An unusual site of gallstones five years after laparoscopic cholecystectomy.

INTRODUCTION: Gallstone spillage during laparoscopic cholecystectomy is a common occurrence. Complications due to spilled gallstones occur in up to 5% of laparoscopic cholecystectomy cases, with complications having been reported up to 20 years after laparoscopic cholecystectomy. CASE REPORT: We report the case of a 70 year old male who presented for elective right inguinal hernia repair. At the time of repair he was found to have multiple foreign bodies embedded within an indirect hernia sac. Subsequent pathology confirmed these to be gallstones, having been spilled during emergency laparoscopic cholecystectomy 5 years prior. DISCUSSION: Gallbladder perforation and gallstone spillage during laparoscopic cholecystectomy occurs frequently, complications due to spilled gallstones are estimated to occur in less than 5% of cases. The most common complications is abscess formation and infection. Though spilled gallstones have been implicated in the formation of colocutaneous, colovesical, and biliocutaneous fistulae. Following gallbladder perforation during cholecystectomy, closure of the hole should be attempted with laparoscopic graspers, surgical clips, or a laparoscopic ligature. Meticulous collection of all visible spilled gallstones should then take place, followed by intraperitoneal lavage ensuring care is taken not to disperse gallstones throughout the peritoneal cavity. CONCLUSION: Gallbladder perforation during in laparoscopic cholecystectomy is common. Prevention of gallstone spillage, and retrieval of spilled gallstones is essential in minimising the risk of complications due to spillage.

Laparotomy causes loss of peritoneal mesothelium prevented by humidified CO2 insufflation in rats.

INTRODUCTION: Avoiding tissue desiccation is a common recommendation to reduce postoperative complications following open abdominal surgery, although difficult to achieve delicately without damaging the peritoneal mesothelium. Insufflation of humidified-warm CO2 into the abdomen during open abdominal surgery is proposed as an invisible, effortless way to prevent desiccation. We hypothesized that desiccation during open abdominal surgery would cause loss of peritoneal mesothelium that would be prevented by insufflation of humidified-warm CO2. METHODS: Nine Wistar rats were assigned to 1 h of anesthesia only, laparotomy only, or laparotomy with insufflation of humidified-warm CO2. Twelve hours after treatment, rats were euthanized and tissue samples were excised. Scanning electron microscopy (SEM) and light microscopy (LM) images of visceral and parietal peritoneum were scored by two independent, blinded examiners for loss of mesothelium and other indications of inflammation, including measurement of apoptosis by detection of DNA cleavage. RESULTS: Loss of peritoneal mesothelium was found in peritoneum exposed to laparotomy only (SEM: P = 0.002; LM: P = 0.01), and mesothelial loss was reduced by humidified-warm CO2 (SEM: P < 0.001; LM P = 0.004). Similarly, DNA cleavage was significantly higher on the peritoneal surface following laparotomy only, compared with anesthesia only (P = 0.0055) and laparotomy with humidified-warm CO2 insufflation (P = 0.0003). CONCLUSIONS: In a rat model, exposing the peritoneal mesothelial to conditions that replicate minimum recommended air flow within an operating room causes inadvertent loss of mesothelium and signs of inflammation that can be prevented by insufflating humidified-warm CO2 into the open abdominal cavity.

Competition and mimicry: the curious case of chaetae in brachiopods from the middle Cambrian Burgess Shale.

BACKGROUND: One of the first phyla to acquire biomineralized skeletal elements in the Cambrian, brachiopods represent a vital component in unraveling the early evolution and relationships of the Lophotrochozoa. Critical to improving our understanding of lophotrochozoans is the origin, evolution and function of unbiomineralized morphological features, in particular features such as chaetae that are shared between brachiopods and other lophotrochozoans but are poorly understood and rarely preserved. Micromitra burgessensis and Paterina zenobia from the middle Cambrian Burgess Shale are among the most remarkable examples of fossilized chaetae-bearing brachiopods. The form, functional morphology, evolutionary and ecological significance of their chaetae are studied herein. RESULTS: Like in Recent forms, the moveable but semi-rigid chaetae fringe both the dorsal and ventral mantle margins, but in terms of length, the chaetae of Burgess Shale taxa can exceed twice the maximum length of the shell from which it projects. This is unique amongst Recent and fossil brachiopod taxa and given their size, prominence and energy investment to the organism certainly had an important functional significance. Micromitra burgessensis individuals are preserved on hard skeletal elements, including conspecific shells, Tubulella and frequently on the spicules of the sponge Pirania muricata, providing direct evidence of an ecological association between two species. Morphological analysis and comparisons with fossil and extant brachiopod chaetae point to a number of potential functions, including sensory, defence, feeding, defouling, mimicry and spatial competition. CONCLUSIONS: Our study indicates that it is feasible to link chaetae length to the lack of suitable substrate in the Burgess Shale environment and the increased intraspecific competition associated with this. Our results however, also lend support to the elongated chaetae as an example of Batesian mimicry, of the unpalatable sponge Pirania muricata. We also cannot discount brachiopod chaetae acting as a sensory grille, extending the tactile sensitivity of the mantle into the environment, as an early warning system to approaching predators.

Intra-operative tissue oxygen tension is increased by local insufflation of humidified-warm CO2 during open abdominal surgery in a rat model.

INTRODUCTION: Maintenance of high tissue oxygenation (PtO2) is recommended during surgery because PtO2 is highly predictive of surgical site infection and colonic anastomotic leakage. However, surgical site perfusion is often sub-optimal, creating an obstructive hurdle for traditional, systemically applied therapies to maintain or increase surgical site PtO2. This research tested the hypothesis that insufflation of humidified-warm CO2 into the abdominal cavity would increase sub-peritoneal PtO2 during open abdominal surgery. MATERIALS AND METHODS: 15 Wistar rats underwent laparotomy under general anesthesia. Three sets of randomized cross-over experiments were conducted in which the abdominal cavity was subjected to alternating exposure to 1) humidified-warm CO2 & ambient air; 2) humidified-warm CO2 & dry-cold CO2; and 3) dry-cold CO2 & ambient air. Sub-peritoneal PtO2 and tissue temperature were measured with a polarographic oxygen probe. RESULTS: Upon insufflation of humidified-warm CO2, PtO2 increased by 29.8 mmHg (SD 13.3; p<0.001), or 96.6% (SD 51.9), and tissue temperature by 3.0°C (SD 1.7 p<0.001), in comparison with exposure to ambient air. Smaller, but significant, increases in PtO2 were seen in experiments 2 and 3. Tissue temperature decreased upon exposure to dry-cold CO2 compared with ambient air (-1.4°C, SD 0.5, p = 0.001). CONCLUSIONS: In a rat model, insufflation of humidified-warm CO2 into the abdominal cavity during open abdominal surgery causes an immediate and potentially clinically significant increase in PtO2. The effect is an additive result of the delivery of CO2 and avoidance of evaporative cooling via the delivery of the CO2 gas humidified at body temperature.

Onychophoran Hox genes and the evolution of arthropod Hox gene expression.

INTRODUCTION: Onychophora is a relatively small phylum within Ecdysozoa, and is considered to be the sister group to Arthropoda. Compared to the arthropods, that have radiated into countless divergent forms, the onychophoran body plan is overall comparably simple and does not display much in-phylum variation. An important component of arthropod morphological diversity consists of variation of tagmosis, i.e. the grouping of segments into functional units (tagmata), and this in turn is correlated with differences in expression patterns of the Hox genes. How these genes are expressed in the simpler onychophorans, the subject of this paper, would therefore be of interest in understanding their subsequent evolution in the arthropods, especially if an argument can be made for the onychophoran system broadly reflecting the ancestral state in the arthropods. RESULTS: The sequences and embryonic expression patterns of the complete set of ten Hox genes of an onychophoran (Euperipatoides kanangrensis) are described for the first time. We find that they are all expressed in characteristic patterns that suggest a function as classical Hox genes. The onychophoran Hox genes obey spatial colinearity, and with the exception of Ultrabithorax (Ubx), they all have different and distinct anterior expression borders. Notably, Ubx transcripts form a posterior to anterior gradient in the onychophoran trunk. Expression of all onychophoran Hox genes extends continuously from their anterior border to the rear end of the embryo. CONCLUSIONS: The spatial expression pattern of the onychophoran Hox genes may contribute to a combinatorial Hox code that is involved in giving each segment its identity. This patterning of segments in the uniform trunk, however, apparently predates the evolution of distinct segmental differences in external morphology seen in arthropods. The gradient-like expression of Ubx may give posterior segments their specific identity, even though they otherwise express the same set of Hox genes. We suggest that the confined domains of Hox gene expression seen in arthropods evolved from an ancestral onychophoran-like Hox gene pattern. Reconstruction of the ancestral arthropod Hox pattern and comparison with the patterns in the different arthropod classes reveals phylogenetic support for Mandibulata and Tetraconata, but not Myriochelata and Atelocerata.

Environmental complexity and biodiversity: the multi-layered evolutionary history of a log-dwelling velvet worm in Montane Temperate Australia.

Phylogeographic studies provide a framework for understanding the importance of intrinsic versus extrinsic factors in shaping patterns of biodiversity through identifying past and present microevolutionary processes that contributed to lineage divergence. Here we investigate population structure and diversity of the Onychophoran (velvet worm) Euperipatoides rowelli in southeastern Australian montane forests that were not subject to Pleistocene glaciations, and thus likely retained more forest cover than systems under glaciation. Over a ~100 km transect of structurally-connected forest, we found marked nuclear and mitochondrial (mt) DNA genetic structuring, with spatially-localised groups. Patterns from mtDNA and nuclear data broadly corresponded with previously defined geographic regions, consistent with repeated isolation in refuges during Pleistocene climatic cycling. Nevertheless, some E. rowelli genetic contact zones were displaced relative to hypothesized influential landscape structures, implying more recent processes overlying impacts of past environmental history. Major impacts at different timescales were seen in the phylogenetic relationships among mtDNA sequences, which matched geographic relationships and nuclear data only at recent timescales, indicating historical gene flow and/or incomplete lineage sorting. Five major E. rowelli phylogeographic groups were identified, showing substantial but incomplete reproductive isolation despite continuous habitat. Regional distinctiveness, in the face of lineages abutting within forest habitat, could indicate pre- and/or postzygotic gene flow limitation. A potentially functional phenotypic character, colour pattern variation, reflected the geographic patterns in the molecular data. Spatial-genetic patterns broadly match those in previously-studied, co-occurring low-mobility organisms, despite a variety of life histories. We suggest that for E. rowelli, the complex topography and history of the region has led to interplay among limited dispersal ability, historical responses to environmental change, local adaptation, and some resistance to free admixture at geographic secondary contact, leading to strong genetic structuring at fine spatial scale.

The role of ventral and preventral organs as attachment sites for segmental limb muscles in Onychophora.

BACKGROUND: The so-called ventral organs are amongst the most enigmatic structures in Onychophora (velvet worms). They were described as segmental, ectodermal thickenings in the onychophoran embryo, but the same term has also been applied to mid-ventral, cuticular structures in adults, although the relationship between the embryonic and adult ventral organs is controversial. In the embryo, these structures have been regarded as anlagen of segmental ganglia, but recent studies suggest that they are not associated with neural development. Hence, their function remains obscure. Moreover, their relationship to the anteriorly located preventral organs, described from several onychophoran species, is also unclear. To clarify these issues, we studied the anatomy and development of the ventral and preventral organs in several species of Onychophora. RESULTS: Our anatomical data, based on histology, and light, confocal and scanning electron microscopy in five species of Peripatidae and three species of Peripatopsidae, revealed that the ventral and preventral organs are present in all species studied. These structures are covered externally with cuticle that forms an internal, longitudinal, apodeme-like ridge. Moreover, phalloidin-rhodamine labelling for f-actin revealed that the anterior and posterior limb depressor muscles in each trunk and the slime papilla segment attach to the preventral and ventral organs, respectively. During embryonic development, the ventral and preventral organs arise as large segmental, paired ectodermal thickenings that decrease in size and are subdivided into the smaller, anterior anlagen of the preventral organs and the larger, posterior anlagen of the ventral organs, both of which persist as paired, medially-fused structures in adults. Our expression data of the genes Delta and Notch from embryos of Euperipatoides rowelli revealed that these genes are expressed in two, paired domains in each body segment, corresponding in number, position and size with the anlagen of the ventral and preventral organs. CONCLUSIONS: Our findings suggest that the ventral and preventral organs are a common feature of onychophorans that serve as attachment sites for segmental limb depressor muscles. The origin of these structures can be traced back in the embryo as latero-ventral segmental, ectodermal thickenings, previously suggested to be associated with the development of the nervous system.

Is it time to include point-of-care ultrasound in general surgery training? A review to stimulate discussion.

BACKGROUND: Point-of-care ultrasound scanning or POCUS is a focused ultrasound (US) scan, performed by non-imaging clinicians during physical examination, an invasive procedure or surgery. As this technology becomes cheaper, smaller and easier to use, its scope for use by surgeons grows, a trend that may generate a gap between use and training. Opportunities for enhanced general surgery skill sets may be reduced unless consideration is given to inclusion of POCUS in general surgery training. AIMS: To stimulate discussion regarding inclusion of POCUS in the general surgery curriculum; to resource this discussion with an overview of current trends and issues around POCUS; and to discuss concerns and controversies that may arise if POCUS was adopted into general surgery training. METHOD: A literature search was performed using PUBMED, MEDLINE, Google and Google Scholar, using the terms 'ultrasound', 'point-of-care-ultrasound', 'bedside ultrasound', 'portable ultrasound' and 'hand-held ultrasound'. Literature, references and non-literature resources found were reviewed for relevance to US education in general surgery. CONCLUSIONS: Increasingly, medical students are graduating with basic POCUS skills. Specialty-specific uses of POCUS are proliferating. Training and assessment resources are not keeping up, in accessibility or standardization. A learned surgical college led training and accreditation process would require aligned education in anatomy and US technology and collaboration with the specialist imaging community to ensure appropriate standards are clarified and met. Research is also required into how general surgery trainees can best achieve and maintain POCUS competence.

Early development in the velvet worm Euperipatoides kanangrensis Reid 1996 (Onychophora: Peripatopsidae).

We present here a description of early development in the onychophoran Euperipatoides kanangrensis with emphasis on processes that are ambiguously described in older literature. Special focus has been on the pattern of early cleavage, blastoderm and germinal disc development and gastrulation. The formation of the blastopore, stomodeum and proctodeum is described from sectioned material using light and transmission electron microscopy as well as whole-mount material stained for nuclei and gene expression. The early cleavages were found to be superficial, contrary to earlier descriptions of cleavage in yolky, ovoviviparous onychophorans. Also, contrary to earlier descriptions, the embryonic anterior-posterior axis is not predetermined in the egg. Our data support the view of a blastopore that becomes elongated and slit-like, resembling some of the earliest descriptions. From gene expression data, we concluded that the position of the proctodeum is the most posterior pit in the developing embryo. This description of early development adds to our knowledge of the staging of embryonic development in onychophorans necessary for studies on the role of developmental changes in evolution.

Review of anatomy education in Australian and New Zealand medical schools.

Anatomy instruction at Australian and New Zealand medical schools has been the subject of considerable debate recently. Many commentators have lamented the gradual devaluation of anatomy as core knowledge in medical courses. To date, much of this debate has been speculative or anecdotal and lacking reliable supporting data. To provide a basis for better understanding and more informed discussion, this study analyses how anatomy is currently taught and assessed in Australian and New Zealand medical schools. A mailed questionnaire survey was sent to each of the 19 Australian and 2 New Zealand medical schools, examining the time allocation, content, delivery and assessment of anatomy for the 2008 academic year. Nineteen of the 21 (90.5%) universities invited to participate completed the survey. There was considerable variability in the time allocation, content, delivery and assessment of anatomy in Australasian medical schools. The average total hours of anatomy teaching for all courses was 171 h (SD +/- 116.7, range 56/560). Historical data indicate a major decline in anatomy teaching hours within medical courses in Australia and New Zealand. Our results reveal that as there is no national curriculum for anatomy instruction, the curriculum content, instruction methodology and assessment is highly variable between individual institutions. Such variability in anatomy teaching and assessment raises an important question: is there also variable depth of understanding of anatomy between graduates of different medical courses?

Head patterning and Hox gene expression in an onychophoran and its implications for the arthropod head problem.

The arthropod head problem has puzzled zoologists for more than a century. The head of adult arthropods is a complex structure resulting from the modification, fusion and migration of an uncertain number of segments. In contrast, onychophorans, which are the probable sister group to the arthropods, have a rather simple head comprising three segments that are well defined during development, and give rise to the adult head with three pairs of appendages specialised for sensory and food capture/manipulative purposes. Based on the expression pattern of the anterior Hox genes labial, proboscipedia, Hox3 and Deformed, we show that the third of these onychophoran segments, bearing the slime papillae, can be correlated to the tritocerebrum, the most anterior Hox-expressing arthropod segment. This implies that both the onychophoran antennae and jaws are derived from a more anterior, Hox-free region corresponding to the proto and deutocerebrum of arthropods. Our data provide molecular support for the proposal that the onychophoran head possesses a well-developed appendage that corresponds to the anterior, apparently appendage-less region of the arthropod head.

Variation in the management of early breast cancer in rural and metropolitan centres: implications for the organisation of rural cancer services.

The study examines the management and outcomes of women with early invasive breast cancer treated in rural and metropolitan centres over a nine-year observation period. A prospective audit of the treatment and outcomes of 2081 women with early breast cancer who underwent potentially curative surgery between 1997 and 2006 in metropolitan Canberra or in the surrounding rural region was completed. Overall, there was good agreement between published guidelines and the treatment received by the women in the study. However, women treated in rural centres were less likely to receive postoperative radiotherapy after breast-conserving surgery, or to undergo axillary lymph node surgery or sentinel lymph node biopsy compared with women treated in metropolitan centres. Surgery in a rural centre was associated with increased breast cancer recurrence (HR = 1.54, p < 0.001) and increased breast cancer mortality (HR = 1.84, p < 0.001), after adjustment for age and tumour characteristics. Non-cancer related mortality was increased in women treated in rural centres compared with women travelling to a metropolitan centre for surgery (HR = 2.08; p = 0.005). There were differences in both the care provided and treatment outcomes between women treated in rural centres and women treated in metropolitan centres. However, the increased non-cancer related mortality in women treated in rural centres suggests an increased medical comorbidity in this group. Initiatives supporting rural-based surgeons to adopt new procedures such as sentinel node biopsy may help to optimise rural breast cancer treatment.

The involvement of engrailed and wingless during segmentation in the onychophoran Euperipatoides kanangrensis (Peripatopsidae: Onychophora) (Reid 1996).

As the putative sister group to the arthropods, onychophorans can provide insight into ancestral developmental mechanisms in the panarthropod clade. Here, we examine the expression during segmentation of orthologues of wingless (Wnt1) and engrailed, two genes that play a key role in defining segment boundaries in Drosophila and that appear to play a role in segmentation in many other arthropods. Both are expressed in segmentally reiterated stripes in all forming segments except the first (brain) segment, which only shows an engrailed stripe. Engrailed is expressed before segments are morphologically visible and is expressed in both mesoderm and ectoderm. Segmental wingless expression is not detectable until after mesodermal somites are clearly distinct. Early engrailed expression lies in and extends to both sides of the furrow that first demarcates segments in the ectoderm, but is largely restricted to the posterior part of somites. Wingless expression lies immediately anterior to engrailed expression, as it does in many arthropods, but there is no precise cellular boundary between the two expression domains analogous to the overt parasegment boundary seen in Drosophila. Engrailed stripes extend along the posterior part of each limb bud, including the antenna, while wingless is restricted to the distal tip of the limbs and the neurectoderm basal to the limbs.

Ultrastructure of the eggshell and its formation in Planipapillus mundus (Onychophora: Peripatopsidae).

Although the majority of onychophorans are viviparous or ovoviviparous, oviparity has been described in a number of species found exclusively in Australia and New Zealand. Light microscopy and scanning and transmission electron microscopy were used to examine developing eggs and the reproductive tract of the oviparous Planipapillus mundus. Deposited eggs and fully developed eggs dissected from the terminal end of the uteri have an outer thick, slightly opaque chorion, and an inner thin, transparent vitelline membrane. The chorion comprises an outermost extrachorion, sculptured with domes equally spaced over the surface; a middle exochorion, with pores occurring in a pattern of distribution equivalent to that of the domes of the extrachorion above; and an innermost, thick endochorion consisting of a spongelike reticulum of cavities comparable to the respiratory network found in insect eggs. The vitelline membrane lies beneath the chorion, from which it is separated by a fluid-filled space. The vitelline membrane tightly invests the developing egg. Examination of oocytes in the ovary and developing eggs at various stages of passage through the uterus indicate that the majority of chorion deposition occurs in the midregion of the uterus, where vast networks of endoplasmic reticulum are present in the columnar epithelium. The vitelline membrane, however, is believed to begin its development as a primary egg membrane, surrounding the developing oocytes in the ovary. The vitelline membrane is transformed after fertilization, presumably by secretions from the anterior region of the uterus; hence, it should be more accurately referred to as a fertilization membrane. Aspects of the reproductive biology of P. mundus are also included.

Colonoscopic preoperative localization using submucosal injection of radiolabelled colloid.

Malignant colonic polyps can be removed endoscopically but surgical resection is sometimes required. However, the polypectomy site can be difficult to locate. Current methods use various tattooing agents, with varying degrees of success. A new technique using preoperative injection of technetium-99m-labelled antimony colloid, with intraoperative localization using a handheld gamma probe, is described. Although unsuccessful in terms of localizing a previously partially resected polyp, the technique itself proved safe and simple, and has some advantages over other endoscopic approaches.

A tale of two flatties: different responses of two terrestrial flatworms to past environmental climatic fluctuations at Tallaganda in montane southeastern Australia.

Comparative phylogeographic studies of animals with low mobility and/or high habitat specificity remain rare, yet such organisms may hold fine-grained palaeoecological signal. Comparisons of multiple, codistributed species can elucidate major historical events. As part of a multitaxon programme, mitochondrial cytochrome oxidase I (COI) variation was analysed in two species of terrestrial flatworm, Artioposthia lucasi and Caenoplana coerulea. We applied coalescent demographic estimators and nested clade analysis to examine responses to past, landscape-scale, cooling-drying events in a model system of montane forest (Tallaganda). Correspondence of haplotype groups in both species to previously proposed microbiogeographic regions indicates at least four refuges from cool, dry conditions. The region predicted to hold the highest quality refuges (the Eastern Slopes Region), is indicated to have been a long-term refuge in both species, but so are several other regions. Coalescent analyses suggest that populations of A. lucasi are declining, while C. coerulea is expanding, although stronger population substructure in the former could yield similar patterns in the data. The differences in spatial and temporal genetic variation in the two species could be explained by differences in ecological attributes: A. lucasi is predicted to have lower dispersal ability but may be better able to withstand cold conditions. Thus, different contemporary population dynamics may reflect different responses to recent (Holocene) climate warming. The two species show highly congruent patterns of catchment-based local genetic endemism with one another and with previously studied slime-mould grazing Collembola.

Surgical management of invasive breast cancer: a 5-year prospective study of treatment in the Australian Capital Territory and South-Eastern New South Wales.

BACKGROUND: Breast cancer is a major health problem in Australia. The aim of the present report is to evaluate the surgical management of invasive breast cancers in our region. METHODOLOGY: As part of a multidisciplinary quality assurance project, data were collected for the majority of breast cancers treated in our region between July 1997 and June 2002. Participants included surgeons, medical and radiation oncologists, pathologists and general practitioners. RESULTS: Over the 5-year period, 1069 invasive breast cancers were treated. Mastectomy (52%) was more common than breast conservation. For cancers less than 2 cm in diameter (61%), breast conservation was achieved in 62%. High nuclear grade cancers (27%) resulted in mastectomy in 60%. This treatment pattern was the same for patients living in urban and rural areas and in all age groups. Those patients requiring two or more operations (30%) to achieve surgical clearance still had a 33% rate of breast conservation. Over the last 5 years there has been an increase in sentinel node biopsies (16 sentinel node biopsies during 1998-1999; 64 during 2001-2002) and axillary dissections started to decrease. A small group has had no axillary node biopsy or dissection, mainly patients over 70 years of age. Multimodality treatments increased over the 5-year period of our study with the use of postoperative radiotherapy increasing from 60% to 65% and chemotherapy from 36% to 55%. CONCLUSIONS: The project has mapped treatment trends for breast cancer in our region and documented the implementation of new treatment methods as well as the increasing use of multidisciplinary management, multimodality treatment and the implementation of best practice guidelines.

Expression of engrailed in the developing brain and appendages of the onychophoran euperipatoides kanangrensis (Reid).

We have cloned an engrailed-class gene in the onychophoran Euperipatoides kanangrensis and investigated its expression using in situ hybridisation. The expression pattern was found to differ drastically from that previously described for another onychophoran species. In the present investigation, engrailed transcripts were detected in a subset of developing neurons in the brain anlage, and in the mesoderm as well as ectoderm of the developing limb buds. The engrailed positive cells of the brain are of differing developmental maturity, ranging from subepidermal neuronal precursors to neurons located basally in the embryo with developing axons. The lack of the traditional expression in the posterior compartment of segments reported earlier in onychophorans is discussed, and we suggest that onychophorans may have acquired two copies of engrailed with different functions.