摘要:

AbstractThis study investigates the effects of advancing age on responses of nasolabialis muscle fibers to denervation and reinnervation. The nasolabialis is innervated by the facial nerve and is responsible for the whisking movement of the animal's large vibrissae. In young adult (3‐month) and middle‐aged (15‐month) rats the muscle on one side of the head was denervated by crushing the facial nerve. At specific days postcrush, animals were sacrificed and thick sections of muscle were incubated to demonstrate cytochrome oxidase activity, a mitochondrial enzyme, which differentiated between red, white, and intermediate fiber types. The rate and extent of atrophy and recovery were evaluated using light microscope morphometric methods for which transverse fiber areas were measured and compared to fibers on the contralateral control side. There was an age‐related delay in the time of functional return since older animals resumed normal whisking behavior 6 days later than the younger animals. In both age groups, white and intermediate fibers atrophied to the greatest extent and red fibers showed least atrophy. Despite the different responses of the fiber types to denervation, there was no age difference in the maximum degree of fiber atrophy within each fiber type. Age differences did occur in the rate of the denervation response since the middle‐aged fibers consistantly showed a more rapid significant atrophy than the young adult fibers. During recovery, older fibers may be limited in their ability to attain the size of fibers on the control side. The results indicate that through middle age, the process of advancing age increases the susceptibility of the nasolabialis muscle to denervation but does not alter the maximum extent of atrophy. The ability to recover to normal fiber size, at least 2 months after denervation, is also ag

ISSN:0003-276X    

DOI:10.1002/ar.1092290202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe initial segment of the epididymis of rats, fixed with glutaral‐dehyde, was postfixed with reduced osmium, a technique that clearly delineates the membranes of cisternae of the endoplasmic reticulum (ER) and the various elements of the Golgi apparatus, or with tannic acid to enhance the coats of vesicles and ribosomes on ER cisternae. The material was also treated to demonstrate various phosphatase activities (NADPase, TPPase, CMPase, G‐6‐Pase) or impregnated with osmium tetroxide.In osmium‐impregnated material, the Golgi apparatus of the epithelial principal cells of the initial segment appeared in the light microscope as a branching, anastomosing ribbon forming a large network in the supranuclear region. In the electron microscope, ER were of two types: the heavily granulated, flattened, rough ER seen in the infranuclear and juxtanuclear regions and the distended, tubular, sparsely granulated ER, showing only few ribosomes, seen interlaced with the Golgi ribbon in the supranuclear region and at the apical pole of the cell.Of particular interest in this cell was the fact that the sparsely granulated ER approximated the Golgi stack on both its cis‐ and trans‐faces. On the cis‐face of the Golgi stack, the sparsely granulated ER cisternae showed the usual finger‐ or bud‐like protrusions directed toward the cis element of the Golgi stack and around which numerous small 80 nm vesicles or membranous tubules were clustered. The Golgi stack consisted of the following elements in a cis‐trans axis: the cis osmio‐philic element, a first saccule slightly dilated, saccules two to four (S2–S4), which were NADPase‐positive, and saccules five to seven and the eight Golgi element, which were TPPase‐positive. On the trans‐aspect of the Golgi stacks, several (up to four) CMPase‐positive trans‐Golgi networks were observed often in close apposition to the sparsely granulated ER cisternae. One of the trans‐Golgi networks showed a “peeling‐off” configuration, i.e. part of it was closely apposed to the overlying Golgi element of the stack, whereas the remaining part was separated from the stack by a space occupied by a cisterna of sparsely granulated ER. The other trans‐Golgi networks were completely separated from the stack and were often seen sandwiched between sparsely granulated ER cisternae. Thus, ER cisternae showed extensive areas of close apposition but no continuity with the trans‐Golgi networks. Although the saccules of the Golgi stacks showed NADPase and/or TPPase activity, the trans‐Golgi networks displayed CMPase activity, thus facilitating their identification from the closely associated unreactive sparsely granulated ER cisternae.The trans‐Golgi networks were variable in appearance but often showed sporadic electron‐lucent dilations along their length that were comparable to uncoated vesicles of similar size (150–300 nm) and appearance found in the trans‐region of the Golgi apparatus and at the apical pole of the cells. Such vesicles appeared to arise from the trans‐Golgi networks that eventually undergo fragmentation. Their identi

ISSN:0003-276X    

DOI:10.1002/ar.1092290203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe present study was designed to characterize the granulosa cell subpopulations derived from rats in which ovarian growth was induced by diethylstilbestrol (DES) or in which growth and differentiation was induced by pregnant mare's serum gonadotropin (PMSG). In the DES model, immature rats were given two separate injections of 2 mg DES/rat s.c. on 25 and 26 days of age and were killed 24 hr after the second injection. In the PMSG model, rats on day 28 were given 8 IU of PMSG s.c. and were killed 54 hr later. Granulosa cells were isolated from the ovaries, separated on a continuous Percoll density gradient, and divided into 12 fractions. The cells in each fraction were cultured in the presence of androstenedione with or without 20 ng/ml of follicle‐stimulating hormone (FSH) and estradiol and progesterone in the incubation medium were measured. In DES‐treated rats, granulosa cells in fractions 4 and 5 and fractions 9 and 10 contained about 30–40% of total cell yield and showed high steroidogenic potential. Granulosa cells from fractions 6, 7, and 8, which represent 55–60% of total cell yield, produced relatively low amounts of steroids on a per‐million‐cell basis. FSH was required for the stimulation of steroidogenesis. In granulosa cells from the PMSG treated rats, aromatase activity appeared maximally induced and incubation with FSH in vitro did not bring about any further increase. However, in vitro incubation with FSH was required for progesterone production. Furthermore, the granulosa cells from the PMSG treated rats also showed much more active estradiol and progesterone synthesis in fractions 9–12 as compared with lower density fractions. These studies suggest functional heterogeneity of granulosa cell populations in their response to FSH‐induced steroidogenesis. In addition, it was observed that in both models, there are two major populations of granulosa cells as evidenced by light and electron microscopy. The functional role of small and large granulosa cells in steroidogenesis is unclear; further studies

ISSN:0003-276X    

DOI:10.1002/ar.1092290204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractCauda epididymal guinea pig spermatozoa are arranged in rouleaux, with the sperm heads stacked one on top of the other; the plasma membranes over the apical segment of the acrosomes of adjacent sperm are linked and form non‐fusigenic “junctional” zones. A complex structural and temporal sequence of membrane fusions occurs during the acrosome reaction of guinea pig sperm in rouleaux. In this study, we have devised a procedure for dispersing the rouleaux and isolating a population of single, motile guinea pig sperm, and have investigated the ultrastructural features of the acrosome reaction in single sperm to determine if the pattern of membrane fusions is different from sperm in rouleaux. The rouleaux were dispersed using trypsin, and damaged cells were removed by passing the sperm suspension through a glass bead column; a population of 70–90% motile, acrosome‐intact, single sperm was obtained. Sperm were then induced to undergo lysolecithin‐mediated, “synchronous” acrosome reactions, and processed for transmission electron microscopy. The acrosome reaction involved a complex sequence of membrane fusions between the plasma membrane (PM) and outer acrosomal membrane (OAM). On the convex surface of the apical segment, sheets of hybrid membrane and parallel arrays of hybrid membrane tubules formed; filaments were associated with the luminal surface of the residual OAM in these regions. Hybrid membrane vesicles were produced on the concave surface of the apical segment, but fusion was delayed relative to the convex surface. In the principal segment, branching arrays of hybrid membrane tubules formed and later vesiculated. Hence, in single guinea pig sperm, the sequence of membrane fusions is similar to sperm in rouleaux except that fusion occurs in regions of the apical segment which form the non‐fusigenic PM “junctional” zones in rouleaux. The results suggest that, regardless of whether the acrosome reaction in vivo occurs before or after rouleaux dispersion, it will involve a complex sequence of membrane fusions which is determined by the structural propert

ISSN:0003-276X    

DOI:10.1002/ar.1092290205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe morphology of spermatozoa and the initial stages of spermegg fusion at fertilization were investigated ultrastructurally in the rose bitterling,Rhodeus ocellatus ocellatus. Each spermatozoon is composed of a spherical head without an acrosome, two centrioles, a large mitochondrion, and a flagellum. Freeze‐fracture of spermatozoa illustrates that specialized arrays of intramembranous particles (IMPs) are present on the protoplasmic facing (PF) surface of the head plasma membrane at the portion slightly in front of the centrioles. The specialized arrays, whose functions are uncertain, are parallelogram‐like in shape. The distribution of the particles is random and less compact in other areas of the head plasma membrane. The number of particles on the PF surface is larger than that on the extracellular facing (EF) surface. The complementary structures of the specialized arrays are also found on a similar portion of the EF surface. An ultrastructural study clearly shows fusion of gamete plasma membranes at the initial stages of sperm entry into the egg. Membrane fusion is first observed in eggs fixed 10 seconds after insemination in fresh water. The fusion site is the microvillus membrane of a sperm entry site on the egg and the head membrane of the spermatozoon. The plasma membrane fusion of gametes is discussed relative to the distribution of the IMPs and the fusion s

ISSN:0003-276X    

DOI:10.1002/ar.1092290206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractThe ischiourethralis (IU), a striated perineal muscle presumed to be involved in sexual reflexes, was studied in the rat. The paired muscle arises from the penile crus and the penile bulb and unites in a raphe over the deep dorsal vein of the penis. Retrograde tracing studies show that the muscle is innervated by neurons in the dorsolateral nucleus of the lumbar spinal cord, a pudendal nerve motor nucleus which also innervates the ischiocavernosus muscle. Excision of the IU muscle did not interfere with the ability of males to display normal copulatory behavior, nor did it affect significantly the number and intensity of reflexive erections. It nevertheless remains possible that the IU may contribute to intense glans erection by compressing the deep dorsal vein.

ISSN:0003-276X    

DOI:10.1002/ar.1092290207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractPraomys natalensis, an African rodent that is phenotypically and cytogenetically intermediate to rats and mice, possesses a submandibular gland that is histologically similar to that in both of these near relatives, but is ultra‐structurally unique. Acinar cells, which are seromucous in nature, contain secretory granules that often contain a perfect “bull's eye” inclusion (or some variant of this configuration) suspended in a dense matrix. The Golgi apparatus in these cells has an unusual structure, with the Golgi saccules often being doubled over, so that the outermost saccule also is the innermost. This peculiar architecture apparently arises fairly late in the secretory process, i.e., a Golgi apparatus of conventional structure gives rise to a nascent granule (condensing vacuole), then its saccules secondarily fold over. Intercalated ducts are preceded by a ring of specialized cells that have a number of serous‐type granules, the duct cells themselves being devoid of such granules. Granular convoluted tubules (GCT) contain large dense granules that appear to be spontaneously involved in chain exocytosis. These GCT granules probably are the repositories of nerve growth factor, which is particularly abundant inPraomys. Striated ducts for the most part are typical in appearance, but they and, to a lesser extent, GCTs contain prominent, membrane‐bound crystalloids with a periodicity of ab

ISSN:0003-276X    

DOI:10.1002/ar.1092290208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractAlthough much is known about the qualitative distribution of mucin‐secreting goblet cells in the small intestine, the quantitative distribution of stored mucins remains undefined. The purpose of this study was to determine the distribution of neutral stored mucin in the rat small intestine by using morpho‐metric techniques and once established, to verify that this methodology could detect secretion in animals exposed to a known mucin secretagogue. Twelve male Wistar rats (five baseline, five pilocarpine‐treated, and two vehicle controls) were fixed by vascular perfusion. After a brief fixation the intestine was removed, cut into 10 equal segments, sliced, and fixed overnight. Methacrylate sections from each segment were stained with periodic acid‐Schiff and toluidine blue. For mor‐phometry, the volume of epithelium per surface area of epithelial basal lamina was calculated with a Merz grid. The volume density of stored mucin per epithelium was determined by point‐counting on a square lattice grid. Volumes were related to either surface area of epithelial basal lamina or mucosal surface area. Due mostly to contributions by villus stored mucin, the total amount of product was found to increase proximally to distally in the small bowel, with the most dramatic increases occurring in the first three segments. When subjected to pilocarpine, a massive secretory response was evoked, resulting in a near total depletion of crypt stored mucin at all levels of the small bowel. Secretion of villus stored mucin also occurred throughout the small intestine, however reaching levels of significance at only a few points. This study describes the distribution of stored mucin in the small intestine under baseline and accelerated secretory

ISSN:0003-276X    

DOI:10.1002/ar.1092290209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractNew methods of tissue preparation were developed to study the morphology and distribution of calcium ions in duodenal enterocytes from normal, rachitic, and vitamin D‐replete (either cholecalciferol [CC] or 1,25‐dihydroxycholecalciferol [1,25‐DHCC]treated) chicks. Frozen hydrated sections were prepared from cryofixed tissues by ultracryomicrotomy at – 125° C. Sections were subsequently freeze‐dried by increasing the temperature to – 100°C. The latter temperature was maintained throughout both the structural and elemental analyses. In cells from normal, rachitic, and vitamin D‐treated [CC] animals the brush border from lanthanum‐infused tissues was electron dense and calcium‐lanthanum positive by x‐ray analysis. In the absence of lanthanum, i.e., sucrose‐infused duodena, the microvilli were still calcium positive. In the terminal web region of normal and CC‐treated enterocytes, numerous, apparently interconnected, tubules and vesicles were seen. Vacuole‐like structures were also seen. Such structures were especially prominent in the enterocytes from the vitamin‐treated [CC]animals. Except for the vacuoles, the tubules and vesicles were electron dense in the lanthanum‐infused duodena, and clear in sucrose‐infused tissues. In both instances, the structures were calcium positive. Similar, but even larger structures were seen below the terminal web. Here however, the tubules and vesicles seemed to be organized into multiple complex interconnecting networks, i.e., tubulo‐vesicular complexes. Both the tubules and the vesicles seemed to be interconnected via smaller channel‐like entities. The extensiveness of this structure was better appreciated in the enterocytes from lanthanum‐infused tissues, where it appeared similar in structure and complexity to an en face view of the sarcoplasmic reticulum of skeletal muscle. These intestinal complexes were less well developed, decreased in number, and quite often absent, in the apical cytoplasm of absorptive cells from rachitic chicks.In the enterocytes from animals treated for 24 hours with 1,25‐DHCC, the same highly developed tubulo‐vesicular networks were again seen in the enterocyte apical cytoplasm. They were even more developed in the 1,25‐DHCC‐treated animals. All structures were intensely calcium positive in enterocytes from both the lanthanum‐ and the sucrose‐infused preparations. Numerous endocytotic (pinocytotic) vesicles were seen at the lumenal plasmalemma. Similar structures were also apparent in the terminal web region of the 1,25‐DHCC‐treated enterocytes. Exocytotic vesicles were seen at the apical aspect of the lateral cell membrane, below the level of the junctional complex. All components of this unique system contained high concentrations of calcium. A similar, apically located, tubulovesicular complex has not been described in the enterocytes of conventionally prepared tissues obtained from either normal or vitamin D‐replete duodena from rats, mice, chicks, etc. Thus it appears that this system, which could play a role in intestinal calcium transport, is extremely labile and apparently not preserved (maintained) by ordinary biological fixatives and/or by routine methods used for the preparation of tissues for electron microscopy. Therefore, cryofixation, ultracryomicrotomy, etc., may prove to be essential for the identification of transiently induced states of cell activation associated with hormones, growth factors, nerve impulses, etc.Since the dilated components of the tubulo‐vesicular system described herein resemble (size, shape, density, etc.) the so‐called calcium lysosomes previously described by our group in normal and vitamin D‐replete chick enterocytes, the effect of 1,25‐DHCC on certain lysosomal acid hydrolases was determined. After 24 hours treatment with 1,25‐DHCC, there was a three to fourfold increase in the release of lysosomal enzymes such as acid phosphatase, cathepsin B, and B‐N‐acetyl‐D‐glucosaminidase into the medium of isolated enterocytes in comparison to untreated control cells. This would seem to indicate that the tubulo‐

ISSN:0003-276X    

DOI:10.1002/ar.1092290210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY

摘要:

AbstractEarly studies in certain avian and mammalian species have described estrogen‐associated bone‐cell changes, which were based on bone cells that were neither quantified nor identified histochemically (osteoclasts). In the experiments described here, weanling female mice were given a pharmacological dose of 17β‐estradiol benzoate (1 mg/week) for 1 and 4 weeks, and changes in osteoclasts and osteoblasts were assessed in tibial metaphyses and diaphyses. In the proximal metaphysis, the number of osteoclasts/mm surface length was significantly reduced by estrogen at 1 week (43%) and 4 weeks (64%), which was accompanied by significant increases in the number of osteoclasts in the marrow space not in contact with bone surfaces (no./mm2: 382% and 999%, respectively). These increases, along with observations of decreased osteoclast size (19%), of changes in osteoclast morphology, and of numerous acid‐phosphatase‐positive fragments in the marrow space, suggest that estrogen treatment causes the dissociation and disintegration, and thus decreased activity, of osteoclasts. The above changes were accompanied by more than 48% increases in the number of trabecular osteoblasts. In the diaphysis, the number of endosteal osteoclasts was significantly decreased by estrogen at 1 week (32%), but was not significantly changed at 4 weeks. These changes were attended by significant increases in the number of osteoclasts in the marrow space not in contact with bone surfaces (no./mm2: 393% at 1 week and 342% at 4 weeks). The number of endosteal osteoblasts was also increased by estrogen at 1 week (132%), and so was the size of endosteal osteoblasts (39% at 1 week and 81% at 4 weeks). Comparable results were obtained when a lower dose of 17β‐estradiol benzoate (20 μg/week) was given to ovariectomized mice. The increase in bone mass and its associated cell changes following estrogen treatment were also found in athymic nude mice, suggesting that these bone/bone cell changes are independent

ISSN:0003-276X    

DOI:10.1002/ar.1092290211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1991

数据来源: WILEY