Elements of histology / by E. Klein.

Edward Emanuel Klein

Date:: 1884

Credit: Elements of histology / by E. Klein. Source: Wellcome Collection.

31/378 page 15

$cleavage of the white corpuscles of the blood of lower Invertebrates has been directly observed by Klein and [Ranvier. 15. In every microscopic specimen of the blood 3f man and mammals are found a variable number 3f large granules^ more or less angular, singly or in groups, which have been specially studied by Osier. According to Bizzozero they are, when observed in the living and fresh blood, \J a jpale, circular, or slightly oval discs Q i(Fig. 12, h). Their size is only \ to \ U of that of the red blood corpuscles. ^ They are called by him hlood 'plates^ and he supposes them to be of essential im- portance in the coagulation of the blood, %5scie?Tb]ood originating the fibrin ferment. Hayem g^Jf^ idescribed them previously as being in- termediate forms in the development of red blood corpuscles, and called them hsematoplasts. 16. Developmemt of Blood Corpuscles.— At an early stage of embryonic life, when blood makes its appearance it is a colourless fluid, contain- ing only white corpuscles (each with a nucleus), which are derived from certain cells of the mesoblast. These white corpuscles change into red ones, wdiich become flattened, and their protoplasm gets homogeneous and of a yellowish colour. All through embryonic life new white corpuscles are transformed into red ones. In the embryo of man and mammals these red corpuscles retain their nuclei for some time, but ultimately lose them. New nucleated red blood corpuscles are, how- ever, formed by division of old red corpuscles. Such division has been observed even in the adult blood of certain lower vertebrates (Peremeschko) as well as in the red marrow of mammals (Bizzozero and Torre). An important source for the new formation of red corpuscles in the embryo and adult is the red marrow$

Elements of histology / by E. Klein.

Licence and re-use

Contents