1. Historical Development Of Cytology, Histology And Embryology

Question 1

Dates of inventions/names and what inventions were?

Answer 1

Scientist Discoveries
1590- Jansen: First microscope made

1610 - Galilei: Microscope improved

1611 - Kepler: Suggested to make a compound
microscope

1611-1628- Scheiner: Constructed the prototype of the compound microscope (based on Kepler’s suggestion)

1665 -Hooke:

• Used compound microscope, made the first observation of cells.
• The term ‘cell’ was formed He looked at a thin piece of cork. The dead wood tissue had rows of tiny boxes reminding him of cells occupied by monks in a monastery.

1674- Leewunhook : Discovered protozoa

1833 - Brown: Observed orchids and discovered the nucleus. (opaque spots). Stressed the nucleus’ importance to fertilisation.

1839- Schledian and Schwann:

Proposed the ‘Cell Theory’:
•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
•Each cell is derived from another cell
•There is a mutual connection between cell structure and function

1857 - Kolliker: Discovered and described mitochondria (known as ‘granules’ then) when studying human muscle cells.

1876 - Abbe: Showed how to optimize microscopic design

1879 - Flemming: Described chromosomal behaviour during mitosis

1881 -Retzius: Described animal tissue

19th Century-
Microscopes developed - Scientists realised that embryos developed in series of stages instead of growing from a small version of a fully developed embryo.

1950 -

Watson and Crick:
Unravelled DNA helical structure – an understanding that genes:
- Were responsible to changes taking place in embryos
- Regulated the process (development)

Question 2

Cytology definition

Answer 2

Study of cells

Question 3

What methods allow us to determine structure/function of cell accurately

Answer 3

Histochemistry
Cytochemistry
Tissue culturing
Other methods

Question 4

Definition of histology

Answer 4

The study of tissues in the body, the way tissues are arranged to constitute organs

General histology
Specialised histology - microscopic anatomy of organs

Question 5

Types of tissues

Answer 5

Epithelial
Nervous
Muscular
Connective

Question 6

How to examine tissues?

Answer 6

Thin slice of tissue to examine
Stain if required
Examine under light/electron microscope

Question 7

Why are stains required?

Answer 7

To identify/ clearly see different microscopic structures

Question 8

Embryology definition?

Answer 8

The study of the development from the fertilisation of the ovum to the foetus

Question 9

Types of embryology?

Answer 9

General embryology - embryogenesis

Special embryology - organogenesis

Question 10

18th and 19th century

Answer 10

18th century:

2 opposing views

–> Preformation: the theory that the semen contains a miniature fully developed embryo (infant) that just slowly becomes bigger as time goes on

–> Epigenesis : the theory that the form of an animal emerges gradually from a relatively formless egg

19th century

Microscopes developed - scientists realised that embryo develops in a series of stages instead of growing from a small version of a fully developed embryo

Watson and crick: unravelled the DNA helical structure, understanding of genetics - how genes control the process/ how genes are responds I learned to changes taking place in the embryo