Elsa Oliveira

An ultrastructural study of Crassostrea angulata (Mollusca, Bivalvia) spermatogenesis

The cytoplasm of Crassostrea angulata (collected from the Atlantic coast of Northern Spain, Galiza, between 1992 and 1993) spermatogonia contains a few proacrosomal dense vesicles and intermitochondrial round granulo-fibrillar dense bodies. In primary spermatocytes, large cytoplasmic spaces appear occupied by large round and more scattered granulo-fibrillar dense bodies which are intermingled with cord-like dense structures and are in close association with mitochondria and the rough endoplasmic reticulum. As a result of Golgian activity, the number of dense proacrosomal vesicles increases and a flagellum arises from the centrioles. During the second meiotic division, several round dense bodies surrounding cord-like dense structures as well as dense proacrosomal vesicles, were observed between chromosomes. During spermiogenesis, no Golgian activity was noticed, and only the rough endoplasmic reticulum was observed in close association with proacrosomal vesicles. Similar results were observed for Ostrea edulis (collected from the Atlantic coast of southern Portugal, Algarve, between 1992 and 1993). Spermatozoa of both species are of the aquasperm type, and although their ultrastructure is quite similar, silver and phosphotungstic acid-chromic acid stainings enabled us to clearly distinguish both species at the ultrastructural level. The different morphological aspects of spermatogenesis in the Pteriomorphia and the use of silver and PTA stainings in the Mollusca are reviewed and discussed.

A glycolytic phenotype is associated with prostate cancer progression and aggressiveness: a role for Monocarboxylate Transporters as metabolic targets for therapy.

Metabolic adaptation is considered an emerging hallmark of cancer, whereby cancer cells exhibit high rates of glucose consumption with consequent lactate production. To ensure rapid efflux of lactate, most cancer cells express high levels of monocarboxylate transporters (MCTs), which therefore may constitute suitable therapeutic targets. The impact of MCT inhibition, along with the clinical impact of altered cellular metabolism during prostate cancer (PCa) initiation and progression, has not been described. Using a large cohort of human prostate tissues of different grades, in silico data, in vitro and ex vivo studies, we demonstrate the metabolic heterogeneity of PCa and its clinical relevance. We show an increased glycolytic phenotype in advanced stages of PCa and its correlation with poor prognosis. Finally, we present evidence supporting MCTs as suitable targets in PCa, affecting not only cancer cell proliferation and survival but also the expression of a number of hypoxia‐inducible factor target genes associated with poor prognosis. Herein, we suggest that patients with highly glycolytic tumours have poorer outcome, supporting the notion of targeting glycolytic tumour cells in prostate cancer through the use of MCT inhibitors.

Fine structure of the branchial epithelium in the teleost Oreochromis niloticus

We have studied the gill epithelium of Oreochromis niloticus using transmission electron microscopy with the particular interested relationship between cell morphology and osmotic, immunoregulatory, or other non‐regulatory functions of the gill. Pavement cells covered the filament epithelium and lamellae of gills, with filament pavement cells showing distinct features from lamellar pavement cells. The superficial layer of the filament epithelium was formed by osmoregulatory elements, the columnar mitochondria‐rich, mucous and support cells, as well as by their precursors. Light mitochondria‐rich cells were located next to lamellae. They exhibited an apical crypt with microvilli and horizontal small dense rod‐like vesicles, sealed by tight junctions to pavement cells. Dark mitochondria‐rich cells had long dense rod‐like vesicles and a small apical opening sealed by tight junctions to pavement cells. The deep layer of the filament epithelium was formed by a network of undifferentiated cells, containing neuroepithelial and myoepithelial cells, macrophage and eosinophil‐like cells and their precursors, as well as precursors of mucous cells. The lateral‐basal surface was coated by myoepithelial cells and a basal lamina. The lamellar blood lacunae was lined by pillar cells and surrounded by a basal lamina and pericytes. The data presented here support the existence of two distinct types of pavement cells, mitochondria‐rich cells, and mitochondria‐rich cells precursors, a structural role for support cells, a common origin for pavement cells and support cells, a paracrine function for neuroepithelial cells in the superficial layer, and the control of the lamellar capillary base by endocrine and contractile cells. Data further suggest that the filament superficial layer is involved in gill osmoregulation, that may interact, through pale mitochondria‐rich cells, with the deep layer and lamellae, whereas the deep layer, through immune and neuroendocrine systems, acts in the regeneration and defense of the tissue. J. Morphol. 2010.

Morphology and phylogeny of Henneguya jocu n. sp. (Myxosporea, Myxobolidae), infecting the gills of the marine fish Lutjanus jocu

Henneguya jocu n. sp. (Myxosporea, Myxobolidae) is described from the gill lamellae of the marine teleost fish Lutjanus jocu, with a focus on ultrastructural and molecular features. This myxosporean forms subspherical cysts up to ∼260 μm × 130 μm long, and develops asynchronously. Mature myxospores ellipsoidal with a bifurcated caudal process. Myxospore length 10.9 ± 0.4 μm (n=50); width, 8.2 ± 0.3 μm (n=50); and thickness, 2.9 ± 0.5 μm (n=50). Two equal caudal processes, 34.1±1.0 μm long (n=50); and total myxospore length, 45.2 ± 1.0 μm (n=50). Two symmetric valves surround two ellipsoidal polar capsules, 5.0 ± 0.3 × 1.4 ± 0.2 μm (n=20), each containing an isofilar polar filament forming 4-5 coils along the inner wall of these structures, as well as a binucleated sporoplasm presenting a spherical vacuole and several globular sporoplasmosomes. Both the morphological data and molecular analysis of the SSU rDNA gene identify this parasite as a new species of the genus Henneguya. Maximum Likelihood and Maximum Parsimony analyses further indicate that the parasite clusters within others marine Myxobolidae species, forming a group alongside other Henneguya species described from marine hosts.

An ultrastructural study of spermatogenesis in Helcion pellucidus (Gastropoda, Prosobranchia)

Summary In Helcion pellucidus the cytoplasm of spermatogonia contains granulo-fibrillar dense bodies, a Golgi apparatus and a pair of centrioles. In primary spermatocytes a flagellum arises and putative small dense proacrosomal vesicles are formed from golgian activity. The mature spermatozoon is of the primitive type and does not contain a perforatorium. Silver stained the centriolar fossa, the periphery of centrioles and the pericentriolar complex, while phosphotungstic acid-chromic acid did not stain the acrosome. Similar cytochemical results were obtained in Patella rustics. The different morphological aspects of spermatogenesis in Patellogastropoda and Archaeogastropoda and the use of silver and PTA stainings in the Mollusca are reviewed and discussed.

The peroxisomes of the hepatopancreas in marine gastropods

Summary— An ultrastructural study of the peroxisomes was performed in the hepatopancreas of six species of marine gastropods. Peroxisome morphology was described in the basophilic cells and digestive cells of each species. The identification of this organelle was supported by the cytochemical detection of catalase. Large peroxisomes, frequently with a diameter between 1.0 and 1.5 μm, possessing a prominent crystalline nucleoid with hexagonal section were observed in Gibbula umbilicalis and Monodonta lineata basophilic cells. In the digestive cells of the same two species, the peroxisomes usually do not exceed 0.5 μm in diameter and in some of them a small nucleoid was found. A diamond shaped nucleoid was observed in the digestive cell peroxisomes of Patella vulgata and Ocenebra erinacea. In the hepatopancreas of Siphonaria algesirae the peroxisomes also presented a diamond shaped nucleoid. On the other hand, nucleoids were not detected in the basophilic cell peroxisomes of P vulgata, O erinacea and Nucela lapillus. In the peroxisomes of N lapillus digestive cells, typical nucleoids were also not found, but in some of them a dense region attached to the peroxisomal membrane was observed. In general, digestive cell peroxisomes were associated with mitochondria and lipid droplets, while basophilic cell peroxisomes were close to endoplasmic reticulum cisternae, mitochondria, lipofuscin granules or secretion granules.

Embryological, clinical and ultrastructural study of human oocytes presenting indented zona pellucida

Human oocyte dysmorphisms attain a large proportion of retrieved oocytes from assisted reproductive technology (ART) treatment cycles. Extracytoplasmic defects involve abnormal morphology of the zona pellucida (ZP), perivitelline space and first polar body. The aim of the present study was to describe a novel dysmorphism affecting the ZP, indented ZP. We also evaluated the clinical, embryological and ultrastructural features of these cases. We evaluated all ART treatment cycles during 7 consecutive years and found 13 treatment cycles (six patients) with all oocytes presenting an indented ZP. In addition, these oocytes presented total or partial absence of the perivitelline space, absence of resistance to ZP and oolemma penetration during microinjection, and low ooplasm viscosity during aspiration. This novel described dysmorphism was recurrent and attained all oocytes in three cases that had more than one treatment cycle. When compared with controls, data showed significant low oocyte maturity (42% versus 81.6%) and high cycle cancellation (30.8% versus 8.5%) rates, normal degeneration (3.4% versus 6.3%) and fertilization rates (69% versus 69.5%), and low pregnancy (15.4% versus 33.3%) and live-birth delivery (7.7% versus 27.7%) rates per cycle. Ultrastructure analysis revealed a zona pellucida structure with large empty electrolucent regions, an outer ZP layer with an indented surface with protuberances and a thick inner ZP that obliterated the perivitelline space. There was evidence of exocytosis of ZP material by the oocyte. In conclusion, oocytes with this novel described dysmorphism (indented ZP) are associated with low maturity, pregnancy and live-birth delivery rates.

Ultrastructural analysis of five patients with total sperm immotility

Asthenozoospermia has been related to structural defects of the sperm flagellum. However, few reports have studied in detail the ultrastructure of sperm with total immotility. We present an ultrastructural study of sperm from five patients with total sperm immotility, four due to dysplasia of the fibrous sheath (DFS) and one with situs-inversus. Of the four patients with DFS, three cases presented a hypertrophic and hyperplastic fibrous sheath that invaded the midpiece space, absence of the annulus, and a short midpiece containing a few disorganized and pale mitochondria. Of these cases, two presented absence of the central complex and radial spokes; another additionally presented absence of dynein arms and nexin bridges; and the other patient presented an intact annulus with a dysplastic fibrous sheath restricted to the principal piece with disorganized microtubule doublets. The patient with situs-inversus presented severe respiratory symptoms, with absence of dynein arms and nexin bridges. In conclusion, we present three cases with DFS associated with total sperm immotility, abnormal mitochondria, and absence of the annulus, central pair complex and radial spokes, of which one had in addition absence of dynein arms and nexin bridges. We also describe a patient, with total sperm immotility and a different presentation of DFS, as the annulus was present and the dysplastic fibrous sheath was restricted to the principal piece. These findings thus confirm the heterogeneity of the DFS condition. The changes observed in the patient with situs-inversus also further support previous observations.

Histochemical and Ultrastructural Characterization of the Posterior Esophagus of Bulla striata (Mollusca, Opisthobranchia)

The posterior esophagus of Bulla striata, running from the gizzard to the stomach, was investigated with light and electron microscopy to obtain new data for a comparative analysis of the digestive system in cephalaspidean opisthobranchs. In this species, the posterior esophagus can be divided into two regions. In the first, the epithelium is formed by columnar cells with apical microvilli embedded in a cuticle. Many epithelial and subepithelial secretory cells are present in this region. In both, electron-lucent secretory vesicles containing filaments and a peripheral round mass of secretory material fill the cytoplasm. These acid mucus-secreting cells may also contain a few dense secretory vesicles. In the second part of the posterior esophagus, the cuticle is absent and the epithelium is ciliated. In this region, epithelial cells may contain larger lipid droplets and glycogen reserves. Subepithelial secretory cells are not present, and in epithelial secretory cells the number of dense vesicles increases, but most secretory cells still contain some electron-lucent vesicles. These cells secrete a mixture of proteins and acid polysaccharides and should be considered seromucous. The secretory cells of the posterior esophagus are significantly different from those previously reported in the anterior esophagus of this herbivorous species.

Comparative ultrastructural studies of spermiogenesis and spermatozoa in some species of Polyplacophora (Mollusca)

Summary Comparative data on the ultrastructure of spermiogenesis and spermatozoa of the Polyplacophora Acanthochitona crinita, Chaetopleura angulata and Callochiton septemvalvis are presented in this study. In contrast to what has been described for this and other classes of Mollusca, no acrosome is present in the spermatozoa of these Polyplacophora. The nucleus is extended by a long, thin apical point. In A. crinita and C. angulata the mitochondria are situated at the basal and lateral regions of the nucleus. They do not present a typical middle piece. These species present a pericentriolar process. In C. septemvalvis the mitochondria are situated at the base of the nucleus, surrounding the centrioles, which are orthogonally positioned in all species. The ultrastructural development during spermiogenesis is similar. In middle spermatids of A. crinita, the chromatin is arranged in fine filaments. In C. septemvalvis and C. angulata the chromatin filaments are thicker, forming coarse bands. In late spermati...