History of cell study

The dawn of cytology and the first optical instruments

The development of cytology (from the Greek words cytos meaning cell and logos meaning science) is traditionally divided into three major stages: descriptive observations, the creation of cell theory, and the establishment of modern cell theory. The first stage would have been impossible without the advent of microscopic technology.

In 1590, Dutch instrument makers Hans and Zacharias Janssen invented the first microscope. Their instrument was a tube on a stand containing two magnifying lenses. It was this basic design that opened up the invisible microworld to humanity.

Discovery of plant cells

In 1665, English researcher Robert Hooke used an improved microscope that already possessed an objective and an eyepiece. While examining a slice of ordinary cork, he discovered tiny cavities that outwardly resembled a honeycomb. To designate them, Hooke introduced the term "cell" (from the Latin cellula — small room). At the same time, it is important to note that Hooke observed not living structures, but exclusively the walls of dead plant cells.

In the second half of the 17th century (between 1671 and 1712), the study of plant specimens was continued by the Italian Marcello Malpighi and the Englishman Nehemiah Grew. During their observations, they confirmed the cellular structure of plants; however, like Hooke, they only recorded cavities bounded by dense cellulose walls.

Study of animal cells and microorganisms

A revolutionary breakthrough was made by the Dutch naturalist Antonie van Leeuwenhoek in 1676. Using well-polished optical lenses that provided a 250–300x magnification, he was the first in history to describe animal cells and living microorganisms.

Among Leeuwenhoek's major discoveries:

• Observation of various single-celled organisms and bacteria.
• Description of animal cells (specifically, frog erythrocytes).
• Study of the microscopic structure of human and animal hair.
• Description of the structure of striated skeletal and cardiac muscles, as well as tendons.

Leeuwenhoek was the first to conclude that the substance inside cells has a definite organization. Later, in 1781, the Italian anatomist and physiologist Felice Fontana also made a significant contribution to the description of animal cells.

19th-century discoveries: nucleus and cytoplasm

With the onset of the 18th and 19th centuries, microscopes continued to be improved. The increase in their resolving power led to the accumulation of vital facts about cellular structure.

In 1830, Czech scientist Jan Evangelista Purkinje set out to study the contents of animal cells. He described the cell nucleus, naming it the "germinal vesicle," and introduced the term protoplasm to designate the substance filling the cell. In modern biology, Purkinje's terminology has a clear division: the protoplasm surrounding the nucleus is called the cytoplasm, and the contents of the nucleus itself are called the karyoplasm.

A year later, in 1831, British botanist Robert Brown detailed the nucleus in plant cells and postulated it as a crucial component of the cell.

The accumulation of these descriptive data paved the way for the transition to the second stage of the science's development. Based on the acquired knowledge, German scientists — the botanist Matthias Schleiden and the physiologist Theodor Schwann — became the founders of cell theory, to the development of which Rudolf Virchow also made an enormous contribution.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Main tenets of Schleiden and Schwann's cell theory
• Rudolf Virchow's contribution to the supplementation of cell theory
• Establishment of modern cell theory (third stage)
• Development of electron microscopy and histological technique

Other topics in the section "Basics of Cytology"

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