Subacrosomal Space Research Articles

Preliminary study on the impact of 900 MHz radiation on human sperm: An in vitro molecular approach

The use of technologies that produce and emit electromagnetic fields (EMF) is growing exponentially worldwide. The biological effects of EMF-emitting equipment, such as mobile phones and other wireless devices, have been studied in the last decade using in vitro and in vivo methods. Infertility is a growing health problem, and nearly half of cases are because of male-factor. This study investigated the direct in vitro effects of 900 MHz radiation exposure on sperm parameters, genetic status, apoptotic markers, and the PI3K/AKT signaling pathway in healthy normozoospermic men. Semen samples were divided into four groups, two control (30 min and 1 h) and two EMF exposure (30 min and 1 h). Sperm parameters (motility, progressive motility, acrosomal index, morphology), genetic status (DNA fragmentation and chromatin integrity), apoptotic markers (cytokine-c and caspase-3 expression) and the PI3K/AKT signaling pathway (phosphoinoitide 3-kinase-PI3K- and phosphorylated AKT- p-AKT-) were analysed. Sperm motility were significantly reduced in 30 min EMF exposure while a significant increase in the expression of p-AKT were observed in 1 h EMF exposure group. An increased vacuolisation, acrosomal defect, extension of subacrosomal space, uncondensed chromatin structure, apoptotic signs and disrupted axoneme were observed in both EMF groups which were not observed in the control group. Other sperm parameters (morphology and acrosomal index), genetic status, apoptotic markers and the PI3K expression rates had no significant change.

Testis-specific actin-like 7A (ACTL7A) is an indispensable protein for subacrosomal-associated F-actin formation, acrosomal anchoring, and male fertility.

Formation of the acrosome during spermiogenesis is an essential process for creating fertilization-competent sperm. Of the numerous aspects required for acrosome biogenesis, adherence of the acrosomal outer membrane to the nuclear surface is mediated by the subacrosomal perinuclear theca. However, the cellular dynamics and congruent functions pertaining to these acrosomal anchoring factors are not well understood despite many of them being implicated as potential causes for human male infertility. Actin-like 7A (ACTL7A) is one such factor for which deleterious polymorphisms have recently been shown to cause human male infertility. It is thought that acrosomal attachment is coordinated by cytoskeletal associations between the acrosome and nucleus via the acroplaxome. To further illuminate the mechanistic underpinnings of ACTL7A for essential acrosome associations, in this study, we investigated its dynamic localization in the developing germline, molecular associations with other cytoskeletal components, and the cellular consequences of ablation. Our intracellular localization data show ACTL7A to be dynamically present within the nucleus and subacrosomal space and later associated with postacrosomal regions of developing spermatids. Through the generation of an Actl7a knock-out mouse model, we consistently observed disruption of acrosomal biogenesis with abnormal migration of the acrosomal granule and peeling acrosomes during spermatid elongation. Significantly, we found a complete loss of subacrosomal filamentous actin (F-actin) structures in knock-out spermatids suggesting a regulatory role for subacrosomal F-actin. Considering our reported data together with existing literature, we propose a mechanistic model explaining the essential role of ACTL7A for acroplaxome-associated F-actin, acrosomal attachment integrity, and male fertility.

Semen qualitative parameters and spermatozoon ultrastructure of Phasianus colchicus mongolicus

In many European countries, the common pheasant is one of the most popular game bird species. Despite its popularity, little information has been published related to its sperm profile, including the common semen parameters used to characterise the quality of this material. Additionally, the spermatozoon’s ultrastructure has never been characterised, and very few data on reproductive performance in the male bird are available. The aim of the present study was to provide these data and fill these gaps in the literature. Semen was collected by the dorso-abdominal massage technique for pheasants and evaluated during the late spring period (May to mid-June). For the ultrastructure and morphometric descriptions, scanning electron and transmission electron images were obtained. The data show that pheasants produce ejaculates of a smaller volume (average volume = 131 µL) but with a higher sperm concentration compared with roosters. Semen pH values tended towards alkaline values (average pH = 8.3). The general shape of the pheasant spermatozoon resembles that of roosters and turkeys, although a bigger sub-acrosomal space was observed compared with these species. As a consequence, its perforatorium occupies two-thirds of the acrosome. A lower number of mitochondria (20–24) was also detected compared with roosters and turkeys. The pheasant spermatozoon’s dimensions are most similar to those observed in turkeys and guineafowl. The present study provides basic information useful for assisted reproductive techniques and conservation programmes. HIGHLIGHTS Basic information on the common pheasant semen is given. A morphometric description of the common pheasant sperm cell is reported. The characterisation of the sperm ultrastructure by scanning and transmission electron microscopy is shown.

Calcium, Ca2+-ATPase, Calmodulin, and Calbindin D-28KD Localization in Testis of Leptodactylus chaquensis (Anura: Leptodactylidae).

The intracellular localization of Ca2+, Ca2+-ATPase, Calmodulin, and Calbindin D-28KD have been studied in testes of the toad Leptodactylus chaquensis, using ultracytochemical and immunohistochemical techniques. The Ca2+ presences in the nucleus and into the mitochondria of the germ cells, together with the activity of Ca2+-ATPase detected in the nuclear envelope and mitochondrial crests, suggest the participation of this transporter in the storage of Ca2+. In Sertoli cells, Ca2+ deposits were also found in vesicles and lamellar bodies. Calmodulin and Calbindin D-28KD were revealed in the cytoplasm of both cell types. At the spermatozoon level, the cation deposits were located in the subacrosomal space and in the acrosomal vesicle. Ca2+-ATPase activity was observed in the acrosomal and plasma membranes of the gamete that suggests the existence of a transport system responsible for maintaining low cytoplasmic Ca2+ levels. The activity of Ca2+-ATPase and the location of Ca2+ deposits in gamete tail would be related to flagellar movement. The colocalization of Ca2+ deposits and their binding proteins in efferent duct cells would probably be associated with secretory activity. Considering that intracellular Ca2+ is present in different gonadal cells, this work would provide a better understanding of the cation importance in the testicular functions of this species.

Ultrastructure of Spermatozoa of Elaphe schrenckii (Reptilia, Squamata)

Elaphe schrenckii (Serpentes, Colubridae), a kind of large nonvenomous snakes and great significance to maintain the stability of ecosystem in China. We provide detailed descriptions of the sperm microstructure and ultrastructure of E. schrenckii, experimented by light microscope and transmission electron microscope. The spermatozoon of E. schrenckii is filiform and consists of head and tail regions. The cross-section of acrosomal vesicle is always rounded and divided into medulla inside and cortex outside. The ultrastructure of acrosome complex observed the unilateral ridge, the single perforatorium, the perforatorium base plate, the epinuclear lucent zone, the subacrosomal space and the nuclear fossa at the end of nucleus connect the neck region. The neck region is short with the stratified laminar structure and observed the distal centriole and the proximal centriole are perpendicular and both consisted of nine triplets. Midpiece is long and observed the extracellular microtubules, the multilaminar membranec, the mitochondria with the dense bodies discontinuity distribting, the fibrous sheath, and the axoneme. The principal piece is after the annulus with no mitochondrias and the end piece with no mitochondrias neither the fibrous sheath. Our study contrasted the spermatozoa ultrastructure of 8 species belong to 5 families and 6 genera and added the sperm measurement compare, summarized that three Colubridae snakes are more similar than others momentarily but some specific characteristics in E. schrenckii and proved that the ultrastructure of sperm related to phylogeny in some ways.

Spermiogenesis in the African sideneck turtle (Pelusios castaneus): Acrosomal vesicle formation and nuclear morphogenesis

Testicular samples were collected from African sideneck turtles (Pelusios castaneus) at the peak of spermiogenesis in order to describe spermatid acrosomal vesicle formation and nuclear morphogenesis. Acrosomal vesicle formation commences with a Golgi transport vesicle attaching to a round spermatid, followed by the emergence of an acrosome granule. This is followed by the development of the sub-acrosomal space, which becomes enlarged as nuclear elongation and condensation continue. The round spermatid elongates and the emerging elongating spermatid successively becomes surrounded by circular, longitudinal and slanting microtubules of the manchette. The acrosomal vesicle becomes visible with an acrosome granule resting on the base of the electron dense material. Acrosomal vesicle morphogenesis in the African sideneck turtle results in a highly compartmentalized acrosome divisible into the acrosomal cortex and medulla. The future position of the flagellum starts to develop, being encircled by mitochondria while the distal centriole becomes obvious and the emerging flagellum grossly divisible into the connecting piece, midpiece, principal piece and endpiece. Although acrosomal vesicle formation and nuclear morphogenesis during spermiogenesis in the turtle are consistent with other reptilian species, a few differences were observed. The major difference observed was the formation of a single acrosome granule, which manifests prior to the attachment of the acrosomal vesicle to spermatid nucleus. The other differences observed were the emergence of two endonuclear canals in the elongating spermatid and the presence of slanting microtubules of the manchette. The observed developmental variations are expected to be valuable in future phylogenetic studies and potentially serve to test certain hypotheses concerning the reproductive status of turtle species. Findings from this study add to the growing database of spermatid morphology in turtles, thereby providing insights into variations in mature sperm morphology in the species.

Functional morphology of the male reproductive system of the white shrimp Litopenaeus schmitti (Burkenroad, 1936) (Crustacea, Penaeidea) compared to other Litopenaeus

The male reproductive system of L. schmitti is described, including spermatozoon ultrastructure. The testis is composed of 8 to 14 lobules arranged as seminiferous tubules. The proximal vas deferens is short and filled with spermatozoa without spikes. The median vas deferens is larger than the other parts of the vas deferens and it shows two ducts separated by typhlosoles, the sperm and accessory ducts. The former is filled with sperm masses, while the accessory duct shows only secretions that are part of the spermatophore material. In this region, the spermatozoa have a spike, indicating the end of the spermatogenesis. The distal vas deferens is a short tube ending in the ampulla, composed of three parts. The spermatozoa have a round main body and an anterior spike associated with the acrosomal cap. The subacrosomal space has a centrosome-like structure above the nucleus. The features of the male reproductive system of L. schmitti share the pattern of penaeoidean shrimps with closed thelyca related to the median vas deferens and the ampulla. All the differences in spermatozoon morphology and vasa deferentia are discussed, and compared to other Litopenaeus species.

Is gamete morphology involved in hybridization in oysters?

Some pairs of oyster species in the genus Crassostrea can produce viable hybrids, and heterospecific fertilization may be symmetric, asymmetric, or very low. For example, with C. angulata and C. gigas, fertilization is equally successful whether the mature oocytes come from the first or the second species. Fertilization is asymmetric between C. ariakensis and C. virginica, i.e., it is higher when C. ariakensis is the source of the oocytes. Fertilization success is low between C. ariakensis and C. gigas. These differences probably relate chiefly to molecular mechanisms of gamete recognition, but the present study examines whether the size and certain aspects of gamete morphology may also play a role. Individuals of four species of the genus Crassostrea (Ostreidae: Bivalvia), collected from different geographic regions between 2006 and 2011, C. angulata (Penghu Island, Taiwan Strait), C. ariakensis (Nha Trang Bay, South China Sea), C. gigas (Peter the Great Bay, Sea of Japan), and C. virginica (Galveston Bay, Gulf of Mexico), were examined for conspecific relationships between the thickness of the vitelline envelope in mature oocytes and the size of the acrosome or subacrosomal spaces in spermatozoa. Thicker vitelline envelopes corresponded with bigger acrosomes and subacrosomal spaces in three of the four species. The exception was C. gigas, which has the thickest vitelline envelope, but the lytic compartments in its spermatozoa are not the largest. Moreover, sizes of acrosome, subacrosomal space, and vitelline envelope are similar between the species with symmetric heterospecific fertilization, while difference in sizes of these structures increases the possibility of asymmetric cross-fertilization or decreased fertilization rate.

Spermatogenesis in the rock oyster, Saccostrea forskali (Gmelin, 1791).

Morphology of the differentiating spermatogenic cells of the rock oyster Saccostrea forskali (Bivalve: Ostreidae) was investigated by light and transmission electron microscopy. The testis is formed by several branching acini containing developing spermatogenic cells, classified into 7 stages based on nuclear characteristics, patterns of chromatin condensation and cytoplasmic contents. The spermatogonium is characterized by a euchromatic nucleus with a prominent nucleolus. The cytoplasm contains several round granulo-fibrillar dense bodies surrounded by numerous mitochondria. The round nucleus of the primary spermatocyte contains patches of electron-dense heterochromatin, numerous proacrosomal vesicles, ribosomes and mitochondria. The secondary spermatocytes contain a reticulated chromatin pattern and reduced number of proacrosomal vesicles. The early spermatids contain a small amount of euchromatin among dense patches of heterochromatin. A large single acrosomal vesicle is located in the posterior part of the cell. The middle spermatid is characterized by the migration of an acrosomal vesicle to the anterior part of the nucleus. The late spermatids contain highly condensed heterochromatin blocks and the acrosomal vesicle becomes cup-shaped and invaginated at the basal part. The spermatozoon contains a barrel-shaped head covered with the cup-like acrosome. At this stage, the subacrosomal space contains an axial rod in subacrosomal materials. Three to four transverse bands appear at the anterior region of the acrosome. The middle piece consists of spherical mitochondria surrounding the proximal and distal centrioles. The flagellum consists of 9+2 axonemal microtubule doublets surrounded by the plasma membrane. Our electron microscopic study of spermatogenesis in the S. forskali provides important new information on the mechanism of development of spermatogenesis of this species.

Ultrastructural observations on spermiogenesis in the peanut worm, Phascolosoma esculenta (Sipuncula: Phascolosomatidea)

Ultrastructural characteristics of spermiogenesis in the peanut worm, Phascolosoma esculenta (Phascolosomatidea), were observed by transmission electron microscopy (TEM). The spermiogenesis principally occurs in the coelom and can be divided into three stages (the early, middle and late stages) based on the chromatin morphology, acrosome development, spermatozoon midpiece and flagellum formation. Spermatids within a given spermatid mass develop synchronously. With the spermiogenesis proceeding, the spermatid masses become loosely structured, and later, adjacent spermatids are interconnected at one extremity of the cells. Gradually, condensation of the chromatin accelerates and is almost completed in late spermiogenesis, leaving the late spermatids with highly condensed homogeneous chromatin. In the spermatid head, the conical acrosome is generally composed of an acrosomal vesicle which is formed by the coalescence of small proacrosomal vesicles within the cytoplasm, a subacrosomal space that situates between the acrosomal vesicle and nucleus, and an acrosomal rod which develops from a bunch of filamentous material within the subacrosomal space. Certain mitochondria move posteriorly towards the nucleus, thus constituting the spermatozoon midpiece. The flagellum, originated from the distal centriole, appears in the early spermiogenesis. Ultimately, mature spermatidium dissociates into numerous spermatozoa, which are subsequently released as a single cell from the coelom into the nephridia. The spermatozoon has a prominent head, containing an acrosome and nucleus, a short midpiece and a slender tail. When compared with other sipunculans or invertebrates with external fertilization, the spermiogenesis of P. esculenta, presumably, is closely associated with its biological adaptations for the reproductive strategy.

Effect of Nigella sativa oil on aluminum chloride-induced testicular damage in male albino rats

Background Aluminum chloride (AlCl3) is an environmental xenobiotic that induces free radical-mediated cytotoxic and reproductive toxicity. Nigella sativa oil (NSO) is an antioxidative agent reported to be important for detoxification. Aim This study aimed to investigate the possible role of NSO in ameliorating the toxic effect of AlCl3 on the histological structure of the testis in male rats. Materials and methods This study was carried out on 40 adult male rats, divided into four equal groups: group I, which served as the control group; group II (the AlCl3-exposed group), which received AlCl3 daily at a dose of 320 mg/kg/l in drinking water through a gastric tube for 1.5 months; group III (the AlCl3+NSO-treated group), which received NSO at a dose of 1 ml/kg orally concomitantly with AlCl3 for 1.5 months; group IV (the withdrawal group), which received only AlCl3 at the same dose for 1.5 months, after which the animals were left untreated for another 1.5 months. The animals of each group were processed for light and transmission electron microscopic study. Morphometric and statistical analyses were conducted. Results Compared with the control group, administration of AlCl3 revealed significant changes in the seminiferous tubules, which appeared shrunken with disorganized germinal epithelium. Cellular vacuolations as well as sloughed spermatogenic cells into the lumen were observed. The interstitium was widened with interstitial hyperplasia. Ultrastructural examination of the AlCl3-exposed group revealed cells with dense cytoplasm and heterochromatic nuclei. Late differentiating spermatids showed deformed heads with widening of the subacrosomal space and redundant acrosome. Concomitant administration of NSO with AlCl3 showed amelioration of most of the histological changes in the AlCl3-intoxicated group. The withdrawal group showed persistence of many structural changes noticed in the AlCl3-intoxicated group with a significant difference compared with the AlCl3+NSO-treated group. Conclusion NSO played a protective role against AlCl3-induced testicular damage.

Fine structural traits of Crocidura shantungensis caudal epididymal spermatozoa

The structural and morphometric traits of spermatozoa reflect species-specific evolutionary and functional characters. The shrew, Crocidura shantungensis, which is an indigenous species of Ulleung-do, is dominant on this island and is suspected to have unique traits different from other shrews. Based on a previous sperm ultrastructural analysis, the structural and morphometric traits of caudal epididymal spermatozoa were evaluated by light, scanning, and transmission electron microscopy. Total length was 110.0 μm. The head was paddle shaped with a globular nucleus and was 16.0 μm in length. The acrosomal cap covered four-fifths of the nucleus, and the subacrosomal space had sawtooth-shaped edges. The number of mitochondrial gyres was 84–86. Nine segmented columns in the neck consisted of 12 knobs, and each column was fused with outer dense fiber. The outer dense fibers 1, 5, and 6 were thicker than the others. Outer fiber 1 was shaped like a horseshoe, whereas 5 and 6 were fused with each other. Numerous satellite fibers were scattered on the mid-piece between outer fibers 4 and 5, and 6 and 7. Two specific strong electron-dense fibers were found uniquely near the satellite fibers. In conclusion, our results demonstrate that the caudal sperm of Ulleung-do C. shantungensis has unique ultrastructural and morphometric traits based on common sperm characters of the subfamilies, suggesting unique physiological roles in reproduction.

Ultrastructure of the spermatozoa of Psammotettix striatus (Linnaeus) and Exitianus nanus (Distant) (Hemiptera: Auchenorrhyncha: Cicadellidae: Deltocephalinae)

Previous studies of insect spermatozoa indicate that these specialized cells have undergone significant morphological evolution and exhibit traits useful for reconstructing phylogenetic relationships. Although leafhoppers (Cicadellidae) are among the largest and most economically important insect families, few comparative studies of their spermatozoa have been published. Here, the ultrastructure of mature spermatozoa of two leafhoppers Psammotettix striatus (Linnaeus) and Exitianus nanus (Distant), representing two different tribes of the largest leafhopper subfamily, Deltocephalinae, was examined by light and transmission electron microscopy. The shape and ultrastructure of spermatozoa of the two species are very similar to those of other Cicadellidae as well as other Auchenorrhyncha, comprising a conical acrosome invaginated to form a subacrosomal space, a filiform homogeneously condensed nucleus, a lamellate centriolar adjunct connecting the nucleus with the mid-piece/flagellum, a long flagellum with a 9 + 9 + 2 axoneme pattern and two symmetrical mitochondrial derivatives with an orderly array of peripheral cristae, and two drop-shaped accessory bodies. They may be distinguished by the size of the sperm, and the shape of the nucleus, accessory bodies, and paracrystalline region of mitochondrial derivatives. The fine morphology and ultrastructure of spermatozoon in P. striatus and E. nanus are illustrated, along with a brief discussion of the implications for classification and phylogenetic analyses of the subfamily.

Fine structure of the spermatozoon of Perinereis macropus (Claparède, 1870) (polychaeta, Nereidae)

The mature spermatozoa of Perinereis macropus were investigated by transmission electron microscopy. The spermatozoon is composed with a large anterior part (head), a short middle piece and a long flagellum. The head contains a large acrosomal complex with a convex acrosomal vesicle, a subacrosomal space, a fibrillar crown and an acrosomal rod which penetrates into the nucleus invagination. The later is U shaped (in longitudinal section). The short middle piece contains about nine to eleven mitochondria and a centriole associated with the flagellum. This centriole, slightly eccentric to the sperm axis, anchors to the plasma membrane by nine satellite rays of the pericentriolar complex. The axoneme has a “9+2″ arrangement of microtubules. In cross section, the flagellar membrane extends in two lateral protuberances, aligned with the axis formed by the two central microtubules of the axoneme. The spermatozoon of P. macropus conforms to the primitive type with an acrosomal extension. Nevertheless, the acrosome complex ultrastructure shows noticeable modifications from the basic form. This finding agrees with the previously observed reproductive pattern (broadcast spawning – free-swimming larvae), and may be helpful to classify the sperm type of P. macropus.

Spermiogenesis in the imbricate alligator lizard,Barisia imbricata(Reptilia, Squamata, Anguidae)

Although the events of spermiogenesis are commonly studied in amniotes, the amount of research available for Squamata is lacking. Many studies have described the morphological characteristics of mature spermatozoa in squamates, but few detail the ultrastructural changes that occur during spermiogenesis. This study's purpose is to gain a better understanding of the subcellular events of spermatid development within the Imbricate Alligator Lizard, Barisia imbricata. The morphological data presented here represent the first complete ultrastructural study of spermiogenesis within the family Anguidae. Samples of testes from four specimens collected on the northwest side of the Nevado de Toluca, México, were prepared using standard techniques for transmission electron microscopy. Many of the ultrastructural changes occurring during spermiogenesis within B. imbricata are similar to that of other squamates (i.e., early acrosome formation, chromatin condensation, flagella formation, annulus present, and a prominent manchette). However, there are a few unique characteristics within B. imbricata spermatids that to date have not been described during spermiogenesis in other squamates. For example, penetration of the acrosomal granule into the subacrosomal space to form the basal plate of the perforatorium during round spermatid development, the clover-shaped morphology of the developing nuclear fossa of the flagellum, and the bulbous shape to the perforatorium are all unique to the Imbricate Alligator Lizard. These anatomical character differences may be valuable nontraditional data that along with more traditional matrices (such as DNA sequences and gross morphological data) may help elucidate phylogenetic relationships, which are historically considered controversial within Squamata.

Ultrastructure of the spermatozoa of Cicadella viridis (Linnaeus) and its bearing on the phylogeny of Auchenorrhyncha

The ultrastructure of mature spermatozoa of the leafhopper Cicadella viridis (Linnaeus) was investigated using light and transmission electron microscopy. The spermatozoon is composed of a head containing an acrosome and an elongated nucleus, and a long tail, which consists of a flagellum. The acrosome is conical and invaginated to form a subacrosomal space, and the acrosomal contents are filled with electron-dense tubular substructures. The nucleus is linear and filled with homogeneously condensed chromatin. The centriolar adjunct is parallel to the nucleus and connects the nucleus with the mid-piece/flagellum. The flagellum is formed by a 9+9+2 axoneme, two mitochondrial derivatives and two accessory bodies. The mitochondrial derivatives with an orderly array of peripheral cristae are symmetrical. The accessory bodies are small and slightly elliptical. The end of the axoneme shows progressive loss of microtubules. Comparison of sperm ultrastructure of C. viridis with those of other Auchenorrhyncha families supports the major relationships within Cicadomorpha as (Membracoidea (Cicadoidea, Cercopoidea)).

Ontogenic development of spermatids during spermiogenesis in the high altitude bunchgrass lizard (Sceloporus bicanthalis)

The body of ultrastructural data on spermatid characters during spermiogenesis continues to grow in reptiles, but is still relatively limited within the squamates. This study focuses on the ontogenic events of spermiogenesis within a viviparous and continually spermatogenic lizard, from high altitude in Mexico. Between the months of June and August, testicular tissues were collected from eight spermatogenically active bunchgrass lizards (Sceloporus bicanthalis) from Nevado de Toluca, México. The testicular tissues were processed for transmission electron microscopy and analyzed to access the ultrastructural differences between spermatid generations during spermiogenesis. Interestingly, few differences exist between S. bicanthalis spermiogenesis when compared with what has been described for other saurian squamates. Degrading and coiling membrane structures similar to myelin figures were visible within the developing acrosome that are likely remnants from Golgi body vesicles. During spermiogenesis, an electron lucent area between the subacrosomal space and the acrosomal medulla was observed, which has been observed in other squamates but not accurately described. Thus, we elect to term this region the acrosomal lucent ridge. This study furthers the existing knowledge of spermatid development in squamates, which could be useful in future work on the reproductive systems in high altitude viviparous lizard species.

Morphological aspects of testes and sperm ultrastructure in the “symphyta” Digelasinus diversipes kirby 1882 (hymenoptera: Argidae: Dielocerinae)

In Digelasinus diversipes, spermatozoa are maintained in bundles, with 74 spermatozoa on average, in the seminal vesicle. These spermatozoa are very short (20 μm) and consist of a head and flagellum. The head includes an acrosome (perforatorium covered by the acrosomal vesicle) and a nucleus. A regular electron-lucent region separates the acrosomal vesicle from the perforatorium, which is inserted parallel to the anterior ending of the nucleus. The small flagellum is composed of two symmetrical mitochondrial derivatives, a centriolar adjunct, an axoneme (9 + 9 + 2), and two accessory bodies. The centriolar adjunct begins above the posterior end of the nucleus and ends covering the anterior tip of two mitochondrial derivatives. In the terminal region of the axoneme, the central microtubules terminate first. The presence of a subacrosomal space, a short mitochondrial derivative diameter, and a short spermatodesm is the ultrastructure characteristics of spermatozoa shared by all "symphyta" species. Differences in the insertion of the perforatorium into the nucleus and the position of the centriolar adjunct distinguish Dielocerinae and the Arginae studied previously. The number of spermatozoa per cyst is variable. Furthermore, additional characteristics that had not been described for "symphyta" were also found, such as the number of follicles per testis.

Comparative ultrastructural study of spermatozoa in some oyster species from the Asian-Pacific Coast

Sperm organization in the oysters Crassostrea gigas, Crassostrea nippona, Crassostrea cf. rivularis and Saccostrea cf. mordax inhabiting Asian Pacific coast was studied. The spermatozoa of all studied species had a number of common morphological characters such as a cup-like acrosome with heterogeneous matrix on its top, an axial rod in the subacrosomal space, a barrel-shaped nucleus, four mitochondria in the midpiece, pericentriolar complexes, and a 9 + 2-organized flagellum. The spermatozoa of C. cf. rivularis differed from the other species by having cytoplasm processes in the midpiece region. Such structures have never been described in the Ostreidae. Additionally, each species could be identified by the shape and size of sperm compartments (acrosome, nucleus, anterior nuclear fossa). The most significant interspecific difference was found in the size of an anterior nuclear fossa. The smallest anterior nuclear fossa was found in C. cf. rivularis (about 0.24 μm in length reaching about 22% of the nuclear length) while the biggest in C. gigas from the Sea of Japan (about 0.53 μm in length reaching about 46% of the nuclear length). The spermatozoa of C. gigas collected from the Sea of Japan and Taiwan Strait differed significantly in almost all the studied parameters. Since sperm morphology has been successfully used for species differentiation, this suggests the existence of two species rather than two populations. The data obtained indicate the species-specific difference in the sperm ultrastructure within the Ostreidae, which may be identified both ultrastructurally and morphometrically.

Light and electron microscopic study of the toxic effect of prolonged lead exposure on the seminiferous tubules of albino rats and the possible protective effect of ascorbic acid

Background Lead has been long recognized as an occupational toxicant. Now, lead is considered to be one of the major environmental pollutants which have serious potential threat to human health. Reports of declining male fertility have renewed interest in the role of environmental and occupational exposures in the etiology of human infertility. Objectives The aim of the present work was to investigate the toxic effect of prolonged exposure to lead on albino rat’s seminiferous tubules and the possible protective effect of ascorbic acid (vitamin C) on lead toxicity. Methods The study was carried out on 40 adult male albino rats divided into three groups: a control group which comprised three subgroups; negative control which received no treatment and two positive controls receiving an oral daily dose of distilled water or ascorbic acid, respectively. Lead acetate – intoxicated group received lead acetate orally in a dose of 25 mg/kg b.w dissolved in distilled water for 3 months. While the protected group received ascorbic acid orally in a dose of 100 mg/kg b.w daily for 3 months, simultaneously with lead acetate in a similar dose to that of the intoxicated group. By the end of the experimental period, blood samples were collected for estimation of blood lead level. Fresh specimens were taken from the testis and processed for light and electron microscopic examination. Results Biochemical analysis demonstrated significant increase in the blood lead level in lead intoxicated group compared to the control group, while ascorbic acid – protected group revealed significant decrease in the blood lead level. Light microscopic examination of lead treated group revealed loss of normal archicture of the testicular tissue in the form of thin walled seminiferous tubules with wide lumen and vacuolations in the spermatogenic epithelium mostly separating primary spermatocytes from spermatogonia and surrounding nuclei of Sertoli cells. Apoptotic bodies were found among the basal part of the spermatogenic epithelium. Ultrastructural examination of the same group revealed degenerating cells with cytoplasmic vacuolations, apoptotic cells with heterochromatic nuclei and dense cytoplasm, irregularities in the basal lamina with increased collagen deposition and shrunken myoid cells. Late differentiating spermatids showed deformed head with widening of the subacrosomal space and redundant acrosome, in addition to the abnormalities in the tail of developing sperms. On the other hand, ascorbic acid – protected group showed amelioration of most of the degenerative changes depicted in the lead intoxicated group. Conclusion Lead had an injurious effect on the testis of the exposed animals. Simultaneous administration of ascorbic acid was efficient in preventing most of such toxic effect and decreasing the blood lead level. Therefore, ascorbic acid can be recommended for protection against lead intoxication.