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Archive: January 2021

Nemaline Rods

Nemaline Rods, neuro notes, neuropathology, Dr. Mrachek
What are these dark (osmophilic) structures seen in this electron micrograph of skeletal muscle?   These osmophilic structures are Nemaline rods (largest, white arrow). These structures are classically seen in "Nemaline Myopathy" (NM; aka rod body myopathy). The rods are located in the sarcoplasm, and may also be seen within nuclei. NM is most commonly caused by dominant mutations of ACTA1 (encoding skeletal a-actin) and recessive mutations of NEB (encoding nebulin).  Intranuclear rods are associated with pathogenic ACTA1 mutations.  There are variable phenotypes of NM ranging from the severe congenital myopathy to adult-onset disease.  Limited numbers of muscle fibers containing...

Diagnose This (January 12, 2021)

antibody-mediated rejection, arkana laboratories, renal pathology, diagnose this, kidney disease
What are the two major changes seen in this image from an allograft kidney and what are these findings concerning for?       ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​...

Sarcomere Bundles of the A Zone

sarcomere, Neuro notes, renal pathology, arkana labs, neuropathology
This week’s interesting image shows the examination of skeletal muscle in cross-section at the level of the A zone by electron microscopy in Figure 1, and corresponding illustration of the sarcomere in longitudinal section, Figure 2. Figure 1. Ultrastructure of sarcomere bundles.  The contractile elements of skeletal muscle are seen in cross-section at the level where myosin thick filaments and actin thin filaments overlap at the "anisotropic" or "A" zone of the sarcomere.  Electron Microscopy (EM): 25000x original magnification. Figure 2.  Illustration of sarcomere bundles.  The sarcomere contractile apparatus viewed in longitudinal section shows various degrees of overlap of the...

Diagnose This (January 4, 2021)

artery with a cholesterol embolus, arkana laboratories, renal pathology, renal disease
What is your diagnosis and what are some possible precipitating events that may lead to this finding?       ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​   ​ ​  ...

Arkana Live- January 2021

february, Renal Intratubular Casts, january, december, Endocarditis-Related Glomerulonephritis, Infection-Related Glomerulonephritis, Light Microscopy, august, FSGS, september, october, July, Arkana Live, arkana laboratories
The next Arkana Live kidney pathology session will be on January 16 @ 10AM CT/11AM ET. Join us as Dr. Zeljko Dvanajscak will be focusing on renal intratubular casts. Moderated by Dr. Samira Farouk and Dr. Matt Sparks! Register here: Renal Intratubular Casts with Dr. Zeljko Dvanajscak  

Arkana Live – January 2021

february, Renal Intratubular Casts, january, december, Endocarditis-Related Glomerulonephritis, Infection-Related Glomerulonephritis, Light Microscopy, august, FSGS, september, october, July, Arkana Live, arkana laboratories
The next Arkana Live is January 16th at 10 AM CT/11 AM ET! Join us as Dr. Zeljko Dvanajscak will be focusing on renal intratubular casts. Moderated by Dr. Samira Farouk and Dr. Matthew Sparks! Register here: Arkana Live January 2021  

Tangential Sections Through Three Triads

Tangential Sections Through Three Triads
Can you identify the structure(s) identified by arrows in this muscle biopsy?   Tangential sections through three triads (pale T-tubules and darker adjacent sarcoplasmic reticulum ….. "Oreo cookie-like") in association with sarcomeres (electron microscopy 15000x magnification). T-tubules distribute the surface action potential into the interior of the muscle fiber, where it triggers release of calcium stored in the adjacent sarcoplasmic reticulum (i.e. excitation-contraction coupling).  Release and reuptake of calcium by the sarcoplasmic reticulum is critical to muscle contraction and relaxation.  Note the location of the triads adjacent to thick filaments where calcium is utilized for contraction.