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1.
白枕鹤的呼吸系统及其生态适应   总被引:2,自引:0,他引:2  
白枕鹤的呼吸系统由喉头、气管、鸣管、肺及气囊组成。喉头有淋巴小结分布。气管在龙骨突起内盘旋,并随年龄而增长,软骨环逐渐骨化。鸣管由左右两个支气管特化而成,呈膜状扁管入肺。肺的长度约占躯干的1/2。气囊几遍布全身,高度发达。整个呼吸系统的结构,与其高空飞翔生活相适应。  相似文献   

2.
Dark melanic color pattern elements, such as bars, stripes, and spots, are common in the skin of fishes, and result from the differential distribution and activity of melanin‐containing chromatophores (melanophores). We determined the histological basis of two melanic color pattern elements in the integument of the Firemouth Cichlid, Thorichthys meeki. Vertical bars on the flanks were formed by three layers of dermal melanophores, whereas opercular spots were formed by four layers (two lateral and two medial) in the integument surrounding the opercular bones. Pretreatment of opercular tissue with potassium and sodium salts effectively concentrated or dispersed intracellular melanosomes. Regional differences in epidermal structure, scale distribution, and connective tissues were also identified. J. Morphol. 2013. © 2013 Wiley Periodicals, Inc.  相似文献   

3.
4.
The dermal skeleton (=exoskeleton) has long been recognized as a major determinant of vertebrate morphology. Until recently however, details of tissue development and diversity, particularly among amniotes, have been lacking. This investigation explores the development of the dermatocranium, gastralia, and osteoderms in the American alligator, Alligator mississippiensis. With the exception of osteoderms, elements of the dermal skeleton develop early during skeletogenesis, with most initiating ossification prior to mineralization of the endoskeleton. Characteristically, circumoral elements of the dermatocranium, including the pterygoid and dentigerous elements, are among the first to form. Unlike other axially arranged bones, gastralia develop in a caudolateral to craniomedial sequence. Osteoderms demonstrate a delayed onset of development compared with the rest of the skeleton, not appearing until well after hatching. Osteoderm development is asynchronous across the body, first forming dorsally adjacent to the cervical vertebrae; the majority of successive elements appear in caudal and lateral positions. Exclusive of osteoderms, the dermal skeleton initiates osteogenesis via intramembranous ossification. Following the establishment of skeletal condensations, some preossified spicules become engorged with many closely packed clusters of chondrocyte-like cells in a bone-like matrix. This combination of features is characteristic of chondroid bone, a tissue otherwise unreported among nonavian reptiles. No secondary cartilage was identified in any of the specimens examined. With continued growth, dermal bone (including chondroid bone) and osteoid are resorbed by multinucleated osteoclasts. However, there is no evidence that these cells contribute to the rugose pattern of bony ornamentation characteristic of the crocodylian dermatocranium. Instead, ornamentation develops as a result of localized concentrations of bone deposited by osteoblasts. Osteoderms develop in the absence of osteoblastic cells, osteoid, and periosteum; bone develops via the direct transformation of the preexisting dense irregular connective tissue. This mode of bone formation is identified as metaplasia. Importantly, it is also demonstrated that osteoderms are not histologically uniform but involve a range of tissues including calcified and uncalcified dense irregular connective tissue. Between taxa, not all osteoderms develop by homologous processes. However, it is concluded that all osteoderms may share a deep homology, connected by the structural and skeletogenic properties of the dermis.  相似文献   

5.
白鱀豚上呼吸道具有前庭囊、鼻额囊及前颌囊三对气囊,没有副囊和连接囊。三对囊均右大于左,其中又以前庭囊最为显著。喉由甲状软骨、环状软骨、会厌软骨及一对杓状软骨组成,从喉腔壁的组织学观察发现有室皱襞(假声带)的存在。    相似文献   

6.
A new species of nematode, Cucullanus costaricensis n. sp., is described from the Red Sea catfish Bagre pinnimaculatus from Río Tempisque, Costa Rica. The new species is characterized by the following traits: spicules and gubernaculum length (0.48 +/- 0.02 [0.45-0.50] and 0.20 +/- 0.02 [0.18-0.21], respectively); a protruding cloacal region in males, and the arrangement of caudal papillae (1 medial unpaired precloacal papilla and 10 pairs of papillae: 3 precloacals [first pair subventral and anterior to ventral sucker; second and third pairs posterior to ventral sucker; second pair asymmetric and subventral; third pair slightly subventral and closer to cloacal opening], 3 subventral adcloacal pairs [pairs 4-6], and 4 pairs of postcloacal papillae [seventh pair lateral, eighth pair subdorsal, ninth and tenth pairs subventral]); and lateral phasmids between the seventh and eighth pairs of postcloacal papillae. This finding represents the first record for a species of Cucullanus in Central America.  相似文献   

7.
The hydroskeleton plays a central role in the architecture of the trunk of the Chaetognath. Its fibrous part is composed by a ‘basement membrane’ which separates the epithelial and nervous level from the locomotory muscle and other tissues which surround the general cavity. This structure corresponds to a dense connective tissue sheath; together with the aqueous phase of the general cavity it constitutes the main part of the hydroskeleton. The axes of the lateral and caudal fins are extensions of this connective tissue; they are rich in ground substance and contain several kinds of fibrils and granules.The ‘basement membrane’ is made of a network of densely packed parallel layers of collagen fibrils which form helices which wrap around the trunk. The collagen fibrils of this connective stratum are sandwiched between two basal lamina; they are embedded in a reduced extracellular matrix whose components are closely related to the architecture of the collagen fibrils. In the core of the fin, the ground substance is very abundant and classical cross-striated collagen fibrils are not to be found. A compact fibrillar transition zone is to be noted between the dense connective stratum surrounding the body and the hyaline axis of the fins. In this zone, no crossbanded collagen fibrils are to be seen.The hydroskeleton and the fins show variations within the phylum. They could be related to speciation, and the ancestral pathway of the phylum. Furthermore these variations are related to the general problem of the evolution of the extracellular matrices and collagen molecule itself.  相似文献   

8.
Akira Chiba  & Masahiko Nakamura 《Ibis》2002,144(2):E96-E104
This paper describes the histological features of the prominent cloacal protuberance (CP) of sexually mature females of the polygynandrous Alpine Accentor Prunella collaris . In the copulation period, the CP of the prelaying mature female developed remarkably and the lips of the vent turned brilliant scarlet. Macroscopic and microscopic examination of the cloacal region from females of different ovarian maturity showed that the formation of the CP was mainly due to the hypertrophy of the cloacal musculature, i.e. the sphincter cloacae muscle and levator cloacae muscle, and to the development of the associated connective tissue in the sexually mature female. The scarlet coloration of the cloacal lips was ascribed exclusively to the development of the dermal vascular plexus accompanied by hyperaemia, as characterized by the dilated blood vessels filled with blood. There was no evidence that skin pigmentation was involved in the scarlet coloration of the cloacal lips. We speculate that the morphological changes in the cloacal lips of the female Alpine Accentor are mediated hormonally by the brain–pituitary–gonadal axis.  相似文献   

9.
The cloacal sacs of Leptotyphlops dulcis are nonglandular, posterior evaginations of the cloaca. The median cloacal gland is tubuloalveolar. Similar unpaired cloacal glands as well as paired sacs are noted in certain colubrid snakes. Terminology applied to these cloacal derivatives is discussed, and a standardization of names is provided.  相似文献   

10.
Summary The organisation of the catecholamine innervation of the rat septal area was investigated by means of the glyoxylic acid fluorescence method in combination with dopamine uptake studies, lesions and retrograde tracing of horseradish peroxidase. The following catecholamine systems to the septum could be established:The Locus Coeruleus Noradrenergic System These axons are widespread in the septum forming a moderately dense innervation in the anterior hippocampus, the medial septal nucleus, the nucleus of the diagonal band, and the interstitial nucleus of the stria terminalis, and a sparse innervation in the lateral septal nucleus and the septofimbrial nucleus.The Medulla Oblongata Noradrenergic System This system originates in the Al, A2 or A3 cell groups, the axons forming a very dense innervation in the ventral part of the interstitial nucleus of the stria terminalis, a moderately dense innervation in the nucleus of the diagonal band and lateral septal nucleus, and a sparse innervation in the medial septal nucleus, the septofimbrial nucleus and the dorsal part of the interstitial nucleus of the stria terminalis.The Mesencephalic Dopaminergic System This system originates in the medial part of the A10 cell group, the axons forming two distinct terminal patterns. In the first type, smooth axons form pericellular arrangements around non-fluorescent neurons in the lateral septal nucleus. The second type is formed by fine-varicose axons which form a dense band around the fornix in the medial part of the lateral septal nucleus.The Incerto-Hypothalamic Dopaminergic System These axons most probably originate in cell bodies of the diencephalic A11, A13 and A14 cell groups, and are found in the lateral septal nucleus at the level of the anterior commissure.  相似文献   

11.
Several studies have evaluated the effects of dietary vitamin A (VA) on the incidence of skeletal deformities during early ontogeny of fish, but little is known about its effects on bones depending on their process of ossification (dermal or chondral). We examined the incidence of skeletal deformities along development (30 and 48 dph) by double staining technique, in dermal (haemal and caudal vertebral bodies) and chondral (neural and haemal spines, epural, parahypural and hypurals) bones in Senegal sole post metamorphosed larvae fed with different dietary VA levels (37 000, 44 666, 82 666 and 203 000 UI total VA kg?1 DW) during Artemia feeding phase (6–37 dph, at 18°C). Results obtained in this study showed that dietary VA disrupted the skeletogenesis in Senegalese sole post metamorphosed larvae by increasing the incidence of skeletal deformities in the axial skeleton and caudal fin complex, which were dependent on both bone morphogenesis and ossification processes. Fish fed with the highest dietary VA content showed the highest incidence of skeletal deformities and its value increased along ontogeny. However, when we compared the incidence of deformities in skeletal structures considering their ossification process, most skeletal structures derived from chondral ossification showed a significant higher increase in deformity incidences in fish fed an excess of VA (44 666, 82 666 and 203 000 UI kg?1 DW), however within chondral bones, hypurals deformity incidence only increased in sole larvae fed Artemia highest VA content. In contrast, this dietary dose‐response effect was only noted in dermal bones from fish fed the highest dose of VA (203 000 UI kg?1 DW). In addition, the incidence of deformities in chondral bones increased even when the dietary imbalance of VA was corrected, whereas dermal bones were not affected at later ages. These results indicated that depending on the ossification process from which different skeletal structures are derived, bones might be differentially affected by high dietary VA content. Those directly originated from the connective tissue with a preliminary cartilage stage were more sensitive to dietary VA excess than those formed by intramembranous ossification.  相似文献   

12.
In areolar “loose” connective tissue, fibroblasts remodel their cytoskeleton within minutes in response to static stretch resulting in increased cell body cross‐sectional area that relaxes the tissue to a lower state of resting tension. It remains unknown whether the loosely arranged collagen matrix, characteristic of areolar connective tissue, is required for this cytoskeletal response to occur. The purpose of this study was to evaluate cytoskeletal remodeling of fibroblasts in, and dissociated from, areolar and dense connective tissue in response to 2 h of static stretch in both native tissue and collagen gels of varying crosslinking. Rheometric testing indicated that the areolar connective tissue had a lower dynamic modulus and was more viscous than the dense connective tissue. In response to stretch, cells within the more compliant areolar connective tissue adopted a large “sheet‐like” morphology that was in contrast to the smaller dendritic morphology in the dense connective tissue. By adjusting the in vitro collagen crosslinking, and the resulting dynamic modulus, it was demonstrated that cells dissociated from dense connective tissue are capable of responding when seeded into a compliant matrix, while cells dissociated from areolar connective tissue can lose their ability to respond when their matrix becomes stiffer. This set of experiments indicated stretch‐induced fibroblast expansion was dependent on the distinct matrix material properties of areolar connective tissues as opposed to the cells' tissue of origin. These results also suggest that disease and pathological processes with increased crosslinks, such as diabetes and fibrosis, could impair fibroblast responsiveness in connective tissues. J. Cell. Physiol. 228: 50–57, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   

13.
The skin reconstructed in vitro has been previously shown to be a useful model to investigate the effects of UVB exposure (Bernerd and Asselineau, 1997). The present study describes the response to UVA irradiation. Major alterations were observed within the dermal compartment. Apoptosis of fibroblasts located in the superficial area of the dermal equivalent was observed as soon as 6 h after irradiation, leading to their disappearance after 48 h. This effect was obtained without major alterations of epidermal keratinocytes suggesting a differential cell type sensitivity to UVA radiations. In addition, collagenase I was secreted by dermal fibroblasts. The UVA dermal effects could be observed even after removal of the epidermis during the post irradiation period, demonstrating that they were independent of the keratinocyte response. The analysis of the tissue regeneration during the following 2 weeks revealed a connective tissue repair via fibroblasts proliferation, migration and active synthesis of extracellular matrix proteins such as fibronectin and procollagen I. This cellular recolonization of the superficial part of the dermal equivalent was due to activation of surviving fibroblasts located deeply in the dermal equivalent. The direct damage in the dermis and the subsequent connective tissue repair may contribute to the formation of UVA-induced dermal alterations.  相似文献   

14.
Clefts between the body and the greater horn of the hyoid bone are reconstructed graphically from histological sections of hyoid bones from children aged 5 months up to 7 a. In 3 cases, the cleft cranially is enclosed by perichondrium at the lateral and medial sides; caudally the perichondral tissue is continued by cartilage on the medial side. On the lateral side, the perichondrium reaches more caudally. In 1 case, the cleft is enclosed on its medial side by cartilage only. In all cases examined, the medial wall is thicker than the lateral. The formation of a joint cleft between the body and the greater horn of the hyoid bone seems to be predominant in the lateral and caudal parts of that diarthrosis.  相似文献   

15.
The biceps brachii of horses is a complex muscle subdivided into two heads which may subserve distinct functions. The lateral head contains a large percentage of type I myofibers. This region is largely composed of short fibers (5-7 mm long) arranged in a pinnate fashion and heavily invested with connective tissue. The medial head contains fewer type I fibers and is composed of relatively longer myofibers (15-20 mm long), also arranged in a pinnate fashion but less heavily invested with connective tissue. It is hypothesized that the lateral muscle head of biceps brachii contributes to the postural role of the muscle in the forelimb passive stay apparatus. The medial head, with its longer fibers and generally fast fiber population may be most important during dynamic activity such as walking, trotting and running.  相似文献   

16.
The development of the tetrapod pectoral and pelvic girdles is intimately linked to the proximal segments of the fore‐ and hindlimbs. Most studies on girdles are osteological and provide little information about soft elements such as muscles and tendons. Moreover, there are few comparative developmental studies. Comparative data gleaned from cleared‐and‐stained whole mounts and serial histological sections of 10 species of hylid frogs are presented here. Adult skeletal morphology, along with bones, muscles, and connective tissue of both girdles and their association with the proximal portions of the anuran fore‐ and hindlimbs are described. The data suggest that any similarity could be attributable to the constraints of their ball‐and‐socket joints, including incorporation of the girdle and stylopodium into a single developmental module. An ancestral state reconstruction of key structures and developmental episodes reveals that several development events occur at similar stages in different species, thereby preventing heterochronic changes. The medial contact of the halves of the pectoral girdle coincides with the emergence of the forelimbs from the branchial chamber and with the total differentiation of the linkage between the axial skeleton and the girdles. The data suggest that morphogenic activity in the anterior dorsal body region is greater than in the posterior one, reflecting the evolutionary sequence of the development of the two girdles in ancient tetrapods. The data also document the profound differences in the anatomy and development of the pectoral and pelvic girdles, supporting the proposal that the pectoral and pelvic girdles are not serially homologous, as was long presumed.  相似文献   

17.
This project aimed to compare gross anatomical measures and biomechanical properties of single lamellae from the annulus fibrosus of ovine and porcine lumbar vertebrae, and bovine tail vertebrae. The morphology of the vertebrae of these species differ significantly both from each other and from human, yet how these differences alter biomechanical properties is unknown. Geometric parameters measured in this study included: 1) absolute and relative intervertebral (IVD) and vertebral body height and 2) absolute and relative intervertebral disc (IVD) anterior‐posterior (AP) and medial‐lateral (ML) widths. Single lamella tensile properties included toe‐region stress and stretch ratio, stiffness, and tensile strength. As expected, the bovine tail IVD revealed a more circular shape compared with both the ovine and porcine lumbar IVD. The bovine tail also had the largest IVD to vertebral body height ratio (due to having the highest absolute IVD height). Bovine tail lamellae were also found to be strongest and stiffest (in tension) while ovine lumbar lamellae were weakest and most compliant. Histological analysis revealed the greatest proportion of collagen in the bovine corroborating findings of increased strength and stiffness. The observed differences in anatomical shape, connective tissue composition, and tensile properties need to be considered when choosing an appropriate model for IVD research. J. Morphol. 277:244–251, 2016. © 2015 Wiley Periodicals, Inc.  相似文献   

18.
Histology of the cloacae of Rhyacotriton olympicus and representative species from the genera Ambystoma and Dicamptodon was examined by light microscopy. Females of Ambystoma possess sperm storage glands, the spermathecae, as well as ventral glands and dorsal glands, both of uncertain function. Females of Ambystoma examined from the subgenus Linguaelapsus differ from those in the subgenus Ambystoma by possessing more extensive ventral gland clusters and a shorter cloacal tube. Females of Dicamptodon possess spermathecae and ventral glands, but differ in cloacal conformation from females of Ambystoma and lack the dorsal glands. Females of R. olympicus possess more extensive epidermal lining in the cloaca than that found in females of Ambystoma and Dicamptodon, and the only glands present are spermathecae, which cluster around a tube in the dorsal roof. Males of Ambystoma, Dicamptodon, and R. olympicus possess five types of cloacal glands (dorsal pelvic glands, lateral pelvic glands, anterior ventral glands, posterior ventral glands, and Kingsbury's glands) that function in spermatophore formation, and vent glands that may produce a courtship pheromone. In Ambystoma and Dicamptodon, vent glands secrete along the medial borders of the cloacal orifice. Males of A. opacum and A. talpoideum differ from males of other species examined from the two genera by possessing more extensive vent glands. Males of R. olympicus possess unique vent glands in which tubules secrete onto the surface of vent lobes lateral to the posterior end of the cloacal orifice, and distal ends of the glands pass anteriorly, superficial to the fascia enclosing the other cloacal glands. The results from analysis of cloacal anatomy support other data indicating that Ambystoma and Dicamptodon are sister groups, and that Rhyacotriton olympicus is not closely related to either of the other two genera and merits placement in a separate family.  相似文献   

19.
The extinct parareptilian clade of pareiasaurs was in the past often presented to constitute a morphocline from larger, less armoured forms to smaller, well armoured forms, indicating that the osteoderm cover became an increasingly prominent aspect in the post‐cranial skeleton of these animals. Here, we describe microanatomical and microstructural aspects of osteoderms of the three pareiasaur taxa Bradysaurus, Pareiasaurus and Anthodon from the Permian of South Africa. A generalized mode of osteoderm formation, consistent with intramembraneous skeletogenesis, is hypothesized to be present in all pareiasaurs. Few characters are shared between pareiasaur dermal armour and turtle shell bones and osteoderms. Otherwise, there is strong evidence from microanatomy and histology (i.e. absence of structures that formed via metaplasia of dermal tissue) that indicates nonhomology between pareiasaur dermal armour and the armour of living eureptiles. Analysis with bone profiler revealed no clear connection between bone compactness and lifestyle in the amniote osteoderm sample.  相似文献   

20.
Spontaneous, continuous release of morphologically normal spermatozoa occurs in males of species of passerine (order Passeriformes) birds that were examined. It was demonstrated and studied quantitatively in temporarily captive and isolated house sparrows and house finches by means of repetitive cloacal lavages and extraction of excreta. It is suggested that this phenomenon could be exploited to facilitate comparative and quantitative evaluations of release of spermatozoa in relation to diverse environmental, physiological, and social factors.  相似文献   

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