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During spermiogenesis, cytoplasmic processes of Sertoli cells invade spermatid cytoplasm to form a canal complex (Sakai et al., 1988). Thin tubules are formed from the canal complex and intertwine with each other to give rise to the "mixed body." In the present study, analysis of the changes undergone by the intertwining thin tubules indicated that they contribute to the removal of cell organelles from spermatid cytoplasm. Intertwining thin tubules were first detected at step 13. By step 15, their number had greatly increased. In the present study, the membranes of the intertwining thin tubules were clearly observed to be continuous with the spermatid plasma membranes. Thus, the mixed body possibly may be formed as a long pit of the spermatid plasma membrane situated close to the invading Sertoli cell process. With the progress of spermiogenesis, the lumens of the intertwining thin tubules gradually became swollen, and the intertwining swollen tubules fused with each other so that the spermatid cytoplasm enclosed by the intertwining swollen tubules isolated into fragments. This fragmented cytoplasm, which contained a large amount of endoplasmic reticulum, became spherical. Small branches of the invading Sertoli cell processes entered into the lumens of the intertwining swollen tubules and occupied their interior to the point that, finally, they completely engulfed the fragmented spermatid cytoplasm. Because the invading Sertoli cell processes were continuous with Sertoli cell bodies surrounding a spermatid at this step, it is possible for the fragmented cytoplasm to be transported into the latter by way of the invading Sertoli cell processes.
Anat Rec 1989 Jan
PMID:Mechanism for the removal of residual cytoplasm from spermatids during mouse spermiogenesis. 246 58

The structure and quantitative contribution of membrane systems (transverse-axial tubular system [TATS] and sarcoplasmic reticulum [SR]) have been investigated in the heart of the adult guinea pig. Although previous quantitative studies have been made of guinea pig myocardium, this is the first such study that has utilized tissue in which membrane system elements were clearly identified by selective staining (in this case by the osmium-ferrocyanide [OsFeCN] postfixation method). Both membrane systems are highly developed in ventricular cells, but a TATS is essentially absent from atrial myocytes. The ventricular TATS consists principally of large-bore elements which may be oriented transversely, axially, or obliquely, making numerous anastomoses with one another to form a highly interconnected system of extracellular spaces that penetrate to all myoplasmic depths of the ventricular cell. The cell coat that lines the lumina of these tubules is structured, containing fibrillar structures that run along the length of the tubule. The volume fraction (VV) of the ventricular TATS is low (2.5-3.2%), in consideration of the qualitative prominence of the TATS in these cells. The relative total population of sarcoplasmic reticulum is higher in the atria (VV of 10-11%) than in the ventricles (VV of ca. 8%). In all guinea pig myocytes, several major structural divisions of SR can be discerned, which include network SR, junctional SR, corbular SR, and cisternal SR. Junctional SR (J-SR) in the atrial cells is limited almost exclusively to peripheral saccules of junctional SR (PJSR), whereas both interior J-SR and PJSR are present in the ventricle. Two distinct morphological types of PJSR appear in atrial cells, including both flattened and distended saccules, the latter resembling PJSR of lower vertebrate heart. Spheroidal bodies of SR with opaque contents (corbular SR) are prominent at or near Z-line levels of the sarcomeres of atrial and ventricular cells. Cisternal SR is likely a subset of network SR, but some examples appear related to rough endoplasmic reticulum. An overall impression obtained from this study is that guinea pig atria are composed of structurally primitive cells, whereas the ventricular cardiac muscle cells are more highly developed entities.
Anat Rec 1988 Dec
PMID:Membrane systems of guinea pig myocardium: ultrastructure and morphometric studies. 246 4

This study was prompted by the observation that cells in mouse lymph nodes (LN) with cytological characteristics of tingible body macrophages (TBM) appeared to be Thy-1 positive. The objective of this study was to determine if these large cells were TBM and to conclusively demonstrate their reactivity for Thy-1. The cells were studied using monoclonal antibodies (MoAb) against Thy-1 and macrophage markers including F4/80 and Ia antigens at both light microscopic (LM) and electron microscopic (EM) levels. Immunocytochemical reactivity by TBM for Thy-1 antigen specific MoAb was demonstrated by LM in both in situ and in vitro LN preparations. Furthermore, ultrastructural examination of these germinal center cells in situ demonstrated that the Thy-1 reactivity visualized at the LM level was associated with ribosomes and endoplasmic reticulum as well as their plasma membrane. Similarly, these cells expressed intracytoplasmic and membrane reactivity for Ia antigens and also for the macrophage specific antigen F4/80. This indicates that the reactivity is due to active synthesis of the Thy-1 antigen and not attributable to reactivity of any phagocytosed Thy-1 positive cells. As defined by their germinal center location and morphological characteristics, these Thy-1 reactive macrophages were identified as TBM. Germinal center TBM thus represent a unique, vigorously phagocytic subset of mature macrophages which express both macrophage and thymocyte markers.
Anat Rec 1988 Dec
PMID:Thy-1 positive tingible body macrophages (TBM) in mouse lymph nodes. 246 5

We studied the ultrastructure of alveolar type 2 cells of sheep. The inclusion bodies of rodlike structures or cisternal bodies derived from the endoplasmic reticulum were found in 13.6 +/- 7.0% (+/- SD) of type 2 cells. The length of the rodlike structure varied, the longest being 2.4 microns; but the width was usually 0.1 micron. Rod-like structures were usually straight and arranged in parallel stacks. An electron-dense line ran longitudinally at the center of the rodlike structures. Serial ultrathin sections revealed that the rodlike structures did not seem to be three-dimensionally rod-shaped structures but were actually plate-disc or cup-shaped, and the piled-up rodlike structures were connected to each other at their ends. This rodlike structure in type 2 cells of sheep seems rather to be a platelike inclusion body. The cisternal body, on the other hand, was circular or oval-shaped cisternae containing aggregated electron-dense materials distributed in an arabesque or speckled pattern. Serial ultrathin section examination revealed the cisternal body to be three-dimensionally a globe. Some plate bodies were arranged near the cisternal body, suggesting the transformation from the latter to the former. The functional significance of these findings has not yet been elucidated.
Anat Rec 1989 Jan
PMID:Platelike and globelike inclusion bodies associated with rough endoplasmic reticulum in alveolar type 2 cells of the sheep. 253 48

A well-developed plate-like cisterna (PLC) associated with trans-Golgi elements was observed in the Golgi apparatus of secretory cells in the rat anterior pituitary gland. This structure corresponds to the trans-most sacculotubular network. The PLC maintains a remarkably uniform thickness of about 33 nm, as measured between the outer leaflets of its unit membrane structure. As to the mechanism by which this peculiar construction of the PLC is maintained, pillar-like structures were noted in the PLC intracisternal space, apparently acting as supports to keep the intermembrane distance constant. The PLC was especially well developed in hypertrophied cells such as gonadotrophs following castration. One noteworthy feature was that the PLC frequently ran parallel with the rough endoplasmic reticulum (RER), maintaining a constant distance from the latter in hypertrophied cells, but no membrane continuity between the PLC and RER was seen.
Anat Rec 1989 Dec
PMID:Ultrastructural observation of the trans-Golgi associated plate-like cisterna in the secretory cells of the rat anterior pituitary gland with special reference to the intracisternal skeleton. 258 42

The production of type I collagen by fibroblasts, odontoblasts, and osteoblasts is reviewed on the basis of results obtained by electron microscopy, 3H-proline radioautography, and immunostaining for type I procollagen. In the three cell types, the precursors of type I collagen are processed along the rough endoplasmic reticulum (rER)-Golgi-secretory granule pathway in the same manner as secretory proteins, but the available evidence suggests a few special features: 1) From the rER site of synthesis, the initial collagen precursors, known as pro-alpha chains, are transported to the Golgi apparatus within tubular structures, referred to as intermediate tubules, rather than within vesicles. 2) The pro-alpha chains coil into a triple helix within spherical distensions present along the saccules on the cis side of Golgi stacks. 3) The resulting procollagens are fairly rigid and form bundles that cause spherical distensions to lengthen into cylindrical ones, whereas by an unknown mechanism these distensions become part of the saccules on the trans-side of Golgi stacks. 4) The procollagen-containing cylindrical distensions are released from trans-saccules to become secretory granules, and some procollagen material finds its way into lysosomes. 5) The secretory granules release their procollagen content by exocytosis at the cell surface. 6) The released procollagen is transformed into collagen before or, more probably, after associating with the surface of a collagen fibril.
Anat Rec 1989 Jun
PMID:Synthesis and secretion of collagen by cells of connective tissue, bone, and dentin. 267 80

Clustered cells with steroid-secreting morphology (SH), located within the paraaortic lymph node (PLN) capsules of normal and pregnant female golden hamsters, were examined by light and electron microscopy. Hydroxysteroid dehydrogenase (HD) activity of the SH cell cluster also was examined by histochemical techniques. The cluster was composed of mostly packed SH cells and surrounding mesenchymal cells. Individual SH cells possessed prominent smooth endoplasmic reticulum, well-developed Golgi complexes, some lipid droplets, and numerous mitochondria containing tubulovesicular cristae common to mammalian SH cells. Intermediate-type junctions were often observed between SH cells. The same SH cells were rarely detected in the subcapsular sinus and in the cortical parenchyma of the PLN. Early oophorectomy of the hamster resulted in cytoplasmic degeneration of the SH cell at day 5 after the operation. On the other hand, normal adult male hamsters possessed similar PLNs, but no SH cells were recognized in the nodes. The present histochemical preparation of normal female PLNs revealed moderate-to-strong HD activity, probably associated with SH cell clusters, in the limited regions of the capsules. Based on the present ultrastructural and histochemical findings, it is proposed that the SH cell cluster consists of steroid hormone producing cells.
Anat Rec 1989 Feb
PMID:An electron microscopic study of cells with steroid-secreting morphology in the paraaortic lymph node of the hamster. 271 41

Vitamin A-containing lipid droplets in the hepatocytes of rat liver were found to be exocytotically released from the cells in the form of a "lipid droplet--retinol-binding protein (RBP)--immunoreactive complex" following intraportal injection of retinol (17, 33, 67, or 100 micrograms). Evidence that the lipid droplets contain vitamin A was obtained by fluorescence microscopy of vitamin A. Intraportal injection of retinol produced varied numbers and sizes of vacuoles in the hepatocytes. The substance within the vacuoles exhibited a meshwork-like configuration in sections from slices incubated in a medium for revealing acid phosphatase activity or the corresponding control medium and was RBP-immunoreactive and proteinaceous in nature. The occurrence and number of the vacuoles depended on the dosage of injected retinol, being greatest at a dosage of 100 micrograms of retinol and becoming progressively less at dosages of 67, 33, and 17 micrograms. The vacuoles were formed by vacuolization of cisternae of the rough endoplasmic reticulum. The formation of vacuoles reached a maximum 30 min after intraportal injection of 100 micrograms retinol, and the vacuoles and lipid droplets had almost disappeared from the hepatocytes after 90 min. Little or no esterase activity was found in lipid droplets in the hepatocytes before intraportal injection of retinol, but after the injection, lipid droplets that had fused with the vacuoles become strongly positive for this enzyme activity. This suggests that hydrolysis of retinyl esters may occur in the process of complex formation in rat hepatocytes.
Anat Rec 1989 Sep
PMID:The morphology of release of vitamin A-containing lipid droplets by hepatocytes in rat liver. 277 9

Osteoclast-like multinucleated cells were formed from mouse bone marrow mononuclear cells, and their morphology on coverslips and on calcified dentine slices was compared by means of transmission electron microscopy. Addition of 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3] to bone marrow cells cultured on coverslips greatly stimulated the formation of multinucleated cells within 8 days. These multinucleated cells had the cytological features of osteoclasts (abundant pleomorphic mitochondria, a large number of vacuoles and lysosomes, many stacks of Golgi membranes, and an extensive canalicular system), but they developed neither ruffled borders nor clear zones. The multinucleated cells appeared to result from direct fusion of mononuclear progenitor cells, whose structural features were similar to those of multinucleated cells. Like isolated osteoclasts, both multinucleated cells and their precursors exhibited an intense reaction for tartrate-resistant acid phosphatase (TRACP) in the cisterns of endoplasmic reticulum and lysosomes. Multinucleated cells formed from alveolar macrophages in the presence of 1 alpha,25(OH)2D3 were totally negative for TRACP reaction. When marrow cells were cultured on dentine slices in the presence of 1 alpha,25(OH)2D3, some of the multinucleated cells were located in the shallow resorption lacunae of dentine surfaces, and they developed the characteristic ruffled borders and clear zones. The narrow extracellular spaces of the ruffled borders, the adjacent pale endocytotic vacuoles, and the dark lysosomes located in the perinuclear cytoplasm of the multinucleated cells contained numerous apatite crystals delete in resorption lacunae. These results indicate that 1) the multinucleated cells formed on coverslips from mouse marrow cells treated with 1 alpha,25(OH)2D3 exhibit non-functional basic features of osteoclast morphology, and 2) differentiation of the multinucleated cells into functional osteoclasts requires some components of calcified dentine.
Anat Rec 1989 Jul
PMID:Multinucleated cells formed on calcified dentine from mouse bone marrow cells treated with 1 alpha,25-dihydroxyvitamin D3 have ruffled borders and resorb dentine. 278 22

The auditory hair cells of adults of eight species of lizards (three gekkonids: Coleonyx variegatus, Gekko gecko, and Cosymbotus platyurus; two teiids: Ameiva ameiva and Cnemidophorus tigris; one anguid: Celestus costatus; one lacertid: Podarcis (Lacerta) sicula; and one iguanid: Crotaphytus wislizeni) were studied by transmission electron microscopy. Heterotopic synaptic bodies were found in some of the auditory hair cells of all of the above species, occurring frequently in the gekkonids but infrequently in other species. The groups of heterotopic synaptic bodies occurred mainly in the infranuclear cytoplasm between the hair cell nucleus and the hair cell plasma membrane. The groups of synaptic bodies that were close to the hair cell nucleus were usually associated with specialized arrays of rough and smooth endoplasmic reticulum. The numbers of heterotopic synaptic bodies were greatest in the gekkonid species and were especially large in Coleonyx variegatus, where an average of 36.8 synaptic bodies occur in one group. The functional significance of the presence of heterotopic synaptic bodies in the auditory hair cells of adults animals is not known.
Anat Rec 1987 Jul
PMID:Heterotopic synaptic bodies in the auditory hair cells of adult lizards. 282 Feb 67


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