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PubMed1991

Histochemical and ultrastructural observations on brown degeneration of human intervertebral disc.

Thirty-eight fresh human intervertebral discs collected during anterior interbody fusion surgery were histochemically and ultrastructurally analyzed for pigments. Macroscopically, five stages of degeneration were classified according to the color, fibrosis, and fragility of the nucleus pulposus of the discs. In order to demonstrate lipofuscin granules, specimens were subjected to special staining procedures, including carbol fuchsin lipofuscin stain, the Schmorl's reaction, and autofluorescence. Lipofuscin granules were distributed from the inner layer of the annulus fibrosus to the nucleus pulposus. Such granules were numerous in cases of slight or severe degeneration, whereas fewer granules were found in cases of moderate degeneration. However, the stage of macroscopic degeneration of the intervertebral disc did not necessarily correlate with the incidence of lipofuscin granules. By ultrastructural observation, the morphological features of the components of the intervertebral disc and the ultrastructure of the lipofuscin granule were clarified. The ultrastructure of the "brown degeneration" disc exhibited markedly increased amorphous electron-dense bodies located among collagen fibrils in the matrix.

Adult↗
PubMed1977

The ultrastructure of skeletal haemangiosarcomas induced in mice by strontium-90.

The commonest skeletal tumour occurring in male CBA and C3H mice injected with 7--13 muCi 90Sr (per mouse) at Harwell was diagnosed with the light microscope as haemangiosarcoma. On the other hand, Nilsson, using male CBA mice injected with similar amounts of 90Sr, recorded the predominant tumour as fibroblastic osteosarcoma. To resolve the apparent discrepancy, samples of non-osteogenic tumours induced by 90Sr at Harwell were examined with the electron microscope and their ultrastructure compared with that described for fibroblastic osteosarcoma by Nilsson. The tumours diagnosed as haemangiosarcoma at Harwell showed ultrastructural features not observed in the fibroblastic osteosarcomas. Vasoformation was marked, the vascular channels varying in shape, size and in the character of their lining cells. Some vascular channels were lined by cuboidal cells, crowded together, and surrounded by a basement membrane. Others were lined by an attenuated endothelium and often formed networks. The tumour cells showed great variation in shape, size and ultrastructure and were sometimes enclosed by a basement membrane. Thus the ultrastructure of the tumours described in this report supports the diagnosis of haemangiosarcoma, rather than fibroblastic osteosarcoma. The question of whether these haemangiosarcomas truly originate from vascular endothelium, or are mimics, is discussed.

Animals↗
PubMed1985

Quantitative and ultrastructural study of Leydig cells in Klinefelter's syndrome.

This ultrastructural and quantitative study of Leydig cells in Klinefelter's syndrome has been performed using the entire testes obtained from four autopsies plus testicular biopsies from 20 patients. The total Leydig cell volume per testis in Klinefelter's syndrome was similar to that of control testes. However, the total number of Leydig cells per testis was significantly lower in the patients with Klinefelter's syndrome than in the controls. This may be attributed to the Leydig cell hypertrophy that these patients underwent. In patients with Klinefelter's syndrome the average volume of each Leydig cell was significantly higher than that of the controls. Electron microscopic findings revealed that besides ultrastructurally normal Leydig cells there were three other morphologically abnormal Leydig cell types: abnormally differentiated cells; multivacuolated cells; and immature Leydig cells. The ultrastructurally normal Leydig cells were probably the cells principally responsible for testosterone biosynthesis in these patients, whereas the other Leydig cell types were probably barely or not at all functional. The hypertrophy showed by the ultrastructurally normal Leydig cells may be interpreted as an attempt to increase testosterone production.

Adult↗
PubMed1993

Ultrastructural heterogeneity in undifferentiated bronchial carcinoma.

Electron microscopy is often suggested as a useful aid to the classification of light microscopically undifferentiated bronchial malignancies, features such as dense-core vesicles, desmosomes or tonofilaments, and microacini, allowing their designation as endocrine, squamous, or adenocarcinomas respectively. However, there is no reason to suppose that the heterogeneity of malignant bronchial tumours so often apparent by light microscopy or on immunolabelling might not occur at the ultrastructural level too. Extensive sampling of all deposits from eight subjects coming to necropsy with undifferentiated bronchial carcinoma revealed ultrastructural features of glandular and squamous differentiation to be widespread and often to occur together, although dense-core vesicles were not seen in any of the tumours studied. Heterogeneity was present within individual tumour deposits and particularly between different deposits of those tumours which had disseminated, such that any ultrastructural diagnosis would have been significantly influenced by sampling. Such variation should be borne in mind when ultrastructural features are used to classify bronchial malignancies.

Bronchial Neoplasms↗
PubMed1988

Ultrastructure of first trimester chorionic villi with regard to the prenatal diagnosis of genodermatoses.

Hopes are held out for chorion villus sampling, a technique which is gaining more and more importance for the first trimester prenatal diagnosis of chromosomal aberrations and metabolic abnormalities. A variety of inherited skin diseases can be diagnosed postnatally and prenatally (in the second trimester) by ultrastructural diagnostic markers. For evaluation of prenatal diagnosis in the first trimester, we investigated chorionic villi derived from the trophoblast layer of the early pregnancy by light microscopy and conventional electron microscopy. The ultrastructure of the cellular layers covering the villi, i.e., the inner cytotrophoblast and the outer syncytiotrophoblast, as well as that of the connective tissue of the inner extraembryonic mesoderm, are thoroughly described in relation to the ultrastructural changes in certain genodermatoses including epidermolyses and keratinization disorders. We found that chorionic villi have only a few of the characteristics differentiated in skin, and none of the structures which are relevant to the diagnosis of genodermatoses. In our view, the ultrastructural approach is not suitable for first trimester prenatal diagnosis of genodermatoses in chorionic villi.

Chorionic Villi↗
PubMedDate not supplied

Ultrastructure and reproduction behaviour of single CHO-K1 cells exposed to near infrared femtosecond laser pulses.

In the present work, the authors investigated ultrastructural changes as well as the reproduction behaviour of preselected single CHO-K1 cells exposed to 170 femtosecond laser pulses at different power output levels in comparison with cells outside the illumination volume. The ultrashort laser pulses were provided by an 80 MHz Ti:sapphire laser at 780 nm. The cells were scanned ten times with a scan rate of 1/16 s(-1). Single CHO-K1 cells exposed to low mean power of 2 mW revealed no significant changes in ultrastructure after laser exposure. In some cases, changes of mitochondria with slight disordering of cristae were found. Cytoplasm was filled with vesicles that seemed to be released from Golgi stacks. Cells irradiated with higher powers demonstrated more dramatic changes in ultrastructure. A considerable number of swollen mitochondria in conjunction with loss of cristae was observed. The main event of mitochondrial changes was the formation of electron dense bodies in the mitochondrial matrix. In addition, lumen of endoplasmatic reticulum was enlarged. Highest applied mean laser power of 12.5 mW lead to complete destruction of mitochondria and their transformation to electron dense structures containing membrane material. Compared with cell targets irradiated with 2 mW mean power, the release of vesicles from Golgi stacks seemed to be rather moderate. Cells localised outside the laser beam revealed no ultrastructural changes. Low mean laser power at 2 mW was unable to impair the reproduction behaviour of CHO-K1 cells. At higher laser power output levels, CHO-K1 cells started to delay cell division. At 12.5 mW, no cell division occurred. The obtained results may be helpful in recommending parameters for safe femtosecond laser microscopy of living specimens.

Animals↗
PubMed1995

Ultrastructural correlates of haloperidol-induced oral dyskinesias in rat striatum.

Neuroleptics given chronically to rats induce behavioral sequelae which mimic tardive dyskinesia in some respects. The intent of this study was to investigate the ultrastructural correlates of oral dyskinesias (vacuous chewing movements [VCMs]), induced by chronic haloperidol treatment. After 6 months of treatment, rats were divided into low or high VCM groups. Rats in the high VCM group were either sacrificed on drug or were withdrawn from drug for 4 weeks. Ultrastructural analyses of the striatum indicated that synaptic density: 1) was significantly decreased in both the low and high VCM groups compared to normal controls; 2) was more profoundly decreased in the high VCM group as compared to the low VCM group; and 3) recovered to normal following drug withdrawal. Compared to controls, the density of asymmetric synapses was reduced by a similar magnitude in both the low and high VCM groups, suggesting that this change is a result of haloperidol treatment and independent of VCMs. Conversely, the density of symmetric synapses was reduced compared to normal, only in the high VCM group, suggesting that this change is specifically related to the expression of VCMs. In addition, mitochondrial profiles were hypertrophied and less frequent in the high VCM group in comparison to controls; size, but not number, recovered following drug withdrawal. These results identify distinct ultrastructural correlates of chronic haloperidol treatment that are unique to rats that develop VCMs and suggest that these ultrastructural features may play a role in the pathophysiology of oral dyskinesias in rats.

Animals↗
PubMed1991

Ultrastructure and function of the rat yolk sac: damage caused by teratogenic anti-VYS serum and recovery.

It was hypothesized that heterologous anti-rat visceral yolk sac serum (AVYS) exerts its teratogenic effect by reducing the endocytosis of serum proteins by the visceral yolk sac (VYS), thus reducing the supply of amino acids to the embryo and VYS. To evaluate this hypothesis, we studied the effect of teratogenic AVYS on the endocytic function of the VYS and the ultrastructure of the VYS and parietal yolk sac (PYS). Rat conceptuses were exposed to a teratogenic dose of AVYS on the 10th day of gestation in vivo or in vitro. Control and AVYS-exposed specimens were collected 24-192 hr later and prepared for scanning and transmission electron microscopy (SEM and TEM, respectively) utilizing standard procedures. The Endocytic Index was calculated for the VYS utilizing standard procedures. Approximately 97% of the in vivo exposed and 94% of the in vitro exposed embryos were morphologically abnormal. Ultrastructural observations showed that exposure to AVYS in vivo or in vitro caused severe damage to the VYS endodermal epithelial cells with loss of cellular borders, reduction in the number and length of microvilli, and increased cellular inclusions; and some damage to PYS endodermal cells with increased blebbling and decreased cell number. Recovery was evident at 72 hr and complete by 96 hr. The Endocytic Index was significantly reduced in the VYS 24 and 48 hr after injecting AVYS into the pregnant rat but was not significantly different at 96 and 192 hr. Our results show that the AVYS antiserum damaged visceral endodermal epithelium experienced ultrastructural recovery with parallel functional recovery. These studies suggest that transient yolk sac placental ultrastructural damage and dysfunction was probably sufficient to cause irreversible damage to the developing embryo during early organogenesis. We conclude that the proximate effect of the AVYS was on the plasma membrane of the visceral endoderm and that decreased pinocytosis is a consequence of this effect.

Animals↗
PubMed1994

Ultrastructural localization of filamentous actin within neuronal interphase nuclei in situ.

Previous biochemical studies utilizing isolated nuclei and nuclear matrices have shown actin to be a constituent of the interphase nucleus. In addition, recent ultrastructural work has shown the presence of actin and myosin within nuclei of interphase cells in situ. It was unclear, however, whether this intranuclear actin is present in the unpolymerized globular actin or the filamentous (F)-actin form. The present work, using confocal microscopy and ultrastructural cytochemical techniques, demonstrates the presence of F-actin within interphase nuclei of intact, uncompromised, dorsal root ganglion neurons in vitro and in vivo. Labeling by FITC-phalloidin detected the presence of intranuclear F-actin adjacent to the nucleolar periphery in a small fraction of cells in vitro, an observation confirmed by three-dimensional reconstruction. Ultrastructural analyses of cells exposed to heavy meromyosin (HMM), showed the presence of typical "arrowhead" complexes. The observation that these complexes were associated with nucleoli confirms that the intranuclear ligand detected by FITC-phalloidin indeed represents F-actin. Postembedding labeling with HMM conjugated to 20-nm colloidal gold (HMM-Au20) resulted in labeling similar to that obtained with HMM. However, HMM-Au20 was found to label a much larger fraction of cells, both in vitro and in vivo, than did FITC-phalloidin or HMM. This finding indicates that labeling with HMM-Au20 more accurately reflects the extent of actin polymerization in nuclei. Results from double labeling with HMM-Au20 and an antibody to alpha-sarcomeric actin confirmed that only a small amount of nuclear actin is in the F-form. Together, these results represent a first ultrastructural demonstration of the presence of F-actin in nuclei of neurons. While the role of nuclear F-actin has yet to be defined, the results suggest that F-actin may represent a component of the molecular motor responsible for the dynamic positioning of specific chromatin domains into the tissue-specific, nonrandom patterns observed in many cell types.

Actins↗
PubMed1997

Ultrastructural and immunocytochemical studies of prolactin-secreting cells in adenohypophysis of the mink (Mustela vison).

This investigation aimed to identify, by the double immunogold procedure, the ultrastructural characteristics of prolactin (PRL) cells in the mink. Such cells showed a marked pleomorphism and had a close topographic relationship with growth hormone cells. A common morphological characteristic of PRL cells in all stages of mink development was the presence of round secretory granules, in contrast to changes in the ultrastructural characteristics of PRL cells with physiological state and photoperiod. Thus PRL cells in prepubertal, pubertal, and sexually inactive adult mink, killed under a short-day photoperiod, showed little development of the organelles but a significantly increased cytoplasmic electron density. In sexually active mink and in lactating females under long-day conditions, PRL cells had a highly developed cytoplasmic organelle structure consisting mainly of rough endoplasmic reticulum. The morphometric study demonstrated that the mean diameter of the secretory granules similarly varied in both sexes. Pubertal mink had PRL cells with smaller secretory granules (female 74.1 +/- 0.6 nm, male 80.4 +/- 1.7 nm), whereas adult mink killed under a long-day photoperiod presented PRL cells with larger secretory granules (female 194.5 +/- 2.2 nm, male 203.3 +/- 1.7 nm). The changes in the ultrastructural characteristics of PRL cells during the annual cycle suggest a photoperiodic influence upon these cells. In addition the heterogeneity in ultrastructural characteristics and storage characteristics of PRL in some adult mink may suggest a varying metabolic role for PRL under certain, as yet not fully characterized, conditions.

Aging↗
PubMed1995

Ultrastructural characterization of normal and abnormal chondrogenesis in micromass rat embryo limb bud cell cultures.

Inhibition of chondrogenesis in limb bud cell micromass cultures has been proposed as a short-term teratogen detection test. Validation studies were performed by testing large series of reference compounds and comparing their teratogenic potential with their ability to inhibit chondrogenesis; however, there are few reports describing the histological and ultrastructural changes associated with inhibition of chondrogenesis in vitro. The objective of this study was to provide a qualitative description of the histological and ultrastructural alterations induced by three chondrogenesis inhibitors: retinoic acid (RA) and 6-aminonicotinamide (6AN), two teratogens, and doxylamine succinate (DS), a nonteratogen compound. In addition, in order to have a basis for the interpretation of the morphological alterations induced by the test compounds, the histological and ultrastructural changes which occur during the time course of chondrogenesis in control cultures were described and compared with those in rat embryo limb buds. We found that RA at 0.5 micrograms/ml led to a marked decrease in the number and size of cartilaginous foci; most cells lacked morphological signs of differentiation but their ability to proliferate was unaffected. At concentrations of 2 micrograms/ml and more, 6AN delayed cell proliferation, reduced staining of the extracellular matrix, and induced the formation of endoplasmic cisternae. DS at 50 micrograms/ml affected both differentiation and proliferation; pigment deposits were observed in chondrocytes, suggesting phospholipid metabolism disorders. In conclusion, this study showed that inhibition of chondrogenesis in this simple cell culture system can be associated with different types of histological and ultrastructural alterations. Examination of these alterations can provide useful information about the teratogenic potential of tested compounds and their mechanism of action.

6-Aminonicotinamide↗
PubMed1995

Gastrointestinal autonomic nerve tumours and their separation from other gastrointestinal stromal tumours: an ultrastructural and immunohistochemical study of seven cases.

Gastrointestinal stromal tumours (GIST) represent a heterogeneous group whose classification frequently requires ultrastructural and immunohistochemical studies. In a retrospective study of the ultrastructural findings of 24 gastrointestinal stromal tumours, whose light microscopic study has yielded ambiguous results and in which accurate diagnosis had required ultrastructural support, seven were found to have the characteristics of gastrointestinal autonomic nerve (GAN) tumours. In all of them the diagnosis was based on the presence of dendritic processes with dense neuroendocrine granules. Immunohistochemically, the seven tumours were negative for smooth-muscle markers. All stained positively for vimentin. NSE, chromogranin, and synaptophysin were positive in most of them, while S-100 protein was positive only in two cases. We present the ultrastructural and immunohistochemical features of seven GANT against the background of the GISTs of our series. We conclude that GAN tumours cannot be diagnosed by light microscopy alone but this tumour group displays characteristic electron microscopic and immunohistochemical features and appears to represent a distinct type of GIST.

Adult↗
PubMed1994

Differential ultrastructural aberrations of collagen fibrils in Ehlers-Danlos syndrome types I-IV as a means of diagnostics and classification.

Among the different subtypes of Ehlers-Danlos syndrome (EDS), the dominant types I-III have, so far, been uninformative biochemically and molecular genetically, and diagnostic problems with subgroup boundaries often arise. We have investigated the ultrastructural pattern of connective tissue macromolecules in skin biopsy specimens of some 85 patients aged 4 months-54 years who exhibit clinical symptoms or the suspicion of EDS I-IV. Based on the differential features of collagen fibrils and ground substance material, four distinct groups could be established. Group I (clinically EDS type I) showed disorganized collagen bundles and dense aggregations of collagen fibrils with bizarre shapes. Group II (clinically varying from EDS types I-III) revealed collagen bundles that regularly contained numerous "composite collagen fibrils" with enlarged "flower-like" cross-sections and rope-like longitudinal sections, often associated with increased amounts of matrix substances in the form of electron-dense irregular strands and filaments in a branched network. Group III (clinically EDS types II-III) presented smaller isolated collagen flowers and ropes associated with excessive filamentous ground substance material and flocculent material. Group IV (with clinical symptoms of EDS type IV) had a dermis thinned to one third of the normal and a reduced number of collagen bundles with small diameter fibrils. In 13 patients, the abnormal ultrastructural dermal architecture did not coincide with any of these four groups or with the pattern of any other inherited connective tissue disorder. In 16 additional patients with mostly mild clinical symptoms, such as muscle weakness and small joint hyperlaxity, no ultrastructural aberrations could be found. Even though the primary defects underlying the respective aberration of the collagen fibrils are still unknown, the differential ultrastructural changes of the collagen fibrils together with clinical symptoms should, as in other heterogeneous genetic disorders, facilitate the (provisional?) classification of EDS and permit the diagnosis of individual cases.

Adolescent↗
PubMed1982

Immunocytochemical and ultrastructural correlates of the pineal inhibition of prolactin cell activity in blind-anosmic female rats.

The effects of the pineal gland on the light microscopic-immunocytochemical and ultrastructural appearance of pituitary mammotrophs were studied in female rats eight weeks after prepubertal blinding and olfactory bulbectomy. Blinding and anosmia resulted in a marked decrease in the size of the pars distalis concomitant with a reduction in the apparent number and size of PRL cells as compared with intact animals. Ultrastructurally, these cells appeared much less active than those of intact rats. The small and angular-shaped mammotrophs of blind-anosmic rats characteristically exhibited scant arrays of rough endoplasmic reticulum, small Golgi complexes with few immature secretory granules, few mature secretory granules and rare exocytosis patterns. Pinealectomy tended to reverse the effects of blinding and anosmia on pars distalis size and PRL cell size, apparent number and ultrastructure. In fact, the mammotrophs of blind-anosmic-pinealectomized rats were quite similar in ultrastructural appearance to those of intact rats. From these data we conclude that the pineal causes mammotroph hypotrophy and hypoplasia in blind-anosmic female rats.

Animals↗
PubMed1987

The sequence of ultrastructural changes in cultured neurons after dendrite transection.

Cultured mouse spinal neurons were fixed at three different intervals after dendrite amputation: within the first 15 min, at 2 h and at 24 h. Dendrites were amputated at lesion distance of either 50 microns (31% probability of cell survival) or 100 microns (53% probability of cell survival) from the edge of their perikarya. When fixed within 15 min, operated neurons showed a two-phase gradient of ultrastructural damage which spread from the transection site towards the perikaryon. At 2 h after dendrite amputation all neurons operated close to their perikarya were categorized as either viable, moribund or dead, based on their appearance with phase contrast microscopy. These categories of response to physical trauma corresponded to distinctly different ultrastructural changes. Moribund neurons were filled with membrane-bound vesicles which were derived from swollen mitochondria and grossly dilated cisternae of the smooth endoplasmic reticulum. The cytoplasm of dead neurons contained large clear areas and many condensed, dark mitochondria. Both moribund and dead neurons lacked cytoskeletal elements. All of these ultrastructural changes are hypothesized to be the result of an increase in the intracellular concentrations of free calcium. Although evidence of residual mitochondrial swelling was present in some surviving neurons at 24 h, the ultrastructure of others was comparable to that of control cells. Some surviving neurons had terminal swellings at the ends of the severed neurites which were very similar to retraction balls of transected axons after CNS trauma.

Animals↗
PubMed1990

Stress-induced peptide release from rat intermediate pituitary. An ultrastructural analysis.

We tested the hypothesis that acute restraint stress results in ultrastructural evidence for enhanced release of alpha-melanocyte-stimulating hormone (alpha-MSH) and beta-endorphin from the intermediate lobe (IL) of the rat pituitary. Measurements of plasma alpha-MSH- and beta-endorphin-immunoreactivity (ir) were used to confirm ultrastructural findings. Plasma alpha-MSH-ir was elevated after 20 and 30 min of restraint while plasma beta-endorphin-ir peaked 10 min after the onset of restraint. Ultrastructural analysis revealed a decrease in the content of secretory granules within IL cells of stressed rats. Analysis of Golgi-related immature secretory granules in IL cells indicated that new peptide synthesis was not enhanced after 30 min of restraint. These results confirm previous studies showing an elevation of plasma beta-endorphin and alpha-MSH-ir during acute restraint. Furthermore, these results indicate that quantitative analysis at the ultrastructural level can be used to assess peptide release from IL secretory cells during stress.

Animals↗
PubMed1983

Uterine glands of the pig during pregnancy. An ultrastructural and cytochemical study.

The ultrastructure of the porcine uterine glands is described from material taken from 11 pregnant pigs at exactly known stages of gestation (day 30; 58; 80; 100; 110). Fixation was performed by perfusion via a branch of the uterine artery and the tissue was routinely processed for electron microscopy. Additionally, cytochemical studies (phosphotungstic acid reaction for glycoproteins, according to Rambourg 1967; acid phosphatase reaction; ultrastructural localization of cellular iron, according to Parmley et al. 1978) were performed. On day 30 of pregnancy the uterine glands are coiled, simple tubular glands with a narrow lumen. The epithelial lining is simple columnar and consists basically of two cell types, ciliated cells and secretory cells. The secretory activity of the glandular epithelium is low; only a few secretory granules are present in the supranuclear cytoplasm. At midpregnancy the ultrastructure of the glands has significantly changed and the cells now show all the characteristics of high secretory activity: numerous parallel cisternae of rough endoplasmic reticulum, an extensively developed Golgi apparatus and many secretory granules which give a positive reaction for acid phosphatase and glycoproteins. The lumina of the glands are significantly enlarged and filled with a great amount of a granular, acid phosphatase-positive material. In the last third of pregnancy, only minor changes in the ultrastructure of the uterine glands are observed. The secretory activity is still high. The amount of rough endoplasmic reticulum has further increased and parallel arrays of cisternae occupy a considerable part of the supranuclear cytoplasm. The importance of the uterine secretion for embryonic nutrition and development is only partly understood. One of the secreted glycoproteins, uteroferrin, is believed to play an important role in the iron transfer from mother to fetus. From midpregnancy onward, a special cell type, the "granule laden cell" is found scattered between normal secretory cells of the uterine glands. Contrary to the opinion of Perry and Cromby (1982), we could demonstrate that these cells frequently extend to the lumen of the gland; hence the term "basal cell" seems inappropriate for this cell type.

Acid Phosphatase↗
PubMed1985

The ultrastructure of sensory nerve endings in the human knee joint capsule.

The ultrastructure of sensory nerve endings in the human knee joint capsule was studied. Three types of nerve endings were found: free nerve endings (FNE), Ruffini corpuscles and Pacini corpuscles. In the joint capsule, FNE are located below the synovial layer and within the fibrous layer near blood vessels. These nerve terminals derive from myelinated A delta-fibres or from unmyelinated C-fibres. Their structure is almost identical to FNE in human hairy and non-hairy skin. Ruffini corpuscles are present within the fibrous layer and the ligaments of the capsule in three variations: small Ruffini corpuscles without a capsule, small with a connective tissue capsule, and large Ruffini corpuscles with an incomplete perineural capsule. Their afferent axons are myelinated and measure 3-5 micron in diameter. Inside the corpuscle, nerve terminals are anchored in the connective tissue belonging to the fibrous layer or to the ligaments respectively. The presence of an incomplete perineural capsule depends on the structure of the surrounding connective tissue. In ligaments with collagenous fibrils oriented in a parallel fashion, the perineural capsule is well-developed and the Ruffini corpuscle resembles a Golgi tendon organ; in areas where the fibrils show no predominant orientation, Ruffini corpuscles lack a capsule. Small Pacini corpuscles are situated within the fibrous layer near the capsular insertion at the meniscus articularis or at the periost. They consist of one or several inner cores and a perineural capsule of 1-2 layers. Larger Pacini corpuscles with one or several inner cores and a perineural capsule consisting of 20-30 layers are found on the outer surface of the fibrous layer. The ultrastructure of these nerve endings is compared with the ultrastructure of articular receptors of various animals and with the ultrastructure of sensory nerve endings in the skin of several mammalian species including man.

Adult↗