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B Fraile

Publications and source records attributed to B Fraile.

At least 55 records · Page 3Linked to original sources
PubMed1996

Immunohistochemical study and western blotting analysis of titin-like proteins in the striated muscle of Drosophila melanogaster and in the striated and smooth muscle of the oligochaete Eisenia foetida.

The presence and distribution of titin-like proteins have been examined in transversely striated muscle of Drosophila melanogaster, in obliquely striated muscles (body wall and inner muscular layer of the pseudoheart) and smooth muscle (outer muscular layer of the pseudoheart) from the earthworm Eisenia foetida by means of Western blotting analysis, light microscopy immunohistochemistry, and electron microscopy immunogold labeling, using antibodies anti vertebrate (chicken) titin (3,000 kDa) and arthropod (D. melanogaster) mini-titin (twitchin or projectin) (700 kDa). To determine whether these antibodies immunoreact non-specifically against vertebrate titin, mouse skeletal muscle was also studied. As negative control, mouse smooth muscle was used. Immunoreaction to mini-titin was found in all the invertebrate muscles studied. For each of these muscles, Western blotting analysis of mini-titin showed a single band, at approximately 700 kDa. Electron microscopy immunolabeling to this protein was observed along the whole sarcomere length (A bands and I bands) in both transversely striated muscles of the insect and obliquely striated muscles of the earthworm, although the number of immunogold particles was more abundant in the insect muscles. Mini-titin immunolabeling was also observed in the smooth muscle cells that formed the outer layer of the earthworm pseudoheart although in lower amounts than in the obliquely striated muscle. The absence of true sarcomeres in the smooth muscle cells did not permit to determine the extension of mini-titin immunolabeling. No immunoreaction to this protein was found in the striated and smooth muscles of the mouse. Immunoreaction to titin was only observed in the mouse skeletal muscle, in which both A bands and I bands appeared immunolabeled. Present results show that mini-titin in the invertebrate muscles studied differs immunohistochemically from vertebrate titin and, in contrast with titin, mini-titin is also present in invertebrate smooth muscles.

Animals↗
PubMed1996

Testicular cell cytoskeleton in the newt, Triturus marmoratus marmoratus, during the annual cycle.

Light and electron microscopy immunohistochemical studies and Western blotting analysis of cytoskeletal proteins have been carried out in the testis of the marbled newt (Triturus marmoratus marmoratus) during the annual testicular cycle. The present findings revealed homologies and differences with regard to those reported in the testes of mammals and other vertebrates. Changes in immunohistochemical expression have also been detected in the course of the annual cycle. Actin and tubulin, which were scanty and diffusely located in spermatogonia and spermatocytes, increased their expression and reorganized during spermiogenesis. Vimentin and keratin, undetected in spermatogonia and spermatocytes, were expressed in differentiating spermatids and spermatozoa. In these cells, actin might be related with the connection of the axial fiber to the undulating membrane and the coordination of movement by both structures, while vimentin might be involved in the maintenance of the spatial relationship between the axoneme and the marginal fiber. During the first stages of spermatogenesis, the cytoplasm of Sertoli cells (follicular cells) showed a diffuse immunoreaction to actin, myosin, and tubulin and no vimentin immunolabeling. In advanced spermiogenesis, the follicular cells showed an intense immunoreaction to actin, myosin, tubulin, and vimentin in the apical projections that surrounded the spermatid heads. These apical cytoskeletal components might be involved in spermatid elongation, since the spermatids display no manchette, and in spermatozoon positioning and grouping. The colocalization of myosin and actin in the follicular cells suggests that actin filaments from contractile bundles and that contraction might be involved in changes in the Sertoli cell shape that accompany germ cell development during spermatogenesis. The interstitial cells immunostained to actin, myosin, tubulin, and vimentin. These cells, together with follicular cells, seemed to form the glandular tissue cells which showed a similar immunophenotype. The cells that surrounded the efferent duct epithelium immunostained to desmin, and they are probably contractile cells involved in sperm evacuation.

Activity Cycles↗
PubMed1996

Immunocytochemical electron microscopic study and Western blot analysis of troponin in striated muscle of the fruit fly Drosophila melanogaster and in several muscle cell types of the earthworm Eisenia foetida.

BACKGROUND: There is little information about troponin in invertebrate muscles, and no previous references to this protein in annelid muscles have been found. The aim of this paper was to study the presence and distribution of troponin in different muscle cell types from the earthworm Eisenia foetida (the muscular body wall, and the inner and outer muscular layer of the pseudoheart). These results were compared with those obtained in the transversely striated muscle of Drosophila melanogaster and in skeletal and smooth muscles of the mouse. METHODS: Immunocytochemical electron microscopic study and Western blot analysis using anti-TnT antibodies were employed in this study. RESULTS: Troponin immunoreaction was detected in the mouse skeletal muscle, the fly flight muscle, and earthworm obliquely striated muscles (body wall musculature and inner muscular layer of the pseudoheart). Immunolabeling for TnT in all these muscle cells appeared in moderate amounts at any point along the sarcomere length, except for the central zone of the A band (H band). This suggests that troponin molecules were located along the thin filaments. The density of immunogold particles was similar in the three muscles, and thus the amount of troponin in each muscle type was proportional to the number and length of actin filaments in each. Troponin was found in neither the mouse smooth muscle nor the outer muscular layer of the earthworm pseudoheart. The latter muscle showed an ultrastructural pattern that was intermediate between obliquely striated and smooth muscle. The estimated molecular weight for TnT in the earthworm was 55 kDa; this is higher than the weight of this protein in the mouse skeletal muscle (40 kDa) but similar to that of the D. melanogaster muscle (52 kDa). CONCLUSIONS: Troponin is present in both types of striated muscle (transversely striated and obliquely striated) of the earthworm with a distribution that is very similar to that observed in the mammalian striated muscle. As in vertebrates, troponin is absent in the smooth muscle of the earthworm. Discrepancies in the classification of some invertebrate muscles are common in the literature, and the use of distinctive markers, such as troponin, may improve our understanding of the nature and properties of many invertebrate muscles showing an ultrastructural pattern that does not resemble any of the classic muscle types.

Animals↗
PubMed1996

The G-cells in the dog: a light and electron microscope immunocytochemical study.

An immunohistochemical study has been performed to analyse the distribution of gastrin cells in the gastrointestinal tract of the dog. This study revealed that G-cells immunoreactive for gastrin were almost exclusively present in the pyloric antral mucosa, mainly in the middle third of the pyloric mucosa. The calculated number of G-cells per surface unit area was 8.5 x 10(3)-1.2 x 10(4) cells cm-2. Some gastrin-immunopositive cells were found in the first 10 mm of the proximal duodenum, mainly in the villous region. The fundic area of the dog stomach, the oesophagus, small intestine, caecum, colon, rectum, salivary glands, liver and pancreas were all immunonegative for gastrin. At the ultrastructural level, three different types of granules (150-400 nm) were evident in G-cells: electron-dense, electron-lucent and intermediate forms. Most of them were located in the subnuclear region of the cell. The effect of fixation of the antral mucosa at different pH levels was studied. In samples fixed with acid solutions, most of the G-cell granules were of the electron-dense type and were strongly immunopositive for gastrin. Fixation of samples at a basic pH resulted in most of the gastrin granules losing their contents into the cytoplasm, and the positive reaction to gastrin was then located in the cytoplasm and at the periphery of the electron-lucent granules.

Animals↗
PubMed1996

Immunocytochemical electron microscopic study and western blot analysis of paramyosin in different invertebrate muscle cell types of the fruit fly Drosophila melanogaster, the earthworm Eisenia foetida, and the snail Helix aspersa.

The presence and distribution pattern of paramyosin have been examined in different invertebrate muscle cell types by means of Western blot analysis and electron microscopy immunogold labelling. The muscles studied were: transversely striated muscle with continuous Z lines (flight muscle from Drosophila melanogaster), transversely striated muscle with discontinuous Z lines (heart muscle from the snail Helix aspersa), obliquely striated body wall muscle from the earthworm Eisenia foetida, and smooth muscles (retractor muscle from the snail and pseudoheart outer muscular layer from the earthworm). Paramyosin-like immunoreactivity was localized in thick filaments of all muscles studied. Immunogold particle density was similar along the whole thick filament length in insect flight muscle but it predominated in filament tips of fusiform thick filaments in both snail heart and earthworm body wall musculature when these filaments were observed in longitudinal sections. In obliquely sectioned thick filaments, immunolabelling was more abundant at the sites where filaments disappeared from the section. These results agree with the notion that paramyosin extended along the whole filament length, but that it can only be immunolabelled when it is not covered by myosin. In all muscles examined, immunolabelling density was lower in cross-sectioned myofilaments than in longitudinally sectioned myofilaments. This suggests that paramyosin does not form a continuous filament. The results of a semiquantitative analysis of paramyosin-like immunoreactivity indicated that it was more abundant in striated than in smooth muscles, and that, within striated muscles, transversely striated muscles contain more paramyosin than obliquely striated muscles.

Animals↗
PubMed1996

Light and electron microscopic immunohistochemical localization of protein gene product 9.5 and ubiquitin immunoreactivities in the human epididymis and vas deferens.

The distribution of protein gene product 9.5 (PGP) and ubiquitin immunoreactivities in the ductuli efferentes, ductus epididymidis, and ductus deferens of humans was studied by Western blot analyses and light and electron microscopic immunocytochemistry. PGP immunoreactivity was intense in the ductuli efferentes and weak in the ductus epididymidis and ductus deferens, while ubiquitin immunoreactivity was intense in the ductuli efferentes and ductus epididymidis and very weak in the ductus deferens. In the ductuli efferentes epithelium, PGP immunolabeling was observed in the cytoplasm of principal cells, whereas ubiquitin immunoreactivity was found in the nucleus and cytoplasm of principal cells and ciliated cells. In the ductus epididymidis epithelium, only scattered cells (mitochondria-rich cells) showed PGP immunoreaction in their cytoplasm, whereas ubiquitin immunostaining was detected in the nucleus and cytoplasm of most epithelial cells, except for the cauda, where ubiquitin immunolabeling was observed only in the nuclei. The ductus deferens showed no immunostaining for PGP, and only nuclear immunoreactivity to ubiquitin. The ultrastructural localization of PGP immunoreactivity was in the apical cytosol and microvilli. In addition to these locations, ubiquitin immunoreactivity was also found in the nucleus of all cell types and cilia of ciliated cells. Although the distribution of PGP and ubiquitin immunoreactivities in humans differs from that reported in rats, it seems that PGP and ubiquitinated proteins are secreted into the epididymal lumen in both species.

Adult↗
PubMed1996

Lectin histochemistry in the human epididymis.

A histochemical study using lectins to identify glycoconjugates present in the efferent ducts and ductus epididymidis of men without testicular or related disease was carried out. The lectins used and the oligosaccharide residues linked were: wheat germ agglutinin (WGA) for beta-N-acetylglucosamine and sialic acid, concanavalin A (ConA) for alpha-mannose, Ulex europaeus agglutinin (UEA-I) for alpha-fucose, Dolichos biflorus agglutinin (DBA) for alpha-N-acetylgalactosamine, soy bean agglutinin (SBA) for beta-N-acetylgalactosamine, and peanut agglutinin (PNA) for beta-galactose. The lectin-binding pattern in the human epididymis presents similarities and differences to those observed in other mammals which also showed differences between species. The present results revealed that regional differences along the human ductus epididymidis were less pronounced than those reported in other mammals. The epithelial cells in the efferent ducts reacted positively to WGA. All along the length of the ductus epididymidis, the principal cells and the luminal content showed staining affinity for WGA and ConA. The epididymal principal cells and luminal content also reacted positively to DBA for alpha-N-acetylgalactosamine but only in the cauda epididymidis. A positive reaction to UEA-I was observed only in the luminal content of the cauda epididymidis. This finding suggests that changes in the oligosaccharide chains of secretions leading to a positive UEA-I reaction occur in the cauda epididymidis. The epididymal principal cells showed positive reactions to SBA and PNA over the apical microvilli but not in the cytoplasm. The reaction was observed in the caput and corpus epididymidis but not in the cauda. Positive reactions to SBA and PNA were also detected in the epididymal fluid and in the cytoplasm of mitochondria-rich cells (a minor population of epididymal epithelial cells). These cells also reacted to other lectins such as WGA, ConA and DBA, which were also detected in the principal cells.

Acetylgalactosamine↗
PubMed1996

Ultrastructure of invertebrate muscle cell types.

The muscular cells of invertebrates can be divided into three major classes on the basis of their striation pattern: transversely striated, obliquely striated, or smooth muscle. Transversely striated muscles have either continuous or discontinuous Z lines and, thus, can be subdivided into two types respectively. Of all invertebrate muscles, the transversely striated muscle with continuous Z lines is the most similar to the vertebrate skeletal muscle and is present in arthropods, whose musculature (including the visceral muscles) only consists of this cell type. These muscles are multinucleate cells that contain myofibrils showing well-defined sarcomeres. Transversely striated muscles with discontinuous Z lines, consisting of multiple small electrondense patches, are found in the translucent portions of adductor muscles of some bivalves and in the heart muscle of the gastropods. This muscle is formed by mononucleated cells with centrally-located nuclei and a single myofibril. The obliquely striated muscle appears in nematodes, annelids, molluscs, brachiopods and chaetognathes and consists of mononucleated cells with both thick and thin myofilaments which form sarcomeres delimited by Z lines. Myofilaments are not perpendicular but oblique to the Z lines, so that both A and I bands may be seen together in each of the three spatial planes of view. Smooth muscle has been reported in coelenterates, annelids, molluscs, brachiopods and echinoderms, but is lacking in arthropods. These muscle cells have a centrally-located nucleus and abundant thin and thick myofilaments without apparent sarcomeres. The most relevant characteristics of invertebrate muscle cells are the following. The thick (myosin) myofilaments show a variable length (from 2.2 microns up to 6 microns) and width (from 14 nm up to 231 nm) and contain a central core of paramyosin, which is absent in vertebrate muscles. Thick filaments are homogenous in transversely striated muscles and either homogeneous or fusiform in the obliquely striated and smooth muscles. Thin filaments measure 6 nm in diameter. They contain tropomyosin and, only in striated muscles, also troponin. The thin/thick filament ratio varies from 3/1 to 6/1, even in smooth muscles. The plaques for filament anchorage (Z lines in striated muscles or electrondense bodies in smooth muscles) contain alpha-actinin. The striated (transversely or obliquely) muscles show long sarcomeres (up to 9 microns) and the number of thin filaments around each thick filament varies from 3 to 12, so that each thin filament is shared by two thick filaments. Z lines in the striated muscles show a variety of structures that differ from one species to another (filament bundles in nematodes, bars in annelids, small patches in molluscs, etc). Many striated muscles contain titin (connectin) and intermediate filaments and display a sarcotubular system consisting of T tubules and sarcoplasmic reticulum tubules. Both structures form dyads and, more rarely, triads. The location of T tubules as well as the configuration and distribution of sarcoplasmic reticulum vary among muscles and species. Invertebrate smooth muscle differs from that of vertebrates principally in the higher proportion and larger diameter of thick myofilaments. These may be fusiform and their size and number may vary widely among cells. These muscle cells may be classified by the characteristics of both the thick filaments and the electrondense bodies for filament anchorage.

Animals↗
PubMed1995

Cytoskeleton in Sertoli cells of the mosquito fish (Gambusia affinis holbrooki).

BACKGROUND: There is little information about the distribution of cytoskeletal components in the testes of teleost fish. The aim of this paper was to know the distribution of some major cytoskeletal proteins (tubulin, actin, vimentin, desmin, and cytokeratins) in the Sertoli cells of Gambusia affinis holbrooki and in their efferent duct epithelial cells which are possibly originated from the Sertoli cells. METHODS: Light and electron microscopic immunocytochemical studies and Western blotting analysis were performed in G. affinis testis. RESULTS: Actin immunoreaction was observed in the Sertoli cells at all spermatogenic stages, although the intensity of this reaction varied from one stage to another. Sertoli cells that support spermatogonia or spermatocytes showed a weak immunoreaction which was uniformly distributed throughout the cytoplasm and somewhat more concentrated at the level of the inter-Sertoli specialized junctions. Immunoreaction to actin increased during the first stages of spermiogenesis and was mainly localized beneath the plasma membrane. This immunoreaction was more intense in the basal than in the apical cytoplasm of Sertoli cells. In a more advanced stage of spermiogenesis, actin immunoreaction become stronger in the apical cytoplasm where Sertoli cells displayed cytoplasmic projections around each spermatid. After sperm release, the apical Sertoli cell cytoplasm still showed an intense actin immunoreaction. Intense immunoreaction to actin was also observed in the epithelial cells lining the efferent ducts. Immunoreaction to tubulin was diffuse throughout the Sertoli cell cytoplasm. No immunoreaction to vimentin or desmin was observed in the Sertoli cells during the spermatogenic process. Immunoreaction to both vimentin and desmin was observed in the efferent duct cells. Desmin immunoreaction was also observed in the seminiferous tubule boundary cells, mainly in the sections showing germ cell cysts at the last stages of spermiogenesis and in the peritubular cells that surrounded the efferent duct epithelium. Immunoreaction to cytokeratins was found in the endothelium of testicular blood vessels but not in the Sertoli cells or in the efferent duct epithelium. CONCLUSIONS: Immunoreaction pattern to cytoskeletal proteins in the Sertoli cells of G. affinis differs from that reported in mammalian Sertoli cells. These differences include the distribution of actin filaments and the absence of detectable vimentin immunoreaction in G. affinis Sertoli cells.

Animals↗
PubMed1995

Intermediate filaments in the testis of the teleost mosquito fish Gambusia affinis holbrooki: a light and electron microscope immunocytochemical study and western blotting analysis.

A light and electron microscope immunocytochemical study and Western blotting analysis has been performed on intermediate filaments (vimentin, desmin and cytokeratins) in the testis of the teleost fish Gambusia affinis holbrooki. An immunoreaction to vimentin was observed in the epithelium of the efferent ducts, testicular canal and their surrounding peritubular cells. Positive vimentin immunostaining was also observed in the cells located around seminiferous tubules (boundary cells), Leydig cells, interstitial fibroblasts, chromatophores, and blood vessel endothelial cells. In contrast to mammals, no vimentin immunoreactivity was found in the Sertoli cells. Immunoreactivity to desmin was weak in the epithelial cells of the efferent ducts and testicular canal and intense in the peritubular cells that surrounded these ducts. Desmin immunoreactivity was also observed in the seminiferous tubule boundary cells. The immunoreactivity was weak in the boundary cells that surrounded germ cell cysts containing spermatogonia or spermatocytes and intense in the boundary cells around cysts with elongated or mature spermatids. Immunoreactivity towards cytokeratins was observed only in testicular blood vessels. Cytokeratin immunolabelling was intense in the endothelium and weak in the vascular smooth muscle cells. No cytokeratin immunoreactivity was found in the Sertoli cells, germ cells, interstitial cells or in the efferent duct epithelium. The absence of intermediate filaments in the Sertoli cells, the absence of cytokeratins in the epithelium of the sperm excretory ducts, and the presence of desmin filaments in these epithelial cells are the most important differences with regards to the intermediate filament phenotype in mammalian testes.

Animals↗
PubMed1995

Ultrastructural localization of PGP 9.5 and ubiquitin immunoreactivities in rat ductus epididymidis epithelium.

The distribution of protein gene product 9.5 (PGP) and ubiquitin in the spermatozoa and epithelial cells in the different regions of the rat ductus epididymidis (proximal caput, distal caput, corpus and cauda) was studied by Western blotting analyses and electron microscopical immunogold labelling. Western blotting analyses showed that the PGP immunoreactive band was very intense in the caput and cauda epididymidis and almost irrelevant in the corpus, while the ubiquitin immunoreactive band was intense in the distal caput and cauda. No ubiquitin immunoreactive band was observed in the proximal caput and only a very weak band was seen in the corpus. The results of electron microscopical immunogold labelling varied from one epididymal region to another. The proximal caput epididymidis presented immunoreaction to PGP in the rough endoplasmic reticulum, cytosol, mitochondria and microvilli of most principal cells, and in the cytosol, rough endoplasmic reticulum and mitochondria of most basal cells. No ubiquitin immunoreaction was observed in this epididymal region. In the distal caput epididymidis, PGP immunoreactivity was detected in some principal and basal cells in the same intracellular locations as described in the proximal caput. In this region, ubiquitin immunoreactivity appears in the apical cytosol and mitochondria of principal cells. The corpus epididymidis showed no immunoreaction to PGP or ubiquitin. In the cauda epididymidis, immunostaining to PGP was observed in most clear cells and in isolated principal cells. The intracellular location of PGP in both cell types was the cytosol, mitochondria and microvilli. Ubiquitin immunoreactivity was detected in the perinuclear cytosol and mitochondria-but not in the digestive vacuoles-of some clear cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Protein gene product 9.5 and ubiquitin immunoreactivities in rat epididymis epithelium.

A quantitative immunohistochemical study was performed of the distribution of protein gene product 9.5 (PGP, a soluble protein localized in neurons and neuroendocrine cells as well as in some non-nervous cells) and ubiquitin along the rat epididymis. In the ductuli efferents, PGP immunoreaction was observed in the whole cytoplasm of some columnar cells; a smaller number of columnar cells showed ubiquitin immunoreactivity with limited apical and basal cytoplasmic localization. In the proximal caput epididymidis, the whole cytoplasm of all columnar cells showed PGP immunoreactivity, ubiquitin immunostaining was negative in this region. In the middle and distal caput epididymidis and the distal cauda, the apical cytoplasm of some columnar cells and the whole cytoplasm of some basal cells showed immunoreactivity to PGP. In these regions, immunoreactivity to ubiquitin was positive in the supranuclear cytoplasm of some columnar cells but not in the basal cells. No immunoreactivity to PGP or ubiquitin was detected in the corpus epididymis and the proximal cauda. Double immunostaining revealed that all the epididymal ubiquitin immunoreactive cells were also PGP immunoreactive, whereas most PGP immunoreactive cells did not immunoreact to ubiquitin. In ubiquitin-PGP immunoreactive cells, the site of the PGP immunoreaction differed from that of the ubiquitin immunoreaction. PGP-ubiquitin immunoreactive cells also seemed to be immunoreactive to anti-AE1/AE3 keratin antibodies. The spermatozoal heads were immunoreactive to PGP antibodies in the epididymal regions from proximal caput to distal cauda but not in the ductuli efferents. The findings suggest that non-ubiquitinated PGP immunoreactive proteins are secreted in the epididymis, mainly in the proximal caput, and attach to spermatozoa.

Animals↗
PubMed1992

The peritubular myofibroblasts in the testes from normal men and men with Klinefelter's syndrome. A quantitative, ultrastructural, and immunohistochemical study.

The ultrastructure and immunostaining with antibodies against actin, desmin, and vimentin were studied in the peritubular myofibroblasts of testes from normal men and men with Klinefelter' syndrome (KS). The seminiferous tubules were classified into five types (a-e), related to the progressive degree of sclerosis measured as thickening of the lamina propria. In control testes, only types a and b tubules were present, whereas the testes from men with KS showed types b, c, d, and e tubules. The ultrastructural study revealed abundant microfilament bundles with electron-dense bodies in the cell periphery of the myofibroblasts in a and b tubules. In c tubules, the microfilament bundles of the myofibroblasts were lacking in electron-dense bodies. Myofibroblasts in tubules d and e showed scanty microfilament bundles. Immunostaining of peritubular myofibroblasts with anti-actin antibodies was intense in tubule types a-c and scanty in types d and e. Immunostaining of myofibroblasts with anti-desmin antibodies was intense in tubule types a and b, and negative in types c-e. Immunostaining with anti-vimentin antibodies was weak in tubule types a-c and intense in types d and e. Quantitative study revealed that with the progression of sclerosis, the number and volume per cross-sectioned tubule of actin-containing cells and, mainly, desmin-containing cells decrease while the number and volume of vimentin-containing cells increase.

Actins↗
PubMed1992

Characterisation of secondary spermatocytes in the marbled newt (Triturus marmoratus).

Secondary spermatocytes in the marbled newt (Triturus marmoratus) were identified by means of cytophotometric quantification of nuclear DNA in the testicular lobules containing primary spermatocytes in advanced stages of the first meiotic division (from pachytene onwards) and newly formed spermatids. The nucleus of secondary spermatocytes has an intermediate size between that of primary spermatocytes and round spermatids and was characterised by the presence of abundant masses of dense chromatin and the absence of a nucleolus. At the prophase the chromatin masses were located at the periphery of the nucleus. The ultrastructural study revealed that the nuclear envelope displayed blebs and that the cytoplasm was very similar to that of primary spermatocytes including the presence of smooth endoplasmic reticulum whorls, multiple small dictyosomes, and a proacrosomal-like granule near the nucleus. This granule stained weakly with aqueous PTA and was observed in about 6% of secondary spermatocytes. Many of the mitochondria were grouped beneath the plasma membrane. Approximately 2% of these cells presented an axoneme which was not associated with other flagellar components.

Animals↗
PubMed1991

Sperm actin and calmodulin during fertilization in the hamster: an immune electron microscopic study.

The distribution of actin and CaM in hamster spermatozoa was examined during the early events of fertilization using postembedding immunogold procedures. Actin was immunolocalized with a polyclonal antibody and two monoclonal antibodies. CaM was immunodetected with a polyclonal antibody. In epididymal sperm, actin labeling was found solely in the principal piece of the flagellum. CaM labeling was observed in the postacrosomal lamina, subacrosomal ring, and tip of the perforatorium. These distributions were not modified after capacitation and acrosome reaction. During the successive steps of sperm-egg fusion actin remained undetected in the sperm head whereas its location did not change in the flagellum. CaM distribution remained unmodified until the sperm head begins to decondense. At later stages of sperm head decondensation the postacrosomal lamina and its CaM labeling disappeared, whereas gold particles were still detected in the subacrosomal layer. The predominant location of actin into the egg cortex, particularly the microvillus-free area was confirmed. Except for the CaM labeling of the meiotic spindle, no special CaM location could be found throughout the egg. Thus, in hamster, a role for sperm actin in sperm-egg fusion appears unlikely. In contrast the CaM present in the Ca(2+)-rich postacrosomal lamina could be involved in the regulation of egg activation.

Actins↗
PubMed1991

Ultrastructure of the aging human testis.

The ultrastructure of the progressive testicular involution with advancing age in men is reviewed. There is no definite age at which testicular involution begins, and the onset and severity of testicular lesions are subjected to pronounced individual variations. Hormone studies also indicate great individual variations, and subtle changes in both the testis and the pituitary develop progressively with age. Testicular size, sperm quality, and numbers of all germ cell types, Sertoli cells, and Leydig cells decrease with age. The volume occupied by the seminiferous tubules decreases, whereas that occupied by the testicular interstitium remains constant. The most frequent histological pattern of the aging testis is a mosaic of different seminiferous tubule lesions, varying from tubules with complete, although reduced, spermatogenesis, to completely sclerosed tubules. The tubules with complete spermatogenesis may show numerous morphological abnormalities in the germ cells, including multinucleation. Abnormal germ cells degenerate causing Sertoli cell vacuolation. These vacuoles correspond to dilations of the extracellular spaces resulting from the premature exfoliation of germ cells. Degenerating cells that are phagocytosed by the Sertoli cells give rise to an accumulation of lipid droplets in the Sertoli cell cytoplasm. The loss of germ cells begins with the spermatids, but progressively affects the earlier germ cell types, and tubules with maturation arrest at the level of the spermatocytes or spermatogonia are observed. The Sertoli cells show morphological abnormalities such as dedifferentiation, mitochondrial metaplasia, and multinucleation. Germ cell loss is associated with thickening of the tunica propria. When all seminiferous epithelial cells have disappeared, only an intensely collagenized tunica propria with myoid cells remains (sclerosed tubules). The Leydig cells progressively dedifferentiate with a decrease in the quantity of both smooth endoplasmic reticulum and mitochondria, together with an accumulation of lipid droplets, crystalline inclusions, and residual bodies, and formation of multinucleate cells. The development of tubular involution with age is similar to that observed after experimental ischemia, suggesting that vascular lesions may play an important role in age-related testicular atrophy.

Aging↗
PubMed1990

The cycle of follicular and interstitial cells (Leydig cells) in the testis of the marbled newt, Triturus marmoratus (Caudata, Salamandridae).

Ultrastructural examination of the marbled newt (Triturus marmoratus) testis throughout the annual cycle revealed that during the period of testicular quiescence (November-February), primordial germ cells proliferate within cords of filament-rich epithelial cells that will become follicular cells (FCs). Fibroblast-like cells surround the FCs and form the lobule-boundary interstitial cells (ICs). During the period of germ cell development from primordial germ cells to round spermatids (March-June), the FCs surrounding the developing germ cells contain scanty cytoplasm with abundant rough endoplasmic reticulum and scarce filaments. With spermatid elongation (July-August), the FC size grows, its nucleus becomes irregularly outlined, and its cytoplasm displays abundant smooth endoplasmic reticulum, residual bodies, lipid droplets, and large vacuoles. After spermatozoon release by the FCs (August-September), the adjacent ICs increase their size and transform into Leydig cells with abundant smooth endoplasmic reticulum, mitochondria with tubular cristae, and lipid droplets. During the period of testicular quiescence (November-February), the Leydig cells undergo involution, eventually developing the morphological attributes of mesenchymal cells. Intermingled among these cells, cords of filament-rich cells are observed. During this period of the cycle, spermatozoon cysts supported by FCs are present. At the beginning of the germ cell proliferation period (March), these spermatozoa are released, and the adjacent ICs undergo a transformation into Leydig cells similar to those observed in August-September. Maturation and involution of ICs occur when testosterone levels are known to be rising and falling, respectively.

Animals↗