Blood vessels and the occurrence of arteriovenous anastomoses in cephalic heat loss areas of mallards,Anas platyrhynchos (Aves)

Summary 1. The blood supply to cephalic heat loss areas (nasal and oropharyngeal mucosa, bill, eyelids) was studied in mallards by using plastic corrosion casts. The structure and organization of the blood vessels, as well as the occurrence of arteriovenous anastomoses (AVAs), were examined by scanning electron microscopy of vascular casts and by paraffin sections.2. Submucosal venous plexuses (cavernous tissue) are present in the nasal cavity, tongue, and lateral margins of the palate. These plexuses receive blood from post-capillary venules, but may also receive a non-nutritive component via numerous AVAs.3. High densities of AVAs were found in the eyelids and in the tip of the bill. In the tongue and nasal mucosa, the AVAs decreased in number caudally. The reason for regional differences in the density of AVAs is discussed in relation to variation in mechanical and thermal stimulation of the tissues.4. The connection of the different heat loss areas with the Rete ophthalmicum, which is a countercurrent heat exchanger important for brain cooling, is pointed out. The vascular pattern of the head suggests that sphincteric veins are involved in regulating the venous return from the evaporative surfaces of the nasal cavity and palate. One of these veins had, in addition to the normal circular smooth muscle fibres, a conspicuous component of longitudinally arranged, subendothelial, smooth muscle fibres.     

Arteriovenous anastomoses and vascularity in the feet of eiders and gulls (Aves)

Summary Arteriovenous anastomoses (AVAs) and vascularity were studied in the webbed feet of eiders and two species of gulls using an injection technique. The density of AVAs was high in the distal part of the web (85–126 AVAs per cm²) and decreased proximally. Anastomoses were also present in the feathered skin of the tibiotarsus (18–39 AVAs per cm²). A positive correlation was found between the density of AVAs and the vascularity of the skin. The role of the AVAs in temperature regulation is briefly discussed.     

Responsiveness of microcirculation and local cold vasodilation to capsaicin in the intact and chronically denervated canine tongue

Lingual blood flow and its distribution were determined at rest and in response to local cooling of the tongue (32 degrees C) in 6 anaesthetized, paralyzed and artificially ventilated dogs before and after two intraarterial (i.a.) injections of capsaicin (2.5 mg) at an interval of about 40 min. In 3 dogs, the same protocol was performed after degeneration of the chorda-lingual and glossopharyngeal nerves due to prior transection. In general the first i.a. injection of capsaicin resulted in a marked and the second injection in a smaller decrease of lingual blood flow. Local cooling of the tongue induced significant increases in lingual blood flow before as well as after capsaicin treatment, regardless of whether sensory innervation was intact or degenerated. In both the untreated and capsaicin treated dogs the increase in lingual blood flow during local cooling of the tongue was solely due to an increase in blood flow through the arteriovenous anastomoses, while blood flow through the capillaries of the mucosa and muscles even decreased. The findings suggest that capsaicin-induced vasoconstriction of the tongue vessels is due to a direct effect on vascular receptors. It is further suggested that cold vasodilatation of the canine tongue is not mediated by axon collaterals releasing substance P. Direct thermal effects on the intramural ganglia and the postganglionic vasomotor efferents innervating the AVAs, or on AVAs basal tone itself are suggested as the underlying mechanism.     

Development of arteriovenous anastomoses in the skin of the chicken and the influence of environmental temperature

Posthatching differentiation of arteriovenous anastomoses (AVAs) and the effect of heat exposure (38 degrees C) and cold acclimation (2-3 degrees C) on AVA density were studied in naked skin areas (eyelids, comb, wattles) of chickens. The AVAs were identifiable in the newly hatched chick, but they were extremely simple. The number of cell layers in the wall of the AVAs increased from two at hatching to four to five in the 5-month-old chickens. The density of the AVAs increased significantly during posthatching maturation. Cold acclimation of the chickens increased the density of AVAs by a factor of 2.1-3.2. Daily heat exposure also increased the density of AVAs significantly in the eyelids but had no effect in the other skin areas. Heat and cold had only minor effect on the vascularity of the skin; the only significant change recorded was a slight increase in the number of blood vessels in the wattles of the cold-acclimated chickens.     

VASOMOTOR RESPONSES OF ISOLATED PERIPHERAL BLOOD VESSELS FROM BOWHEAD WHALES: THERMOREGULATORY IMPLICATIONS

Temperature regulation in bowhead whales, Balaena mysticetus , is supported by the characteristic cetacean peripheral circulation, especially notable in the tail flukes. Blood vessels serving this function consist of countercurrent heat exchangers (network of veins surrounding a central artery) favoring heat conservation and an alternate routing via arteriovenous anastomoses (AVAs) providing for heat dissipation. We tested the vasomotor responses of isolated segments of countercurrent arteries and AVAs from the bowhead tail flukes to norepinephrine (NOR), the sympathetic adrenergic neurotransmitter. Isometric tension developed during exposure to a micromolar concentration of NOR was consistently higher in AVAs than in arteries. Accordingly, the AVAs are subject to sympathetic vasoconstriction, and this activation directs blood flow to countercurrent heat exchangers and results in heat conservation. In contrast, AVA relaxation by reduced sympathetic activation favors increased blood flow through AVAs and consequent peripheral heat loss.     

Optical and scanning electron microscopy observation of the mucosa of human fetal tongue

The structural features of the human foetal tongue have been studied in foetuses from 8th to 20th week of pregnancy. The characteristics of the developing papillae as well as of epithelial and mesenchymal layers have been pointed out. An early differentiation of the mesenchymal tissue has been observed, concerning phenomena of cellular condensation and reticular fibers organization both in superficial and deep layers. The hypothesis of the existence of straight interactions between epithelium and mesenchyme also in the developing human tongue mucosa has been suggested. Also the observations at SEM demonstrate that from the 8th to the 20th week the epithelial surface of the tongue reaches a stable structural pattern. From 11th week a characteristic cellular polymorphism occurs: cells with microvilli that diminish progressively, ciliated cells that disappear almost completely at the 20th week and cells whose free surface show microplicae, definitive stage of the tongue cell evolution.     

Occurrence of substance P-like immunoreactive nerve fibers in Krause corpuscles of the dog's tongue

Substance P-like immunoreactive (SPLI) nerve fibers were demonstrated in the Krause corpuscles of the dog's tongue using the indirect immunofluorescence method and cholinesterase histochemistry. SPLI nerve fibers were often in contact with Krause end bulbs and occasionally entered them. From this result it was suggested that substance P might be involved in sensory mechanism of the Krause apparatus.     

Temporal and spatial selection against parthenogenetic cells during development of fetal chimeras

The fate of parthenogenetic cells was investigated during development of fetal and early postnatal chimeras. On day 13 of embryonic development, considerable contribution of parthenogenetic cells was observed in all tissues of chimeric embryos, although selection against parthenogenetic cells seemed to start before day 13. Between days 13 and 15 of development, parthenogenetic cells came under severe selective pressure, which was most striking in tongue. The disappearance of parthenogenetic cells from tongue coincided with the beginning of myoblast fusion in this tissue. Severe selection against parthenogenetic cells was also observed in pancreas and liver, although in the latter, parthenogenetic cells were eliminated later than in skeletal muscle or pancreas. In other tissues, parthenogenetic cells may persist and participate to a considerable extent throughout the gestation period and beyond, although a significant decrease was observed in all tissues. Parthenogenetic in equilibrium fertilized chimeras were significantly smaller than their non-chimeric littermates at all developmental stages. These results suggest that the absence of paternal chromosomes is largely incompatible with the maintenance of specific differentiated cell types. Furthermore, paternally derived genes seem to be involved in the regulation of proliferation of all cell types, as indicated by the drastic growth decceleration of parthenogenetic in equilibrium fertilized chimeras and the overall decrease of parthenogenetic cells during fetal development. Chromosomal imprinting may have a role in maintaining a balance between cell growth and differentiation during embryonic development. The major exception to the selective elimination of parthenogenetic cells appear to be the germ cells; viable offspring derived from parthenogenetic oocytes were detected, sometimes at a high frequency in litters of female parthenogenetic in equilibrium fertilized chimeras.     

Inhibition of connexin 43 alters <Emphasis Type="Italic">Shh</Emphasis> and <Emphasis Type="Italic">Bmp-2</Emphasis> expression patterns in embryonic mouse tongue

The morphogenesis of fungiform papillae occurs in a stereotyped pattern on the dorsal surface of the mammalian tongue via epithelial–mesenchymal interactions. These interactions are thought to be achieved via intercellular communication. Gap junctions can be observed in many developing tissues and have been suggested to participate in a variety of functions, including the regulation of cell proliferation, differentiation, and apoptosis. Here, we demonstrate that the expression of Connexin 43 (Cx43), a gap junction protein, is correlated significantly with the development of fungiform papillae, which exhibit a pattern formation and morphogenesis similar to the development of other epithelial appendages. Antisense-oligodeoxynucleotide (AS-ODN) against Cx43 was used to assess the developmental functions of Cx43. The expression patterns of the signaling molecules were disrupted by Cx43 inhibition. Interestingly, the expression patterns of Shh, a key molecule in the determination of the spacing patterns of fungiform papillae, were disturbed after treatment with Cx43 AS-ODN. We have also attempted to determine the functions of Bmp-2 by applying NOGGIN protein to tongue cultures. Our results indicate that upstream regulation via Cx43 controls the Shh and Bmp-2 pathways for the morphogenesis and pattern formation of fungiform papillae.This work was supported by grant no. R01-2003-000-11649 from the Korea Science and Engineering Foundation.     

Effects of atrial natriuretic peptide AP II on proliferation processes in the epithelial tissue of white rats]

The effect of atrial natriuretic peptides synthetic analog AP II on corneal, skin, tongue and duodenum epithelium proliferation have been studied on male rats. The epithelium mitotic activity and DNA synthesis were evaluated in 4 and 24 h after intraperitoneal injection of 10 or 100 micrograms/kg AP II. 10 micrograms/kg AP II was found to have different influence on organs epithelium: it decreased the mitotic activity of skin and corneal epithelium, but activated the proliferation processes in tongue and duodenum epithelium. 100 micrograms/kg AP II stimulated cell mitogenesis in all organs studied. According to data obtained atrial natriuretic peptides are able to participate in cell division regulation in vivo.     

Structural and functional characteristics of the special regulatory devices in the peripheral pulmonary circulation in rabbits

The present study intended to describe in detail the several blood vessels harboring special regulatory devices in rabbit’s pulmonary tissue using light and electron microscopy and immuno-histochemistry. Numerous throttle arteries were recorded within the adventitia of the segmental and sub-segmental bronchi and within pulmonary pleura. These arteries showed characteristic narrow or obliterated lumens and some of them bear longitudinal muscular intimal bolsters. For the first time, TEM revealed some structural modifications of the vascular endothelial cells of these arteries indicating that they become more activated to perform some additional functions. Arteriovenous anastomoses (AVAs) including direct shunt vessels and glomus organs were also recognized. Direct arteriovenous shunts appeared as small connecting devices communicating between small arteries and small veins while glomus organs consisted of the tortuous glomus vessels and the related afferent and efferent vessels. Several arteries and veins showing unique unusual structural characteristics were also described. For the first time, serotonin (5-HT) was strongly expressed in the vascular endothelium and muscle fibers of throttle arteries, in glomus cells of the glomus vessels, and in vascular endothelium of some veins and venules of special structure. The exact role of 5-HT is still unknown and further investigations are required to determine the types and distribution of 5-HT receptors present in these vascular devices. We concluded that these special vascular devices can play a critical role in controlling blood flow and pressure in the peripheral pulmonary circulation; however, the exact physiological mechanisms by which they work or are controlled remain unknown providing a ripe area for further investigation.     

Sauropod haemal arches: morphotypes,new classification and phylogenetic aspects

Sauropod haemal arches are caudal bony structures that have been traditionally incorporated into two different types observed in different anatomical views: Y-shaped (anterior view) and forked (lateral view). This research proposes a classification combining information observed in anterior and lateral views. Four types of ‘Y-shaped’ and six types of ‘V-shaped’ chevrons were recognised. Complete chevron series in some eusauropods allows the comparison of topological equivalent structures along the tail and also among taxa. A basal titanosaur from Argentina exhibits mid-caudal chevron morphology in which more than one cranial and caudal process is present, arising from the distal blades as well as from the proximal rami, a condition not seen before in a sauropod dinosaur. The morphological variability seen in sauropod chevrons along the tail is in close relationship with the development and distribution of muscle. caudofemoralis longus, as seen in extant crocodiles and as previously proposed for non-avian theropods and for caudal centra and transverse processes of sauropod dinosaurs. Two new characters related to middle chevrons are proposed here, in which the transitional morphology is described.     

内蒙古达斡尔族舌运动类型的遗传学研究

调查了内蒙古达斡尔族舌运动类型（卷舌、叠舌、翻舌、尖舌、三叶舌）,共480例（男239例,女241例）。研究结果显示：（1）卷舌、叠舌、翻舌、尖舌、三叶舌出现率分别为80．42％、4．58％、31．25％、81．88％、31．46％;（2）卷舌、三叶舌出现率存在性别间明显差异;（3）卷舌基因与翻舌、三叶舌基因间存在互作关系,翻舌基因与叠舌、尖舌、三叶舌基因间存在互作关系;（4）卷舌、叠舌、翻舌、三叶舌的出现率存在民族间或种族间差异。     

Proliferation of arteriovenous anastomoses in the developing rabbit ear is enhanced after denervation

The innervation of the rabbit ear vasculature by noradrenergic and substance P-immunoreactive (SP-IR) nerves was investigated in both young and adult animals. All vascular segments were supplied by both noradrenergic and SP-IR nerves. In the ear margins, the arteriovenous anastomoses (AVAs) were more densely innervated than other vessels. In general, the density of both noradrenergic and SP-IR nerves increased with age until 10-12 weeks postnatum. The ear vasculature was denervated in young rabbits to test whether the normal proliferation of AVAs in the growing ear was altered in the absence of nerves. Surgical resection of all auricular nerve trunks except the auricular branch of the auriculo-temporal nerve, and removal of the ipsilateral superior cervical ganglion in 10- to 12-day-old rabbits left the ear devoid of both noradrenergic and SP-IR nerves for at least four weeks. Repeated administration of 6-hydroxydopamine (6-OHDA) to young rabbits produced degeneration of noradrenergic terminal axons, but preterminal nerve trunks survived. SP-IR nerves did not appear to be affected by 6-OHDA. These denervation regimes resulted in a 1.5- to 2-fold increase in the number of AVAs formed in the growing ear. Surgical denervation and 6-OHDA treatment also led to retarded growth of the media of the central ear artery, but this effect of 6-OHDA was probably not due to a specific action on vascular smooth muscle. Surgical resection of most of the dorsal auricular nerves in adult rabbits did not affect AVA density. Large differences in AVA density were apparent between groups of control animals from different parts of the country, or groups examined at different times of the year. These results demonstrate that the labile nature of AVAs in the rabbit ear can result in considerable variability in the absolute number of AVAs and suggest that both intrinsic and extrinsic factors may influence development of the microvasculature.     

磷脂酶D的细胞信号转导作用

磷脂酶D(PLD)是一类重要的跨膜信号转导酶类.分别由一个基因家族的不同成员编码.植物PLD的总体域结构相似,只是不同类型之间在某些单元上有重要差异.它们各具独特的生物化学特性.不同的PLD在不同的胁迫类型启动的特定的细胞过程中执行独特的细胞信号转导功能.PLD与其它磷脂酶及Ca2 信使之间有交互作用,形成复杂的信号转导网络.这一网络在不同植物种类、器官、组织和细胞类型中表现出特异性.文章最后讨论了PLD研究中有待揭示的问题并展望了今后的发展方向.     

Development of the vascular bed in the rabbit ear: scanning electron microscopy of vascular corrosion casts

The development of the vascular bed in the rabbit ear was investigated using vascular corrosion casts from animals of various ages. Examination of the casts revealed that the arrangement of the major auricular arteries and veins was determined before birth and was maintained during postnatal growth of the ear. Furthermore, the number of arteries branching off the central ear artery and the lateral arteries did not increase with increasing ear length. Scanning electron microscopic examination of lateral segments of adult ear casts revealed many anastomoses between marginal arteries and veins. These arteriovenous anastomoses (AVAs) occurred singly, in pairs, or in clusters of three to six. Their size and shape were variable, even in the same cast. The central segment of many AVA casts showed surface impressions of endothelial cell nuclei which were different from the impressions on adjacent arteries and veins. Arteriovenous anastomoses were also detected in ear casts from animals as young as 8 days. The density of AVAs in lateral ear segments ranged from 95-165 cm-2 in 8- to 11-day-old rabbits to 80-115 cm-2 in adults. However, estimates of the total number of AVAs in the lateral ear margin indicated that AVAs continued to be formed at a steady rate during growth of the ear. During the early neonatal period the cutaneous capillary plexuses developed prominent tufts projecting toward the skin surface, which were apparently associated with developing hair follicles. These capillary tufts were not seen in casts from fetal or adult rabbits.     

The degree of tongue‐coating reflects lingual motor function in the elderly

Objectives: The aim of this study was to examine the relation between the degree of tongue‐coating and oral function. Background: Tongue‐coating is a moss‐like deposit which forms over the tongue surface, and includes micro‐organisms, food residues, and abrasive epithelia. It is considered that motor function of the tongue and lips and saliva secretion decrease in the aged and have some effect on the accumulation of tongue‐coating. Although saliva secretion has been reported as a factor amongst these oral functions in contributing to tongue‐coating, the correlation with the motor function of oral structures is unknown. Subjects and methods: The factors that contribute to the accumulation of tongue‐coating were examined in 48 subjects of advanced age (mean age 80.8 ± 7.8 years) with no severe levels of periodontal disease. Changes in the degree of tongue‐coating were also examined after oral functional training in these subjects. The frequency of oral cleaning, status of oral hygiene, motor function of the tongue, and masticatory performance were examined as potential factors associated with the degree of coating. Results: The results showed that tongue pressure and the frequency of oral diadochokinesis measured by pronouncing the single syllable ‘ka’ as an indicator were statistically significantly correlated with the degree of tongue‐coating. Several factors in oral function improved with training, and also the degree of tongue‐coating decreased in 27 subjects. Conclusion: These results suggest a correlation between the degree of tongue‐coating and a reduction in lingual motor function and, in addition, possible improvement in level of coating by functional training of the tongue.     

Actin isoform and α1B-adrenoceptor gene expression in aortic and coronary smooth muscle is influenced by cyclical stretch

Summary The occurrence of vascular domains with specific biological and pharmacological characteristics suggests that smooth muscle cells in different arteries may respond differentially to a wide range of environmental stimuli. To determine if some of these vessel-specific differences may be attributable to mechano-sensitive gene regulation, the influence of cyclical stretch on the expression of actin isoform and α_1B-adrenoceptor genes was examined in aortic and coronary smooth muscle cells. Cells were seeded on an elastin substrate and subjected to maximal stretching (24% elongation) and relaxation cycles at a frequency of 120 cycles/min in a Flexercell strain unit for 72 h. Total RNA was extracted and hybridized to radiolabeled cDNA probes to assess gene expression. Stretch caused a greater reduction of actin isoform mRNA levels in aortic smooth muscle cells as compared to cells from the coronary artery. Steady-state mRNA levels of α_1B -adrenoceptor were also decreased by cyclical stretch in both cell types but the magnitude of the response was greater in coronary smooth muscle cells. No changes in α_1B-adrenoceptor or β/γ-actin steady-state mRNA levels were observed in H4IIE cells, a nonvascular, immortalized cell line. The relative gene expression of heat shock protein 70 was not influenced by the cyclic stretch regimen in any of these cell types. These results suggest that stretch may participate in the regulation of gene expression in vascular smooth muscle cells and that this response exhibits some degree of cell-specificity.     

Episodic hypoxia induces long-term facilitation of neural drive to tongue protrudor and retractor muscles.

Hypoxic episodes can evoke a prolonged augmentation of inspiratory motor output called long-term facilitation (LTF). Hypoglossal (XII) LTF has been assumed to represent increased tongue protrudor muscle activation and pharyngeal airway dilation. However, recent studies indicate that tongue protrudor and retractor muscles are coactivated during inspiration, a behavior that promotes upper airway patency by reducing airway compliance. These experiments tested the hypothesis that XII LTF is manifest as increased inspiratory drive to both tongue protrudor and retractor muscles. Neurograms were recorded in the medial XII nerve branch (XIIMED; contains tongue protrudor motor axons), the lateral XII nerve branch (XIILAT; contains tongue retractor motor axons), and the phrenic nerve in anesthetized, vagotomized, paralyzed, ventilated male rats. Strict isocapnia was maintained for 60 min after five 3-min hypoxic episodes (arterial Po(2) = 35 +/- 2 Torr) or sham treatment. Peak inspiratory burst amplitude showed a persistent increase in XIIMED, XIILAT, and phrenic nerves during the hour after episodic hypoxia (P < 0.05 vs. sham). This effect was present regardless of the quantification method (e.g., % baseline vs. percent maximum); however, comparisons of the relative magnitude of LTF between neurograms (e.g., XIIMED vs. XIILAT) varied with the normalization procedure. There was no persistent effect of episodic hypoxia on inspiratory burst frequency (P > 0.05 vs. sham). These data demonstrate that episodic hypoxia induces LTF of inspiratory drive to both tongue protrudor and retractor muscles and underscore the potential contribution of tongue muscle coactivation to regulation of upper airway patency.     

A survey of 1,000 cases referred for cytogenetic study to King Khalid University Hospital, Saudi Arabia.

We reviewed cytogenetic studies that have been done in 1,000 consecutive non-oncology samples that were referred to the Cytogenetics Unit at King Khalid University Hospital, Riyadh, Saudi Arabia. The cases were grouped according to the referral diagnosis and the requested cytogenetic service. The frequency of the different types of numerical and structural abnormalities was determined and the relative frequency of cases with abnormal karyotype was calculated in each group. This study should assist physicians in Saudi Arabia and surrounding countries by increasing the awareness of the frequency of cytogenetic abnormality in different diagnostic groups. It also gives figures for comparison with other countries and research centers.