Developmental potential of trunk neural crest cells in the mouse

The availability of naturally occurring and engineered mutations in mice which affect the neural crest makes the mouse embryo an important experimental system for studying neural crest cell differentiation. Here, we determine the normal developmental potential of neural crest cells by performing in situ cell lineage analysis in the mouse by microinjecting lysinated rhodamine dextran (LRD) into individual dorsal neural tube cells in the trunk. Labeled progeny derived from single cells were found in the neural tube, dorsal root ganglia, sympathoadrenal derivatives, presumptive Schwann cells and/or pigment cells. Most embryos contained labeled cells both in the neural tube and at least one neural crest derivative, and numerous clones contributed to multiple neural crest derivatives. The time of injection influenced the derivatives populated by the labeled cells. Injections at early stages of migration yielded labeled progeny in both dorsal and ventral neural crest derivatives, whereas those performed at later stages had labeled cells only in more dorsal neural crest derivatives, such as dorsal root ganglion and presumptive pigment cells. The results suggest that in the mouse embryo: (1) there is a common precursor for neural crest and neural tube cells; (2) some neural crest cells are multipotent; and (3) the timing of emigration influences the range of possible neural crest derivatives

A vital dye analysis of the timing and pathways of avian trunk neural crest cell migration

To permit a more detailed analysis of neural crest cell migratory pathways in the chick embryo, neural crest cells were labelled with a nondeleterious membrane intercalating vital dye, DiI. All neural tube cells with endfeet in contact with the lumen, including premigratory neural crest cells, were labelled by pressure injecting a solution of DiI into the lumen of the neural tube. When assayed one to three days later, migrating neural crest cells, motor axons, and ventral root cells were the only cells types external to the neural tube labelled with DiI. During the neural crest cell migratory phase, distinctly labelled cells were found along: (1) a dorsolateral pathway, under the epidermis, as well adjacent to and intercalating through the dermamyotome; and (2) a ventral pathway, through the rostral portion of each sclerotome and around the dorsal aorta as described previously. In contrast to those cells migrating through the sclerotome, labelled cells on the dorsolateral pathway were not segmentally arranged along the rostrocaudal axis. DiI-labelled cells were observed in all truncal neural crest derivatives, including subepidermal presumptive pigment cells, dorsal root ganglia, and sympathetic ganglia. By varying the stage at which the injection was performed, neural crest cell emigration at the level of the wing bud was shown to occur from stage 13 through stage 22. In addition, neural crest cells were found to populate their derivatives in a ventral-to-dorsal order, with the latest emigrating cells migrating exclusively along the dorsolateral pathway

Pathways of trunk neural crest cell migration in the mouse embryo as revealed by vital dye labelling

Analysis of neural crest cell migration in the mouse has been difficult due to the lack of reliable cell markers. Recently, we found that injection of DiI into the chick neural tube marks premigratory neural crest cells whose endfeet are in contact with the lumen of the neural tube (Serbedzija et al. Development 106, 809–819 (1989)). In the present study, this technique was applied to study neural crest cell migratory pathways in the trunk of the mouse embryo. Embryos were removed from the mother between the 8th and the 10th days of development and DiI was injected into the lumen of the neural tube. The embryos were then cultured for 12 to 24 h, and analyzed at the level of the forelimb. We observed two predominant pathways of neural crest cell migration: (1) a ventral pathway through the rostral portion of the somite and (2) a dorsolateral pathway between the dermamyotome and the epidermis. Neural crest cells were observed along the dorsolateral pathway throughout the period of migration. The distribution of labelled cells along the ventral pathway suggested that there were two overlapping phases of migration. An early ventrolateral phase began before E9 and ended by E9.5; this pathway consisted of a stream of cells within the rostral sclerotome, adjacent to the dermamyotome, that extended ventrally to the region of the sympathetic ganglia and the dorsal aorta

Vital dye labelling demonstrates a sacral neural crest contribution to the enteric nervous system of chick and mouse embryos

We have used the vital dye, DiI, to analyze the contribution of sacral neural crest cells to the enteric nervous system in chick and mouse embryos. In order to label premigratory sacral neural crest cells selectively, DiI was injected into the lumen of the neural tube at the level of the hindlimb. In chick embryos, DiI injections made prior to stage 19 resulted in labelled cells in the gut, which had emerged from the neural tube adjacent to somites 29–37. In mouse embryos, neural crest cells emigrated from the sacral neural tube between E9 and E9.5. In both chick and mouse embryos, DiI-labelled cells were observed in the rostral half of the somitic sclerotome, around the dorsal aorta, in the mesentery surrounding the gut, as well as within the epithelium of the gut. Mouse embryos, however, contained consistently fewer labelled cells than chick embryos. DiI-labelled cells first were observed in the rostral and dorsal portion of the gut. Paralleling the maturation of the embryo, there was a rostral-to-caudal sequence in which neural crest cells populated the gut at the sacral level. In addition, neural crest cells appeared within the gut in a dorsal-to-ventral sequence, suggesting that the cells entered the gut dorsally and moved progressively ventrally. The present results resolve a long-standing discrepancy in the literature by demonstrating that sacral neural crest cells in both the chick and mouse contribute to the enteric nervous system in the postumbilical gut

You are not alone: an existential-phenomenological exploration of how inner dialogue is experienced by rape survivors

This research investigated how inner dialogue is experienced by rape survivors. Eight women were interviewed about their experiences and the data was analysed using Structural Existential Analysis (SEA). A novel application of SEA was developed and a step-by-step model for application and verification is provided. The findings are presented in two parts. Part 1 “Characteristics of Inner Dialogue” provides a novel conceptualisation of a personalised inner dialogical community, detailing its development, dominance, and functions with specific emphasis on self-creation, healing, and meaning. Part 2 “Long-Lived Experiences” offers in-depth understandings of how inner dialogue is experienced in the aftermath of rape. Implications and specific interventions for counselling psychologists, practitioners, the judiciary system, the general public, and survivors of sexual trauma are suggested and discussed in detail. The findings conclude that inner dialogue is a multifaceted innate phenomenon, not a pathological symptom of mental unwellness. Active engagement with inner dialogue facilitates deeper connection with the self and increased control over life experiences. The experience of rape is not an isolated physical violation, it has the potential to violate all areas of a person ’s lived experience, shattering previously held values with long-term implications for the victim and the people in their lives. The healing process is individually unique. Societies’ perceptions of stigmas, stereotypes, and rape-myths create hostile environments and directly impede healing from trauma

The first definitive Middle Jurassic atoposaurid (Crocodylomorpha, Neosuchia), and a discussion on the genus Theriosuchus

Atoposaurids were a clade of semiaquatic crocodyliforms known from the Late Jurassic to the latest Cretaceous. Tentative remains from Europe, Morocco, and Madagascar may extend their range into the Middle Jurassic. Here we report the first unambiguous Middle Jurassic (late Bajocian–Bathonian) atoposaurid: an anterior dentary from the Isle of Skye, Scotland, UK. A comprehensive review of atoposaurid specimens demonstrates that this dentary can be referred to Theriosuchus based on several derived characters, and differs from the five previously recognized species within this genus. Despite several diagnostic features, we conservatively refer it to Theriosuchus sp., pending the discovery of more complete material. As the oldest known definitively diagnostic atoposaurid, this discovery indicates that the oldest members of this group were small-bodied, had heterodont dentition, and were most likely widespread components of European faunas. Our review of mandibular and dental features in atoposaurids not only allows us to present a revised diagnosis of Theriosuchus, but also reveals a great amount of variability within this genus, and indicates that there are currently five valid species that can be differentiated by unique combinations of dental characteristics. This variability can be included in future broad-scale cladistics analyses of atoposaurids and closely related crocodyliforms, which promise to help untangle the complicated taxonomy and evolutionary history of Atoposauridae

Tracking Cardiovascular Responses To Anticipation Of An Exercise Test In Cardiac Rehabilitation: A Preliminary Test

Cardiovascular reactivity (CVR) refers to relatively high heart rate (HR) and blood pressure (BP) increases in the face of a mental stressor. CVR may be a concern for heart patients since it may precede ischemic events and CVR may be an indicator of relatively poor prognosis. Anticipation of an exercise tolerance test (ETT) results in rapid increases in HR and BP and has been used as a stressor in heart patient to study CVR. However, it is not clear how CVR changes associated with an ETT change after a course of cardiac rehabilitation (CR). PURPOSE: To examine CVR, specifically HR and systolic (SBP) and diastolic blood pressure (DBP) responses, to anticipation of an exercise tolerance test before and after a course of CR. METHODS: CVR was recorded for 76 patients at baseline and for a subsample of 23 patients who completed 6 weeks of CR. Identical procedures were used for baseline and post-CR data collection. Resting HR and BP were measured 3 times, 1 minute apart, by an automated oscillometric BP monitor after the patient had been seated quietly and alone for 5 minutes. The patient was then prepped for an ETT and met in the exercise stress testing lab by the researcher. Standing HR and BP measures were taken by the same automated BP device after 1 and 3 minutes of standing on the treadmill immediately prior to beginning exercise. The mean of the 3 seated measures was considered the resting BP and HR. Peak BP and HR standing were used to calculate the cardiovascular response to anticipation of exercise. CVR was defined as peak BP and HR minus resting BP and HR, respectively. RESULTS: Anticipation of exercise resulted in significant increases (all p’s < .002) in CV parameters with an average CVR at baseline for HR, SBP and DBP of 4.0 bpm, 16.6 mmHg, and 13.5 mmHg, respectively. CVR after a course of CR for HR, SBP and DBP were 4.3 bmp, 15.9 mmHg, and 9.2 mmHg (ps < .001). Differences between baseline and post-CR CVR was significant only for the change in DBP (p = .05). CONCLUSION: Patients responded with a predictable increase in HR and BP in anticipation of an ETT before and after a course of CR. After CR, DBP increases in anticipation of an ETT were lower in magnitude than before CR. Future research should investigate specific components of CR that may help reduce CVR