How a small intestinal roundworm contributed to genetics

Cross-sections at the right place in the uterus of a female Ascaris megalocephala can be used to locate eggs in different stages of the first segmentation mitosis*.

After fixation and coloration of the sections, the chromosomes appear colored. The egg of this parasitic nematode can then serve as a support for studying the chromosomal phenomena that characterize the mitosis.

The grainy taste of pear flesh

Sclerenchyma cells are derived from parenchymal cells, which form secondary thickening edges in the cell wall. These are rich in lignin, which practically does not allow any substances getting through, which finally leads to dying of the cell content. Sclerenchyma is thus usually a dead support tissue, whose task is mainly to provide support an mechanical strength. Depending on the shape of the cells, stone cells (sclereids) and sclerenchyma fibers are distinguished.

Silverberry and the universe

A prepared slide of Silverberry scaly hair is often found in microscopy starters packages for amateurs. The beautiful colors and shapes do well under the microscope.

Smell at a distance

The female silk worm moth (Bombyx mori) makes the pheromone bombykol in a special organ in her abdomen. When she is prepared to mate she releases this to attract males. A male silk worm moth has two long antennas that are very sensitive to the odor of the female. One single molecule is enough to cause a reaction in the sensory cells on the male's antenna. In this way he can locate the female. Even at a distance of 10 kilometers, he can still smell her!

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

Muscovite under polarization microscope

Muscovite has an anisotropic crystal structure, with two optical axis and a negative optical sign. The images and video taken with a polarization microscope with crossed polarizers and the Bertrand lens in place, are showing interference images (without lambda filter) in the plane perpendicular to the bisector between the two optical axes.To obtain these images, a thin slice of muscovite was split off from the crystal and taken for examination. Light entering this slice of crystal, produces the typical interference images for this type of crystal.

Click here for more information about Muscovite Mineral.

Basics of Light Microscopy: Incident Light Microscopy for opaque samples (I)

A closer look on Incident Light Microscopy reveals a new and noticeable fact. In a compound microscope for opaque samples, the objective plays two roles. First, like in a Transmitted light setup the objective is part of the imaging process. Quality and performance of the objective are essential elements to get reliable and “close-to-truth” results. 

Secondly, the objective additionally is part of the illumination system. Light from the lamp house passes the illumination axis and is deflected by a 45° orientated semi-transparent mirror. Sent through the objective, the light is reflected by the sample surface and brings back sample information to the eyepieces/camera. For a beginner it is difficult to accept that both illumination and imaging processes do not interfere visually. 

A pest on grapes

Uncinula necator or powdery mildew, a basidiomycete, is a pest on grapes. Its septate hyphae forms a mycelium on the surface of the leaves similar to a spider web. Special hyphal branches, the haustoria, penetrate the host cells to absorb food substances, thereby weakening the grape and reducing the harvest.

A medicinal parasite

Mistletoe (Viscum album), sinkers in host tissue, longitudinal.

The evergreen, spherical shrub of about 1 m in diameter grows on different trees. As a semi-parasite the mistletoe assimilates with its leaf green. The sinkers of the mistletoe penetrate deep into the wood body of the host plants and withdraw only water and mineral salts from the host, but this causes the part above the infestation site to suffer. The opposite, oblong-ovate leaves evaporate only a little water due to their leathery texture.

Computer chips out of sand

Sand is very rich in the element silicon. This substance can have a very pure grid form, which gives interesting electrical properties. Such a grid consists of almost only silicon atoms. Some of these atoms can be replaced by boron or phosphorus, resulting in semiconductors or transistors in the grid.