Adaptations to a semiaquatic lifestyle in the external ear of southern pinnipeds (Otariidae and Phocidae, Carnivora): Morphological evidences.

Pinnipeds are semiaquatic carnivorans that spend most of their lives in water and use coastal terrestrial, or ice pack, environments to breed, molt and rest. Certain characteristics of the ear have been linked to ecological aspects. In our contribution we focus on the study of the macroscopic and microscopic morphology of the external ear (with the exception of the osseous outer ear canal) of six species of Southern pinnipeds. In order to recognize the different components of tissues, sections were stained following several routine protocols. In addition, double-staining and enzymatic clearing (Alcian blue-alizarin red) was performed to assess the arrangement of skeletal elements in the OEC. The basic structure of the pinna in the southern otariids studied match those previously analyzed for Northern Hemisphere species. The cartilage macro anatomy of the OEC of Mirounga leonina and Arctocephallus gazella is different from that of the Northern Hemisphere species, with only one plate of cartilage, but markedly different between them. The histology of the otariids OEC is homogeneous along the entire extension, but phocids has three different regions (distal, middle, and proximal). The cartilage histology of most phocids is also different from that of analyzed otariids, with an elastic cartilage that resembles a myxoid-like tissue, but is not present in M. leonina, were the tissue around the OEC is very rich in adipocytes. The southern elephant seal M. leonina OEC has a combination of features similar to both the rest of the phocids and to the otariids. An auditory organ that is functional both over and under water could be essential for social behavior in these species.

Renal Myxoma- A Rare Variety of Benign Genitourinary Tumour.

Renal myxomas are rare neoplasms and very few cases have been reported in literature. Here we report a renal myxoma in a 48-year-old lady with hypothyroidism who presented with abdominal pain. She was found to have a mass lesion of 67 x 61 x 74 mm with exophytic component in the right kidney on ultrasonography and computed tomography. Right radical nephrectomy was performed due to suspicion of malignancy. Grossly the resected kidney showed a gelatinous, semi-translucent mass involving the mid and lower poles. Microscopy revealed marked hypocellular appearance of loose myxoid tissue with foamy histiocytes. Tumour cells were reactive for vimentin. At eight months of follow-up, patient is doing well.

Macroscopic and histological investigation of guanaco footpads (Lama guanicoe, Müller 1776).

The surface of guanaco footpads is characterized by hairless skin with up to 4-mm-thick stratum corneum that protects from abrasion. The horny layer is pliable and elastic, and ensures firm contact with irregular ground. It is padded with a particular structure of the subcutaneous layer, the digital cushion. The flat cushions of each of the two digits are of elongated ovate shape, each about 45-mm long, up to 20-mm wide, and 8-mm thick. The cushions are lined by a 1-2-mm-thick capsule that resembles a tunica albuginea. The capsule consists of coarse collagen fibers, with elastic fibers absent. The cushion capsule and dermis approach each other, and fuse along a line that runs parallel to the longitudinal axes of cushion and digit. Loose connective tissue rich in elastic fibers and acidic glycosaminoglycans separates dermis and cushion capsule lateral to the narrow interconnecting zone. The cushion capsule encloses cloudy yellowish, gelatinous material. Microscopy shows bundles of elastic fibers in abundant mucinous matrix. Tightly gathered elastic bundles adjoin the inner surface of the capsule. Rough cords of elastic fibers branch out from there and traverse to the opposite side. The cushion is pressed flat, and elastic fibers are stretched when bearing weight. With relief of load, elastic fibers contract and reset the cushion's shape. Contractile cells are absent. A resistant capsule and easily malleable mucinous contents establish the functioning as a gel pad. Mucinous connective tissue between elastic fiber bundles contains abundant basophilic matrix. Hyaluronan, chondroitin sulfate, and dermatan sulfate are main matrix constituents. Spindle-shaped or stellate fibroblasts contain vimentin, S100 protein, and neuron specific enolase. Moprhology, staining characteristics and synthesis activities of these cells meet the criteria to be classified as myxoid cells. The connective tissue in guanaco digital cushions represents myxoid tissue.

Histopathological Characteristics of Human Coronary Stent Restenosis

BACKGROUND AND OBJECTIVES: Neointimal ingrowth rather than stent recoil is thought to be important for coronary in-stent restenosis. However only limited pathologic data are available to adress the mechanisms of in-stent restenosis. With the specific aim of measuring cell replication and of assessing cellularity and extracellular matrix (ECM) composition, we analyzed atherectomized coronary arterial in-stent restenotic specimens. METHODS AND RESULTS: In the present study, we analyzed 29 atherectomized coronary arterial in-stent restenotic tissue samples (14 LAD, 10 RCA, and 5 LCX) retrieved from 25 patients (m/f:18/7: age 59+/-13 yr) at 0.5-23 (mean 5.7) months after deployment of Palmaz-Schatz stent. Histopathological analysis of cellular components and ECM was performed using H & E, modified Movat pentachrome, and immunocytochemical staining. Cellular proliferation rate, as estimated by use of antibodies to Ki-67 nuclear antigen showed low proliferation rate with the range of 0-4%, and no positive cells were found in 62% of cases. Myxoid tissue having ECM enriched with versican and hyaluronan was found in 69% of cases, and decreased over time after stenting. Foci of cell poor area were found in 57% of cases, and could be classified into as: (1) containing collagen-rich ECM and (2) containing a proteoglycan-rich ECM. Versican, biglycan, perlecan, and hyaluronan were identified with varying individual distributions in the proteoglycan rich area. Specimens with foci of cell poor area tended to increase over time after stenting (31% in & 4 mo vs. 81% in > or =4 mo after stenting, p<0.01). alpha-smooth muscle actin staining identified the majority of cells as smooth muscle cells (SMC) and occasional macrophages (< or =12 cells per section) were detected by CD68 antibody. CONCLUSIONS: These data suggest that enhanced ECM accumulation rather than cell proliferation may be important mechanisms for stent restenosis. Angioplasty of stent restenosis may therefore fail due to transient compression of this hygroscopic matrix.

A Histopathologic Analysis of Atherectomized Human Coronary Stent Restenosis :Potential Role of Cell Migration and Extracellular Matrix Formation

BACKGROUND: Neointimal ingrowth rather than stent recoil has thought to be important for coronary arterial in-stent restenosis. Intuitively cell migration and extracellular matrix (ECM) formation seems to be important in the pathogenesis of stent restenosis. Therefore, with specific aim of identifying molecules implicated in cell migration and extracellular matrix formation, histopathologic analysis on atherectomized coronary arterial in-stent restenotic tissue was performed. METHODS: In the present study we analyzed 29 atherectomized coronary arterial in-stent restenotic tissue specimens (LAD 14, LCX 5, RCA 10) retrieved (5.7+/-5.4 months after stent deployment) from 25 patients (age 59+/-13, M/F:18/70) in whom restenosis complicated previous revascularization with Palmaz-Schatz stent. Histopathologic analysis was performed after immunostaining. Antibodies against TGF- 1, hyaluronan synthase (HAS) 1, MMP1, MMP9, urokinase type plasminogen activator, PDGF receptor were used for immunostaining. RESULTS: Myxoid tissue characterized by stellate-shaped cells embedded in a loose ECM was present in 20 out of 29 specimens, and tends to decrease over time after stenting. Foci of cell poor area (48-320 cells/mm2) in a microscopic field was present in 17 out of 29 specimens, and tends to increase over time after stenting (13/16 in or =4 mo, p<0.01). Various proportions of specimens show positive stained cells with respect to each antibodies: TGF 1 in 16 out of 20:HAS1 in 10 out of 13:MMP1 in 8 out of 16:MMP9 in 4 out of 13:PDGF receptor in 12 out of 17 specimens. Abundant cells labled with certain antibodies (TGF 1, uPA, PDGF receptor) were frequently found in myxoid tissue. CONCLUSIONS: Myxoid tissue, frequently found in stent restenotic tissue, may be a biologically active tissue in terms of cell migration and of ECM formation. ECM accumulation tends to increase over time after stenting and may be important in pathogenesis of coronary arterial stent restenosis.