Chondroitin sulfate proteoglycan at the basal lamina beneath high endothelial cells in human palatine tonsils: a light and electron microscopic study using the cationic colloidal iron method

Substrate accumulation and extracellular matrix remodelling promote persistent upper airway disease in mucopolysaccharidosis patients on enzyme replacement therapy

Introduction

Mucopolysaccharide diseases are a group of lysosomal storage disorders caused by deficiencies of hydrolase enzymes, leading to pathological glycosaminoglycan accumulation. A number of mucopolysaccharidosis (MPS) types are characterised by severe airway disease, the aetiology of which is poorly understood. There is ongoing evidence of significant clinical disease in the long-term despite disease modifying therapeutic strategies, including enzyme-replacement therapy (ERT). To provide a better understanding of this aspect of disease, we have characterised extracellular matrix (ECM) and inflammatory alterations in adenotonsillar tissue samples from 8 MPS patients.

Methods

Adenotonsillar samples from MPS I, IVA and VI ERT treated patients and from a single enzyme naïve MPS IIIA individual were compared to non-affected control samples using quantitative immunohistochemistry, qPCR and biochemical analysis.

Results

Significantly increased lysosomal compartment size and total sulphated glycosaminoglycan (p = 0.0007, 0.02) were identified in patient samples despite ERT. Heparan sulphate glycosaminoglycan was significantly elevated in MPS I and IIIA (p = 0.002), confirming incomplete reversal of disease. Collagen IV and laminin α-5 (p = 0.002, 0.0004) staining demonstrated increased ECM deposition within the reticular and capillary network of MPS samples. No significant change in the expression of the pro-inflammatory cytokines IL-1α, IL-6 or TNF-α was seen compared to control.

Conclusion

This study suggests a role for ECM remodelling contributing to the obstructive phenotype of airway disease in MPS. Current therapeutic strategies with ERT fail to normalise these pathological alterations within adenotonsillar samples. Our findings lend novel insight into the pathological cascade of events, with primarily structural rather than inflammatory changes contributing to the continuing phenotype seen in patients despite current therapeutic regimes.

Distribution of elastic fibers in the head and neck: a histological study using late-stage human fetuses

There is little or no information about the distribution of elastic fibers in the human fetal head. We examined this issue in 15 late-stage fetuses (crown-rump length, 220-320 mm) using aldehyde-fuchsin and elastica-Masson staining, and we used the arterial wall elastic laminae and external ear cartilages as positive staining controls. The posterior pharyngeal wall, as well as the ligaments connecting the laryngeal cartilages, contained abundant elastic fibers. In contrast with the sphenomandibular ligament and the temporomandibular joint disk, in which elastic fibers were partly present, the discomalleolar ligament and the fascial structures around the pterygoid muscles did not have any elastic fibers. In addition, the posterior marginal fascia of the prestyloid space did contain such fibers. Notably, in the middle ear, elastic fibers accumulated along the tendons of the tensor tympani and stapedius muscles and in the joint capsules of the ear ossicle articulations. Elastic fibers were not seen in any other muscle tendons or vertebral facet capsules in the head and neck. Despite being composed of smooth muscle, the orbitalis muscle did not contain any elastic fibers. The elastic fibers in the sphenomandibular ligament seemed to correspond to an intermediate step of development between Meckel's cartilage and the final ligament. Overall, there seemed to be a mini-version of elastic fiber distribution compared to that in adults and a different specific developmental pattern of connective tissues. The latter morphology might be a result of an adaptation to hypoxic conditions during development.

Fetal development and variations in the cartilages surrounding the human external acoustic meatus

In contrast to the osseus part that develops from the tympanic ring of the squamous part of the temporal bone after birth, there is little information on fetal development of the cartilages surrounding the human external acoustic meatus. Using routine histology and immunohistochemistry, we examine sections of 22 fetuses (CRL 100-270mm) to study the development of these cartilages. Early external ear cartilages are composed of three groups: (1) a ring-like cartilage at the putative tragus on the anterior side of the meatus, (2) two or three bar-like cartilages along the inferior wall of the meatus, and (3) a plate-like cartilage in a skin fold for the putative helix on the posterior side. In contrast to the first and second pharyngeal arch cartilages, all the external ear cartilages express glial fibrillary acidic protein. Notably, the bar-like cartilages along the meatus are connected with a fascia-like structure to the second pharyngeal arch cartilage. Later, with considerable individual variation, new cartilage bars extend from the inferior cartilages to the superior side of the meatus. Thus, via an intermediate stage showing a chain of triangular elastic cartilages, a chain of bar-like cartilages on the inferior side appears to change into a complex of H-shaped cartilages. Numerous ceruminous glands are seen in the thick subcutaneous tissue overlying the cartilaginous part of the meatus. However, they do not insert into the cartilage. The external ear cartilages develop much earlier than, and independently of, the osseus part.

Elastic fiber-mediated enthesis in the human middle ear

Adaptation to constant vibration (acoustic oscillation) is likely to confer a specific morphology at the bone-tendon and bone-ligament interfaces at the ear ossicles, which therefore represent an exciting target of enthesis research. We histologically examined (i) the bone attachments of the tensor tympani and stapedius muscles and (ii) the annular ligament of the incudostapedial joint obtained from seven elderly donated cadavers. Notably, both aldehyde-fuchsin and elastic-Masson staining demonstrated that the major fibrous component of the entheses was not collagen fibers but mature elastic fibers. The positive controls for elastic fiber staining were the arterial wall elastic laminae included in the temporal bone materials. The elastic fibers were inserted deeply into the type II collagen-poor fibrocartilage covering the ear ossicles. The muscle tendons were composed of an outer thin layer of collagen fibers and an inner thick core of elastic fibers near the malleus or stapes. In the unique elastic fiber-mediated entheses, hyaluronan, versican and fibronectin were expressed strongly along the elastic fibers. The hyaluronan seemed to act as a friction-reducing lubricant for the elastic fibers. Aggrecan was labeled strongly in a disk- or plica-like fibrous mass on the inner side of the elastic fiber-rich ligament, possibly due to compression stress from the ligament. Tenascin-c was not evident in the entheses. The elastic fiber-mediated entheses appeared resistant to tissue destruction in an environment exposed to constant vibration. The morphology was unlikely to be the result of age-related degeneration.

Anatomical reevaluation of the anococcygeal ligament and its surgical relevance

BACKGROUND

With the development and spread of surgical procedures for total mesorectal excision and intersphincteric resection, rectal surgeons have gained frequent opportunities to observe connective tissues around the anal canal. However, uncertainty remains as to the exact identity and location of these structures.

OBJECTIVE

The aim of this study was therefore to identify and describe the morphology of connective tissue structures extending between the coccyx and anal canal.

DESIGN AND SETTING

This was a descriptive study carried out at university facilities for anatomic research. The study comprised histologic evaluation of paraffin-embedded tissue specimens from preserved cadavers of 20 elderly adults and examination of frozen pelves from 6 fresh cadavers.

MAIN OUTCOME MEASURES

From each cadaver, we obtained a tissue mass containing the dorsal wall of the distal rectum and anal canal, the coccyx, and the covering skin. Most sections were stained with Masson-Trichrome solution for collagen and smooth muscle fibers.

RESULTS

Dissection of fresh cadaver demonstrated the anococcygeal ligament extending from the coccyx to the anal canal between bilateral slings of the levator ani. Histologic examination showed that the anococcygeal ligament was divided into a ventral and a dorsal layer and contained abundant smooth muscles, elastic fibers, and small vessels. The ventral layer extended from the presacral fascia to the conjoint longitudinal layer of the anal canal. The dorsal layer was recognized as a bundle extending between the coccyx and external anal sphincter. The dorsal layer was much thicker along and near the midsagittal plane than the lateral areas. The levator ani was located independently of and dorsal to the anococcygeal ligament.

LIMITATIONS

This study used cadavers from elderly donors; thus, the specimens might have had age-related degeneration.

CONCLUSIONS

The anococcygeal ligament is divided into 2 layers: a thick ventral layer, rich in thin vessels and extending from the presacral fascia to the conjoint longitudinal layer of the anal canal, and a thin dorsal layer extending between the coccyx and external anal sphincter. The anococcygeal ligament is one of the critical structures for decision-making regarding rectal and upper anal canal mobilization.

Binding of Lymphoid Chemokines to Collagen IV That Accumulates in the Basal Lamina of High Endothelial Venules: Its Implications in Lymphocyte Trafficking

Certain lymphoid chemokines are selectively and constitutively expressed in the high endothelial venules (HEV) of lymph nodes and Peyer's patches, where they play critical roles in the directional migration of extravasating lymphocytes into the lymphoid tissue parenchyma. How these chemokines are selectively localized and act in situ, however, remains unclear. In the present study, we examined the possibility that basal lamina-associated extracellular matrix proteins in the HEVs are responsible for retaining the lymphoid chemokines locally. Here we show that collagen IV (Col IV) bound certain lymphoid chemokines, including CCL21, CXCL13, and CXCL12, more potently than did fibronectin or laminin-1, but it bound CCL19 and CCL5 only weakly, if at all. Surface plasmon resonance analysis indicated that Col IV bound CCL21 with a low nanomolar K(D), which required the C-terminal region of CCL21. Col IV can apparently hold these chemokines in their active form upon binding, because the Col IV-bound chemokines induced lymphocyte migration efficiently in vitro. We found by immunohistochemistry that Col IV and CCL21, CXCL13, and CXCL12 were colocalized in the basal lamina of HEVs. When injected s.c. into plt/plt mice, CCL21 colocalized at least partially with Col IV on the basal lamina of HEVs in draining lymph nodes. Collectively, our results suggest that Col IV contributes to the creation of a lymphoid chemokine-rich environment in the basal lamina of HEVs by binding an array of locally produced lymphoid chemokines that promote directional lymphocyte trafficking from HEVs into the lymphoid tissue parenchyma.

Histological features of the rectovaginal septum in elderly women and a proposal for posterior vaginal defect repair

To get support from morphological findings to develop a novel surgical procedure for posterior vaginal defect repair, we histologically examined the rectum-vagina interface tissues obtained from 20 elderly female cadavers. The rectovaginal septum (RVS) was defined here as an elastic fiber-rich plate (EFRP) along the posterior vaginal wall. It lined the posterior surface of the vein-rich zone of the vaginal wall and extended between the bilateral paracolpiums. The septum was more evident in the lower half of the interface than in the upper half. The RVS was often thin and interrupted. Since the RVS was not so clearly demonstrated in the upper vagina histologically, augmentation using some implant is considered to be necessary for the enterocele and high rectocele. Since the thickness and tightness of the RVS vary with the case in the lower vagina, surgical procedures for low rectocele repair should be individualized, including implant-augmentation.

Histology, Immunohistochemistry and Ultrastructure of the Equine Palatine Tonsil

The palatine tonsils of five young horses formed 10-12 cm elongated follicular structures extending from the root of the tongue on either side to the base of the epiglottis and lateral to the glossoepiglottic fold. The stratified squamous non-keratinized epithelium of the outer surface was modified into crypts as reticular epithelium by heavy infiltration of lymphoid cells from underlying lymphoid follicles. In places, lymphoid tissue reaching almost to the surface and with only one to two cell layers intact was identified as the lymphoepithelium. Langerhans cells with Birbeck granules were interspersed between epithelial cells. Lymphoid tissue organized in lymphoid follicles constituted the parenchyma of the palatine tonsil. CD4-positive cells were more numerous and CD8-positive lymphocytes less numerous compared with their distribution in the lingual tonsil. B cells and macrophages were also more numerous than in the lingual tonsil and lectins showed a different pattern of attachment. M cells were not observed. High endothelial venules with well-developed vesiculo-vacuolar organelle had structural evidence of transendothelial and interendothelial migration of lymphocytes. Striated muscles as seen in the deeper lamina propria mucosae of the lingual tonsil were absent. The immunohistological and ultrastructural characteristics of the equine palatine tonsil are similar to those of humans but differ from those of the lingual tonsil and are consistent with a role as an effector and inductor immunological organ.

Morphologies of the interfaces between the levator ani muscle and pelvic viscera, with special reference to muscle insertion into the anorectum in elderly Japanese

A specific, smooth muscle-mediated interface between the levator ani muscle (LA) and the pelvic viscera has been reported. Using 110 sagittally trimmed anorectal tissue strips (80 lateral, 15 anterior and 15 dorsal specimens) obtained from the donated cadavers of 46 elderly subjects, we examined variations in the interface between the LA and the rectal muscularis propria, including the so-called conjoined longitudinal muscles. In type A (9/46), little or no tissue connected the LA to the external rectal muscularis propria, but the LA and external sphincteric mass formed a definite complex. In type B (26/46), the covering fascia of the LA changed abruptly into smooth muscles, which merged into the external rectal muscularis propria. In type C (11/46), most of the LA-associated connective tissues, composed of smooth muscles, were tightly connected to the internal and external rectal muscularis propria. These variations seemed to depend on the morphology of the recto-urethralis, the lateral extension of which reinforced the LA-associated smooth muscles sufficiently to form type B and C insertions. We also demonstrated differences in the interfacial tissues between the LA and other pelvic viscera. We hypothesize that, to avoid injury of the LA and its interfaces during strong movement of the pelvic viscera, for example during childbirth, coitus or squeezed evacuation, the pelvic connective tissue-like smooth muscles play an important role as an autonomic buffer and/or modulator of pelvic floor function. Digital examination and transrectal or transvaginal sonography may be useful for evaluating interindividual variation in these interfacial tissues in elderly patients.

HPLC identi?cation of oversulphated chondroitin as the major glycosaminoglycan of human tonsils

The glycosaminoglycans of human nasopharyngeal and palatine tonsils, obtained after surgical dissection due to tonsillitis, were isolated and characterized by means of enzyme susceptibility and HPLC. Chondroitin/dermatan sulphate were the major glycosaminoglycans identified. A large proportion of this glycosaminoglycan was made up of oversulphated structures, namely DeltaDi-di(4,6)S, which were found mainly in invertebrate tissues and in mast cells.

Blood vascular architecture of the palatine tonsil in the musk shrew (Suncus murinus): scanning electron microscopic study of corrosion casts

The musk shrew, Suncus murinus, is one of the primitive mammals and has a pair of palatine tonsils. In the present study, we investigated the blood microvascular architecture of the tonsil in this animal by scanning electron microscopy of corrosion casts. The paranodular arterioles entered the lymph nodule to form a coarse capillary plexus within the nodule. Some of the arterioles reached the dome region to give rise to a fine meshwork of dome subepithelial capillaries. This dome subepithelial capillary network did not show any hairpin or switch-back patterns, as seen in human and rabbit tonsils. Both of the nodular and dome capillaries were drained into the postcapillary venules in the periphery of the nodular or the paranodular region. On the surface of these cast venules, oval-shaped indentations were seen corresponding to the luminal surface of the high endothelial venules. These venules were collected into the large vein at the bottom of the tonsil. The blood vascular architecture of the musk shrew tonsil is basically the same as those of other mucosa-associated lymphoid tissues in mammals.