This figure presents a comparative biological and biochemical analysis of Branchiostoma belcheri eggs before and after fertilization, serving as a model for chordate egg coat (EC) and zona pellucida (ZP) protein evolution. Panels A and B are light microscopy images illustrating morphological changes: the unfertilized egg (A) measures approximately 145.77 μm in diameter with a tight egg coat, whereas the fertilized egg (B) displays significant elevation of the egg coat, expanding the total diameter to approximately 400 μm while the central cytoplasm remains constant. Panels C and D show SDS-PAGE gel electrophoresis of protein extracts from unfertilized and fertilized egg coats, respectively. Panel C reveals a high density of protein bands ranging from 30 kDa to over 100 kDa, with 11 marked slices used for LC-MS/MS analysis. Panel D demonstrates a simplified protein profile post-fertilization, with a dominant band clustered around 55 kDa and distinct minor bands at higher molecular weights (e.g., 110-170 kDa). This comparison highlights the structural remodeling and protein biochemical shifts associated with the cortical granule reaction and egg coat maturation in basal chordates.

This composite of fluorescence microscopy images illustrates the distribution and co-localization of the active Arp2/3 complex (pArp2) in amphioxus eggs from unfertilized to late fertilized stages. Section (a) shows the orientation of the egg using the polar body (pb) and vegetal tuft-like structure (tu). Section (b) is a time-series showing pArp2 (green) immunopositive signals shifting from a ubiquitous cortical distribution in unfertilized eggs to a localized concentration on one side of the egg 35 minutes post-fertilization, migrating via the animal pole. Section (c) demonstrates the co-localization of pArp2 (red) and F-actin (green), where the merged image (yellow) indicates overlapping signals in the late fertilized cortical region. Section (d) presents co-localization between pArp2 and tubulin (microtubules) in lateral and vegetal views. A prominent tuft-like structure (tu) at the vegetal pole shows strong overlap of pArp2 and tubulin. These visual data highlight the role of cortical cytoskeletal remodeling in establishing embryonic asymmetry and axis determination during early development. Scale bar represents 100 µm.

A multi-panel clinical graphic demonstrating gastric ascariasis and associated complications. Panel A shows a white-light endoscopic view of the gastric antrum containing a long, slender, pale yellowish cylindrical roundworm, identified as Ascaris lumbricoides. An inset displays the extracted intact worm. Panel B features an endoscopic ultrasound (EUS) image alongside a transverse CT slice of the abdomen. The EUS reveals a complex, heterogeneous region adjacent to the pancreatic tail containing multiple hypoechoic, roughly circular cystic structures (indicated by white arrows), representing egg collections or localized inflammation. The associated CT scan shows diffuse edematous enlargement of the pancreas consistent with acute interstitial pancreatitis. Panel C shows a follow-up EUS image after anthelmintic treatment with albendazole, demonstrating complete resolution of the cystic structures and return to more homogeneous pancreatic parenchyma. This sequence illustrates the diagnostic utility of EUS in identifying parasitic etiologies for acute pancreatitis and monitoring treatment response.

This clinical photograph displays a specimen of Ascaris lumbricoides, a human parasitic roundworm, following extraction via Endoscopic Retrograde Cholangio-Pancreaticography (ERCP). The specimen is a single, elongated, cylindrical nematode with a smooth, tan-to-brownish exterior. One visible extremity tapers to a sharp, curved point, which is characteristic of the adult worm's morphology. The organism is placed on sterile white surgical gauze, illustrating the outcome of a procedural intervention for biliary ascariasis. This image demonstrates the clinical manifestation of hepatobiliary parasitism where a nematode has migrated into the common bile duct, potentially causing obstructive jaundice or biliary colic. The educational focus is on the macroscopic identification of common helminthic infections and the visual confirmation of parasitic extraction in gastroenterology and tropical medicine.

This composite clinical photograph displays two distinct dermatological manifestations of Strongyloides stercoralis infection. Image A shows larva currens in the perianal region, characterized by a serpiginous, erythematous, and slightly raised linear track (indicated by a red arrow). This pathognomonic lesion represents the rapid intradermal migration of filariform larvae. Image B displays a periumbilical 'thumbprint' purpura in a patient with disseminated strongyloidiasis. The abdominal skin exhibits extensive, non-blanching purpuric macules and petechiae, appearing as clusters of reddish-purple spots that are most concentrated in the periumbilical area. These lesions result from larvae migrating through the vessel walls into the dermis. The educational focus is on distinguishing the localized cutaneous signs of chronic infection from the systemic vascular signs associated with severe, disseminated hyperinfection syndrome in immunocompromised hosts.

Content Type: Clinical Photograph. This four-panel composite image displays a patient's inferior abdomen and flank, showcasing pathognomonic dermatological signs of disseminated Strongyloides stercoralis hyperinfection. The primary findings are multiple, raised, erythematous, serpiginous lesions known as larva currens. These linear, wavy tracks represent the rapid cutaneous migration of filariform larvae. Red arrows highlight the specific morphology and orientation of the lesions, which appear as slightly edematous, urticarial-like streaks across the wrinkled skin of an older adult. Contextual elements include medical monitoring cables and gloved hands of healthcare providers, indicating an inpatient clinical setting. Educational Focus: Recognition of the distinctive 'racing larva' morphology and its clinical significance as a hallmark of systemic strongyloidiasis, particularly in immunosuppressed patients. Specialty: Infectious Disease, Dermatology, Tropical Medicine.

Two-panel clinical photograph (A and B) demonstrating a pathognomonic purpuric rash on the abdomen and flank of an immunocompromised patient with disseminated strongyloidiasis. Figure A provides a wide view of the torso, showing an extensive distribution of non-blanching, violaceous macules and small papules primarily concentrated in the periumbilical region, lower abdomen, and extending toward the flank. Figure B is a high-magnification view of the periumbilical area, highlighting specific morphological patterns. A black arrow indicates a classic 'thumbprint sign,' characterized by serpiginous and linear purpuric tracks caused by the subcutaneous migration of Strongyloides stercoralis filariform larvae (larva currens). The lesions appear as petechiae and ecchymoses with a distinctive reticulated or serpiginous arrangement. This finding is a critical clinical marker for Strongyloides hyperinfection syndrome or disseminated disease, often seen in the context of HIV infection or corticosteroid therapy.

This composite educational image features a Scanning Electron Micrograph (SEM) of a hookworm specimen superimposed with a three-dimensional protein ribbon diagram. The anatomical background shows the anterior end of a parasitic nematode, likely Ancylostoma or Necator species, highlighting the buccal capsule with visible tooth-like structures or cutting plates used for mucosal attachment and blood-feeding. The specimen displays a granular, textured grey and tan surface. Overlaid is a multi-colored ribbon model representing a recombinant protein, such as those secreted by the parasite (e.g., Ancylostoma-secreted proteins). The protein structure illustrates tertiary folding patterns including alpha-helices (blue and green) and beta-pleated sheets (orange and yellow) interconnected by loops. This visual is designed to illustrate concepts in parasitology and vaccine development, specifically targeting hookworm-induced iron deficiency anemia by utilizing secreted recombinant proteins as immunogens to disrupt the parasite's life cycle or feeding mechanisms in humans.

**Modality:** Differential interference contrast (DIC) light microscopy. **Subject:** Anterior end of a nematode, likely an *Ancylostoma* or *Necator* species (hookworm), viewed from a lateral perspective. **Key Anatomical Features:** * **Buccal Capsule:** A prominent, deep, and sclerotized buccal cavity is visible at the anterior terminus. * **Ventral Cutting Elements:** The image demonstrates the characteristic armature of the oral aperture, showing thickened, tooth-like or plate-like structures (cutting teeth) used for mucosal attachment. * **Esophageal Junction:** The posterior base of the buccal capsule transitions into the muscular esophagus, with visible longitudinal striations in the esophageal wall. * **Cephalic Structure:** The cuticle appears smooth with subtle longitudinal markings. **Clinical Significance:** This microscopic view is a primary diagnostic feature for identifying parasitic helminths in clinical samples (e.g., stool concentrates or tissue biopsies). The morphology of the buccal capsule—specifically the shape and number of ventral teeth—is the key taxonomic differentiator between hookworm species that cause human ancylostomiasis and necatoriasis. **Scale:** A white vertical scale bar is present in the upper right quadrant for morphometric reference.

This diagnostic micrograph displays an embryonated egg of the nematode Nematodirus battus, a clinically significant helminth. The image captures the parasite in a late developmental stage, specifically featuring a well-developed third-stage larva (L3) coiled within the egg shell. The egg is characterized by a distinctive large, oval shape and a smooth, translucent outer shell. Internally, the larva is clearly visible as a complex, elongated, and folded structure with a segmented, textured appearance, occupying a significant portion of the internal volume. This 'larvated' stage is a critical diagnostic marker in parasitology, indicating maturity and readiness for hatching. Such images are used in medical and veterinary parasitology to identify species-specific egg morphology and to assess the life cycle progression of strongyle-type parasites in environmental or clinical specimens.

The composite image contains two panels relevant to a clinical case of sepsis. (A) Light microscopy (Gram stain, 1000x magnification) of a blood culture smear. It shows numerous small, pink-stained, Gram-negative rod-shaped bacteria (coccobacilli) scattered individually and in clusters among circular pink-stained host cells, characteristic of Yersinia pseudotuberculosis. (B) A clinical photograph of a patient's hand demonstrating distal cutaneous desquamation. The thumb displays characteristic peeling and flaking of the superficial epidermis, revealing raw, erythematous underlying skin at the fingertip. This visual finding is a classic clinical sign of Far East scarlet-like fever (FESLF) or toxic shock-like syndromes. Collectively, these images illustrate the diagnostic progression from microbiological identification of a pathogen to the manifestation of dermatological sequelae in systemic infection.

Recommendations	Strength rating
Perform the quickSOFA score to identify patients with potential sepsis.	Strong
Take a urine culture and two sets of blood cultures before starting antimicrobial treatment.	Strong
Administer parenteral high dose broad spectrum antimicrobials within the first hour after clinical assumption of sepsis.	Strong
Adapt initial empiric antimicrobial therapy on the basis of culture results.	Strong
Initiate source control including removal of foreign bodies, decompression of obstruction and drainage of abscesses in the urinary tract.	Strong
Provide immediate adequate life-support measures.	Strong

Educational infographic highlighting the global and domestic impact of sepsis, set against a background illustration of red blood cells in the bloodstream. The central text describes sepsis as 'the Equal Opportunity Killer'. Key epidemiological data points include: 258,000 Americans die from sepsis annually; it is the third leading cause of death in the United States after heart disease and cancer; 1.6 million cases occur in the U.S. every year; and more than 5 million children die from sepsis worldwide annually. Additionally, the graphic notes a public awareness gap, stating that only 55% of Americans have ever heard the word 'sepsis'. The visual uses iconography like the map of the United States, a globe, and human figures to contextualize the statistics. This infographic serves as a public health awareness tool to emphasize the high mortality and prevalence of this critical medical condition.

This slide shows a para-nasal sinus mucin specimen examined by brightfield light microscopy after Hematoxylin and Eosin (H&E) staining. The specimen is thick, rubbery, gelatinous, with a greenish-brown coloration typical of allergic mucin. Microscopically, the material is largely amorphous and chondroid-like, may display laminated architecture, and contains clusters of inflammatory cells within a proteinaceous matrix. The inflammatory infiltrate is eosinophil-predominant, with scattered neutrophils, plasma cells, and histiocytes. Charcot-Leyden crystals are frequently present, reflecting eosinophil breakdown, together with desquamated respiratory epithelial cells. Rare fungal hyphae are visible at the upper left and lower right corners of the field, consistent with a minority fungal component without evidence of tissue invasion. The surrounding sinus mucosa shows inflammatory exudate and mucinous debris. Collectively these features support allergic fungal rhinosinusitis (AFRS) with eosinophilic mucin rather than invasive fungal rhinosinusitis or bacterial rhinosinusitis. Diagnostic significance includes recognition of AFRS by eosinophilic mucin with Charcot-Leyden crystals and sparse hyphae, aiding differential diagnosis against chronic rhinosinusitis, fungal ball, and invasive disease. Clinically, findings correlate with chronic nasal obstruction, allergic rhinitis, and asthma; educational and research relevance spans rhinology, otolaryngology, pathology, and radiology. Morphologic features include laminated mucin, eosinophil-rich debris, and occasional contact with respiratory epithelium. Important for education.

Imaging modality: Histopathology, light microscopy of hematoxylin and eosin (H&E) stained lung tissue. Specimen derived from pulmonary parenchyma via biopsy. Microscopic field reveals cellular interstitial infiltrates containing numerous Langerhans cells with vesicular, grooved nuclei and moderate to abundant eosinophilic cytoplasm, accompanied by eosinophils, lymphocytes, plasma cells, pigment-laden macrophages and occasional neutrophils. Early lesions are cellular with abundant Langerhans cells and eosinophils and minimal fibrosis; later stages show progressive fibrosis and foamy macrophages with reduced Langerhans cell density and fewer eosinophils. Langerhans cells may form cohesive clusters within airspaces and interstitium, sometimes surrounding necrotic debris; Charcot-Leyden crystals may be present in eosinophil-rich microabscesses. The histology may resemble granulomatous inflammation but lacks classic granulomas; immunophenotype is typically CD1a and CD207 (Langerin) positive in diagnostic settings. Diagnostic significance: this pattern is characteristic of pulmonary langerhans cell histiocytosis (PLCH), which commonly associates with smoking and can progress to cystic lung disease; differential includes eosinophilic pneumonia, hypersensitivity pneumonitis, granulomatous infections, and smoking-related interstitial fibrosis. Clinical correlation: correlate with smoking history, respiratory symptoms, and imaging; confirm with immunohistochemistry; assess for complications such as pneumothorax; management focuses on smoking cessation and, in selected cases, targeted therapies. Additional molecular testing may guide prognosis and targeted anti-LCH therapy in cases.

Modality and technique: Light microscopy of a paranasal sinus mucin biopsy stained with Periodic acid–Schiff (PAS). The specimen shows thick, eosinophil-rich allergic mucin containing discrete, pigmented fungal hyphae consistent with dematiaceous organisms. Hyphae are septate with acute-angled branching, noninvasive within the mucus rather than invading sinus mucosa. The pigment imparts a brown-black coloration to the hyphae, typical of Bipolaris species. No tissue invasion or necrosis is evident. The surrounding stroma demonstrates an inflammatory milieu with eosinophils, Charcot-Leyden crystals, and mucus with sparse inflammatory cells. The microbiologic appearance is consistent with allergic fungal sinusitis (AFS) rather than invasive mycosis. The case highlights Bipolaris as the causative agent among dematiaceous fungi such as Bipolaris, Exserohilum, Curvularia, Alternaria, and Drechslera; yet histology of allergic mucin remains similar irrespective of organism. For diagnosis, identification relies on fungal morphology in mucus and culture/molecular confirmation if available. Clinically, this pattern correlates with chronic rhinosinusitis with nasal polyposis and hypersensitivity reactions. Differential includes Aspergillus and other dematiaceous fungi. Recognizing dematiaceous hyphae within eosinophilic mucin guides management by guiding surgical debridement and antifungal therapy decisions, and informs prognosis regarding recurrence risk. This documentation supports educational training, targeted research, and standardized reporting of noninvasive fungal mucin infections in sinuses.