inserted medio-laterally into the head, contains the conventional 9+2 axoneme.
The Biological Bulletin, 1994
We have isolated and characterized for the first time the chromosomal proteins from the nucleus of the sperm of a lancelet (amphioxus) Branchiostoma floridae (Hubbs, 1922) (Phylum Chordata: Subphylum Cephalochordata) and of a lamprey Petromy:on marinus (Linnaeus, 1758) (Phylum Chordata: Subphylum Vertebrata: Class Agnatha). In the first case, the major protein component of the sperm-chromatin of a lancelet is a highly specialized protamine-like (PL) protein that has structural and compositional features similar to those of PL-Ill from bivalve mollusks. In contrast, the chromatin of the sperm of the lamprey has a structural arrangement and protein composition (histones) very similar to that found in the somatic cells of all eukaryotic organisms. Among the deuterostomes, chromosomal protein variability is considerably greater in representatives of the Phylum Chordata than in echinoderms. The possible evolutionary significance of these findings is discussed.