Acrosomal Granule Research Articles

A missense mutation in Ehd1 associated with defective spermatogenesis and male infertility.

Normal function of the C-terminal Eps15 homology domain-containing protein 1 (EHD1) has previously been associated with endocytic vesicle trafficking, shaping of intracellular membranes, and ciliogenesis. We recently identified an autosomal recessive missense mutation c.1192C>T (p.R398W) of EHD1 in patients who had low molecular weight proteinuria (0.7-2.1g/d) and high-frequency hearing loss. It was already known from Ehd1 knockout mice that inactivation of Ehd1 can lead to male infertility. However, the exact role of the EHD1 protein and its p.R398W mutant during spermatogenesis remained still unclear. Here, we report the testicular phenotype of a knockin mouse model carrying the p.R398W mutation in the EHD1 protein. Male homozygous knockin mice were infertile, whereas the mutation had no effect on female fertility. Testes and epididymes were significantly reduced in size and weight. The testicular epithelium appeared profoundly damaged and had a disorganized architecture. The composition of developing cell types was altered. Malformed acrosomes covered underdeveloped and misshaped sperm heads. In the sperm tail, midpieces were largely missing indicating disturbed assembly of the sperm tail. Defective structures, i.e., nuclei, acrosomes, and sperm tail midpieces, were observed in large vacuoles scattered throughout the epithelium. Interestingly, cilia formation itself did not appear to be affected, as the axoneme and other parts of the sperm tails except the midpieces appeared to be intact. In wildtype mice, EHD1 co-localized with acrosomal granules on round spermatids, suggesting a role of the EHD1 protein during acrosomal development. Wildtype EHD1 also co-localized with the VPS35 component of the retromer complex, whereas the p.R398W mutant did not. The testicular pathologies appeared very early during the first spermatogenic wave in young mice (starting at 14 dpp) and tubular destruction worsened with age. Taken together, EHD1 plays an important and probably multifaceted role in spermatogenesis in mice. Therefore, EHD1 may also be a hitherto underestimated infertility gene in humans.

Kinesin-14 KIFC1 promotes acrosome formation and chromatin maturation during mouse spermiogenesis

KIFC1, a member of kinesin-14 subfamily motors, is essential for meiotic cell division and acrosome formation during spermatogenesis. However, the functions of KIFC1 in the formation and maintenance of the acrosome in male germ cells remain to be elucidated. In this study, we report the structural deformities of acrosomes in the in vivo KIFC1 inhibition mouse models. The proacrosomal vesicles diffuse into the cytoplasm and form atypical acrosomal granules. This phenotype is consistent with globozoospermia patients and probably results from the failure of the Golgi-derived vesicle trafficking and actin filament organization. Moreover, the multinucleated and undifferentiated spermatogenic cells in the epidydimal lumen after KIFC1 inhibition reveal the specific roles of KIFC1 in regulating post-meiotic maturation. Overall, our results uncover KIFC1 as an essential regulator in the trafficking, fusion and maturation of acrosomal vesicles during spermiogenesis.

The SLC9C2 Gene Product (Na+/H+ Exchanger Isoform 11; NHE11) Is a Testis-Specific Protein Localized to the Head of Mature Mammalian Sperm.

Na+/H+ exchangers (NHEs) are a family of ion transporters that regulate the pH of various cell compartments across an array of cell types. In eukaryotes, NHEs are encoded by the SLC9 gene family comprising 13 genes. SLC9C2, which encodes the NHE11 protein, is the only one of the SLC9 genes that is essentially uncharacterized. Here, we show that SLC9C2 exhibits testis/sperm-restricted expression in rats and humans, akin to its paralog SLC9C1 (NHE10). Similar to NHE10, NHE11 is predicted to contain an NHE domain, a voltage sensing domain, and finally an intracellular cyclic nucleotide binding domain. An immunofluorescence analysis of testis sections reveals that NHE11 localizes with developing acrosomal granules in spermiogenic cells in both rat and human testes. Most interestingly, NHE11 localizes to the sperm head, likely the plasma membrane overlaying the acrosome, in mature sperm from rats and humans. Therefore, NHE11 is the only known NHE to localize to the acrosomal region of the head in mature sperm cells. The physiological role of NHE11 has yet to be demonstrated but its predicted functional domains and unique localization suggests that it could modulate intracellular pH of the sperm head in response to changes in membrane potential and cyclic nucleotide concentrations that are a result of sperm capacitation events. If NHE11 is shown to be important for male fertility, it will be an attractive target for male contraceptive drugs due to its exclusive testis/sperm-specific expression.

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.

Testis-specific serine protease PRSS54 regulates acrosomal granule localization and sperm head morphogenesis in mice†.

Serine proteases (PRSS) constitute nearly one-third of all proteases, and many of them have been identified to be testis-specific and play significant roles during sperm development and male reproduction. PRSS54 is one of the testis-specific PRSS in mouse and human but its physiological function remains largely unclear. In the present study, we demonstrate in detail that PRSS54 exists not only in testis but also in mature sperm, exhibiting a change in protein size from 50kDa in testis to 42kDa in sperm. Loss of PRSS54 in mice results in male subfertility, acrosome deformation, defective sperm-zona penetration, and phenotypes of male subfertility and acrosome deformation can be rescued by Prss54 transgene. Ultrastructure analyses by transmission electronic microscopy further reveal various morphological abnormalities of Prss54-/- spermatids during spermiogenesis, including unfused vacuoles in acrosome, detachment and eccentrical localization of the acrosomal granules, and asymmetrical elongation of the nucleus. Subcellular localization of PRSS54 display that it appears in the acrosomal granule at the early phase of acrosome biogenesis, then extends along the inner acrosomal membrane, and ultimately presents in the acrosome region of the mature sperm. PRSS54 interacts with acrosomal proteins ZPBP1, ZPBP2, ACRBP, and ZP3R, and loss of PRSS54 affects the distribution of these proteins in testis and sperm, although their protein levels are largely unaffected. Moreover, Prss54-/- sperm are more sensitive to acrosome reaction inducers.

Loss of myosin VI expression affects acrosome/acroplaxome complex morphology during mouse spermiogenesis†.

During spermiogenesis in mammals, actin filaments and a variety of actin-binding proteins are involved in the formation and function of highly specialized testis-specific structures. Actin-based motor proteins, such as myosin Va and VIIa, play a key role in this complex process of spermatid transformation into mature sperm. We have previously demonstrated that myosin VI (MYO6) is also expressed in mouse testes. It is present in actin-rich structures important for spermatid development, including one of the earliest events in spermiogenesis—acrosome formation. Here, we demonstrate using immunofluorescence, cytochemical, and ultrastructural approaches that MYO6 is involved in maintaining the structural integrity of these specialized actin-rich structures during acrosome biogenesis in mouse. We show that MYO6 together with its binding partner TOM1/L2 is present at/around the spermatid Golgi complex and the nascent acrosome. Depletion of MYO6 in Snell’s waltzer mice causes structural disruptions of the Golgi complex and affects the acrosomal granule positioning within the developing acrosome. In summary, our results suggest that MYO6 plays an anchoring role during the acrosome biogenesis mainly by tethering of different cargo/membranes to highly specialized actin-related structures.

Spermatid differentiation, with particular reference to acrosomogenesis, in the passeridan bird, Carib grackle (Quiscalus lugubris)

Only a few studies on the development of the passerine spermatozoon are available, yet species variations in the conformation as well as structure of the generally helical acrosome have been reported. This study of spermiogenesis in the Carib grackle (Quiscalus lugubris) intended to provide a deeper understanding of the development of the sperm, and in particular to investigate the bi-partite nature and development of the acrosome as well as its relationship with the nucleus, in the absence of a perforatorium that is found in most non-passerine birds. The acrosomal vesicle already displays a bi-partite nature in the acrosomal granule within the Golgi complex, and the attachment of the dense granule (future acrosomal core) within the crest part (future acrosomal crest) establishes polarity as it approaches and attaches to the nucleus. Thereafter, they develop variably. The acrosomal crest leads the elongation and spiraling of the acrosome, and the core portion contributes significantly to the formation of the keel of the crest part. The rounded, core-bearing part of the base of the acrosome progressively indents and fits into the concavity, thus formed, at the anterior part of the nucleus. The possible homology of the acrosomal complex (including the perforatorium) and the nucleus between non-passerine and passerine birds was discussed. The centriolar complex comprises both the proximal and distal centrioles in all spermatids and spermatozoa. The mitochondria undergo a number of morphological changes, including size and electron-density, from the round spermatid through to the mature spermatid; changes that are probably influenced by their functional states in the different evolving phases of the spermatids.

Immunohistochemical investigation of testicular morphogenesis in offspring rats, developing under the influence of maternal hypothyroidism.

Background. Thyroid disorders are currently among the most widespread endocrine pathologies, influencing morphogenesis and histophysiology of multiple organs. Objective . The aim of present investigation was to study the impact of maternal hypothyroidism on the testicular development of rats progeny using immunohistochemical detection of cell proliferation marker Ki-67 and vascular endothelium growth factor VEGF. Methods. Hypothyroidism was induced by daily food supplementation of experimental group rats with 10 mg/kg of anti-thyroid drug Merkazolil during two weeks before pregnancy, throughout the whole gestation and lactation periods. Testes of their progeny on postnatal days 1st, 10th, 20th and 40th were removed after euthanasia, fixed in Bouin’s fluid, embedded in paraffin and subjected to immunohistochemical investigation. Results. On postnatal day 1st in control group rats Ki-67 labeling was restricted to cytoplasmic granularity of gonocytes – fetal germ cells, located centrally in within the seminiferous cords. Under hypothyroid conditions additionally to gonocytes Ki-67 binding was detected in macrophages and Leydig cells, number of both significantly elevated. On postnatal day 10th control group animals demonstrated moderate labeling of Sertoli cells, spermatogonia and gonocytes being completely non-reactive. In hypothyroidism affected testes was revealed disperse distribution of Ki-67 marker with predominant accumulation on the periphery of seminiferous cords and in Leydig cells. On postnatal day 20th Ki-67 reactivity was detected in spermatogenic cells of seminiferous tubules. In hypothyroidism affected animals cytoplasmic granularity labeling of maturating spermatogenic cells was higher compared to control, though seminiferous tubules were smaller in diameter and lacking luminae. On postnatal day 40th Ki-67 labeled predominantly spermatogonia, immunoreactivity of which enhanced under hypothyroid conditions. Distribution of VEGF label was generally similar to that of Ki-67, indicating a direct correlation of cell proliferation intensity on saturation of tissues with oxygen. Unlike Ki-67, VEGF exposed strong reactivity with acrosomal granules of early spermatids on postnatal day 20th, as well as more intense spermatogenic cells labeling compared to Ki-67. Conclusion. Testicular morphogenesis in offspring rats, developing under maternal hypothyroidism, was accompanied by the increased immunoreactivity of spermatogenic cell cytoplasm on postnatal days 20th and 40th with Ki-67 and VEGF, as well as acrosomal granules labeling with VEGF. This trend was supplemented with the increased count of macrophages and Leydig cells in testicular interstitium, decreased count and size of spermatogenic cells, damage of their syncytial complexes, all these signs encompassing degenerative changes in seminiferous tubules.

PH-dependent Ca+2 oscillations prevent untimely acrosome reaction in human sperm

During transit through the female reproductive tract, sperm encounter metabolites and environmental conditions that modulate various processes leading to fertilization. Intracellular Ca2+ dynamics regulate the acrosome reaction (AR), which involves exocytosis of the acrosomal granule, a prerequisite for successful fertilization. We explored the ability of progesterone, prostanglandin-E1, and GABA to induce Ca2+ mobilization and AR in single human spermatozoa capacitated under external pH (pHe) conditions found in different regions of the female reproductive tract (pHe 6.5, 7.4 and 8.0). The highest percentage of AR induction, regardless of the inducer, occurred when sperm were capacitated at pHe 7.4. Interestingly, at pHe 6.5 a high percentage of cells exhibit Ca2+ oscillations, which prevent AR. These oscillations involve extracellular and intracellular Ca2+ channels. Pharmacological inhibition of Ca2+ oscillations restores the ability of spermatozoa to undergo the AR when exposed to progesterone, even if capacitated at pHe 6.5.

Expression of the GM2 activator protein in mouse testis

The GM2-activator protein (GM2-AP), revealed by Li et al. in 1973 in human liver, was initially identified as a protein cofactor that stimulated β-hexosaminidase A to hydrolyze N-acetylgalactosamine from GM2 ganglioside. This cofactor was found to be missing in human variant AB Tay-Sachs disease. Over the years, the GM2-AP has also been shown to be involved in kidney vesicular transport, lipid presentation by CD1 molecule to T-cells, and interaction of human sperm with zona pellucida. Since the expression of the GM2-AP via mRNA detection in mouse tissues was found to be the highest in testis, we became interested in the localization of the GM2-AP at cellular level in mouse testis during spermatogenesis. Using immunohistochemical analysis and electron microscopy, we found that the GM2-AP was predominantly localized in the basal cytoplasm and the attenuated processes of Sertoli cells. The stained structure appeared to be lysosomes. The most interesting finding was the association of the GM2-AP with the acrosomal apparatus in early spermatids. A modest to intense staining was observed in some acrosomal granules and acrosomal caps. The GM2-AP seemed to disappear from acrosomal caps in the later stage of spermatids, in which the nucleus became elongated and condensed. These results suggest that the GM2-AP may be involved in the normal functions of Sertoli cells and play important roles during the development of acrosomal caps in the early spermatids.

Molecules involved in acrosomal exocytosis and cortical granule exocytosis

At fertilization, the acrosome reaction and cortical reaction are crucial process to block polyspermy and the prevention of triploidy. Although molecules involved in trigger secretion are various in different exocytosis events, the two processes may share the similar exocytosis mechanism. Exocytosis is an accurate regulated process that consists of multiple stages such as recruitment, targeting, tethering and docking of secretory vesicles with the plasma membrane, priming of the fusion machinery and calcium-triggered membrane fusion. After fusion, the membrane around the secretory vesicle is incorporated into the plasma membrane and the granule releases its contents. The proteins involved in these processes belong to several highly conserved families: Rab GTPases, SNAREs (soluble NSF-attachment protein receptors), α-SNAP (α-NSF attachment protein), NSF (N-ethylmaleimide-sensitive factor), Munc13, Munc18, complexins and synaptotagmins. This review discussed that molecules believed to participate in the secretory function and their involvement in acrosome and cortical granule exocytosis.

Loss of the Na+/H+ exchanger NHE8 causes male infertility in mice by disrupting acrosome formation

Mammalian sperm feature a specialized secretory organelle on the anterior part of the sperm nucleus, the acrosome, which is essential for male fertility. It is formed by a fusion of Golgi-derived vesicles. We show here that the predominantly Golgi-resident Na+/H+ exchanger NHE8 localizes to the developing acrosome of spermatids. Similar to wild-type mice, Nhe8-/- mice generated Golgi-derived vesicles positive for acrosomal markers and attached to nuclei, but these vesicles failed to form large acrosomal granules and the acrosomal cap. Spermatozoa from Nhe8-/- mice completely lacked acrosomes, were round-headed, exhibited abnormal mitochondrial distribution, and displayed decreased motility, resulting in selective male infertility. Of note, similar features are also found in globozoospermia, one of the causes of male infertility in humans. Germ cell-specific, but not Sertoli cell-specific Nhe8 disruption recapitulated the globozoospermia phenotype, demonstrating that NHE8's role in spermiogenesis is germ cell-intrinsic. Our work has uncovered a crucial role of NHE8 in acrosome biogenesis and suggests that some forms of human globozoospermia might be caused by a loss of function of this Na+/H+ exchanger. It points to NHE8 as a candidate gene for human globozoospermia and a possible drug target for male contraception.

A novel testis-specific protein, PRAMEY, is involved in spermatogenesis in cattle.

Preferentially expressed antigen in melanoma (PRAME) is a cancer/testis antigen that is predominantly expressed in normal testicular tissues and a variety of tumors. The function of the PRAME family in spermatogenesis remains unknown. This study was designed to characterize the Y-linked PRAME (PRAMEY) protein during spermatogenesis in cattle. We found that PRAMEY is a novel male germ cell-specific, and a germinal granule-associated protein that is expressed in spermatogenic cells during spermatogenesis. The intact PRAMEY protein (58 kDa) was detected in different ages of testes but not in epididymal spermatozoa. A PRAMEY isoform (30 kDa) was highly expressed only in testes after puberty and in epididymal spermatozoa. This isoform interacts with PP1γ2 and is likely the mature protein present in the testes and sperm. Immunofluorescent staining demonstrated that PRAMEY was located predominantly in the acrosome granule of spermatids, and in acrosome and flagellum of spermatozoa. Immunogold electron microscopy further localized the PRAMEY protein complex to the nucleus and several cytoplasmic organelles, including the rough endoplasmic reticulum, some small vesicles, the intermitochondrial cement, the chromatoid body and the centrioles, in spermatogonia, spermatocytes, spermatids and/or spermatozoa. PRAMEY was highly enriched in and structurally associated with the matrix of the acrosomal granule (AG) in round spermatids, and migrated with the expansion of the AG during acrosomal biogenesis. While the function of PRAMEY remains unclear during spermatogenesis, our results suggest that PRAMEY may play an essential role in acrosome biogenesis and spermatogenesis.Free Chinese abstract: A Chinese translation of this abstract is freely available at http://www.reproduction-online.org/content/153/6/847/suppl/DC1.FreeSpanish abstract: A Spanish translation of this abstract is freely available at http://www.reproduction-online.org/content/153/6/847/suppl/DC2.

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.

Ultrastructural differentiation of spermiogenesis in Scincus scincus (Scincidae, Reptilia).

BackgroundKnowledge of spermiogenesis in reptiles, especially in lizards, is very limited. Lizards found in Arabian deserts have not been considered for detailed studies due to many reasons and the paucity of these animals. Therefore, we designed a study on the differentiation and morphogenesis of spermiogenesis, at an ultrastructural level, in a rare lizard species, Scincus scincus.ResultsThe spermiogenesis process includes the development of an acrosomal vesicle, aggregation of acrosomal granules, formation of subacrosomal nuclear space, and nuclear elongation. A role for manchette microtubules was described in nuclear shaping and organelle movement. During head differentiation, the fine granular chromatin of the early spermatid is gradually replaced by highly condensed contents in a process called chromatin condensation. Furthermore, ultrastructural features of sperm tail differentiation in S. scincus were described in detail. The commencement was with caudal migration toward centrioles, insertion of the proximal centriole in the nuclear fossa, and extension of the distal centrioles to form the microtubular axoneme. Subsequently, tail differentiation consists of the enlargement of neck portion, middle piece, the main and end pieces.ConclusionsThis study aids in the understanding of different aspects of spermiogenesis in the lizard family and unfurls evolutionary links within and outside reptiles.

Biogenesis of sperm acrosome is regulated by pre-mRNA alternative splicing of Acrbp in the mouse

Proper biogenesis of a sperm-specific organelle, the acrosome, is essential for gamete interaction. An acrosomal matrix protein, ACRBP, is known as a proacrosin-binding protein. In mice, two forms of ACRBP, wild-type ACRBP-W and variant ACRBP-V5, are generated by pre-mRNA alternative splicing of Acrbp Here, we demonstrate the functional roles of these two ACRBP proteins. ACRBP-null male mice lacking both proteins showed a severely reduced fertility, because of malformation of the acrosome. Notably, ACRBP-null spermatids failed to form a large acrosomal granule, leading to the fragmented structure of the acrosome. The acrosome malformation was rescued by transgenic expression of ACRBP-V5 in ACRBP-null spermatids. Moreover, exogenously expressed ACRBP-W blocked autoactivation of proacrosin in the acrosome. Thus, ACRBP-V5 functions in the formation and configuration of the acrosomal granule during early spermiogenesis. The major function of ACRBP-W is to retain the inactive status of proacrosin in the acrosome until acrosomal exocytosis.

Kinetics of human sperm acrosomal exocytosis.

The acrosome reaction is a unique event in the lifespan of sperm characterized by the exocytosis of the acrosomal content and the release of hybrid vesicles formed by patches of the outer acrosomal membrane and the plasma membrane. This unique regulated exocytosis is mediated by essentially the same membrane fusion machinery present in neuroendocrine cells. However, whereas secretion in neuroendocrine cells occurs in less than a second, the acrosome reaction is normally assessed after several minutes of incubation with inducers. In this report, we measured the kinetics of human sperm exocytosis triggered by two stimuli (calcium ionophore and progesterone) by using electron microscopy and three different approaches based on the incorporation of fluorescent Pisum sativum agglutinin into the acrosome upon opening of fusion pores connecting the extracellular medium with the acrosomal lumen. The results with the different methods are consistent with a slow kinetics (t½ = 14 min). We also manipulated the system to measure different steps of the process. We observed that cytosolic calcium increased with a relatively fast kinetics (t½ = 0.1 min). In contrast, the swelling of the acrosomal granule that precedes exocytosis was a slow process (t½ = 13 min). When swelling was completed, the fusion pore opening was fast (t½ = 0.2 min). The results indicate that acrosomal swelling is the slowest step and it determines the kinetics of the acrosome reaction. After the swelling is completed, the efflux of calcium from intracellular stores triggers fusion pores opening and the release of hybrid vesicles in seconds.

Ultrastructure developments during spermiogenesis in Polydora ciliata (Annelida: Spionidae), a parasite of mollusca

Spionid worms of Polydora ciliata inhabit the shells of many commercially important bivalves and cause disease in molluscan aquaculture. Their sperm structure is closely related to their fertilization method. To give an insight into the sperm structure and spermatogenesis, ultrastructure details of the subcellular components of germ cells during spermiogenesis of Polydora ciliata are detected by transmission electron microscopy (TEM). In P. ciliata, during spermiogenesis, chromatin is regularly arranged as dense fibrils and becomes more condensed when the nucleus elongates. Microtubules do not surround the nucleus during its elongation. The Golgi phase is characterized by the formation of proacrosomal granules within the Golgi apparatus. The proacrosomal granules fuse to form a single, spherical acrosomal vesicle that migrates to the anterior pole of the cell. At the time of nuclear condensation, mitochondria become reduced in number but increased in size, causing deep indentation at the base of the nucleus. The mid-piece has a few mitochondria. The cap phase includes the spreading of the acrosomal granule over the surface of the nucleus of the differentiating spermatid. The acrosomal phase of spermiogenesis is typically associated with changes in the shape of the nucleus, acrosome and tail. The relationship of sperm ultrastructure to spermiogenesis in spionidae species was discussed.

Histological and ultrastructural studies on the toxic effect of pan masala and its amelioration by Elettaria cardamomum

AimTo investigate the histological and ultrastructural changes observed in pan masala intoxicated mammalian testes under the effect of cardamom. MethodsMale Swiss mice were given pan masala orally at a dose of 2% of the feed and cardamom at a dose of 0.2% of the feed. They were divided into three groups, control (Group I), pan masala-treated (Group II), and a combination of pan masala and cardamom-treated group (Group III). Histologically, the testes of Group II mice displayed degeneration of tubular epithelium, disruption of spermatogenesis, and a marked reduction in germ cells. ResultsWhen cardamom was given, damage was less with fewer distorted cells and also improvement with normal tubules and spermatid differentiation in Group III. Ultrastructurally, pan masala-treated testes showed cytoplasmic vacuolation, shrinkage and pyknotic nuclei of spermatogonia, and abnormal acrosomal granules. ConclusionWhen cardamom was given, the amelioration process was more evident showing a comparable morphology with control.

Ultrastructural study of spermiogenesis in a rare desert amphisbaenian Diplometopon zarudnyi

Spermiogenesis, in particular the head differentiation of Diplometopon zarudnyi, was studied at the ultrastructural level by Transmission Electron Microscope (TEM). The process includes acrosomal vesicle development, nuclear elongation, chromatin condensation and exclusion of excess cytoplasm. In stage I, the proacrosomal vesicle occurs next to a shallow fossa of the nucleus, and a dense acrosomal granule forms beneath it. This step commences with an acrosome vesicle forming from Golgi transport vesicles; simultaneously, the nucleus begins to move eccentrically. In stage II, the round proacrosomal vesicle is flattened by projection of the nuclear fossa, and the dense acrosomal granule diffuses into the vesicle as the fibrous layer forms the subacrosomal cone. Circular manchettes surrounded by mitochondria develop around the nucleus, and the chromatin coagulates into small granules. The movement of the nucleus causes rearrangement of the cytoplasm. The nucleus has uniform diffuse chromatin with small indices of heterochromatin. The subacrosome space develops early, enlarges during elongation, and accumulates a thick layer of dark staining granules. In stage III, the front of the elongating nucleus protrudes out of the spermatid and is covered by the flat acrosome; coarse granules replace the small ones within the nucleus. One endonuclear canal is present where the perforatorium resides. In stage IV, the chromatin concentrates to dense homogeneous phase. The circular manchette is reorganized longitudinally. The Sertoli process covers the acrosome and the residues of the cytoplasmic lobes are removed. In stage V, the sperm head matures.