摘要:

AbstractOrthotopic transplants of whole extensor digitorum longus muscles were performed on six 4–6‐week‐old 129 ReJ mice. One hundred days posttransplantation, the animals were killed and the regenerated muscles were processed for electron microscopy. The grafts contained polygonal‐shaped myofibers with persistent central nuclei, organized into discrete muscle fascicles. No central area of fatty infiltration or fibrosis was observed. The mean number of myofibers in a regenerating transplanted muscle, as determined from an ultrathin section taken from the graft's widest girth, was 631 (SEM = ± 59), a reduction of ∼ 32% from that found in age‐matched control muscle (Ontell et al., 1983). By following the myofibers in spaced, serial ultrathin sections along their length, it was found that the branched, regenerating myofibers found in immature grafts of normal muscle (Ontell et al., 1982) persisted in stabilized, long‐term transplanted muscle. The frequency of branching was determined by following each fiber found at the widest girths of four of the grafts in spaced, serial ultrathin sections (15‐μm intervals) for ∼2% of the total length of the grafts. Over this distance, 6.6% of the fibers were involved in the branching phenomenon. The persistence of branched fibers in long‐term grafts and the frequency with which the branching phenomenon was found to occur may have physiological consequences and s

ISSN:0003-276X    

DOI:10.1002/ar.1092090304

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe distribution of approaches of rough endoplasmic reticulum to the cell membrane within the supranuclear region of the secretory ameloblast of the rat incisor was quantitated using a Zeiss MOP‐3. In ameloblasts cut in cross section, most of these approaches appear as circular profiles representing cross sections of elongated cisternae, which are aligned parallel to the long axis of the cell. Because of their position, orientation, and distribution of ribosomes, these approaches were consistent with the appearance of subsurface cisternae. Using cross‐sectioned ameloblasts, the lengths of apposed plasma membranes either between or within rows of cells were measured from electron micrographs. Along these lengths, matched approaches of rough endoplasmic reticulum from opposite sides of the apposed plasma membranes were counted. Approaches from either side that were unmatched were also counted. Thirteen percent of the approaches were matched between rows of ameloblasts, and 13.5% of the approaches were matched within rows, demonstrating no significant difference between the two sites. Furthermore, mathematical analysis showed that the theoretical probability of two approaches coinciding is 17%. The experimental values are not statistically different from the theoretical probability, and it is concluded that the matching of rough endoplasmic reticulum approaches to the plasma membrane, or subsurface cisternae, occurs at ran

ISSN:0003-276X    

DOI:10.1002/ar.1092090305

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

年代:1984

数据来源: WILEY

摘要:

AbstractNerves exhibiting substance P‐like immunoreactivity were demonstrated in the human periosteum. A network of nerves showing substance P‐like immunoreactivity was seen in the periosteum, while finer strands of immunoreactive nerve fibers were present immediately beneath the surface of the periosteum. Enkephalin‐like immunoreactivity was also studied but could not be demonstrated.Substance P has previously been suggested to be involved in the mediation of the sensation of pain. The clinically observable marked pain sensitivity of periosteal tissue might be explained by the peptidergic nerves described in this

ISSN:0003-276X    

DOI:10.1002/ar.1092090306

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe muscle fibers of the cranial slip of M.pectoralis pars thoracicaof an emu (Dromaius novaehollandiae) were studied histochemically for intracellular lipid, succinic dehydrogenase, myofibrillar adenosine triphosphatase, and acetylcholinesterase. It was concluded that the muscle consisted of approximately 28% slow‐tonic and 72% fast‐twitch glycolytic fibers. The tonic fibers were considered to be characteristic of a postural muscle, and the fasttwitch glycolytic fibers to reflect the inability of the muscle to engage in sustained activity. The general absence of slow‐tonic fibers from the pectoralis of other avian species so far studied may be attributed to inadequate sampling of the deeper regions of the m

ISSN:0003-276X    

DOI:10.1002/ar.1092090307

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

年代:1984

数据来源: WILEY

摘要:

AbstractVincristine (VC) was used to arrest metaphases in the epithelium of the cornea and rectum. The cornea was studied by light microscopy (mitotic index). The rectum was analyzed by flow cytometry (%G2+M). The results of a dose range finding study showed that 3.0 mg/kg body weight VC did not increase the number of metaphases in the cornea or the %G2+M for the rectum over that recorded for a dose of 1.0 mg/kg VC. Therefore 1.0 mg/kg VC was selected as the dose to use. Mice were kept on a 12:12 light‐dark cycle with light from 0600 to 1800. Mice were treated with 1.0 mg/kg VC at either 0200 or 1400. 0200 is a time when the native mitotic index is increasing toward a peak level, which is attained at 0800–1000 under these conditions. 1400 is a time when the mitotic index is decreasing to trough level, which is attained at 2000 to 2200. In one experiment, subgroups of mice were killed at +3 (0500 or 1700) and +6 (0800 or 2000) hours after VC. In a replicate experiment subgroups were killed at +2 (0400 or 1600), +4 (0600 or 1800), and + 6 (0800 or 2000) hours after VC. The data from the cornea (mitotic indices) and the rectum (%G2+M) were graphed against time. For both organs the slope of the metaphase accumulation line was different when VC at 0200 data were compared to VC at 1400 data. The conclusion reached was that by changing the biological time of the experiment one can significantly change the slope of the line obtained with the stathmokinetic techni

ISSN:0003-276X    

DOI:10.1002/ar.1092090308

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

年代:1984

数据来源: WILEY

摘要:

AbstractBiochemical analyses ofSqualustestis indicates that key enzymes involved with androgen production increase progressively from immature regions containing spermatogonia to mature regions in the late spermatid stage of maturation (Canick et al., 1983). In an effort to identify cells possessing the cytological characteristics of steroid production and to determine the structural correlates of the observed functional changes, we have carried out an electron microscopic study ofSqualustestis. This report demonstrates that Sertoli cells contain a well‐developed agranular reticulum, mitochondria with tubulovesicular cristae, and numerous lipid droplets. Moreover, as germ cells mature, there is an increase in abundance of agranular reticulum in the adjacent Sertoli cells. By the time of spermatid elongation, this has reached dramatic proportions and fills the Sertoli cell as a mass of tubules. These results lead us to conclude that the Sertoli cell is responsible for secretion of the increasing amounts of androgen during the spermatogenetic cycle inSqualu

ISSN:0003-276X    

DOI:10.1002/ar.1092090309

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe site of hormone synthesis in the testis of elasmobranchs has been the subject of much controversy. This is primarily due to the problem of whether Leydig cells are present or absent in the testes of many species of elasmobranchs. In previous studies we have shown that key enzymes associated with the biosynthesis of androgen increase in activity during the spermatogenetic cycle ofSqualus acanthias(Canick et al., 1983). To determine the site of this activity we undertook an electron microscope study ofSqualustestes to identify cells that possessed the structural correlates of steroid production. This report describes cells present in the interstitial tissue that are morphologically analogous to Leydig cells occurring in the testes of higher vertebrates. Although these cells possessed an agranular reticulum, tubulovesicular mitochondria, and lipid droplets, they were mesenchymal in appearance. We have, therefore, preferred to describe these cells as Leydig‐lik

ISSN:0003-276X    

DOI:10.1002/ar.1092090310

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

年代:1984

数据来源: WILEY

摘要:

AbstractSubcutaneous autografts of ovarian tissue were made in unilaterally ovariectomized adult rats and were examined by light microscopy at various times after implantation. The implants were surrounded by a dense connective tissue capsule. They were well vascularized and contained follicles in varying stages of development as well as in different stages of atresia. Oocytes and fresh corpora lutea indicated that grafts ovulated in the presence of the in situ ovary but that the number of ovulations and their frequency were reduced when compared to normal ovaries or ovaries grafted in bilaterally castrated animals. Ovulation results in the formation of a cyst that contains follicular fluid, the oocyte, and cumulus in the ovarian stroma. Macrophages are associated with the oocyte‐cumulus complex but are not prominent in association with the fluid in the cyst. It is suggested that follicular fluid is retained owing to inefficient resorption mechanisms and that this coupled with occasional ovulations results in the formation and maintenance of the large cyst

ISSN:0003-276X    

DOI:10.1002/ar.1092090311

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe locomotion of chick primordial germ cells (PGCs) in vitro was observed using 16‐mm time‐lapse microcinematography and 35‐mm timelapse film. The PGCs isolated from circulating blood of stage 14 to 16 embryos (Hamburger and Hamilton, 1951) were cultured on a substrate of mesenchymal feeder cells obtained from the dorsal mesentery of stage 40 embryos, using modified medium 199 containing 10% fetal calf serum. The PGCs were found to move actively and to show a tendency to move along the longer axis of the underlying cells. The velocity of PGC locomotion averaged 26 μm/hr and reached 58 μm/hr as a maximum.After observation, the PGCs were processed for scanning electron microscopy. They had a considerable number of microvilli about 0.2 μm in thickness and some cytoplasmic blebs on their surfaces. It was observed that the PGCs in the migrating phase adhered to the substrate with its filopodia only at the leading edge, while a large part of the cell appeared to be apart from the s

ISSN:0003-276X    

DOI:10.1002/ar.1092090312

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

年代:1984

数据来源: WILEY

摘要:

AbstractThe secretory acinar cells of parotid glands from rats of varying ages have been examined by electron microscopy to determine what age‐related changes occur in these cells. The most prominent change noted in these cells is the progressive increase in the amount of lipofuscin granules with age. Lipofuscin granules are membrane‐bound structures consisting of lipids, other subcomponents, and a matrix. In addition, these cells contain lipid droplets that are not associated with any other components and tend to accumulate at the base of the cells in older rats. Also, many acinar cells in the glands of old rats contain altered secretory granules which appear to be in the process of degeneration. The accumulation of lipid and degenerating secretory granules appears to be related to the reduced level of cellular secretory activity in the glands of older rats. It is possible that these two types of inclusions contribute to the formation of lipofuscin granules. Lipofuscin and degenerating secretory granules are associated with acid phosphatase, which is demonstrated cytochemically, indicating that these granules are lysosomal structu

ISSN:0003-276X    

DOI:10.1002/ar.1092090313

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

年代:1984

数据来源: WILEY