historical development of cytology histology and embryology Flashcards
when was the first microscope made and who improved it
the first microscope was made in 1590 by Jenson, later improved by Galilei in 1610.
what is the cell theory and what does it dictate?
The cell theory was invented by individuals named Schwann and schleiden in 1839. It dictates;
1. Life exists only in the form of cells and therefore all organisms consist of cells and cells are the basic unit for all life function
2. Each cell is derived from another cell
3. There is a mutual connection between cell structure and function
how did cells come about?
Robert Hooke used this microscope to discover the first ‘Cells’ and coined the term in 1665. He used the term cell as when looking at a thin piece of cork he noted rows of tiny
boxes that made up the dead wood tissue and they reminded him of the small cells occupied by monks in a monastery
when was the first microscope with double convex lens made and by whom?
The first double lens microscope was made by Van Leeuwenhoek in 1674. it was 300x more stronger than earlier models and it as constructed to give a more accurate description of red blood corpuscles
who distinguished sarcomas and carcinomas and when?
1838 muller distinguished carcinomas and sarcomas setting foundations for modern clinical cytology.
when was the first electron microscope invented and by whom?
1931- ernst ruska developed first electron microscope
what is histology?
Histology is study of the tissues of the body and how these tissues are arranged to constitute organs. It involves all aspects of tissue biology, with the focus on how cells’ structure and arrangement optimize functions specific to each organ.
what is staining?
Most cells and extracellular material are completely colorless, and to be studied microscopically tissue sections must be stained (dyed). Methods of staining have been devised that make various tissue components not only conspicuous but also distinguishable from one another.
who is marphigi?
17th century: Marphigi, Italian scientist invented one of first microscopes for studying biological entities. He discovered capillaries in the alveoli of lungs.
when was histology established?
By 19th Century histology was academic discipline in its own right.
what is embryology?
Embryology- science about the development of an embryo from the fertilization of the ovum to the foetus stage.
how did we discover that genes were responsible for embryo development?
After the 1950s when Watson and Crick unravelled the DNA helical structure we began to understand the genes that were responsible for each change that takes place in the embryo and how genes regulate the process.
what was the first conception of embyryology
Ancient Greece: Aristotle proposed epigenesis (animal forms gradually from a relatively
formless egg).
what was the previous notion of embyology?
Untill 18th century: Prevailing notion in human embryology was preformation (the idea that
semen contains a preformed embryo, a miniature infant or homunculus that becomes larger
during development).
which is now the approved notion?
During 19th century: Microscopy improved and it was clear that embryos developed through
series of progressive steps so epigenesis became the approved theory.
