HISTORY OF PLATELETS AND MEGAKARYOCYTES

A picture is worth a thousand words and this is so true in terms of microscopic structures. Our understanding is greatly increased when we see a picture rather than reading only the description. In this post, I shall take you through the imaging of platelets and megakaryocytes.

I was little occupied last month and so I could not post regularly. Sorry for that.

Imaging of platelets and megakaryocytes has come a long way since nineteenth century when simple microscopes were used.

Max Johan Sigismund Schultze, German microscopist anatomist,was the first to give the accurate description platelets in 1865.

Giulio Bizzozero was an Italian doctor and medical researcher. He was the first  person who coined the term ‘platelets’ and also demonstrated their role in hemostasis and thrombosis in 1882.

Any idea on what their descriptions were based on?

They viewed unstained samples in simple light microscope, so their observations were restricted to high contrast morphological features.

James Homer Wright was an American pathologist. He was the chief of Pathology at Massachusetts General Hospital for 30 years from 1896 to 1926. He was the first person who discovered that platelets were derived from megakaryocyte in bone marrow in 1906. He saw stained histological sections in simple light microscope.

Can you recollect his name somewhere in Pathology?

He is the Wright in Wrights stain and Homer Wright rosettes associated with neuroblastoma.

The earlier descriptions of platelets were based on observations made in simple microscopes either in stained or unstained preparations. Recently, there are more technological advancements in microscopy, staining and labeling cells.

Fluorescence microscopy

The development of fluorescence microscopy began a revolution in modern microscopy enabling us to see multiple proteins in living cells. In recent years, a number of ‘super-resolution’ fluorescence microscopy techniques have been invented to overcome the diffraction barrier, including techniques that employ nonlinear effects to sharpen the point-spread function of the microscope, such as stimulated emission depletion (STED) microscopy. There are many ‘super-resolution’ fluorescence microscopy techniques like Saturated structured- illumination microscopy (SSIM), also techniques that are based on the localization of individual fluorescent molecules, such as stochastic optical reconstruction microscopy (STORM), photoactivated localization microscopy (PALM) and fluorescence photoactivation localization microscopy (FPALM).

These super resolution fluorescence microscopy has facilitated in elucidating biological processes at the cellular and molecular level. For the first time, I read these names while reading for the post only.

Electron microscopy

Then came the electron microscopy (EM), first developed in 1930s, has the highest resolution of all and provides structural details of cells. In the 1950s and 1960s, became vital in the advances of cellular biology. It has also developed so much in recent years. EM has been used for many years in the study of platelets and megakaryocytes and is still the gold standard in the diagnosis of various platelet related disorders like gray platelet syndrome, Hermansky- Pudlak syndrome.

Imaging

The early microscopists such as Schultz and Bizzozero made beautiful hand drawn pictures of what they saw in their microscopes. Wrights manuscripts are noted for his water colour drawings.

The granular formations which often occur in larger collections in normal human blood. The same after the fibrous material of the drop of blood has clotted under the cover slip. Source: Schultze (1865). Douglas B. Brewer. Max Schultze and G.Bizzozero and the discovery of the platelet. British Journal of Hematology. 2006:133(3); 251-258

There were not only in rapid development in microscopes themselves, but also concomitant advancement in digital camera technology to enable the recording of vast dreams of images at high frame rates. These digital data have allowed for improvements of both spatial and temporal resolution.

In the subsequent posts, we shall see more about history of platelets and recent advancements.

References:

1.     Steven G. Thomas & Natalie S. Poulter (2020): Seeing is believing: use of advanced imaging to study platelets and megakaryocytes, Platelets.

2.    Pictures taken from Wikipedia, Google images.

                                                                                      Written by Dr.Priyavadhana