Essentials of physiology for veterinary students / by D. Noël Paton.

  • Diarmid Noel Paton
Date:
1908
Catalogue details

Licence: Public Domain Mark

Credit: Essentials of physiology for veterinary students / by D. Noël Paton. Source: Wellcome Collection.

    45/488 page 25
    particles. These cells do not merely take up material from the blood and pass it out, but they may profoundly alter it before getting rid of it. 4. Ciliated Epithelium (fig. 5, p. 22).—The cells are usually more or less columnar, and the free border is provided with a series of hair-like processes, the cilia, which vary in size in different situations. In the living state the cilia are in constant rhythmic motion, each cilium being suddenly whipped or bent down in one direc¬ tion, and then again assuming the erect position. All the cilia on a surface work harmoniously in the same direction, and the movement passes from the cilia of one cell to those of the next in regular order, beginning at one end of the surface and passing to the other. As a result of this constant harmonious rhythmic movement, any matter lying upon the surface is steadily whipped along it; and since the cilia usually work from the inner parts of the body to the outside, this matter is finally expelled from the body. The movements of the cilia are dependent on the changes in the protoplasm, and everything which influences the rate of chemical change modifies the rate of ciliary movement, which may thus be taken as an index of the protoplasmic activity. II. CONNECTIVE TISSUES 1. Mucoid Tissue.—The cells of the mesoblast of the embryo, which at first lie in close apposition with one another, become separated, remaining attached by elongated processes. Between the cells, a clear, transparent substance makes its appearance, forming a soft jelly-like tissue. This tissue is widely distrib¬ uted in the embryo as a precursor of the connective tissues, and after birth it is still to be seen in the pulp of a developing tooth and in the vitreous humour of the eye (fig. 7). 2. Fibrous Tissue.—As development advances, the cells of mucoid tissue elongate and become spindle-shaped, and are con¬ tinued at their ends into fibres (fig. 8). These cells are often called fibroblasts. The connective tissues are thus clearly distinguished from
    digitised image 1
    digitised image 2
    digitised image 3