Illustration of the behavior of neurotransmitters in a synapse
between two neurons. Neurotransmitters are endogenous chemicals that
transmit signals from a neuron to a target cell across a synapse. In
response to an electrical signal in the transmitting neuron, vesicles
containing neurotransmitters fuse with the cell wall allowing the
neurotransmitters to enter the synapse. They move toward the receiving
neuron and attach themselves to receptors (green), relaying the message.
Extra neurotransmitters migrate back to the transmitting cell via
Beta DNA. Computer representation of a segment of the beta form of
the molecule Deoxyribonucleic Acid (DNA). This molecule contains all
inherited instructions necessary for the development of a living
organism. Atoms are shown as spheres. The DNA molecule is composed of
two strands of atoms twisted into a helical shape. Each strand consists
of an outer sugar-phosphate backbone (gold) from which the bases project
inwardly (silver). The bases are thus paired in a complementary fashion
like rungs on a ladder, making up the genetic code. This code is
divided into segments called genes. DNA is also the vehicle of genetic
inheritance between different generations.
This anonymous Persian anatomical illustration (Iran or Pakistan,
ca. 1680-1750) depicts a man with his abdomen and chest opened to reveal
the internal organs. In his right hand, he holds a second set of
genitalia, and there is a sketch of the liver and gallbladder in the
upper left corner. The artistic conventions employed in the production
of this illustration indicate Western India as a place of production.
The 16th- to 18th-century European convention of picturing partially
dissected bodies as if they were alive, offering up parts of their own
body for further inspection, can be seen here transferred to the Indian
subcontinent. The anatomy of the exposed organs reflects indigenous
Indian concepts as well as some medieval Galenic anatomy. This is one of
six anonymous anatomical drawings on folia 554-559 at the end of a
volume containing Tibb al-Akbar (Akbar's Medicine) by Muhammad Akbar,
known as Muhammad Arzani (d. 1722/ 1134) in an undated copy probably
made in the 18th century.
A polarized light micrograph of living Saccharomyces cerevisiae, a
species of budding yeast used in baking and brewing. Magnification:
400x. Differential Interference Contrast microscopy (DIC), also known
as Nomarski Interference Contrast (NIC) or Nomarski microscopy, an
optical microscopy illumination technique used to enhance contrast.
Brain pathways. Coloured 3-dimensional magnetic resonance imaging
(MRI) scan of the white matter pathways of the brain, side view. White
matter is composed of myelin-coated nerve cell fibres that carry
information between nerve cells in the cerebrum of the brain (top half
of image) and the brain stem (bottom centre). This image was created by
an MRI scanner sensitised to the movement of water around the brain.
Blue represents neural pathways from the top to the bottom of the brain,
green represents pathways from the front (left) to the back (right),
and red shows pathways between the right and left hemispheres of the