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Y Clermont

Publications and source records attributed to Y Clermont.

At least 73 records · Page 4Linked to original sources
PubMed1983

Ultrastructural features of six types of neurons in rat dorsal root ganglia.

Sections of glutaraldehyde-fixed lumbar dorsal root ganglia of the rat were examined in the electron microscope following impregnation with the uranyl-lead-copper technique or postfixation in potassium ferrocyanide-reduced osmium. Three types of ganglion cells (A, B, C) were identified on the basis of their size and the distribution of their organelles. They were further subdivided into six subtypes according to the arrangement and three-dimensional organization of the Nissl bodies and Golgi apparatus in the perikarya. Type A1 cells were large, clear neurons in which Nissl bodies, separated from each other by pale narrow strands of cytoplasm containing small stacks of Golgi saccules and rod-like mitochondria, were evenly distributed throughout the perikaryon. In type A2, the Nissl bodies assumed a similar distribution but were separated by much wider strands of cytoplasm. Type A3, the smallest of the type A category, displayed densely packed Nissl bodies and long stacks of Golgi saccules which formed a perinuclear ring in the midportion of the perikaryon. Type B cells were smaller and showed a concentric zonation of their organelles. In type B1, large Nissl bodies located in an outer cytoplasmic zone were made of long piles of parallel cisternae interrupted by curved Golgi stacks. Type B2 was characterized by a ring-like Golgi apparatus separating the perikaryon in a cortical zone composed mainly of Nissl substance and a juxtanuclear zone containing mitochondria and smooth endoplasmic reticulum. Type C cells were the smallest of the ganglion cells and contained small, poorly demarcated Nissl bodies and a juxtanuclear Golgi apparatus.

Animals↗
PubMed1983

Renewal of type A spermatogonia in adult rats.

The origin of type A spermatogonia in the rat, formed at each cycle of the seminiferous epithelium, has been investigated in segments of tubules dissected from the testes of animals killed at 1 and 44 hr after a single injection of [3H]thymidine. After fixation and staining these tubular segments were radioautographed according to the technique of Huckins & Kopriwa (1969). Labelled and unlabelled type A0, A4, A1 and intermediate spermatogonia were mapped and scored in tubular segments at stages I-IV of the cycle of the seminiferous epithelium, i.e. before, during and after the stage I peak of spermatogonial mitosis. In stage I of the cycle, the relatively rare type A0 spermatogonia (0.7 per frame) were infrequently labelled at the two time intervals, while the large majority of numerous type A4 spermatogonia (8.7 per frame) were labelled. In stages II-IV of the cycle, of the numerous aligned type A1 spermatogonia, only a few were labelled at 1 hr, whereas many were labelled at 44 hr after [3H]thymidine injection. At the latter time interval, the intermediate spermatogonia were also well labelled. Thus, considering cell numbers and labelling indices, it appears that the type A4 spermatogonia may serve as precursors for both type A1 and intermediate spermatogonia.

Animals↗
PubMed1982

A cytochemical study of the Golgi apparatus of the spermatid during spermiogenesis in the rat.

The reactivity of the various components of the Golgi apparatus of rat spermatids for three phosphatase activities (nicotinamide adenine dinucleotide phosphatase, NADPase; thiamine pyrophosphatase, TPPase; cytidine monophosphatase, CMPase) and the incorporation of 3H-fucose by the spermatids was analyzed at the 19 steps of spermiogenesis, i.e., during and after this organelle elaborated the glycoprotein-rich acrosomic system. During steps 1-3, the Golgi apparatus produced, in addition to the proacrosomic granules, multivesicular bodies that became associated with the chromatoid body. NADPase was located within the four of five intermediate saccules of Golgi stacks, and TPPase was found in the last one or two saccules on the trans aspect of the stacks from steps 1 to 17 of spermiogenesis. CMPase was located within the thick saccular GERL elements found in the trans region of the Golgi apparatus from steps 1 to 7 of spermiogenesis, but the CMPase-positive GERL disappeared from the Golgi apparatus after its detachment from the acrosomic system at step 8. Th acrosomic system itself was reactive from CMPase and TPPase but was negative for NADPase, while the multivesicular bodies were CMPase and NADPase positive but unreactive for TPPase. Tritiated-fucose was readily incorporated within the Golgi apparatus of steps 1-17 spermatids; in steps 1-7 it was subsequently incorporated within the acrosomic system and multivesicular bodies. These various data indicated (1) that the Golgi apparatus of spermatids, although it loses its CMPase-positive GERL element in step 8, retains evidence of functional capacity until it degenerates in step 17; (2) that in early spermatids the various saccular components of the Golgi are specialized with respect to enzymatic activities; and (3) that each Golgi region may contribute in a coordinated fashion to the formation of the acrosomic system and multivesicular bodies.

Animals↗
PubMed1982

Kinetics of fibrous sheath formation in the rat spermatid.

The morphogenesis of the fibrous sheath in the rat spermatid has been studied by electron microscopy and by EM radioautogaphy following injection of 3H-proline. The appearance of the developing fibrous sheath from the distal to proximal end of the principal piece has been examined in spermatids in each of the 19 steps of spermiogenesis. The precise timing of the various steps of its formation has been established and related to radioautographic observations on the synthesis and incorporation of proteins into the developing fibrous sheath. The longitudinal columns form slowly over a period of 15 days, appearing first at the distal end of the principal piece in step 2 and gradually extending in a proximal direction, ending at the level of the annulus in step 17. Throughout this 15-day period, proline-containing proteins are synthesized and incorporated into the growing columns. All of the ribs, on the other hand, arise from anlagen which are assembled along the length of the principal piece during a much shorter (4.5-day) period between steps 11 and 15 of spermiogenesis. New rib anlagen seemingly originate from bundles of proteinaceous filamentous material which are synthesized in the cytoplasm of step 11-15 spermatids and become aligned along the plasma membrane of the principal piece, starting at the distal end. These observations suggest that the two components of the fibrous sheath are assembled by means of two independent mechanisms that proceed asynchronously except during an overlap period of 2.5 days between steps 12 and 14.

Animals↗
PubMed1982

Formation of the outer dense fibers during spermiogenesis in the rat.

The morphogenesis of the outer dense fibers (ODF) in rat spermatids has been studied by electron microscopy, and the synthesis and incorporation of proteins into the ODF during this process have been followed by radioautography using 3H-proline and 3H-cystine as precursors for ODF proteins. In the first phase (step 8-14), nine very fine fibers termed anlagen of the ODF develop in association with the microtubule doublets. These first appear along the most proximal portion of the axoneme in step 8 of spermiogenesis; during steps 9-14 they gradually increased in length in a proximal-to-distal direction, being first observable along the forming midpiece and later along the principal piece as well. In the second phase (steps 15-16), the rudimentary fibers suddenly increase in diameter, with the most dramatic growth occurring in step 16, and assume a close resemblance to the mature ODF. This striking transformation, which appears to result from simultaneous deposition of electron-dense material along the length of anlagen of the ODF, coincides with a period of rapid incorporation of 3H-proline-and 3H-cystine-containing proteins, which become permanent structural components of the ODF. These proteins, which comprise the bulk of the ODF, are synthesized in the cytoplasm of spermatids during the acrosome and early maturation phases. In the final phase (steps 17-19) the fibers continue to enlarge very slowly, assuming their definitive form in step 19 of spermiogenesis. Thus formation of the ODF in the rat is a lengthy multistep procedure, requiring from step 8-19 of spermiogenesis and utilizing proteins synthesized throughout most of this period.

Animals↗
PubMed1982

Evolution of Sertoli cell processes invading the cytoplasm of rat spermatids.

Sertoli cell processes invaginating the cytoplasm of rat spermatids were investigated in thin or thick sections stained respectively with ferrocyanide-reduced osmium (Karnovsky, 1971) and the Ur-Pb-Cu metallic impregnation method (Thiéry and Rambourg, 1976). Two types of Sertoli cell processes were observed: Some, seen in steps 11-15 of spermiogenesis, were associated with a tight network of ER cisternae located within the spermatid cytoplasm subjacent to the plasma membrane facing the Seertoli cell process; others, seen from step 11 until the end of spermiogenesis, were not associated with such a spermatid subsurface ER network. Following their formation, the ER-associated Sertoli cell processes were cleaved into double-walled vesicles. Concomitantly, the enclosed Sertoli cell cytoplasm underwent autolysis followed by the dissolution of the Sertoli cell plasma membrane leaving within the spermatid cytoplasm many empty-looking vacuoles delimited only by the plasma membrane of the spermatid. Thereafter, i.e., in steps 15 and 16 of spermiogenesis, these vacuoles clustered, and with the collapse of the vacuoles they gave rise to a single compact mass of interlaced ER cisternae and small vacuoles. With the dissolution of ER cisternae, in step 18, this mass was finally dispersed. These observations suggested that the ER-associated Sertoli cell processes may constitute a pathway for the delivery of material from the Sertoli cells into spermatids. In contrast, the Sertoli cell processes not associated with a network of ER cisternae did not show cleavage or autolysis and appear to be involved mainly in holding the cytoplasm of the spermatid in place.

Acrosome↗
PubMed1981

Structural changes of the head components of the rat spermatid during late spermiogenesis.

The transformation of the nucleus, acrosomic system, and peri-nuclear theca (perforatorium and post-acrosomal dense lamina) was analyzed during the maturation phase, i.e., steps 14 to 19 of spermiogenesis. Following partial condensation of chromatin from steps 11-14, the nucleus continues to condense during the following steps until the end of spermiogenesis. The redundant nuclear envelope which forms along the apical and ventral aspects of the nucleus and around the implantation fossa regresses during steps 17-19. The acrosomic system splits into two portions early in step 15 to give rise to: a) the main portion with its crest-like acrosome running along the dorsal aspect of the nucleus and head cap extending over the lateral surfaces of the nucleus: and b) a smaller head-cap segment which is seen in steps 15 and 16 along one side of the nucleus at its apical extremity. This separated head-cap segment reaches the apical-ventral aspect of the head during step 17 and condenses in synchrony with the rest of the acrosomic system in step 19 of spermiogenesis. The large crescentic acrosome, which in step 15 forms a large fin at the caudal extremity of the acrosomic apparatus, moves anteriorly during steps 16 and 17, while the whole acrosomic system extends farther apically beyond the tip of the nucleus. The perforatorium and post-acrosomal dense lamina form a rigid capsule (perinuclear theca) that covers tightly the sickle-shaped nucleus and binds the inner acrosomal membrane and the post-acrosomal membranes. The post-acrosomal dense lamina, which includes the ventral spur, appears early in step 15 as a dense cytoplasmic layer applied to the nuclear envelope at the caudal extremity of the nucleus except over the perifossal zone. The perforatorium forms during step 19 of spermiogenesis as a result of the condensation of a wispy cytoplasmic material which has accumulated in the subacrosomal space during steps 14-18. Thus the spermatid's head is deeply modified during the maturation phase and takes its definitive shape only at the last step of spermiogenesis.

Acrosome↗
PubMed1981

Three dimensional arrangement of mitochondria and endoplasmic reticulum in the heart muscle fiber of the rat.

The three-dimensional arrangement of mitochondria and endoplasmic reticulum was studied in thick sections of the heart left ventricle fixed in glutaraldehyde and impregnated with the Ur-Pb-Cu technique and in thin sections of glutaraldehyde-fixed tissue post-fixed in potassium ferrocyanide-reduced osmium. Squarish flattened mitochondria, approximately the size of a sarcomere, were arranged in longitudinal columns in the clefts between the myofibrils. At the periphery of the fiber, the endoplasmic reticulum took the appearance of a subsarcolemmal network of plate-like and tubular cisternae running parallel to the cell surface. Between the myofibrils, the ER network formed longitudinally oriented repetitive units whose structure varied according to their position in relation to the A- or I- bands of the myofibrils. In front of the A-band, the endoplasmic reticulum appeared as a single layered network of anastomotic tubules compressed between the adjacent myofibrils. In front of the I-band, it formed a multilayered network the three-dimensional arrangement of which was dependent upon the presence or absence of the T-tubule. In the absence of the T-tubule, the ER cisternae were loosely anastomosed and occasionally displayed bulbous terminal swellings. In the presence of T-tubules, tubular ER cisternae were seen running parallel on both sides of the T-tubules and were continuous with sheet-like cisternae sandwiched between the distended T-tubule and adjacent extremities of longitudinally arranged mitochondria. These tubular or flattened cisternae were connected to each other by numerous bridging cisternae around the T-tubules.

Animals↗
PubMed1981

Ultrastructural localization of nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and cytidine monophosphatase (CMPase) in the Golgi apparatus of early spermatids of the rat.

At the early steps 3-7 of spermiogenesis the hemispherical Golgi apparatus elaborates and is closely associated to the acrosomic system which grows at the surface of the spermatid's nucleus. It shows two distinct zones, a cortex made up of flattened saccules and related membranous tubules, and a medulla containing various types of vesicular profiles. The various components of the cortex of the Golgi apparatus were tested for their reactivity to three phosphatases. Nicotinamide adenine dinucleotide phosphatase activity (NADPase, Smith, 1980) was observed in the middle two to six saccules in the stack with a midsaccule being more reactive than the saccules above and below. A weak and spotty reaction was also noted in the remaining saccules on the trans-face of the stack and in the thick elements making up the GERL on the trans aspect of the stacks of saccules. Thiamine pyrophosphatase activity (TPPase, Novikoff and Goldfisher, 1961) was found in one or two saccules on the trans-face of the stacks but was absent from the other Golgi components. Cytidine monophosphatase activity (CMPase, Novikoff, 1967) was observed in the GERL, in vesicles of the medulla and in the developing acrosomic system. In the intersaccular regions of the cortex the branching membranous tubules showed the same reactivity for the phosphatases to that of the saccules to which they are connected. ER cisternae associated with the Golgi apparatus, anastomotic membranous tubules seen in the peripheral Golgi region, small vesicles, as well as the first saccule on the cis-face of the stacks were all negative for the three enzymes studied. These data indicated that in the cortex of the Golgi apparatus there were several distinct compartments that could be distinguished on the basis of structural and cytochemical features.

Animals↗
PubMed1980

Three-dimensional architecture of the cortical region of the Golgi apparatus in rat spermatids.

Glutaraldehyde-fixed testes were impregnated with the Ur-Pb-Cu technique of Thiéry and Rambourg ('76) or postfixed in ferrocyanide-reduced osmium (Karnovsky, '71). Thin and thick (0.5 micron) sections were examined with a Philips 400 electron microscope at 80 or 100 kv. Stereopairs were prepared from pictures of the same field after tilting the specimen every 6 degrees from the -45 degree to the +45 degree position of EM goniometric stage. The cortex of the compact hemispherical Golgi apparatus of young spermatids (steps 2-8) was found to be composed of saccular and intersaccular regions similar to those described in the Golgi apparatus of Sertoli cells (Rambourg et al., '79). In the saccular region, the stacks were composed of three to nine parallel saccules perforated with pores of various dimensions. On the mature or trans-face of the stack, one or two membranous elements with a wider lumen were either closely applied to the overlying saccules or were separated from them and intermixed with the vesicular components of the medulla. On the forming or cis-face of the stack, three or four saccules were frequently interrupted by gaps in register from one saccule to another. In three dimensions, these gaps appeared as pan-shaped spaces or "wells," often containing a few vesicles. Immediately overlying the first saccule on the cis-face, a regular network of anastomotic tubules was present, corresponding to the cis-osmiophilic element observed in other cell types. In the intersaccular region, membranous tubules connected to the edges of the saccules branched, intertwined, anastomosed, and bridged adjacent stacks of saccules. Such membranous tubules bridged saccules with the cis-osmiophilic element or saccules of the same stack. Between the ER cisternae capping the surface of the Golgi apparatus and the cis-network of anastomotic tubules, there was a space called the peripheral Golgi region containing small vesicles and membranous tortuous tubules. The vesicles were frequently arranged in clusters that were capped by an ER cisterna and displayed a size gradient from the periphery to the center of the cluster. Thus, although there were similarities between the three-dimensional architectures of the Golgi apparatus in Sertoli cells and young spermatids (e.g., saccular and intersaccular regions), several structural features distinguished the spermatid's Golgi apparatus.

Animals↗
PubMed1980

Evolution of the endoplasmic reticulum in the Sertoli cell cytoplasm encapsulating the heads of late spermatids in the rat.

Throught stage VII and early stage VIII of the cycle of the seminiferous epithelium, the heads of the late spermatids, located in a juxtaluminal position, are embedded in apical processes of Sertoli cells. These processes contain cisternae of endoplasmic reticulum (ER) of two main types, i.e., flattened and tubular, which communicate with each other to form a continuous system. Throughout the long stage VII of the cycle, these two types of cisternae undergo marked changes. In early stage VII, the flattened cisternae, developing from the subsurface cisternae which compose the "junctional specialization," form concentric sheets at the periphery and in the middle of each apical process. The less conspicuous tubular cisternae form a continuous network which is present in the bridge connecting the Sertoli cell body to the apical process, and extends along the dorsal and ventral aspects of the spermatid's head to end up as cup-shaped flattened cisternae capping the bulbs of the tubulobulbar complexes described by Russell and Clermont ('76). In mid stage VII, the flattened cisternae start to regress, while the tubular cisternae become more abundant. In late stage VII, only fragments of the flattened cisternae are present, while the tubular cisternae form a profuse and elaborate network throughout the apical process. In the following stage VIII, the tubular cisternae disperse and only remnants of ER are present at the time of the release of the spermatid into the tubular lumen. These transformations of ER cisternae suggest a complex alteration in the relationship between Sertoli cells and late spermatids prior to their release as spermatozoa.

Animals↗
PubMed1979

Three-dimensional architecture of the golgi apparatus in Sertoli cells of the rat.

Glutaraldehyde-fixed testes were stained "en bloc" with the Ur-Pb-Cu technique of Thiéry and Rambourg ('76) or post-fixed and stained with the osmium tetroxide-potassium ferrocyanide method of Karnovsky ('71). Thin or thick (up to 3 micron) sections were examined with the Philips (301 or 400) EM or the high voltage EM. Stereopairs were prepared with photographs of tilted specimens (+/- 7 degrees). At low magnification, in thick sections (0.5-3 micron) stained with Ur-Pb-Cu, the whole Golgi apparatus formed a single network of interconnected wavy ribbon or platelike structures extending from the juxtanuclear region toward the apex of the cell. At higher magnifications, with the two staining techniques, this Golgi network showed two distinct types of regions: the "saccular region" corresponding to the conventional stack of saccules and the "intersaccular connecting region" made up of anastomotic tubules which bridge adjacent stacks. In the saccurlar regions, there was, on the cis-face of the stack, a tight polygonal meshwork of anastomotic tubules (osmiophilic element). Underlying it there were three to seven closely apposed saccules perforated with pores of various diameters, and finally, on the trans-face, a network of tubules was usually connected to the last saccule of the stack, which seemed to peel off" from the pile. The intersaccular connecting regions showed proximal and distal zones with regard to the associated stacks. The proximal zone was made up of superimposed and parallel polygonal networks of membranous tubules which were continuous with corresponding saccules of the stack. In the distal zone they interdigitated, intertwined, anastomosed and bridged adjacent saccular regions; others turned at right angles and established connections with tubular extensions arising at various levels of the same stack. While cisternae of endoplasmic reticulum were contiguous with tubules or saccules located on the transface of the Golgi apparatus, a close association between the ER cisternae and the cis-face of the stacks was not usually observed.

Animals↗
PubMed1977

Arrangement of connective tissue components in the walls of seminiferous tubules of man and monkey.

In primates the membrane separating the seminiferous epithelium from the interstitial space is composed of one to three (monkey) or two to six layers (man) of myoid cells associated with one to two layers of fibrocyte-like adventitial cells. All these cells are separated from each other by irregular spaces filled with various connective tissue intercellular components. Subjacent to the elements of the seminiferous epithelium is a continuous, often redundant, basement membrane. A similar basement membrane-like material forms a layer next to and over small areas of the plasma membrane of myoid cells. Collagen fibrils grouped in bundles of various sizes are seen in all connective tissue layers but are particularly abundant in the space between the seminiferous epithelium and the innermost layer of myoid cells. Elastic fibrils demonstrated by the Verhoeff iron hematoxylin technique are also present. Composed of a homogeneous material, the elastic fibrils are short, irregular, branching entities with a diameter comparable to or smaller than that of collagen fibrils. In addition, an abundance of microfibrils with a diameter of 12-15 nm is present in the various connective tissue layers. These microfibrils have a densely stained cortex and a lightly stained core. When seen close to the myoid cells, bundles of micro fibrils appear to insert on well defined areas next to the plasma membrane. These areas commonly face the patches of electron-dense material observed on the inner aspect of the plasma membrane of the myoid cells and in which the actin filaments are inserted. Bundles of microfibrils often span the gap between myoid cells of the same layer as well as those of adjacent layers. Microfibrils are also closely related to the surface of elastic fibrils and are seen intertwining with collagen fibrils. Thus microfibrils appear to bridge and bind together adjacent myoid cells and anchor the surface of these cells to the bundles of elastic and collagen fibrils present in the intercellular spaces of the limiting membrane.

Animals↗