Histologic studies of cartilaginous structures in the anterior region of the head of the sperm whale Physeter macrocephalus

Recently discovered cartilaginous structures in the forehead of the sperm whale (Behrmann and Klima 1985) were investigated histologically. The largest and most important of these structures is the nasal roof cartilage which can be derived from the tectum nasi, a part of the embryonic nasal capsule (Klima et al. 1986). In the investigated sperm whale fetuses, this structure consists of embryonic hyaline cartilage which is well suited for morphogenetic processes and fast growth. In the investigated adult sperm whale, the originally hyaline cartilage has been transformed into a special kind of elastic cartilage. The arrangement of cells, territories, and extracellular substance resembles hyaline cartilage. This component represents an adaptation to pressure load. The appearance and arrangement of elastic fibres resembles elastic cartilage. This component is an adaptation to distortion forces. Obviously, pressure and distortion are the strongest mechanical strains that the nasal roof cartilage is exposed. We see the function of this cartilage structure therein that, being a pressure-elastic skeletal support and following the left nasal meatus along its whole extension through the massive and soft forehead, it secures the only direct respiratory passage. Additionally, fibre bundles of transversely striated muscles are anchored in the perichondrium of the nasal roof cartilage. The function of this delicately interwoven muscle system is seen by us in the fine tuning of contraction and dilatation of the respiratory passage. Moreover, a possible function as a sound conducting cartilaginous structure serving the echolocation system is considered (c.f. Pilleri et al. 1983).     

Chondrogenesis and Osteogenesis in Ectopic Transplants of the Fetal Liver in Mice

It was shown for the first time that when the livers of 14 day-old mouse fetuses was transplanted under the renal capsule or in the subcutaneous connective tissue of adult recipients, successive de novo formation of hyaline cartilage, bone, and hemopoietic foci took place. We propose that the liver mesenchyme, which preserves wider differentiation potencies in fetuses, is the cellular source of different types of mechanocytes: cartilaginous, bone, and reticular cells.     

Chondro- and osteogenesis in ectopic transplants of embryonic mouse liver]

It was shown for the first time that when the liver of 14 day-old mouse fetuses was transplanted under the renal capsule or in the subcutaneous connective tissue of adult recipients, successive de novo formation of hyaline cartilage, bone, and hemopoietic foci took place. We propose that the liver mesenchyme, which preserves wider differentiation potencies in fetuses, is the cellular source of different types of mechanocytes: cartilaginous, bone, and reticular cells.     

Expression of NGF, Trka and p75 in human cartilage

Nerve growth factor (NGF) exerts its action through two types of receptor: high-affinity tyrosine kinase A receptor (trkA) and low-affinity p75 receptor. NGF has a neurotrophic role in central and peripheral nervous system development, but there is also clear evidence of its involvement in the developing skeleton. The aim of the present immunohistochemical study was to investigate the expression and distribution of NGF, trkA, and p75 in normal cartilaginous tissues from adult subjects: articular and meniscal cartilage of the knee, cartilage from the epiglottis, and intervertebral disc tissue. Detection of NGF mRNA was also performed by in situ hybridization. Immunoreaction for NGF and the two receptors in articular chondrocytes, chondrocyte-like cells of meniscus and annulus fibrosus, and chondrocytes of the epiglottis demonstrated that they are all expressed in hyaline, fibrous and elastic cartilaginous tissues, suggesting that they could be involved in cartilage physio-pathology.     

THE SPERM WHALE'S NOSE: SEXUAL SELECTION ON A GRAND SCALE?1

The world's largest nose belongs to the sperm whale, yet its functional significance remains equivocal. In order to help shed light on its function, the head of a postmortem neonate sperm whale was subjected to CT scanning. Geometric comparisons between homologous cephalic structures in sperm whales and dolphins (normalized for body size) show extreme hypertrophy and size sexual dimorphism in the sperm whale's lipid spermaceti organ. Anatomic geometry, energetics, and behavior suggest that this immense nasal apparatus is a bioacoustical machine. Sexual selection via an acoustic display is suggested as an explanation for the size and continuous (physiologically isolated) energy investment in the construction and maintenance of the male's spermaceti organ.     

Innervation pattern of different cartilaginous tissues in the rat

BACKGROUND: The innervation of skeletal tissues by sensory nerves is poorly understood - especially of nerve fibres which reach into the bony and cartilaginous tissue. METHODS: Samples of rat cartilaginous tissues from different locations (knee joint, vertebral column, temporomandibular joint) were fixed by perfusion and decalcified. The distribution of protein gene product (PGP) 9.5-, calcitonin gene-related peptide (CGRP)- and tachykinin (TK)-immunoreactive axons was analysed using fluorescence immunohistochemistry. RESULTS: Nerve fibres were detected in the outer regions of the hyaline cartilage of the knee joint, in the hyaline cartilage of the vertebral body, in the fibrocartilage of the intervertebral disc and menisci, and in the articular disc of the temporomandibular joint. Predominantly, they were found to be CGRP-immunoreactive. CONCLUSION: The neuropeptidergic innervation of the hyaline cartilage in different locations and the presence of nerve fibres in the fibrocartilage might indicate that in addition to the classical neuronal afferent and efferent pathway these fibres may also mediate trophic actions like tissue adaptation and repair.     

In vitro differentiation and mineralization of cartilaginous nodules from enzymatically released rat nasal cartilage cells

Nasal cartilage cells from 21-day-old rat fetuses were cultured at high density in the presence of ascorbic acid and β-glycerophosphate over a 12-day period. Immediately after plating, the cells exhibited a fibroblastic morphology, lost their chondrocyte phenotype and expressed type I collagen. On day 3, clusters of enlarged polygonal cells were found. These cell clusters synthetised type II collagen and formed an alcian-blue-positive matrix. The following days, a progressive increase in the number of cells positive for type 11 collagen was noted and, on day 8, typical cartilaginous nodules were formed. These nodules increased in size and number, spreading outward, laying down a dense matrix which mineralized. Light and electron microscopy observations of cross-sections of nodules confirmed the cartilaginous nature of this tissue formed in vitro with typical chondrocytes embedded in a hyaline matrix. Furthermore, at the electron microscopic level, matrix vesicles were seen in extracellular matrix associated with the initiation of mineralization. Typical rod-like crystals were present in the intercellular spaces along the collagen fibers. These results indicated that in a specific environment, dedifferentiated chondrocytes were able to redifferentiate and to form nodular structures with morphological ultrastructure of calcified cartilage observed in vivo.     

Doublecortin is expressed in articular chondrocytes

Articular cartilage and cartilage in the embryonic cartilaginous anlagen and growth plates are both hyaline cartilages. In this study, we found that doublecortin (DCX) was expressed in articular chondrocytes but not in chondrocytes from the cartilaginous anlagen or growth plates. DCX was expressed by the cells in the chondrogenous layers but not intermediate layer of joint interzone. Furthermore, the synovium and cruciate ligaments were DCX-negative. DCX-positive chondrocytes were very rare in tissue engineered cartilage derived from in vitro pellet culture of rat chondrosarcoma, ATDC5, and C3H10T1/2 cells. However, the new hyaline cartilage formed in rabbit knee defect contained mostly DCX-positive chondrocytes. Our results demonstrate that DCX can be used as a marker to distinguish articular chondrocytes from other chondrocytes and to evaluate the quality of tissue engineered or regenerated cartilage in terms of their "articular" or "non-articular" nature.     

SUCKLING BEHAVIOR IN SPERM WHALE CALVES: OBSERVATIONS AND HYPOTHESES

This study is the first to describe quantitatively the apparent suckling behavior of sperm whale, Physeter macrocephalus (Linnaeus, 1758), calves using observations from both above and below the surface. Peduncle dives are short (mean 14 s) dives made by sperm whale calves beside the peduncle of an adult female, which were previously assumed to be indicative of suckling. Photo-identification and focal calf-follows were used to collect data during 177 peduncle dive bouts from 22 different calves (11 calves from the Caribbean Sea, 11 from the Sargasso Sea), one of which was followed on forty different days. We found that peduncle diving in sperm whale calves is laterally asymmetrical with a bias to the left side of the escorting adult (69.8% of peduncle dives) and that calves generally do not switch sides during a bout of peduncle dives (switches occurred in only 10.8% of bouts). Further subsurface observations gave insight into potential alternative functions of peduncle diving. These alternative hypotheses, including nasal suckling, and the existing supporting evidence for each are discussed. It is likely that peduncle diving is related to suckling but that the exact function of the dives and manner in which sperm whale calves ingest milk remains unclear.     

Trabecular, nasal, branchial, and pericardial cartilages in the sea lamprey, Petromyzon marinus: fine structure and immunohistochemical detection of elastin

Immunohistochemical and ultrastructural methods were used to examine the distribution of elastin and the fine structure of the trabecular, nasal, branchial, and pericardial cartilages in the sea lamprey, Petromyzon marinus. The cells and matrix, as well as the overall organization of these components, in larval and adult trabecular cartilage resemble those of adult annular and piston cartilages (Wright and Youson: Am. J. Anat., 167:59-70, 1983) Chondrocytes are similar to those in hyaline cartilage. Lamprin fibrils and matrix granules, but no collagen fibrils, are found in a matrix arranged into pericellular, territorial, and interterritorial zones. Branchial, pericardial, and nasal cartilages differ from trabecular, annular, and piston cartilages in the organization of their matrix and in the structural components of their matrix and perichondria. Furthermore, immunoreactive elastin-like material is present within the perichondria and peripheral matrices of nasal, branchial, and pericardial cartilages in both larval and adult lampreys. Oxytalan, elaunin, and elastic-like fibers are dispersed between collagen fibers in the perichondrium. The matrix contains lamprin fibrils, matrix granules, and a band of amorphous material, which is reminiscent of elastin, in the periphery bordering the perichondrium. The presence of elastic-like fibers and elastin-like material within some lamprey cartilages implies that this protein may have evolved earlier in vertebrate history than has been previously suggested.     

The cartilaginous skeleton of an elasmobranch fish does not heal.

The inability of articular cartilage to heal satisfactorily is becoming, with ageing populations, an important medical problem. One question that has not been raised is whether a mechanism for the repair of cartilage evolved in animals with cartilaginous skeletons. Fin rays of dogfish were cut and the fish maintained for up to 6 months. The initial inflammatory reaction around the cut rays lasts for 2 weeks. By 4 weeks the cut ends are covered by fibrous tissue. At 12 weeks some areas of cartilage-like tissue are developing. Development of these areas continues and at 26 weeks large chondrocyte-like cells are surrounded by matrix. This tissue is in regions of poor vascularity. It does not have the typical appearance of hyaline cartilage, nor is it integrated with the cartilage of the fin rays. No changes in the cut surfaces of the fin rays are observed at any time. It is concluded that no mechanism has evolved in the elasmobranch fishes for the repair of their cartilaginous skeleton. This is discussed in relation to previous investigations of the reactions of cartilage to injury in embryonic, neonatal and adult tissues of higher vertebrates.     

The distribution of different molecular species of collagen in fibrous, elastic and hyaline cartilages of the pig.

The distribution of type II collagen, considered to be characteristic of cartilaginous tissues, was determined in various specialized cartilages of the mature pig. The tissues examined were: (1) fibrocartilage of the semilunar meniscus of the knee; (2) elastic cartilage of the external ear; (3) hyaline cartilage of (a) the synovial joint (b) the thyroid plate of the larynx, and (c) the nasal septum. The predominant species of collagen in each tissue, whether type I or type II, was appraised semi-quantitatively by analysis of purified collagen solubilized by pepsin and of peptide fragments produced by cyanogen bromide. Cyanogen bromide-derived peptides were characterized by column chromatography on CM-cellulose and by electrophoresis in sodium dodecyl sulphate-polyacrylamide gels. The proportion of each type of collagen was determined precisely by isolating the homologous small peptides alpha1(II)CB6 [nomenclature of Miller (1973) Clin. Orthop. 92, 260-280], by column chromatography on phosphocellulose and determining their relative proportions by amino acid analysis. Thus collagen of the fibrocartilage of the meniscus proved to be all type I; type II was not detected. In contrast, collagen of elastic cartilage of the outer ear, after rigorous exclusion of perichondrium, was type II. Similarly, type II was the only collagen detected in all the mature hyalline cartilages examined.     

The structure and physicochemical properties of human hyaline cartilage in the disorganization of the carbohydrate-protein complexes of the ground substance]

In the experiments in vitro we studied the influence of the process of disorganization of the carbohydrate-protein complexes of the ground substance on the structure, water content and biomechanical properties of the human hyaline cartilage. It was shown that the disorganization process of the cartilage ground substance and the subsequent removal of the formed products resulted in the increasing porosity of the cartilaginous tissue. This is expressed in the exposure of the fibrillar frame of the cartilage and formation of cavities of various volumes between its elements. The mentioned changes of the cartilage structure are followed by the reduction of the amount of monomolecular-bound water and simultaneous increase in swelling in water and water vapor sorption at maximal relative humidity. The removal of about 25% of glycosaminoglycanes of the ground substance resulted in the reduction of the rigidity of the cartilagenous tissue, and the increase in the residual deformation. The examination of the hyaline cartilage did not reveal any interrelation between the contents of proteoglycanes and the water content of the cartilagenous tissue.     

Immunochemical and mechanical characterization of cartilage subtypes in rabbit.

Cartilage is categorized into three general subgroups, hyaline, elastic, and fibrocartilage, based primarily on morphologic criteria and secondarily on collagen (Types I and II) and elastin content. To more precisely define the different cartilage subtypes, rabbit cartilage isolated from joint, nose, auricle, epiglottis, and meniscus was characterized by immunohistochemical (IHC) localization of elastin and of collagen Types I, II, V, VI, and X, by biochemical analysis of total glycosaminoglycan (GAG) content, and by biomechanical indentation assay. Toluidine blue staining and safranin-O staining were used for morphological assessment of the cartilage subtypes. IHC staining of the cartilage samples showed a characteristic pattern of staining for the collagen antibodies that varied in both location and intensity. Auricular cartilage is discriminated from other subtypes by interterritorial elastin staining and no staining for Type VI collagen. Epiglottal cartilage is characterized by positive elastin staining and intense staining for Type VI collagen. The unique pattern for nasal cartilage is intense staining for Type V collagen and collagen X, whereas articular cartilage is negative for elastin (interterritorially) and only weakly positive for collagen Types V and VI. Meniscal cartilage shows the greatest intensity of staining for Type I collagen, weak staining for collagens V and VI, and no staining with antibody to collagen Type X. Matching cartilage samples were categorized by total GAG content, which showed increasing total GAG content from elastic cartilage (auricle, epiglottis) to fibrocartilage (meniscus) to hyaline cartilage (nose, knee joint). Analysis of aggregate modulus showed nasal and auricular cartilage to have the greatest stiffness, epiglottal and meniscal tissue the lowest, and articular cartilage intermediate. This study illustrates the differences and identifies unique characteristics of the different cartilage subtypes in rabbits. The results provide a baseline of data for generating and evaluating engineered repair cartilage tissue synthesized in vitro or for post-implantation analysis.     

Differentiation of the secondary elastic cartilage in the external ear of the rat.

The cartilage in the external ear of the rat belongs to the group of secondary cartilages and it has a unique structural organization. The chondrocytes are transformed into typical adipose cells, the proteoglycan cartilage matrix is reduced to thin capsules around the cells and the rest of the extracellular matrix is occupied by a network of coarse elastic fibers. It appears late in development (16-day fetus) and needs more than one month for final development. The differentiation proceeds in several steps which partly overlap: the appearance of collagen fibrils, elastin fibers, the proteoglycan matrix, and the adipose transformation of chondrocytes. The phenotype of this cartilage and the course of its differentiation are very stable, even in very atypical experimental environmental conditions. The only exceptions are explants in organ culture in vitro and perichondrial regenerates. In these conditions the development of elastic fibers is slow and poor while the production of the proteoglycan matrix is abundant. The resulting cartilage then displays structural characteristics of hyaline cartilage rather than those of the initial elastic one.     

Histological study of the fetal development of the human acetabulum and labrum: significance in congenital hip disease.

Seventy-four acetabula from a total of 140 normal human fetuses, obtained from abortions and deaths in the prenatal period, were used. The fetuses ranged from 9.1 to 40 cm in crown-rump length and are believed to be between 12 weeks and term. Acetabula were decalcified embedded in paraffin or celloidin, sectioned, and stained using conventional histologic techniques. Sections from the superior one-quarter of the acetabulum were examined for the initial appearance and later spread of osseous tissue. Throughout the fetal period bone was present only in the floor of the acetabulum and did not extend into the socket walls. Ossification was detected initially more posteriorly in the socket floor, and at all ages, ossification was more prominent on the ischial side of the socket. Despite the lack of osseous tissue a well-formed hyaline cartilage socket was present. The fetal labrum was composed of fibrous tissue with the density of fibers increasing with age. Typical-appearing chondrocytes were detected at only the inner articular margin of the labrum. Contributing from one-fifth to one-half of the socket depth, the labrum may play a greater role in containing the femoral head at birth than it does in the mature joint. In seven acetabula, from joints that were neither subluxated nor dislocated, an area of areolar tissue with capillaries was detected at the hyaline cartilage-labrum junction. Such defects may weaken the labrum and contribute to neonatal hip instability.     

Deformation of nasal septal cartilage during mastication

The cartilaginous nasal septum plays a major role in structural integrity and growth of the face, but its internal location has made physiologic study difficult. By surgically implanting transducers in 10 miniature pigs (Sus scrofa), we recorded in vivo strains generated in the nasal septum during mastication and masseter stimulation. The goals were (1) to determine whether the cartilage should be considered as a vertical strut supporting the nasal cavity and preventing its collapse, or as a damper of stresses generated during mastication and (2) to shed light on the overall pattern of snout deformation during mastication. Strains were recorded simultaneously at the septo‐ethmoid junction and nasofrontal suture during mastication. A third location in the anterior part of the cartilage was added during masseter stimulation and manipulation. Contraction of jaw closing muscles during mastication was accompanied by anteroposterior compressive strains (around ?1,000 με) in the septo‐ethmoid junction. Both the orientation and the magnitude of the strain suggest that the septum does not act as a vertical strut but may act in absorbing loads generated during mastication. The results from masseter stimulation and manipulation further suggest that the masticatory strain pattern arises from a combination of dorsal bending and/or shearing and anteroposterior compression of the snout. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

Growth and differentiation of fetal rat limb buds transplanted in athymic (nude) mice

Limb buds of day 14 rat fetuses were cut into pieces and transplanted into the subcutaneous tissue of athymic (nude) mice. In day 14 fetal limbs, mesenchymal cells have begun to condense to form cartilaginous anlage, but no cartilage has been formed. Within 7 days after grafting, masses of hyaline cartilage developed. Numerous osteoblasts appeared, and new bone formation began by 14 days. By 20 days, osteoclasts appeared, and the formation of bone trabeculae and marrow cavities progressed. The cytological characteristics of chondrocytes, osteoblasts and osteoclasts were essentially the same as those seen in vivo. Many grafts developed into long bones, having the diaphysis and epiphysis. The mode of chondrogenesis and osteogenesis in the grafts was histologically similar to the corresponding process in vivo, although the differentiation was slower in the grafted limbs. Since the grafted limb buds showed remarkable growth and tissue differentiation for at least several weeks, this heterotransplantation system would be of potential use for the study of bone formation and resorption as well as for developmental toxicological studies.     

江豚气管和肺的解剖学与组织学研究

鲸类气管和肺的解剖学研究,早在17世纪末就开始进行。近年来,我国的珍稀动物白鱀豚(Lipotes vexillifer)已分别由陈宜瑜等(1975)进行了形态解剖,刘仁俊等(1980)进行了呼吸系统的解剖和组织学研究。有关江豚(Neophocaena asiaeorientalis)的呼吸系统仅秉志(1926)作过极简短的大体结构描述,有关其组织学的观察,目前尚无报道。本文对江豚气管、肺的解剖和组织学进行了详细的观察。