Type Of Spine Research Articles

Molecular hydrogen attenuates sepsis-induced cognitive dysfunction through regulation of tau phosphorylation.

Sepsis-associated encephalopathy (SAE) is a cognitive dysfunction caused by sepsis. Hyperphosphorylated tau is considered to play a significant role in the progression of neurodegenerative disease and also contributes to cognitive dysfunction in septic mice. Molecular hydrogen (H2) plays an antioxidant and anti-inflammatory role, and plays a protective role in septic mice. This study explored the possible effects of H2 on cognition and tau phosphorylation in a mouse model of SAE. The model of sepsis was established in C57BL/6J male mice by cecal ligation and puncture surgery. Mice treated with 2% H2 inhalation for 60min at 1h and 6h after surgery, respectively. HY-15769, the inhibitor of Tau Tubulin Kinase 1 (TTBK1), was injected 1h before the surgery. The 7-day survival rates of the mice were recorded. Cognitive behavior was tested with both novel object recognition and the Y-maze novelty arm recognition on day 7 after surgery. Hematoxylin-eosin staining was used to observe the histological damage in CA1 region of hippocampus. The expression of inflammatory factors in hippocampus was assessed by Elisa. Western blotting was adopted to determine the tau phosphorylation levels at AT8 epitopes (pSer202 and pThr205) and T22 epitopes (neurofibrillary tangle protein oligomer), and the GSK3β phosphorylation levels (Tyr216), as well as p-Ser422 and TTBK1 levels in the hippocampus. The number of dendritic spine and mushroom type of dendritic spines in the hippocampus were assessed by Golgi staining. The survival rate, visual and spatial learning ability, and memory ability were improved in septic mice treated with H2. After H2 treatment, the density of dendritic spine, mushroom type of dendritic spine, and the number of normal hippocampal neurons were progressively elevated. H2 decreased the levels of phosphorylated tau protein, tau oligomer and TTBK1, as well as the phosphorylation of tau key kinase. Furthermore, the injection of HY-15769 (a TTBK1 inhibitor) protected SAE through the similar way. The protective effect of H2 on cognitive dysfunction induced by SAE may be achieved by inhibiting tau phosphorylation, which is perhaps related with the inhibition of TTBK1.

Quantifying the Spinal Lordosis Ratio Unique to the Type of Spinal Sagittal Alignment in a Normal Population.

Data collection of radiological parameters in non-pathological adult spines. Establishing a baseline database for measurements of the spinal lordosis ratio between upper and lower arcs of the lumbar spine unique to each type of spine described by Roussouly's classification. Illustrating the importance of correct rationing of the upper and lower arcs. Standardised standing true lateral plain radiographs of the spine (including base of skull and proximal femurs) from 373 adult volunteers were obtained. Exclusion criteria : any history of disease involving the spine, pelvis, hips or lower limbs. Incidental detection of any spinal deformity on radiography also excluded further participation in this study. Sacro-pelvic parameters data collected : Pelvic Incidence (PI), Pelvic Tilt (PT), Sacral Slope (SS), location of Inflection Point, number of vertebras in the spinal lordosis and type of Roussouly's spine. Values of upper arc, lower arc and spinal lordosis ratio (SLR) was determined. Bivariate analysis revealed statistically significant (P < .0001) correlation between the types of sagittal spinal alignments based on Roussouly's classification and the SLR. Type 1: SLR .76 ± .17, Type 2: SLR .60 ± .18, Type 3 with anteverted pelvis: SLR .53 ± .11, Type 3: SLR .49 ± .12, Type4: SLR .41 ± .11. With this data we are able to quantify the ratio of lumbar lordosis unique to each type of Roussouly's spine. It functions as a guide when planning lumbar spine surgeries in order to restore the SLR correctly and thus prevent post-op complications such as proximal junction kyphosis.

Rehabilitation on a treadmill induces plastic changes in the dendritic spines of spinal motoneurons associated with improved execution after a pharmacological injury to the motor cortex in rats

Lesions to the corticospinal tract result in several neurological symptoms and several rehabilitation protocols have proven useful in attempts to direct underlying plastic phenomena. However, the effects that such protocols may exert on the dendritic spines of motoneurons to enhance accuracy during rehabilitation are unknown. Thirty three female Sprague-Dawley adult rats were injected stereotaxically at the primary motor cerebral cortex (Fr1) with saline (CTL), or kainic acid (INJ), or kainic acid and further rehabilitation on a treadmill 16 days after lesion (INJ+RB). Motor performance was evaluated with the the Basso, Beatie and Bresnahan (BBB) locomotion scale and in the Rotarod. Spine density was quantified in a primary dendrite of motoneurons in Lamina IX in the ventral horn of the thoracolumbar spinal cord as well as spine morphology. AMPA, BDNF, PSD-95 and synaptophysin expression was evaluated by Western blot. INJ+RB group showed higher scores in motor performance. Animals from the INJ+RB group showed more thin, mushroom, stubby and wide spines than the CTL group, while the content of AMPA, BDNF, PSD-95 and Synaptophysin was not different between the groups INJ+RB and CTL. AMPA and synaptophysin content was greater in INJ group than in CTL and INJ+RB groups. The increase in the proportion of each type of spine observed in INJ+RB group suggest spinogenesis and a greater capability to integrate the afferent information to motoneurons under relatively stable molecular conditions at the synaptic level.

CT Diagnosis of the Fracture of Anterior Nasal Spine.

To study anterior nasal spine fractures, including the incidence, missed diagnosis rates, and relationship with shapes using computed tomography (CT). Two hundred cases of axial CT images performed for maxillofacial trauma were reviewed. The incidence, correct, and missed diagnosis rates of anterior nasal spine fractures were studied. The relationship between the fracture and the shape of the anterior nasal spine was also analyzed. The rate of anterior nasal spine fractures was 22.00% (44 of 200). The diagnostic accuracy was 4.55% (2 of 44) and the missed diagnosis rate was 95.45% (42 of 44). The fracture rates of the double rod, single rod, triangle, and irregular anterior nasal spine were 33.85% (22 of 65), 32.26% (10 of 31), 12.24% (12 of 98), and 0.00% (0 of 6), respectively. The double and single rod types of anterior nasal spine were most likely to be fractured than the type of triangle (χ2 = 11.05, 6.67, P < .0167). No fracture was found in the irregular type of anterior nasal spine. Anterior nasal spine fractures are not rare and the high missed diagnostic rate results from unfamiliarity with the structure. Double and single rod types of anterior nasal spines are easy to fracture. Bony reconstruction and thin thickness of CT images are necessary for diagnosis.

Toric Spines at a Site of Learning.

We discovered a new type of dendritic spine. It is found on space-specific neurons in the barn owl inferior colliculus, a site of experience-dependent plasticity. Connectomic analysis revealed dendritic protrusions of unusual morphology including topological holes, hence termed “toric” spines (n = 76). More significantly, presynaptic terminals converging onto individual toric spines displayed numerous active zones (up to 49) derived from multiple axons (up to 11) with incoming trajectories distributed widely throughout 3D space. This arrangement is suited to integrate input sources. Dense reconstruction of two toric spines revealed that they were unconnected with the majority (∼84%) of intertwined axons, implying a high capacity for information storage. We developed an ex vivo slice preparation and provide the first published data on space-specific neuron intrinsic properties, including cellular subtypes with and without toric-like spines. We propose that toric spines are a cellular locus of sensory integration and behavioral learning.

IDENTIFICATION OF CORRELATION OF TEMPOROMANDIBULAR DYSFUNCTION AND CERVICAL SPINE DISORDERS

Relevance. Temporomandibular dysfunction is associated with imbalance of the whole body in static and dynamic. Myofascial Pain in Temporomandibular joint often coexist with chronic neck pain, impacting on posture straightly by changing head position or indirectly by instability of muscles chains.&#x0D; Objective. This study aimed to evaluate frequency of cervical spine disorders (CSD) in case of Temporomandibular dysfunction (TMD), possible correlations between TMD and CSD in frontal and lateral planes depends on ethiological factors.&#x0D; Materials and methods. The study included 208 patients. Study group consisted of 170 patients with TMD (female – 62,9 %, male – 37,1 %). Contol group consisted of 38 patients. Subjects were examined according to international clinical protocol RDC/TMD, NDI, masticatory,neck motor system were analysed by (BioPak EMG), position of condyles and bone structure – via computed tomography, position and disc reduction – via magnetic resonance imaging, occlusion – via TScan III, cephalometric analysis (frontal, lateral view), statistical analyses with program IBM SPSS Statistic Base v.22.&#x0D; Results. Female more often has temporomandibular dysfunction (62,9 %) than male (37,1 %) among the population. 47,05% were under 30 years. About 98,2 % of patients, presented complaining of Temporomandibular disorder symptoms had neck pain concomitantly and cervical spine disorders in different planes, 44,7% of patients without TMD, but with CSD, value at risk 2,2(95% VaR 1,54-3,13). Moreover 100% of those who did not report pain in the Temporomandibular joints, but presented only with clicking, had reported pain in the neck during physical examination. After examination patients were divided into 4 different clinical groups of TMD depends on ethiology-TMD-neck spinal disability. The largest is combined group – 67,67 % of total patients and is clinical manifested with TMD, spinal neck disorders in several planes. Different dysfunctional conditions between facial skull boned and cervical spine are closely interconnected with each other.&#x0D; Conclusions. There is positive, mild power of correlations between muscles groups trapezius-masseter, trapezius-temporalis (r=0,477, p&lt;0,05), sternocleidomastoideus-temporalis (0,527, p&lt;0,05), sternocleidomastoideus-masseter (0,575, p&lt;0,05), which indicates cooperation between facial muscles and cervical spine muscles. There is changes in cervical spine depends on clinical group: lateral group – C type scoliosis, sagittal – from straightening of cervical lordosis to kyphosis, vertical – «wave» type of cervical spine, combined – combine of pathology in different planes. Initial form of lateral group TMD is characterized as myofascial pain syndrome with specific clinical symptoms, but without condyle and disc displacement, thus it can be as an early prophylactic stage and risk of disc subluxation.

Treatment of Spinal Tumors in a High Volume Center has Direct Impact on Local Recurrence, Morbidity, and Mortality

En bloc resections of spine tumors aim at locally controlling the disease for both improving the patient's quality of life as well as improving mortality. The purpose of this study was to compare the outcome between patients who were initially treated in a high volume specialized center, and patients who initially underwent either invasive diagnostic procedure or an initial surgical attempt to treat the disease in a different center. A retrospective study of 1681 patients affected by spine tumors-treated from 1990 to 2015 by the same team. A total of 220 en bloc resections that were performed on 216 patients during that period. Most of the tumors were primary-165 cases (43 benign and 122 malignant), metastases occurred in 55 cases. One hundred sixty-eight patients (77.8%) were solely treated in the institute and were considered noncontaminated cases (NCCs) and 48 (22.2%) were previously treated elsewhere and were considered contaminated cases (CCs). Median follow-up was 45 months (0-371).Thirty-three local recurrences (15.28%) were recorded. Fourteen patients (29.17%) from the CC and 19 (11.31%) from the NCC group.A total of 153 complications were observed in 100 out of 216 patients (46.2%). Sixty-four of these patients (30%) suffered 1 complication, while the rest had 2 or more. Twenty-eight (58%) of the CC group and 72 (42.85%) of the NCC group, had at least 1 complication.Sixty patients died as a result of the disease during the follow-up period. Twenty-one (43.75%) and 39 (23.21%) patients died in the CC and NCC cohorts, respectively.CC, surgical margins of the resected tumor-intralesional, marginal, and malignant tumors, were statistically significant independent risk factors for local recurrence of the tumor. Contamination, local recurrence, neoadjuvant radiotherapy, the number of level resected, and metastatic tumors compared with primary malignant tumor, were shown to be independent risk factors for patient's death. It is apparent that there is a substantial added risk in performing either invasive diagnostic procedures or attempting a surgical resection of the tumor in a nonspecialized center. This risk includes both higher recurrences of the tumor as well as increased mortality. It is therefore reasonable to conclude that the whole treatment, from biopsy to resection, should be performed in the same center, and this center should be a high volume, specialized in treating these type of spine pathologies.The surgeon who treats the patient first has a great responsibility, as it is the first treatment that most affects prognosis. To reduce the chance of local recurrence, morbidity, and mortality, all invasive diagnosis and treatment, should be performed by an experienced team, as the consequences are dramatic.

Functional outcome of management of lower lumbar (L-3 to L-5) burst fractures: A multicentre study of 34 cases

Aim and Objective: Lower lumbar burst fractures are rare entity with most of the literature restricted to small case series. There is no clear cut consensus on the guidelines for management. Here we present functional results of different modalities of treatment of this rare type of spine injury.Material and Methods: The study was conducted at two tertiary care centres over a period of 9 years. Patients with lower lumbar burst fractures were evaluated for associated injuries, modality of treatment, Pain score (VAS) and neurological status (Frankel Grade) at the time of injury and at final follow up were recorded. The final functional outcome was evaluated using Smiley-Webster functional score.Results: A total of 34 patients with an average age of 37.3 years (24 males; 10 females) and a mean final follow up of 27.9 months were enrolled. 21 patients had L3, 8 had L4 and 5 had L5 burst fractures. 10 patients were managed conservatively by brace and 24 underwent surgical intervention. The pain score (VAS) improved from a mean of 8.5 at the time of injury to a mean of 1.6 at final follow up. Patients with neurological injury had on average improvement of one Frankel grade. 88% patients had excellent to good final functional outcome.Conclusion: Lower lumbar burst fractures are high velocity injuries with other non-spinal injuries being associated. Most of the patients have good functional outcome with both conservative as well as surgical intervention. Patients with complete cauda equina have poor outcome with respect to neurological recovery.

A new benthic dinoflagellate Spiniferodinium palauense sp. nov. (Dinophyceae) from Palau

Horiguchi T., Hayashi Y., Kudo H. and Hara Y. 2011. A new benthic dinoflagellate Spiniferodinium palauense sp. nov. (Dinophyceae) from Palau. Phycologia 50: 616–623. DOI: 10.2216/11-15.1A new benthic dinoflagellate Spiniferodinium palauense Horiguchi, Hayashi, Kudo & Hara sp. nov. is described from the marine lake, Uet era Ongael, on Ongael Island, Koror, Republic of Palau. The genus Spiniferodinium is unique in that the benthic non-motile form possesses a helmet-shaped cell covering, termed the ‘helmet shell’, which is rigid, transparent and covered in many small regularly-distributed spines and covers the entire protoplasm. The dinoflagellate reproduces asexually by the formation of Gymnodinium-like motile cells within the helmet shell. The released motile cells directly return to the non-motile state by forming the helmet shell. The dinoflagellate from Palau is the second species for the genus and shares these characteristics. However, the new species is distinguished from the type species, Spiniferodinium galeiforme, in having a thinner cell body, a smaller epicone, a right-handed cingulum and a different type of spine on the shell. Phylogenetic analyses based on small subunit ribosomal RNA gene (SSU rDNA) sequences indicated that Spiniferodinium galeiforme and Spiniferodinium palauense formed a strongly-supported clade, suggesting these are closely related. However, Their SSU rDNA sequences differ by 22 base pairs, indicating they are distinct species. Our phylogenetic tree suggests that these unique benthic dinoflagellates evolved within the Gymnodinium clade sensu stricto.

A new genus and two new species of multiplacophorans (Mollusca, Polyplacophora, Neoloricata), Mississippian (Chesterian), Indiana

Deltaplax new genus, Deltaplax burdicki new species, and Deltaplax dellangeloi new species (Mollusca, Polyplacophora, Neoloricata, Multiplacophora) from the Mississippian Lower Buffalo Wallow Group (Chesterian) of Indiana, USA are described. the new genus is established by one partially articulated and one associated specimen with marginal fringes of two types of large spines, bilaterally symmetrical head and tail valves, and fifteen medial valves arranged in three longitudinal columns similar to those described previously for other multiplacophorans. the two specimens represent separate species differentiated by morphologies of the auxiliary valves, one type of spine, and subtrapezoidal versus triangular tail valves. the tail valve of the articulated specimen also had sutural laminae that projected under the preceding intermediate valve. the presence of sutural laminae allows for placement of multiplacophorans in Subclass Neoloricata of Class Polyplacophora. the head, intermediate, and tail valves are mucronate with comarginal growth lines and ridged insertion plates that probably inserted into soft tissue comparable to the girdle of modern polyplacophorans. the new specimens also indicate one left-handed, one auxiliary, and one right-handed valve in multiplacophorans was equivalent to a single bilaterally-symmetrical intermediate valve of extant polyplacophorans. However, multiplacophoran head valves have plates that project from the lower layer at the lateral margins and articulate with the first intermediate valves that overlap the head and second intermediate valves. These features have not been observed in more typical neoloricates, fossil or modern. Pending systematic revision of the class, Multiplacophora thus is retained as a separate order distinguished by the unique shared characters.

Spine-type densities of hippocampal CA1 neurons vary in proestrus and estrus rats

Spines-mediated synaptic activity has been associated to learning ability. Dendritic spines from hippocampal CA1 pyramidal neurons of proestrus rats have been reported to be more numerous than in estrus animals, but some behavioral studies have reported a better performance during the estrus stage of the estrous cycle. Because spine shape has been shown to be strongly related to the post-synaptic processing of information, a quantitative morphological study related to the proportional density of each type of spine, was conducted in Golgi material of hippocampal CA1 pyramidal cells of proestrus and estrus rats. After three regular estrous cycles had been asserted, seven Sprague–Dawley female adult rats in proestrus and eight in estrus, were used. Mushroom-shaped spines from hippocampal pyramidal cells predominated in proestrous rats, being 15.1% more numerous in this stage than in estrus; while thin spines were the predominant type of spine in estrous animals, being 15.5% more abundant in estrus than in proestrus. The predominance of the mushroom-shaped or thin spines in the hippocampal CA1 pyramidal neurons during the respective stages of the rat estrous cycle, could be related to the organization of the hippocampal activity-dependent mnemonic information.

A new marine sand-dwelling Prorocentrum species, P. clipeus sp. nov. (Dinophyceae, Prorocentrales) from Helgoland, German Bight, North Sea

A marine sand-dwelling dinoflagellate species of the genus Prorocentrum is described from light and scanning electron micrographs. The species was distinguished from other Prorocentrum species by total cell shape and size, thecal surface morphology and architecture of the periflagellar area. Prorocentrum clipeus sp. nov. is a large, nearly round, photosynthetic species, with an average diameter of 52 μm. The large kidney-shaped nucleus is posteriorly located. This new species differs from all known Prorocentrum species in having a wide arc-shaped periflagellaer area, and in forming a unique type of apical spine and thin smooth, upright apical list. The thecal surface is smooth without large pores.

Various types of suprameatal spines and depressions in the human temporal bone.

Since it covers the lateral wall of the mastoid air system, the suprameatal triangle is of importance to otologic surgeons during mastoidectomy. Because of this clinical importance, topographic anatomy of the suprameatal spine and depression was studied on Anatolian skulls. In all, 363 male and 231 female skulls were studied. The most prevalent type of suprameatal spine resembled a crest and was found in both sexes on the right (77.6%) and left (80%) sides. The absence of a suprameatal depression was significantly higher in females (right 9.1%; left 8.7%) than in males (right 1.7%; left 2.5%). Suprameatal depressions were mostly shallow in female subjects, but were mostly observed in males to be at a medium depth or deep.

GENETIC VARIATION AND POLYMORPHISM IN THE INDUCIBLE SPINES OF A MARINE BRYOZOAN.

Of particular value in understanding the evolution of genotypes with broad phenotypic ranges (phenotypic plasticity) are the few examples of organisms with adaptive plasticity, such as those that develop a defensive morphology in response to cues from predators. We know little about the heritability of inducible defensive characters or the range of phenotypes available for selection to act on in the field. Membranipora membranacea is a colonial marine bryozoan that produces spines within two days of exposure to waterborne predator extracts. Surveys done in 1993 and 1995 showed that the population at Friday Harbor Labs, Washington, was polymorphic for inducible spine type and was composed of a constitutively spined type that produced spines in the absence of a predator stimulus, an unspined phenotype that did not produce spines irrespective of a stimulus, and an inducibly spined phenotype that would produce spines if exposed to the appropriate cue. In 1995, the frequencies of these types were determined through a laboratory common-garden experiment; 178 colonies were cultured from metamorphosis through approximately 30 days and then exposed to the cue. The inducible type was the dominant, comprising 80.3% of the population. The constitutive type made up 6.2% of the population, and the remaining 13.4 % was the unspined type. The frequency of the three types was similar to a preliminary trial of the experiment run in 1993. Experiments also showed that the lengths of the spines of the inducible type varied continuously among genotypes. To assess causes of variation in the inducible spine response and its clonal heritability, 16 clones were subdivided and grown in a common environment and exposed to a single dosage of spine inducing substance (SIS). Spine length showed high clonal heritability. The range of colony responses from a single environment varied from relatively unresponsive to highly responsive colonies with a very low threshold of response. Norms of reaction were quantified for spine lengths of inducible genotypes originating from two field environments by testing them in a concentration series of SIS. Both spine length and spine type varied with concentration of inducer. Within a clone, colonies were more likely to produce membranous spines than corner spines at higher concentrations. At low concentrations, only straight spines were produced. This study showed that populations of M. membranacea at Friday Harbor are a mix of inducible, nonspined and constitutively spined individuals. Even the inducible individuals showed high heritable variation in the length of spine activated, suggesting that there is considerable scope for the evolution of this character. A norm-of-reaction experiment further showed that the type of spine produced, membranous or corner, varied with the concentration of the cue. Factors maintaining the polymorphism and the broad range of genotypes could include high costs of defending the spined types coupled with a shifting biotic regime.

Calcium dynamics in thorny excrescences of CA3 pyramidal neurons.

Confocal laser scanning microscopy was used to visualize Ca2+ transients in a particular type of dendritic spine, known as a thorny excrescence, in hippocampal CA3 pyramidal neurons. These large excrescences or thorns, which serve as the postsynaptic target for the mossy-fiber synaptic inputs, were identified on the basis of their location, frequency, and size. Whole cell recordings were made from superficial CA3 pyramidal neurons in thick hippocampal slices with the use of infrared video microscopy; cells with proximal apical dendrites close to the surface of the slice were selected. Changes in intracellular Ca2+ levels were monitored by imaging changes in fluorescence of the dyes Calcium Green-1 and Fluo-3. Dual-emission fluorescence imaging was also employed with the use of a combination of Fluo-3 and the Ca2+-insensitive dye seminaphthorhodafluor-1. This method was used to decrease the potential influence of background fluorescence on the calculated changes in intracellular Ca2+ concentration ([Ca2+]i). Somatic depolarization produced increases in [Ca2+]i in both the thorn and the immediately adjacent dendrite. Changes in [Ca2+]i were time locked with the onset of depolarization and the decay began immediately after the termination of depolarization. The peak increase in the Ca2+ signal was significantly greater in the thorns than in the adjacent dendritic shafts. With the use of high-temporal-resolution methods (line scans), differences were also seen in the time course of Ca2+ signals in these two regions. The decay time constants of the Ca2+ signal were faster in thorns than in the adjacent dendritic shafts. These observations suggest that voltage-gated Ca2+ channels are localized directly on the dendritic spines receiving mossy-fiber input. Furthermore, Ca2+ homeostasis within thorny excrescences is distinct from Ca2+ regulation in the dendritic shaft, at least over brief time periods, a finding that could have important implications for synaptic plasticity and signaling.

Ultrastructural identification of entorhinal cortical synapses in CA1 stratum lacunosum‐moleculare of the rat

The goal of the present study was to identify and characterize, at the electron microscopic level, the synapses formed by entorhinal cortical (EC) axons in the hippocampal CA1 stratum lacunosum-moleculare of the adult rat. Phaseolus vulgaris leucoagglutinin was ionotophoresed at various loci throughout the mediolateral and dorsoventral extent of the EC to label EC-CA1 synapses. Virtually all labeled synapses were asymmetric and axospinous. EC axons did not preferentially synapse with any particular type of dendritic spine; rather, EC axons formed synapses with the range of dendritic spine morphologies observed in CA1 s. lacunosum-moleculare. Spines with either perforated or nonperforated postsynaptic densities were contacted by EC axons. Occasionally both a labeled and an unlabeled axon synapsed on a single dendritic spine head. The data are discussed in relation to the morphology of other afferent systems synapsing in s. lacunosum-moleculare and to the physiology of the EC-CA1 system.

Structure and function of the female reproductive ducts of the fish blood-flukeAporocotyle simplexOdhner, 1900 (Digenea: Sanguinicolidae)

Abstract A combined study using the light and electron microscopes was undertaken on the oocytes, vitelline cells, oviduct, vitelline collecting duct, vitelline reservoir, vitelloduct, ovi-vitelloduct, ootype, Mehlis' gland, and uterine regions. Cortical granules were not observed beneath the plasmalemma of the oocyte. The general structure of the vitelline cell corresponds to that found in other digeneans. The results indicate that in A. simplex fertilization occurs in the distal part of the oviduct. The path of the vitelline cells and the oocyte towards their point of meeting is described and discussed. It is suggested, as a working hypothesis for further studies, that the combined lengths of the vitelloduct and the ovi-vitelloduct in this species is a regulatory factor for the determination of the number of vitelline cells in the egg. A possible course of events for this process is presented. Three types of cells, two of which are secretory, are present in the region of the Mehlis' gland. Two types of secretory products are found in the long cytoplasmic processes which open into the ootype. One of these types is discharged only into the proximal ootype, while the other is discharged into the remainder of the ootype. Previous ultrastructural reports on similar secretory products on other digeneans are reviewed and discussed, as is the terminology of these secretory products. The related terms DB- and MB-secretory products are proposed for the two types of secretion. Both types of secretory product drastically change their characteristics upon entering the lumen of the ootype where, nevertheless, it was possible to identify both types of secretion. It is suggested that the third and interstitial non-secretory type of cell present in the region of the Mehlis' gland has a ‘skeletal’ function; a function which is also suggested for the microtubules of the cytoplasmic processes (unicellular ducts) projecting from the secretory cells. The earlier proposed sensory function of the surface bulbs around the genital atrium is confirmed and their characteristics indicate that they function as tango-receptors for use in copulation. A third type of tegumental spine, the genital spine, is described and discussed.

Effects of climbing fiber destruction on large dendrite spines of Purkinje cells.

The number and freeze-fracture membrane organization of spines on Purkinje cell dendrites were studied in rats after destruction, by intraperitoneal injection of 3-acetyl-pyridine (3-AP), of the climbing fiber afferents to the cerebellum. The results obtained show that: (1) there is a 1.6 fold increase in the total number of dendritic spines in the 3-AP-treated animals as compared to controls, but no change in the total number of spine synaptic profiles; (2) the spines from main dendrites in both control and 3-AP-treated animals have more than 1,000 IMP/micron 2 of P-face membrane; and, (3) the spines formed on Purkinje cell dendrites in the absence of their presynaptic axons have the same P-face membrane organization (i.e. more than 1,000 IMP/micron 2) as spines normally innervated by afferent climbing fibers. These data suggest that each type of Purkinje cell spine has a specific P-face membrane organization which does not appear to be influenced by presynaptic terminals.

Aging and environmental influences on two types of dendritic spines in the rat occipital cortex

The density of dendritic spines was determined by counting spines on 34-μm segments from basal branches of pyramidal cells in layers II and III of the rat occipital cortex. Counts began at the first bifurcation site from the soma, and one segment from each side of the neuron was studied. The results of this investigation indicated a marked decrease in spines with a lollipop (type L) configuration from 90 to 414 days of age. After this decrease, the density of type L spines increased to 630 days to the same density as they were at 90 days. The presence or absence of type L spines was not affected by housing the animals in an enriched environment. In contrast to the type L spines, another type of spine, those with a nubbin configuration (type N) increased in density at each age. The density of these type N spines also appeared subject to environmental influences in the oldest group. We conclude that type L spines, after decreasing to the adult level, increase as the animal approaches senescence perhaps as a compensatory mechanism. On the other hand, type N spines increase with age and are responsive to the environment in the old animals. Type N spines possibly represent degenerating spines.

Functional significance of spines in the Pennsylvanian horseshoe crabEuproops danae

Euproops danae, a xiphosuran from the Mazon Creek (Braidwood) Fauna, had two sets of spines—genal and ophthalmic—extending from the posterior margin of its prosoma. In young individuals, the genal spines were longer than the ophthalmic spines. During growth, the relative length of each type of spine increased, but the rate of increase was much greater for ophthalmic spines. In order to explain these morphological and ontogenetic features, I have studied the hydrodynamic behavior of whole-animal models representing the actual morphology ofE. danae, and various modifications thereof, at different body sizes. It can be argued that passive settling, while in an enrolled posture, was probably the primary defensive reaction that a swimming individual would have exhibited in response to an encounter with a potential predator. Experiments show that the array of spines onE. danaewas an important control on the style of settling experienced by an enrolled individual. Models of the actual morphology settle steadily, while models with either longer or shorter prosomal spines tend to undergo lateral oscillations induced by turbulence in the wake. Steady fall would have rendered the horseshoe crab less perceptible to either the visual or lateral line systems of contemporary aquatic vertebrates, and thus a morphology capable of producing it would have been an important adaptation for reducing the risk of predation. This minimization of oscillatory movement would actually obtain for a variety of conceivable spine morphologies, but actual morphologies represent those ‘solutions’ which simultaneously optimize other aspects of spine function, such as mechanical protection. This optimum design changes during ontogeny because settling dynamics scale non-linearly with size. This work has both specific applications to the interpretation of similar structures in other arthropods and more general implications for the study of evolutionary functional morphology.