Spicules bring light

Sponges, like all animals, possess some sort of a skeleton that gives their bodies shape. As a whole, poriferans have diverse skeletal elements including calcareous laminae, organic filaments, and siliceous and calcareous spicules. The skeletons of each of the major poriferan groups are distinctive and have been used to reconstruct their evolutionary relationships.

This is a second brief publication about spicules, but this image is completely different however; here the darkfield technique has been adapted, using a turret condenser.

Hydra vulgaris

There are several types of Hydra that we can encounter in fresh water, for instance the Hydra Fusca, Hydra Viridis (Green Hydra) and the Hydra Vulgaris. All species have the same nutritional and environmental needs, only the appearance may differ slightly. 

A hydra can have 4 to 12 tentacles with which they catch their prey and can reach a length of 3 centimeters. These tentacles are equipped with nettle cells that paralyze their prey. They can reproduce in various ways, including division. For example, if they are pulled through the middle, both parts will recover and live on. 

Tardigrades - Microscopic space travellers

Tardigrades are possibly some of the cutest and most popular microorganisms in the world. These microscopic animals can be found in all kinds of habitats all over the planet from high mountains to deep oceans, and even on the poles. However, even though they are very common almost everywhere you will need a microscope to spot them as most species are around 500 microns in size and the biggest ones rarely exceed 1 mm. Tardigrades are more commonly known as water bears, because of their bear-like appearance when they waddle around in the microworld looking for food. Some also call them moss piglets because of their high abundance in moss and lichen samples.

The darkfield illumination makes the individual storage cells clearly visible inside the body cavity, 

as well as the digestive system in the middle of the animal.

Tardigrades have eight legs which all end in a various number of claws depending on the species. Inside the body we find a lot of anatomical resemblance to larger animals as tardigrades both have a fully functioning nervous-, muscle-, and digestive system as well as primitive eyes. But despite a somewhat complex body structure, the animal only consists of a few thousand cells. Some of these are called storage cells which can be seen in the image above. These cells slush around inside of the animal when it walks. In the front tardigrades have a feeding apparatus consisting of stylets used to pierce the food and a pharynx used for chewing. Most tardigrades are herbivores and eat things like algae and other plant material. However, some species are hunters and eat things like bacteria, single celled organisms, rotifers and even other tardigrades.

A better image for your stereo microscope

In compound microscopes, an illumination parallel to the optical axis is the standard. A lot of hardware is implemented to ensure this axial illumination: Center-adjustable Field and Aperture diaphragm, centerable light rings for Phase contrast and Darkfield for transmitted light, center-adjustable objectives and/or centerable rotatable stages in Polarization microscopes. With all these microscopes we are working on 2-dimensional samples.

In stereo microscopy, a 3D image from a 3-dimensional sample is our ambition. Different viewing angles for both eyes create different images on the retina of the left and the right eye. Our brain is going to process both images. This concept is best comprehensible in the Greenough construction of a traditional stereo microscope: two complete separate beam paths from objective to the eyes, mounted in a relative angle of 11°-16°. But even in the modern, more flexible CMO (Central Main Objective) concept a different viewing angle is realized.

Greenough type                       CMO (Galilean) type 

Yeast - The helpful and harmful organism

Yeast is a big part of our lives and human culture in general. It is involved in everything from alcohol production and bread making, to scientific research and probiotics. However, some yeasts can also be pathogenic and cause human infections.

Yeasts are unicellular fungi that mainly metabolism sugars for energy. They are very common in the wild where they can be found on the skins of fruit and other sugar-rich places like cereal grain crops. Even though yeast plays a huge role in many aspects of our everyday lives, most species are only about 4 microns in diameter, which is about half the size of our red blood cells. in comparison, a single human hair is roughly 80 microns thick.

Tardigrades - Some of the toughest, and smallest, animals on earth!

Tardigrades are some of the smallest animals on the planet. Most are around 500 microns (half a millimeter), but newly hatched tardigrades can be 10 times smaller than that. And the biggest ones only reach about a 1.5 millimeters. Tardigrades are more commonly known as water bears. This is because of their bear like appearance when they waddle around looking for food. But, unlike a bear, tardigrades have eight legs which all end in several claw-like toes. Most tardigrades are herbivores and eat thing like algae and other plant material. However, not all tardigrades are grazers, some are hunters and eat things like bacteria, single celled organisms, rotifers and even other tardigrades.

Living tardigrade from the genus Ramazzottius.

Tardigrade from the genus Milnesium mounted in hoyer's medium.

Surface structures easily revealed

As it is known, revealing the surface structure of minerals and fossils can be done by making an ultra-thin section or an acetate peel. An ultra-thin section is a thin slice of a mineral or fossil mounted on a glass slide and viewed under a microscope. Preparing thin sections produces excellently detailed images, but the techniques are relatively difficult and can require expensive equipment. Making acetate peels is much easier and much cheaper.

Acetate peels are made by polishing a surface, etching it with acid to give it some relief, and then chemically melting a piece of acetate film onto that surface with the

Feather facts

Feathers appear to have evolved from scales and are composed of B-keratin. Scales and feathers develop in a similar fashion. In actuality, birds have both feathers and scales. You can find scales on the legs and feet of most birds.

Feathers are incredibly strong and yet are incredibly flexible. To allow both lift and forward movement, feathers can bend at almost a right angles.

Introduction to Darkfield illumination - Slider solution

For transparent samples in light microscopy, dark field illumination is a simple and affordable contrast method. The idea of this technique is to display and to emphasize border structures, means abrupt changes of the refractive index within the sample. Especially for single-celled organism in fresh or sweet water environments, with a refractive index close to water, this contrast method gives aesthetic and informative images.

Dark field emphasizes borders and isolated, single structures, flagella of protozoa and tiny particles. The comparison of a diatom sample in bright field and dark field clearly shows this:

How such an image is achieved? We need to eliminate the direct light which ordinarily passes the specimen and which is responsible for the bright background in bright field illumination. For objectives with a Numerical Aperture ≤ 0.65 this

The microscope objective - the key issue for best image performance

Different samples require different microscopes. This rule refers to the fact that an opaque, bulky sample with a reflective surface needs another treatment than a transparent, unstained smear from the cavitas oris. The microscope stand offers the necessary space for a correct positioning of the sample and all options for the appropriate illumination method.

 The microscope objective is an even more specific item. Here we talk about the required resolution power (= numerical aperture), but also about cover glass correction, immersion method and working distance.

1. The standard upright microscope for transmitted light is constructed for glass slides with a 0.17mm cover slip. This restriction is indicated on the objective sleeve:

Cover slip thickness indicated on Motic's Plan UC Fluor objectives

The cover slip has to be placed on top of the sample. A slight pressing of a dissecting needle will help to avoid too much embedding medium (water, etc.) between sample and cover slip. The embedding medium in this case works as an