Atlas and epitome of human histology and microscopic anatomy / by Johannes Sobotta ; edited, with extensive additions, by G. Carl Huber.

  • Sobotta Johannes, 1869-1945.
Date:
1903
Catalogue details

Licence: In copyright

Credit: Atlas and epitome of human histology and microscopic anatomy / by Johannes Sobotta ; edited, with extensive additions, by G. Carl Huber. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    33/476 (page 27)
    So^nientatioii of tlie iinprognatod ovum also occurs after the manner of mitotic division; in this case, however,liaIf of its chromosomes are supplied hy the s})ermatozoon, the male promicleus, and half l)v the female pronnclens, the nu- clear constituents of the matured ovum. It is not always true that the resultant cells of a mitotic unclear division are of ('(pial size. 1 n the processes of maturation of the ovum, an uiKMpial division of the protoplasm takes place, since the polar ImhIv, one of the division products, is very much smaller tlian the other,the egg-cell. In the formation of the second of the two polar bodies a reduction of the chro- matin takes place, sinc(‘the longitudinal cleavage is omitted and the nnml)cr of chromosonu's is reduced one-half. In many tissues of th(‘ human body, cell division takes place continwdhj, as in the germ centers of the Ivmphoid tissues (sec page 121), in the tubular glands of the intes- tines, and in the deeper layers of the epidermis. Other cells of the human body, on the other hand, have a verv long life, so fiir as we know. Ganglion-cells, the majoritv of gland-cells, many epithelial cells, probably e.xist during the whole life and never show the phenomcnaof cell divi- sion. In cold-l)looded animals, in whic^h it is ])ossible to make observations during the life of the animal, the time of a mitosis has been established at si.v to eight hours; in the warm-blooded animals the process is probablv eom- ])letc(| in less than an hour. d'he secondary elementary constituents of the hu- man l)odv may be present in the form of /hoV/.v, regarded as the e.xeretoiy |)rodnets of tlie cells. 'FIk' plasma of blood and Ivmph, intercellular fluid, the synovial fluid and serous fluids of bnrsa‘, joint eavitie- and body cavities may be men- tioned nmler this head. If the excu’etoi'v product of the cell is semi-fluid or more or less solid we speak of (/roimd sidj.stanee or rniind Huhxldncc, the lattei’ when the iiiteiau'l- lular sid)stanee is found between the cells in small amount, as in e|)ithelial tissues, the funnel' when the amount of intercellular substance is predominant, as in cartilage,