Ossification - formation of bone tissue - can occur by two processes: intramenbranous ossification and endochondral ossification. In the first case, bone tissue gradually appears in a conjunctival, non-cartilaginous membrane. In endochondral ossification, a bone-shaped cartilage piece serves as a template for making bone tissue.
In vertebrates, the brain lodges within the skull and the spinal cord within a canal in the spine. The brain and spinal cord are formed by glial cells, neuron cell bodies, and dendrite and axon bundles. White and gray matter The outermost layer of the brain is gray in color and is formed mainly of neuron cell bodies.
The vaginal ring containing etonogestrel and ethinyl estradiol is placed in the vagina on the 5th day of menstruation, remaining in this position for three weeks. The biggest advantage is that women will not have to take the pill every day nor will they forget. Another advantage is that hormones will be absorbed directly into the circulation, avoiding some unpleasant side effects of the oral pill.
Satellites Until 1610, the only known satellite was Earth's - the Moon. At that time, Galileo Galilei (1564-1642), with his spyglass, discovered satellites orbiting the planet Jupiter. Today we know of dozens of satellites. In astronomy, a natural satellite is a celestial body that moves around a planet thanks to gravitational force.
Alfred Lothar Wegener (1880 - 1930) was a German meteorologist proponent of tectonic plate theory and continental drift. In the fall of 1911 in Marburg, Wegener was researching in the university library when he came across a scientific article that recorded fossils of identical animals and plants found on opposite sides of the Atlantic.
Flatworms are worms that appeared on Earth probably about 600 million years ago. These animals have a generally flat body, hence the name of the group: flatworms (from the Greek platy: 'flattened'; and helmin: 'worm'). Flatworms, which comprise about 15,000 species, live mainly in aquatic environments such as oceans, rivers and lakes; They are also found in humid terrestrial environments.