cytological

11:14 || Here’s my first post as a studyblr blogger!! This morning I’ve started studying for my last final of the year. I know I’ve procrastinated so bad until the point of staring studying two days before taking the exam, but at least this is a subject I love, so it’s not that bad (I guess).

10:47 || Good morning guys! Today is my last day of study before summer! Can’t wait to be free!! Today it’s retouching time. I’ve been practising some tests and questions earlier in the morning and now I’m gonna read everything again, so I don’t forget about the little things. I’m so excited about holidays!!

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The black liquid was aspirated from a growing mass on the shoulder of a 2y.o. male neutered crossbreed dog. After sending the sample to the labs, it was suspected to be a pigmented basal cell carcinoma, so we made the quick decision to book him in for surgical excision.

After removing the mass, we sent the mass to the labs again for histopathology analysis, which came back and said it was a benign follicular cyst!

This highlights the importance to always perform histopathology on masses you remove!

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Spotlight on Dr. Nettie Stevens

Dr. Nettie Stevens was an American geneticist who was the first person to describe the XY sex determination system in animals happens due to chromosomes, not some other factor like the environment. Nettie was born on July 7, 1861 in Vermont. She had an unusual childhood in the fact that she attended school until she graduated at 19, at which time she became a teacher. Eventually, after attending a teaching school, Nettie would enroll at Bryn Mawr College at the age of 39 to get her Ph.D. in cytology (the study of chromosomes). She is also one of the worst victims of the Matilda Effect.

After getting her Ph.D. in 1903, Nettie began studying sex determination in mealworms. In 1905, Nettie noticed that male mealworms would produce sperm with either an X chromosome or Y chromosome, but female mealworms would only produce eggs containing X chromosomes. However, her theory was not widely accepted in the scientific community, partially due to the fact that the chromosomal theory of inheritance was not accepted in the scientific community. However, Nettie’s gender almost certainly played a role as well. Sadly, Nettie died in 1912 at the age of 50 from breast cancer.

At a slightly later date then Nettie Stevens, a researcher named Edmund Beecher Wilson independently discovered the same thing as Nettie Stevens (that sex determination had to do with chromosomes). However, unlike Nettie, he only looked at male gametes as he found female eggs too fatty and hard to work with. He later edited his original paper to include a thank you to Nettie Stevens for her findings in female gametes. Although Wilson acknowledged her contributions, it is usually either Wilson or Thomas Hunt Morgan that get credited with the discovery of the XY sex-determination system.

Thomas Hunt Morgan was a very famous and influential American geneticist from the early 1900’s. He was a contemporary of Nettie Stevens, and used to correspond with her regularly. Usually in his letters to other scientists, Morgan would discuss his own theories with them. However, as Laura Hoope, a professor of Biology at Pomona college noted, his letters with Nettie were mostly just him asking for the details and findings from her experiments (Lee, National Geographic)

Following Nettie’s death, Morgan wrote an obituary on her for the famous and reputable science journal Nature. In it, he dismissed her importance and wrote that she didn’t have a broad view of science. This was a disgusting oversight and purposeful snub of Nettie Stevens. It is largely because of him (other factors such as misogyny in science also play a role) that Stevens does not get the recognition or credit she deserves for her crucial discovery. Stevens is also a female scientist with comparatively few things written about her (at least in comparison to scientists like Barbara McClintock and Rosalind Franklin). There is no published long form biography of her that I can find, but I encourage you to check out the sources below I have provided. As well, to honor her, teach everyone you know about Dr. Nettie Stevens and how her accomplishments were forgotten.

Sources: National Geographic, Nature

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This is a sad post for me because it involved my own animal. My female G. marginata was dead in her enclosure the other morning. Since getting her from the reptile expo she never did seem right and this should have been a signal to me. She never was a good eater, she would lay out in the open often, and she had a bad shed.

I did a necropsy and she looked very empty. No body fat anywhere, empty stomach, and she had white nodules throughout her liver. The cytology photos are from impressions I made of the liver. You can see scattered RBC’s, hepatocytes, and some rod shaped bacteria. I sent out tissue samples for histopathology so hopefully I will get an answer back soon. The male seems completely fine and has been eating and behaving normally from day 1 but I will be watching him closely.

This just goes to show that even veterinarians make mistakes. The moment I noticed something was amiss I should have acted but I incorrectly assumed she was just very stressed and would eventually settle in.

Mast cell tumor. In a cat! I so rarely see cats with external masses. Surgical removal was offered to the owner, they may proceed with surgery at a later date. The purple granules throughout the photo contain substances like histamine, which cause swelling, itching, and nausea in large amounts; they can be released simply by squeezing or handling the mass and in large masses could potentially cause anaphylaxis.

Aggression causes new nerve cells to be generated in the brain

A group of neurobiologists from Russia and the USA, including Dmitry Smagin, Tatyana Michurina, and Grigori Enikolopov from Moscow Institute of Physics and Technology (MIPT), have proven experimentally that aggression has an influence on the production of new nerve cells in the brain. The scientists conducted a series of experiments on male mice and published their findings in the journal Frontiers in Neuroscience.

Researchers from the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences (ICG SB RAS), MIPT, Cold Spring Harbour Laboratory, and Stony Brook University and School of Medicine studied the changes that occurred in the brains of mice demonstrating aggressive behaviour, which attacked other mice and won in fights. After a win, these mice became even more aggressive, and new neurons appeared in their hippocampus - one of the key structures of the brain; in addition to this, in mice that were allowed to continue fighting certain changes were observed in the activity of their nerve cells.

Dmitry A. Smagin, June-Hee Park, Tatyana V. Michurina, Natalia Peunova, Zachary Glass, Kasim Sayed, Natalya P. Bondar, Irina N. Kovalenko, Natalia N. Kudryavtseva, Grigori Enikolopov. Altered Hippocampal Neurogenesis and Amygdalar Neuronal Activity in Adult Mice with Repeated Experience of Aggression. Frontiers in Neuroscience, 2015; 9 DOI: 10.3389/fnins.2015.00443

Mouse hippocampal neurons labeled with GFP. Imaged with a 20X objective on Zeiss 710, Dr. Fu-Ming Zhou

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Cervical mass in a 11 year-old, male-castrated, black Labrador Retriever.  For the past two weeks the patient has been intermittently coughing, especially after voraciously eating his  kibbles.  He is described as healthy otherwise.  On physical examination his primary care veterinarian palpated a very large, 10cm firm mass in his ventral neck.  We got the aspirate samples of the mass and found….

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…and found numerous apparently cohesive clusters of these mononuclear cells.  Their cohesive nature is typical of an epithelial population.  The cells look relatively bland - that is, they all appear very similar to their neighbor.  Such monomorphism suggests a more benign process…but we’ll come back to that interpretation!  Additionally, few clusters were associated with this brilliant magenta extracellular material - could be matrix, secretory product, or colloid.  What tumor type do think this is?!

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Cytologic diagnosis: Neuroendocrine epithelial tumor.  Based upon the mass location, this is consistent with a Thyroid tumor.  Although the population looks relatively benign cytologically, canine thyroid tumors are usually aggressive adenocarcinomas.  Conversely, kitty thyroid tumors are usually benign and equine tumors a 50-50 shot on benign versus malignant.  No word yet on what therapy the owner has elected to pursue - but the prognosis is sadly grave :-(

On an aside, other neuroendocrine origin tumors (like insulin secreting pancreatic tumors or some adrenal tumors) have a very similar cytologic appearance.