The anatomical record. Part A, Discoveries in molecular, cellular, and evolutionary biology最新文献

Insulin-dependent diabetes mellitus compromises the salivary glands, altering their morphology and the mechanisms of salivation, which are fundamental for oral health. Thus, the aim of the present study was to determine the effects of prolonged insulin treatment on the morphology of the salivary glands in Nod mice. Forty-five female mice were divided into five groups: nine positive diabetic Nod mice for 10 days (group 1), nine positive diabetic Nod mice for 20 days (group 2), nine diabetic Nod mice for 10 days (group 3), nine diabetic Nod mice for 20 days (group 4), and nine nondiabetic BALB/c mice (group 5). Animals of groups 3 and 4 received 4-5 U of insulin daily, whereas animals of groups 1, 2, and 5 received the same dose of physiological saline simulating the experimental conditions. Samples of the salivary glands were analyzed by light, transmission, and scanning electron microscopies. The results showed intense alterations in diabetic animals characterized by nuclear and cytoplasmic atrophy, biomembrane disorganization, an increase in fibrillar components of the extracellular matrix, and the presence of inflammatory cells. Insulin treatment exerted positive effects on the recovery of the changes resulting from the diabetic state in both parotid and submandibular glands but the pattern continued to be altered. It can be concluded that, in addition to compromising the processes of tissue maintenance and renewal, tissue destructuring leads to alterations in functional mechanisms in both diabetic animals and animals submitted to glycemic control.

Alveolar epithelial type II cells synthesize and secrete surfactant. The surfactant-associated proteins A and D (SP-A and SP-D), members of the collectin protein family, participate in pulmonary immune defense, modulation of inflammation, and surfactant metabolism. Both proteins are known to have overlapping as well as distinct functions. The present study provides a design-based stereological analysis of adult mice deficient in both SP-A and SP-D (A(-)D(-)) with special emphasis on parameters characterizing alveolar architecture and surfactant-producing type II cells. Compared to wild-type, A(-)D(-) mice have fewer and larger alveoli, an increase in the number and size of type II cells, as well as more numerous and larger alveolar macrophages. More surfactant-storing lamellar bodies are seen in type II cells, leading to a threefold increase in the total volume of lamellar bodies per lung, but the mean volume of a single lamellar body remains constant. These results demonstrate that chronic deficiency of SP-A and SP-D in mice leads to parenchymal remodeling, type II cell hyperplasia and hypertrophy, and disturbed intracellular surfactant metabolism. The design-based stereological approach presented here provides a framework for the quantitative lung structure analysis in gene-manipulated mice as well as in human lung disease.

Caspase-14, a member of the caspase family of cysteine proteases, is almost exclusively expressed in the epidermis. Studies on human and mouse cells and tissues have implicated caspase-14 in terminal differentiation of epidermal keratinocytes and in the formation of the stratum corneum. Here we investigated evolutionary aspects of the role of caspase-14 by analyzing its distribution in the epidermis and hair follicles of representative species of placental mammals, marsupials, and monotremes. Immunocytochemical staining showed that caspase-14 is consistently expressed in the granular and corneous layer of the epidermis of all mammalian species investigated. Ultrastructural analysis using gold-labeled anticaspase-14 antibodies revealed that caspase-14 is associated preferentially with keratin bundles and amorphous material of keratohyalin granules, but is also present in nuclei of transitional cells of the granular layer and in corneocytes. In hair follicles, caspase-14 was diffusely present in cornifying cells of the outer root sheath, in the companion layer, and, most abundantly, in the inner root sheath of all mammalian species here analyzed. In Henle and Huxley layers of the inner root sheath, labeling was seen in nuclei and, more diffusely, among trichohyalin granules of cornifying cells. In summary, the tissue expression pattern and the intracellular localization of caspase-14 are highly conserved among diverse mammalian species, suggesting that this enzyme is involved in a molecular process that appeared early in the evolution of mammalian skin. The association of caspase-14 with keratohyalin and trichohyalin granules may indicate a specific role of caspase-14 in the maturation of these keratinocyte-specific structures.

Relative length of metapodials and digits is sexually dimorphic in most primates and one rodent and one bird species studied so far. Recently, interest in digit ratios has increased because of their correlation with diverse physiological, psychological, and performance traits in humans. These correlations may reflect the effect of androgens during early ontogeny on digit development and their long-term organizational effects on extragenital organs. Inter- and intrasexual variation in digit ratios may be ultimately controlled by modulation of the expression of Hoxa and Hoxd genes. Since Hox genes are conserved in vertebrates, similar patterns of sex-related variation in length ratios may be expected across taxa. In fact, sexual dimorphism in length ratios has been documented for metapodials or digit bones in nonhuman vertebrates, but the specific pattern of sex-related variation varies considerably. However, no study has investigated sexual dimorphism in length ratios between all ray segments (metapodials plus phalanges) using osteometrical measures. In an outbred wild population of wood mice (Apodemus sylvaticus), we found extensive sex-related variation in ratios between osteometrical length of the phalanges, but not metatarsals, similar to that recorded on undissected digits of humans and laboratory mice. Most sexually dimorphic ratios involved the second digit. We found very weak evidence for directional asymmetry in length ratios. The present study shows that sex-related variation in length ratios between digit segments observed in mammals may actually depend on relative bone length. Hence, other species may be used to investigate the causal and semeiotic implications of variation in human digit ratios.

Aging is mostly characterized by a progressive decline of neuronal function that involves both the central and the peripheral nervous system. The aging process is accompanied by changes in either the number or the size of neurons. However, these data are controversial and not very well known in the sympathetic ganglia of large mammals. Hence, the present investigation aimed to study the dog's caudal mesenteric ganglion (CMG) in three different periods of postnatal development, searching for qualitative and quantitative alterations. The CMG is responsible for the large intestine, internal anal sphincter, and partially the urogenital system innervations. Nine dead male dogs from the Veterinary Hospital of the College of Veterinary Medicine at University of São Paulo were divided into three well-defined age groups (1-2 months old, 1-2 years old, and 5-10 years old). The stereological study was pursued using the physical disector method combined to the Cavalieri principle. The postnatal development was accompanied by an increase in the nonneuronal tissue amount and in ganglion volume. Additionally, the total number of neurons also increased during aging (from 70,140 to 1,204,516), although the neuronal density showed an opposite trend (from 29,911 to 11,500 mm(-3)). Due to the interrelation between either body weight or ganglion volume and aging in the dogs investigated in this study, it was possible to predict the total number of neurons in CMG using both body weight and ganglion volume in an attempt to verify whether or not size and total number of neurons are both allometrically and aging ruled, i.e., if either the animal's body weight and ganglion volume or aging influence these parameters. The prediction of the total number of neurons was very close to the initially estimated values.

The purpose of this study is to test predicted form-function relationships between cranial suture complexity and masticatory muscle mass and biomechanics in a mouse model. Specifically, to test the hypothesis that increased masticatory muscle mass increases sagittal suture complexity, we measured the fractal dimension (FD), temporalis mass, and temporalis bite force in myostatin-deficient (GDF8(-/-)) mice and wild-type CD-1 mice (all male, 6 months old). Myostatin is a negative regulator of muscle mass, and myostatin-deficient mice show a marked increase in muscle mass compared to normal mice. We predicted that increased sagittal suture complexity would decrease suture stiffness. The data presented here demonstrate that increased suture complexity (measured as FD) was observed in a hypermuscular mouse model (GDF8(-/-)) with significantly increased temporalis muscle mass and bite forces. Hypermuscular mice were also found to possess suture connective tissue that was less stiff (i.e., underwent more displacement before failure occurred) when loaded in tension. By decreasing stiffness, suture complexity apparently helps to dissipate mechanical loads within the cranium that are related to chewing. These results suggest that cranial suture connective tissue locally adapts to functional demands of the biomechanical suture environment. As such, cranial sutures provide a novel model for studies in connective tissue mechanotransduction.

A detailed study of so-called communicating cartilage canals, which penetrate deeply up into the lower hypertrophic zone of the epiphyseal growth plate in the embryonic chicken femur (E20), was carried out with the aim to clarify whether or not these canals are involved in the bone-forming process. In addition, we examined the manner in which cartilage canals are formed and compare the present data with our previous data. The canals were investigated by means of light microscopy, electron microscopy, immunohistochemistry (VEGF, VEGFR2/Flk1, type I collagen), and 3D reconstruction. Some communicating canals deeply penetrate into the upper hypertrophic zone where they terminate, showing electron-dense cells at their end. Subcellular characteristics of these cells are hardly detectable and we suppose that they undergo cell death. Other canals pass down deeper into the lower hypertrophic zone. The upper segment of these canals is composed of capillaries, mesenchymal cells, and macrophage-like cells. Precursors of osteoblasts are adjacent to the canals. The lower segment of communicating canals is composed of bone matrix or osteoid, which contains type I collagen fibrils and cells having the typical subcellular features of osteoblasts. No vessels are found in these segments. Immunohistochemistry shows that the matrix of the canals labels positively for type I collagen. In addition, staining with sirius red demonstrates that bone matrix is formed in these parts. We assume that the osteoblast-like cells of the lower segments of communicating canals originate either from mesenchymal cells or even from hypertrophic chondrocytes. Our immunohistochemical data also reveal that vascular endothelial growth factor (VEGF) and the corresponding receptor VEGFR2/Flk1 (VEGF receptor 2/Flk1) are localized in cartilage canals of the reserve zone, the proliferative zone, and the hypertrophic zone. The receptor is found in the endothelial cells of the vessels. Furthermore, VEGF is present in hypertrophic chondrocytes. The results of our study suggest that cartilage canals penetrate actively into the cartilage anlage and that bone is formed in the lower segments of the communicating canals where no vessels are detectable.

The synovial lining layer of the temporomandibular joint (TMJ) consists of macrophage-like type A cells and fibroblast-like type B cells. Until now, little information has been available on the development of the synovial membrane in TMJ. In the present study we examined the development of the synovial lining layer in the rat TMJ by light- and electron-microscopic immunocytochemistry for heat shock protein (Hsp) 25, which is a useful marker for type B cells. At embryonic day 19 (E19), a few Hsp25-positive cells first appeared in the upper portion of the developing condyle. During the formation of the upper articular cavity (E21 to postnatal day 1 (P1)), a few positive cells were arranged on its surface. Immunoelectron microscopy demonstrated that these cells had ultrastructural features of fibroblast-like type B cells. In addition, some Hsp25-positive cells moved to the deep portion by extending their cytoplasmic processes toward the articular cavity at P3. At that time, the presence of typical macrophage-like type A cells in the lining layer was confirmed by immunoelectron microscopy. The slender processes of Hsp25-positive cells showed a continuous covering with the synovial surface at P7, followed by a drastic increase in the Hsp25-positive cells at P15 and later, when active jaw movement occurred. These findings suggested that the arrangement and morphological maturation of type B cells are closely related to the formation of the articular cavity in the embryonic period and the commencement of active jaw movement after birth, respectively.

The capillaries of the area postrema (AP) lack the morphological peculiarity of the blood-brain barrier (BBB), and the AP neurons are considered located outside the BBB. Using the immunofluorescent method, we have investigated the expression of membrane transport systems that are instrumental to the BBB function, such as caveolin-1, -2, P-glycoprotein, and glut-4, in the capillary endothelium of the rat and calf AP. The expression of these molecules was verified after fibronectin immunostaining of the microvessels. Both in the rat and calf, caveolin-1, -2, and P-glycoprotein were expressed in the AP capillaries. A quantitative analysis revealed that the proportion of the capillary profiles expressing these transport systems was very close to 100% of the fibronectin immunolabelled profiles. On the contrary, none of the AP capillaries showed glut-4 immunoreactivity. The present investigation demonstrates that the endothelial layer of the AP capillaries, in spite of the paracellular passage of polar molecules through the leaky tight junctions and fenestrations, could be an active interface which is able to control the entry of a wide range of blood-borne compounds into the brain by means of specific mechanisms, including an efflux pump.