Artery from another perspective

The preparation of the artery shown in both images is of unknown origin and the staining method is unknown as well.

A fluorescence image of an artery tissue as shown here is not usual. The preparation is more or less evenly green fluorescent colored, because the dye used has attached itself to the structural parts of the preparation. We see a fluorescence color image with details as you might encounter in bright field microscopy with dyes such as e.g. toluidine blue. Such dyes show more or less the same details in the preparation with ordinary bright field microscopy as is shown in the first image.

As mentioned before, visualizing a histological specimen completely by using a fluorescent substance is unusual, because here you apply only one color that shows no specific adhesion, except for proteins, because e.g. fat is uncolored in this preparation. With a normal hematoxylin and eosin staining you have more differentiation, namely in the cell core (DNA, dark blue) and proteins, cytoplasm (pink)

In histology, fluorescence is mainly used after a fluorescent substance has been chemically attached to a specific component present in the tissue.

On the fluorescent image of the preparation the parts of an artery can also be seen. The lumen is filled with green colored red blood cells, then there is a very thin (barely visible) layer of endothelium, the meandering lamina elastica interna (clearly visible) a layer of smooth muscle, the thinner lamina elastica externa (clearly visible), the adventitia (connective  tissue) that turns into adipose (fat) tissue. 

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A switching station

Ganglia are part of the peripheral nervous system. The peripheral nervous system includes all nerves outside the central nervous system (bundles of long nerve shoots with supporting cells) and small centers of nerve cells the ganglia.

A ganglion is a combination of mainly cell bodies (ganglion cells) with the nucleus of the nerve cell surrounded by cytoplasm without further shoots. This cell body with the nucleus as its center forms the metabolic center of the cell and is sensitive to stimuli. Ganglia function as switching stations for nerve impulses.

What’s in a rat’s eye

The photos show various parts of the rat's eye. There are many similarities between the eyes of the rat and those of humans, but also some striking differences. A few of these are mentioned here.

The eyeball of the rat’s eye can be rotated to change the viewing direction without having to turn the head. What is special is that rats can move both eyes in opposite directions. This both horizontally and vertically. Researchers at the Max Planck Institute found this out in 2013 and were able to record this using high-speed cameras. They are able to keep an eye on the sky while also looking forward. They can interpret a double field of view. Probably this has evolved in the wild to deal with great threat to raptors.

Rabbits

The reproductive organs of the rabbit female are seen as primitive. The fixing of the gender of the rabbit occurs during the embryonic phase, on the 16th day after conception. The ovaries develop from a mass of cells that are located near the testicles. The development of the ovaries is accompanied by the degeneration of the male testicles. The development of egg cells occurs approximately from the 21st day and will continue until birth, around the 30th day.

The first follicle, the "bags" in which the eggs (ova) mature, develops 13 days after birth. (See the accompanying photo on which the follicles containing the eggs can be seen at various stages of development) The development of the ovary starts around the 21st day after birth and continues until the 30th day. The first eggs do not begin to develop until 13 days after birth. The ovaries, ellipse shaped bodies of approximately 1.5 cm, are found at the end of each uterus, just below the kidneys.

What makes a human tooth

The images of a cross-section of the root of a tooth (a ground preparation) show various details of the structure of a tooth. Many of the visible details will not be discussed here. To go more deeply, scientific literature is available.