Variations in the course and microanatomical study of the lateral femoral cutaneous nerve and its clinical importance

The lateral femoral cutaneous nerve (LFCN), a branch from the lumbar plexus, may come to the clinician's or surgeon's attention. We studied this nerve to determine its location and its relationship with neighboring structures around the anterior superior iliac spine (ASIS) and the inguinal ligament (IL). Additionally, cross‐sectional microanatomy of the LFCN at the IL was studied. The LFCN was dissected in 47 lower limbs from formalin‐fixed cadavers. The distances from the ASIS to the point where the LFCN crossed the IL and the lateral border of the sartorius were measured. The distance between the ASIS and the point it pierced the deep fascia was also measured. Twelve nerve specimens at the IL were collected for histological sectioning and were stained with hematoxylin and eosin. On examination of the cross‐sectional area, the nonfascicular area was wider than the fascicular area because of an increased amount of thick collagen fibers. This study may be of help to clinicians managing meralgia paresthetica and may also assist in defining a safe area for surgical intervention on the anterolateral aspect of the thigh. Clin. Anat. 23:978–984, 2010. © 2010 Wiley‐Liss, Inc.     

Microscopic anatomy of brachial plexus branches in Wistar rats

In the present study, we analyze the morphology and morphometry of the lateral proper digital nerve of the third finger, and of the proximal and distal segments of the ulnar, median, and radial nerves, in Wistar rats 4 or 7 weeks old. The fascicular area and diameter were generally significantly greater in the proximal compared to distal segments and tended to be larger in 7‐week‐old compared to 4‐week‐old rats (e.g., median nerve area of 0.13 mm² for the proximal and 0.07 mm² for distal segments in 4‐week‐old rats, and 0.17 and 0.10 mm², respectively, for the proximal and distal segments of 7‐week‐old rats). The number of fascicles was significantly greater while the number of myelinated fibers was significantly less in the distal segments (e.g., 1,359 and 509 myelinated fibers, respectively, in the proximal and distal segments of the radial nerve 4‐week‐old rats). There was no significant difference in these parameters between the two age groups. The diameter of the myelinated fibers and their respective axons increased from 4 to 7 weeks of age (e.g., myelinated fiber diameter of 4.10 μm in 4‐week‐old animals and 4.7 μm in the ulnar nerve proximal segment of 7‐week‐old rats). The g‐ratio regression line (axon diameter vs. fiber diameter quotient) was outlined for all the nerves studied here. Differences in myelinated fiber density were detected between the segments of the radial nerve, accompanying the number of myelinated fibers. Detailed knowledge of the microscopic anatomy of rat forelimb nerves provides control data for comparison with studies of experimentally induced neuropathies, which can shed more light on human neuropathies. Anat Rec, 290:477–485, 2007. © 2007 Wiley‐Liss, Inc.     

Significant Differences in Sympathetic Nerve Fiber Density Among the Facial Skin Nerves: A Histologic Study Using Human Cadaveric Specimens

Sympathetic nerve fibers in the skin nerves are connected with vasomotor, thermoregulatory, sensory input modulatory, and immunologic events; however, to our knowledge, no histological information is available for skin nerves in the human face. Using specimens from 17 donated cadavers (mean age, 86 years), we measured a sectional area of tyrosine hydroxylase (TH)‐positive fibers in (1) the frontal nerve (V1), (2) the infraorbital nerve (V2), (3) the mental nerve (V3), (4) the greater auricular nerve (C2), (5) the auriculotemporal nerve (ATN), and (6) the zygomatic branch of the facial nerve (VII). The V1, V2, and V3 were obtained at their entrances to the subcutaneous tissue from the bony canal or notch. The V1, C2, ATN, and/or VII usually contained abundant TH‐positive fibers (almost 3%–8% of the nerve sectional area), whereas the V2 and V3 consistently carried few TH‐positive fibers (<1%). The difference between these two groups was quite significant (P < 0.001). Thus, from the superior cervical ganglion, the sympathetic nerve fibers reached the forehead through the frontal nerve trunk, whereas artery‐bounded fibers came to the cheek, nose, and mouth. The sympathetic palsy caused by trigeminal nerve involvement is mainly characterized by the symptoms seen in the distribution of the ophthalmic division of the trigeminal nerve, such as in Horner's syndrome. It suggests that the forehead and the other facial areas are representative parts of those different sympathetic innervations that could be useful for evaluating the sympathetic function of the face in various diseases. Anat Rec, 299:1054–1059, 2016. © 2016 Wiley Periodicals, Inc.     

Denervation and Castration Effects on the Cross‐Sectional Area of Pubococcygeus Muscle Fibers in Male Rats

The number of fibers in skeletal muscles changes little through life; however, the cross‐sectional area of its fibers is modified as result of denervation and in some muscles by castration. The pubococcygeus muscle (Pcm) participates in micturition and ejaculatory processes and its fibers cross‐sectional area is reduced in castrated rats, but denervation effects remained unknown. Here, we used a model in which unilateral denervation of this muscle in gonadally intact and castrated male rats, allowed us to explore the neural and gonadal hormone effects on the cross‐sectional area of its fibers. Denervation significantly reduced the mean cross‐sectional area values; likewise, the percentage distribution of its fibers. We found that castration had a greater effect than denervation. Castration resulted in a lack of fibers from 2,000 to 3,999 μm², while in denervation it was from 2,500 to 3,999 μm². It was interpreted that the castration effect was due to a lack of the direct gonadal hormone effect on muscle fibers, and to a reduction of the indirect hormonal action in its neuromuscular complex. In denervated Pcm of gonadally intact animals these effects were present; however, in denervated but castrated animals these were absent. Thus, combined surgeries resulted in the lowest mean cross‐sectional area values with a restricted fiber distribution from 500 to 1,499 μm². In conclusion, the study in this important muscle showed that cross‐sectional area of its fibers depends on neural and direct/indirect gonadal hormone effects. Anat Rec, 296:1634–1639, 2013. © 2013 Wiley Periodicals, Inc.     

The cerebral basal arterial network: morphometry of inflow and outflow components

The aim of this project was to study how the morphology of the incoming and outgoing arterial components of the cerebral basal arterial network influence the blood flow to the brain. The cerebral basal arterial network consists of the circulus arteriosus cerebri anteriorly and the basilar artery posteriorly. Diameters of inflow vessels (bilateral vertebral and internal carotid arteries), connecting vessels (anterior communicating, basilar and bilateral posterior communicating arteries) and outflow vessels (anterior, middle and posterior cerebral arteries) were measured and cross‐sectional areas calculated in 51 cadaveric brain specimens. The individual and the average cross‐sectional areas of inflow arteries (51.43 mm²) were significantly bigger than the major outflow arteries (37.76 mm²) but smaller than the combined cross‐sectional areas of outflow (37.76 mm²) and connecting (25.33 mm²) arteries. The difference in the size of arterial cross‐sectional area and the presence of the connecting arteries in the cerebral basal arterial network provides a mechanism for lowering peaks in pressure, and demonstrates a function of the cerebral basal arterial network.     

The Effects of Castration and Hormone Replacement on the Cross‐Sectional Area of Pubococcygeus Muscle Fibers in the Female Rat

In this study, we analyzed the effect of ovariectomy and gonadal hormone replacement on the cross‐sectional area of pubococcygeus (Pcm) fibers. It was found that in comparison to intact animals, ovariectomized animals [for 2 or 6 weeks] had an increased cross‐sectional area average in Pcm fibers. Ovariectomy also reduced the percentage of fibers with smaller cross‐sectional area. In ovariectomized animals after 4 weeks of hormone replacement with an empty Silastic capsule or filled with testosterone propionate or dihydrotestosterone, significantly increased the cross‐sectional area average and the percentage of fibers with larger size. However, 17β‐estradiol but not estradiol benzoate treatment reduced the cross‐sectional area average and increased the percentage of Pcm fibers with smaller size. Progesterone did not have an effect on the cross‐sectional area of this muscle. We conclude that Pcm fibers of female rats are sensitive to gonadal hormones, and contrary to male castration, ovariectomy promotes an increase in their cross‐sectional area. Also, we discuss according to other studies that an external mechanism which lies within the neuromuscular periphery could also participate in the modulatory hormonal effect on mass or muscle fiber size. Furthermore, in this process, estradiol is likely to regulate the fiber cross‐sectional area growing produced by androgens. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

What Protects Certain Nerves from Stretch Injury?

The human tibial nerves is less prone to injury following joint arthroplasty compared with the peroneal nerves. Besides the anatomical distribution, other features may confer protection from stretch injury. We therefore examined the size, shape and connective tissue distribution for the two nerves. The tibial and peroneal nerves from each side of nine fresh human cadavers we reharvested mid‐thigh. Proximal segments manually stretched 20%–25% were fixed in aldehyde, while the adjacent distal segments were fixed in their natural length. Paraffin sections stained by Masson's trichrome method for connective tissue were examined by light microscopy. Tibial nerves had 2X more fascicles compared with the peroneal, but the axonal content appeared similar. Analysis showed that neither nerve had a significant reduction in cross sectional area of the fascicles following stretch. However, fascicles from stretched tibial nerves become significantly more oval compared with those from unstretched controls and peroneal nerves. Tibial nerves had a greater proportion that was extrafascicular tissue (50‐55%) compared with peroneal nerves (38%–42%). This epineurium was typically adipose tissue. Perineurial thickness in both nerves was directly related to fascicular size. Tibial nerves have several unique histological features associated with size, shape and tissue composition compared with the peroneal nerve. We suggest that more fascicles with their tightly bound perineurium and more robust epineurium afford protection against stretch injury. Mechanical studies should clarify how size and shape contribute to nerve protection and/or neurapraxia. Anat Rec, 299:111–117, 2016. © 2015 Wiley Periodicals, Inc.     

Microanatomical structure of the human sciatic nerve

Background  Sciatic nerve is the largest peripheral nerve of the human body. It gives motor and sensitive innervation for the most of lower limb. The aim of the present investigation was revealing his fascicular pattern in relation to microanatomic morphometric characteristics of its connective tissue sheaths. Methods  The material consisted of sciatic nerve slices, excised from 17 cadavers of humans aging 8–93 years. After routine histologic processing and light microscopic examination of the preparations, morphometric analysis was performed at magnifications of 40 and 630×. Results  Sciatic nerve showed to be polyfascicular nerve type, with the group pattern of nerve fascicless distribution. The number of fascicless ranged from 27 to 70, whereas the number of fascicless per square millimeter was 1–4. Morphometric and correlation analysis confirmed the significant increase of whole sciatic nerve cross section area, which was associated with the significant increase of its epi- and perineural connective tissue sheaths. Interfascicular sciatic nerve domains of elderly persons contained more adipose tissue. Moreover, already detected loss and degeneration of the large myelinated nerve fibers within fascicles was accompanied by the significant increase of endoneural connective tissue. Conclusions  In conclusion, our study revealed comparative connective tissue enlargement of human sciatic nerve in the course of aging. These phenomena might influence on result of injured nerve’s surgical reparations. We interpret this finding as non-specific compensatory phenomenon elicited by loss of thickest myelinated nerve fibers, higher vulnerability of remaining ones, and age-dependent decrease of connective tissue elasticity.     

Reparative myogenesis in long‐term denervated skeletal muscles of adult rats results in a reduction of the satellite cell population

This study, conducted on 25‐month denervated rat hindlimb muscles, was directed toward elucidating the basis for the poor regeneration that is observed in long‐term denervated muscles. Despite a ～97.6% loss in mean cross‐sectional area of muscle fibers, the muscles retained their fascicular arrangement, with the fascicles containing ～1.5 times more fibers than age‐matched control muscles. At least three distinct types of muscle fibers were observed: degenerating, persisting (original), and newly formed (regenerated) fibers. A majority of newly formed fibers did not appear to undergo complete maturation, and morphologically they resembled myotubes. Sites of former motor end‐plates remained identifiable in persisting muscle fibers. Nuclear death was seen in all types of muscle fibers, especially in degenerating fibers. Nevertheless, the severely atrophic skeletal muscles continued to express developmentally and functionally important proteins, such as MyoD, myogenin, adult and embryonic subunits of the nicotinic acetylcholine receptor, and neural‐cell adhesion molecule. Despite the prolonged period of denervation, slow and fast types of myosin were found in surviving muscle fibers. The number of satellite cells was significantly reduced in long‐term denervated muscles, as compared with age‐matched control muscles. In 25‐month denervated muscle, satellite cells were only attached to persisting muscle fibers, but were never seen on newly formed fibers. Our data suggest that the absence of satellite cells in a population of immature newly formed muscle fibers that has arisen as a result of continuous reparative myogenesis may be a crucial, although not necessarily the only, factor underlying the poor regenerative ability of long‐term denervated muscle. Anat Rec 263:139–154, 2001. © 2001 Wiley‐Liss, Inc.     

Regional differences in fiber characteristics in the rat temporalis muscle

The behavioral differences in muscle use are related to the fiber type composition of the muscles among other variables. The aim of this study was to examine the degree of heterogeneity in the fiber type composition in the rat temporalis muscle. The temporalis muscle was taken from 10‐week‐old Wistar strain male rats (n = 5). Fiber types were classified by immunohistochemical staining according to their myosin heavy chain content. The anterior temporalis revealed an obvious regional difference of the fiber type distribution, whereas the posterior temporalis was homogeneous. The deep anterior temporalis showed a predominant proportion of type IIA fibers and was the only muscle portion displaying slow type fibers (< 10%). The other two muscle portions, the superficial anterior and posterior temporalis, did not differ significantly from each other and contained mainly type IIB fibers. Moreover, the deep anterior temporalis was the only muscle portion showing slow type fibers (< 10%). In the deep portion, type IIX fibers revealed the largest cross‐sectional area (1943.1 ± 613.7 µm²), which was significantly (P < 0.01) larger than those of type IIA and I + IIA fibers. The cross‐sectional area of type IIB fibers was the largest in the remaining two muscle portions and was significantly (P < 0.01) larger than that of type IIX fibers. In conclusion, temporalis muscle in rats showed an obvious heterogeneity of fiber type composition and fiber cross‐sectional area, which suggests multiple functions of this muscle.     

The Relationship Between the Infraorbital Foramen,Infraorbital Nerve,and Maxillary Mechanoreception: Implications for Interpreting the Paleoecology of Fossil Mammals Based on Infraorbital Foramen Size

Osteological cranial features, such as foramina, assist in phylogenetic and ecological interpretations of fossil mammals. However, the validity of using foramina in these interpretations when their contents are not well documented is questionable. For decades, the infraorbital foramen (IOF) has been used to interpret aspects of the fossil record, yet there are conflicting accounts about what passes through the foramen and little known about how neural and vascular structures contribute to its contents. This study tracks and documents the neural and/or vascular anatomy of the IOF and examines the correlation of infraorbital nerve (ION) and IOF cross‐sectional area. To address this question, 161 mammalian cadavers, including 80 primates, were injected with latex dye to track the vascular anatomy associated with the IOF. All ION fibers were then removed from the infraorbital canal, and ION cross‐sectional area was calculated from histological slides. Latex injections and histological slides revealed that only the ION and a small infraorbital artery pass through the IOF. Variation in ION size explains 85% of variation in IOF area, and the artery represents a negligible portion of the foramen. The strong positive correlation between the ION and IOF size suggests that, in the absence of nerve tissue, the IOF can serve as a proxy for ION area. IOF area maybe used to evaluate differences in maxillary mechanoreception in both extinct and extant taxa. Anat Rec, 291:1221–1226, 2008. © 2008 Wiley‐Liss, Inc.     

Distribution of ganglionic sympathetic neurons supplying the subcutaneous,perirenal and mesentery fat tissue depots in the pig

Previous morphological studies revealed that the adipose tissue is innervated by adrenergic nerve fibers. Furthermore, physiological studies showed that the metabolism of adipose tissue is controlled by the adrenergic component of the nervous system. However, nothing is known on the sources of innervation of different fat tissue depots. Therefore, we decided to study the distribution of ganglionic sympathetic neurons innervating adipose tissue in the pig by means of a retrograde tracing method. We used 9 male and 9 female pigs of approximately 50 kg body weight. The retrograde tracer, Fast Blue (FB), was injected into the subcutaneous, perirenal and mesentery fat tissue depots. Results of the present study showed that numerous centers of the sympathetic nervous system innervate adipose tissue in the pig. FB+ neurons projecting to the subcutaneous fat tissue were placed in the thoraco-lumbar region of the sympathetic chain ganglia (SChG). However, neurons supplying perirenal and mesentery fat tissue depots were found in both the SChG and prevertebral ganglia (PVG). We conclude that different adipose tissue depots (subcutaneous, perirenal and mesentery) have different sources of innervation and that there is no significant difference in the distribution of neurons innervating adipose tissue in male and female pigs.     

Quantitative study of the effects of denervation and castration on the levator ani muscle of the rat

The levator ani muscle (LA) of the rat is highly androgen‐sensitive and, like all skeletal muscles, deteriorates structurally and functionally when denervated. In order to elucidate the interplay of neural and endocrine influences, the separate and combined effects of denervation and castration on myofiber cross‐sectional area and nuclear populations were quantitatively studied. In one group of 4‐month‐old male rats (A), the LA was denervated. Another group (B) was surgically castrated and a third group (C) was both denervated and castrated. The control rats (D) remained both gonad‐ and nerve‐intact. After two months, the LA was obtained for myofiber and nuclear enumeration, cross‐sectional area and satellite cell frequency determination. In the denervated muscle of gonad‐intact rats (Group A), myofiber cross‐sectional area was markedly diminished (265.84 ± 11.38μm²; compared with controls [Group D]: 1519.98 ± 79.41μm²; P < 0.05). Satellite cell nuclei, as a percentage of total sublaminar nuclei (i.e., satellite cell ratio), increased significantly (4.26%, from a control value of 1.91%). Castration alone (Group B) resulted in pronounced myofiber atrophy (mean cross‐sectional area: 754.03 ± 89.63μm²) but had no significant effect on satellite cell ratio (2.36%). The combination of castration and denervation (Group C) elicited the same degree of myofiber atrophy as denervation alone (Group A) but had no significant impact on satellite cell ratio. Instead, the nuclear count per myofiber declined to about a third of the control level (300.5 ± 38.49 compared with 861.7 ± 24.8; P < 0.05). The results indicate that the atrophic effects of denervation and castration on the LA are non‐synergistic and mechanistically similar. They also show that the inability of satellite cells to respond mitotically to the withdrawal of neural input under disandrogenized conditions is a factor in the myonuclear depletion of the denervated muscle of castrated rats. Anat Rec 255:324–333, 1999. © 1999 Wiley‐Liss, Inc.     

A note on the limb nerves of the frog (Rana tigrina)

In the frog (Rana tigrina) the mean length of the brain was 17.5 mm and that of the spinal cord 61 mm. The weight of the brain and spinal cord (together) was 389 mg. The fascicular number, fascicular area, total number of fibres and their density were studied in the left and right brachial nerves, left and right sciatic nerves and the sympathetic trunk (nerve). The largest number of nerve fascicles (12) was noticed in the sympathetic trunk while the right brachial nerve comprised of only one nerve fascicle. As for the mean fascicular area, the left brachial nerve had the greatest area (0.7963 mm2) while the least (0.1312 mm2) was noticed in the sympathetic trunk. The sympathetic trunk revealed the highest number (mean value 2176) of myelinated fibres. The least value in this regard (598) was noticed in the left sciatic nerve. As for the external diameter of the nerve fibres, more than 50% of the fibres in all the nerves were of the order 6--8 micrometer. The histograms confirmed this trend. The greatest density of myelinated nerve fibres was noted in the left brachial nerve (288/mm2). Based on the retrograde degeneration, the ventral horn neurons giving origin to the motor fibres in the brachial nerves were traced to spinal cord segments 2 (Preponderantly) and 3. The ventral horn neurons of spinal cord segments 7 and 8 appear to contribute motor fibres to the sciatic nerves.     

Activation of lateral hypothalamic neurons stimulates brown adipose tissue thermogenesis

The lateral hypothalamic area, containing orexin neurons, is involved in several aspects of autonomic regulation, including thermoregulation and energy expenditure. To determine if activation of lateral hypothalamic area neurons influences sympathetically-regulated thermogenesis in brown adipose tissue, we microinjected bicuculline (120 pmol, 60 nl, unilateral) into the lateral hypothalamic area in urethane/chloralose-anesthetized, artificially-ventilated rats. Disinhibition of neurons in lateral hypothalamic area evoked a significant increase (+1309%) in brown adipose tissue sympathetic nerve activity accompanied by parallel increases in brown adipose tissue temperature (+2.0 degrees C), in expired CO2 (+0.6%), in heart rate (+88 bpm) and in mean arterial pressure (+11 mm Hg). Subsequent microinjections of glycine (30 nmol, 60 nl) to inhibit local neurons in raphe pallidus or in dorsomedial hypothalamus or of glutamate receptor antagonists into dorsomedial hypothalamus promptly reversed the increases in brown adipose tissue sympathetic nerve activity, brown adipose tissue temperature and heart rate evoked by disinhibition of neurons in lateral hypothalamic area. We conclude that neurons in the lateral hypothalamic area can influence brown adipose tissue sympathetic nerve activity, brown adipose tissue thermogenesis and heart rate through pathways that are dependent on the activation of neurons in dorsomedial hypothalamus and raphe pallidus.     

Cubital fossa venipuncture sites based on anatomical variations and relationships of cutaneous veins and nerves

Venipuncture is a routine procedure performed at medical institutions for blood collection and blood donation, as well as for health screening and testing. Venipuncture is invasive and usually mildly painful, but it occasionally causes internal bleeding and chronic persistent pain, which is referred to as complex regional pain syndrome. The most common site of venipuncture is the upper arm. The present study macroscopically and anatomically ascertained positional relationships between cutaneous nerves and veins in the cubital (aka antecubital) fossa in many cadaveric dissections to determine the risk of peripheral nerve injury during venipuncture. We identified the most suitable venipuncture site in the upper arm. The medial cutaneous nerve of the forearm (MCNF) passed above the median cubital vein (MCBV) in 27 of 128 cases (21.1%), and was located inferior to the MCBV in 37 of 128 cases (28.9%). The MCBV also passed above the lateral cutaneous nerve forearm (LCNF) in 8 of 128 cases (6.2%). The LCNF was located deeper than the MCBV in 56 of 128 cases (43.8%). The distribution of cutaneous veins and nerves widely varies, and while no single area suitable for all individuals was identified, puncture of the MCBV near the cephalic vein is the least likely to cause nerve damage.     

Effect of Sympathetic Nerve Stimulation on Net Transvascular Movement of Fluid in Canine Adipose Tissue

Net transvascular movement of fluid has been studied in the isolated, autoperfused subcutaneous adipose tissue of the dog, during and after sympathetic nerve stimulation (1–15 Hz) and during infusion of 50% glucose i.a. Net fluid movement was calculated as the difference between change in tissue volume and change in blood volume. Tissue volume was measured by plethysmography and blood volume by external monitoring of circulating ¹³¹I-albumin. No net fluid movement of statistical significance was found during or after nerve stimulation except during the first minute of stimulation at 15 Hz when a small net absorption (p<0.05) was obtained. In contrast, infusion of glucose at 25–75 mOsm/kg H₂O produced a dose-dependent net absorption lasting several minutes, amounting maximally to 0.30 ml × min^-1× 100 g^-1. The absence of prolonged net absorption in subcutaneous adipose tissue during nerve stimulation as well as the absence of net filtration after stimulation may be explained by an essentially unaltered mean hydrostatic capillary pressure. The results indicate that adipose tissue does not contribute to the fluid homeostasis of the body via sympathetic resetting of the pre-postcapillary resistance ratio. Thus, mobilisation of fluid from the nterstitial space in adipose tissue into the blood does not seem to occur by nerve activity.     

Relation between cell length and force production in urinary bladder smooth muscle

Guinea-pig and rabbit urinary bladders were fixed in glutaraldehyde at different volumes. Strips were dissected out, embedded and cut for phase contrast and electron microscopy. Muscle wall thickness decreased with increased bladder volume as did the radial number of muscle cells. Cell length, measured by a morphometric method increased linearly with bladder radius, indicating that no slippage between the muscle cells occurred. Number of cells per mm² cross sectional area increased linearly with bladder radius. Volume-active force relations were obtained by pelvic nerve stimulations of guinea pig bladders filled to different volumes. Maximum pressure was obtained at 0.15 ml bladder volume, and maximum wall tension at a volume of 2.5 ml which corresponds to a cell length of 400 μm and a cell packing density of about 107000×mm^-2. Estimation of the length-active tension curve for the average muscle cell in the guinea-pig bladder indicated a maximum active force of 5.5 μN/cell. Maximum active force per cm² muscle bundle was calculated to be about 59 N. No compensation for extracellular space and nonmuscular tissue within the muscle bundle was made.     

Changes in ATP and Cyclic Nucleotide Levels during Sympathetic Nerve Stimulation in Canine Subcutaneous Adipose Tissue in situ

Subcutaneous adipose tissue in fed, female dogs was isolated. Biopsies of the tissue (30–150 mg) were taken and rapidly frozen in liquid nitrogen before, during and after nerve stimulation (3–4 Hz). In unstimulated adipose tissue the levels of ATP¹ were 74 ± 7 nmol/g, of cyclic AMP 90 ± 12 pmol/g and of cyclic GMP 18 ± 3 pmol/g (mean + S.E.). During sympathetic nerve stimulation the levels of ATP and cyclic GMP fell by 30 and 50% respectively (p < 0.01), while the cyclic AMP content increased by 50 % (p < 0.05). After nerve stimulation there was a marked increase in glycerol release, and the levels of all three nucleotides returned to control. The fall in ATP during nerve stimulation was essentially eliminated by prior adrenergic a-receptor blockade. It is concluded that 1) sympathetic nerve stimulation induces a rapid, reversible fall in tissue ATP content, which may be related to hypoxia secondary to the vasoconstriction, and 2) lipolytic responses to sympathetic nerve stimulation in vivo are preceeded by small increases in the tissue cyclic AMP level, and a 3-fold increase in the cyclic AMP/cyclic GMP ratio.     

Regional maps of rib cortical bone thickness and cross‐sectional geometry

Here we present detailed regional bone thickness and cross‐sectional measurements from full adult ribs using high resolution CT scans processed with a cortical bone mapping technique. Sixth ribs from 33 subjects ranging from 24 to 99 years of age were used to produce average cortical bone thickness maps and to provide average ± 1SD corridors for expected cross‐section properties (cross‐sectional areas and inertial moments) as a function of rib length. Results obtained from CT data were validated at specific rib locations using direct measurements from cut sections. Individual thickness measurements from CT had an accuracy (mean error) and precision (SD error) of ?0.013 ± 0.167 mm (R² coefficient of determination of 0.84). CT‐based measurement errors for rib cross‐sectional geometry were ?0.1 ± 13.1% (cortical bone cross‐sectional area) and 4.7 ± 1.8% (total cross‐sectional area). Rib cortical bone thickness maps show the expected regional variation across a typical rib's surface. The local mid‐rib maxima in cortical thickness along the pleural rib aspect ranged from range 0.9 to 2.6 mm across the study population with an average map maximum of 1.4 mm. Along the cutaneous aspect, rib cortical bone thickness ranged from 0.7 to 1.9 mm with an average map thickness of 0.9 mm. Average cross‐sectional properties show a steady reduction in total cortical bone area from 10% along the rib's length through to the sternal end, whereas overall cross‐sectional area remains relatively constant along the majority of the rib's length before rising steeply towards the sternal end. On average, male ribs contained more cortical bone within a given cross‐section than was seen for female ribs. Importantly, however, this difference was driven by male ribs having larger overall cross‐sectional areas, rather than by sex differences in the bone thickness observed at specific local cortex sites. The cortical bone thickness results here can be used directly to improve the accuracy of current human body and rib models. Furthermore, the measurement corridors obtained from adult subjects across a wide age range can be used to validate future measurements from more widely available image sources such as clinical CT where gold standard reference measures (e.g. such as direct measurements obtained from cut sections) are otherwise unobtainable.