Histogenesis

histogenesis [‚his·tə′jen·ə·səs]

(embryology)

The developmental process by which the definite cells and tissues which make up the body of an organism arise from embryonic cells.

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Histogenesis 

the development of tissues; the complex of natural processes that ensures the emergence, existence, and restoration of animal tissues and their specific properties in various organs.

The study of the histogenesis of various tissues and its principles is one of the most important aspects of histology. The term “histogenesis” is customarily used to designate the ontogenetic development of tissues. However, the patterns of histogenesis cannot be regarded separately from the evolutionary development of tissues. The basis of histogenesis is cell differentiation (the development of growing morphological and functional differences between newly specializing cells), which begins during the earliest stages of embryonic development. This is a complex molecular-genetic process that regularly involves the activity of the genes that determine the specifics of protein syntheses in the cell. The multiplication of cells, their relative migrations, and other processes lead to the formation of embryonic rudiments, which consist of groups of cells distributed according to a regular pattern in the body of the embryo. The entire diversity of tissues of various organs of the body arises as a result of the tissue differentiation of these embryonic rudiments.

During the postembryonic period the processes of histogenesis are divided into three basic types: the processes within tissues whose cells do not multiply (for example, in nervous tissue), those in tissues whose cell division is associated primarily with the growth of the organ (for example, in the parenchyma of the digestive glands and kidneys), and those in tissues characterized by constant cell renewal (for example, in hemopoietic tissue and many integumental epithelia). Cells that effect definite histogenesis are subdivided into a series of successive groups, including a stock of parent cells, capable of differentiation as well as of making up a loss of its own kind; a stock of precursor cells that undergo differentiation and are capable of division; and a stock of mature cells that have completed differentiation. The regeneration of damaged or partially depleted tissues after injury is accomplished through so-called reparative histogenesis. Under pathological conditions the processes of histogenesis may undergo profound qualitative changes and lead to the development of tumorous tissues.

REFERENCES

Khlopin, N. G. Obshchebiologicheskie i eksperimental’nye osnovy gistologii. Moscow, 1946. (Bibliography.)
Zavarzin, A. A. “Ocherki evoliutsionnoi gistologii krovi i soedinitel’noi tkani.” Izbr. trudy, vol. 4. Moscow-Leningrad, 1953.
Krushchov, N. G. Funktsional’naia tsitokhimiia rykhloi soedi nitel’noi tkani. Moscow, 1969. (Bibliography.)

N. G. KHRUSHCHOV