Cytology, General Histology and Embryology - V. K. Napkhanyuk 2002

Cytology

Cytology (cytologia, cytos — Cell, logos — science) is the science of the Structure, development, and Functions of animal and plant Cells.

A cell (cellula) is the fundamental living unit of an Organism, bounded from the external environment by an active membrane, representing a structurally ordered system of Biopolymers that form The Nucleus, Cytoplasm, and other subcellular components (Organelles and inclusions), and participating in an integrated network of metabolic processes aimed at maintaining and restoring the system as a whole.

Cells in living organisms can be of two types: those containing a nucleus (eukaryotic) and those lacking a nucleus (prokaryotic).

Organisms composed of Eukaryotic cells are called eukaryotes, and those composed of Prokaryotic Cells are called prokaryotes.

In addition to cells, the organism also contains non-cellular structures that are derivatives of cells. Non-cellular structures are classified as follows:

— nuclear — structures containing a nucleus that arise from Cell Fusion (symplasts) or incomplete Cell Division (syncytia);

— anuclear — structures that are products of the vital activity of specific groups of cells (such as the amorphous ground substance of Connective Tissue).

All eukaryotic cells share a common basic architecture: they consist of three main components—The Cell membrane, cytoplasm, and nucleus (Fig. 6).

The cell membrane separates the Cell Cytoplasm from the external environment or neighboring cells and mediates cellular interactions with environmental elements.

The cytoplasm consists of hyaloplasm and organized structures, which include organelles and inclusions.

The nucleus consists of the nuclear envelope, karyoplasm, Chromatin (Chromosomes), and nucleolus.

Class="center">

Fig. 6. Structural components of the cell

Interacting with one another, these cellular components ensure the existence of The Cell as a unified whole.