It may also take place where rapid proliferation of the cell is going on, as in the budding of the Yeast plant.
The ovary and testes are heaped-up masses of red or yellow cells due to a proliferation of the cells lining the coelom.
If the white cells be required, as in local suppurating abscess, general septicaemia, acute pneumonia, &c., there is an active proliferation of the myelocytes to form the polymorpho-nuclear leucocytes, so that we have in this condition a leucoblastic transformation of the fatty marrow.
This phenomenon is known as proliferation of the floral axis.
In the posterior portion this epithelium in certain Heteronemertea has a more glandular appearance, and sometimes the interior cavity is obliterated by cell-proliferation in this region.
By the proliferation of the 16.
If the demand be for the red cells owing to loss from haemorrhage or any of the anaemias, the fatty marrow is rapidly replaced by cellular elements; this is mainly an active proliferation of the nucleated red cells, and gives rise to the erythroblastic type of marrow.
These, having the full equipment of the vegetative order, will now develop the inherent power of proliferation to a greater or lesser extent.
It may merely act locally in some way, and so render that part susceptible to unknown tissue stimuli which impart to the cells that extraordinary power of proliferation characteristic of new growth.
The gonads originate by proliferation of the anterior wall of the pericardium.
(Many such changes are usually grouped together under the heading of " inflammation " of varying degree--acute, subacute and chronic.) Degeneration and death of cells, haemorrhages, serous and fibrinous exudations, leucocyte emigration, proliferation of connective tissue and other cells, may be mentioned as some of the fundamental changes.
The comparison of the metagenetic type of development, such as that of Aurelia, with the more primitive genera of Scyphomedusae, indicates clearly that the scyphistoma and ephyra are recapitulative larval stages which are represented by the adult forms of primitive genera, making such allowances as are necessary when comparing adult and larval forms. The metagenesis has arisen through the scyphistoma-larva acquiring the power of larval proliferation by budding.
In some cases the inner layer is formed not by invagination but by proliferation or by de lamination.
Lecaillon (1898) on various leaf beetles, tend to show that the organ " in the embryos of the lower Arthropoda corresponds with whole of the " mid-gut " arises from the proliferation of cells at the the region invaginated to form the serosa of the hexapod embryo.
Should there be much loss of tissue of an organ, the cells of the remaining part will enlarge and undergo an active proliferation (hyperplasia) so that it may be made up to the original amount.
This call is immediately answered by an active proliferation and steady maturing of the myclocytes in the marrow to form the polymorpho-nuclear leucocytes.
The separated cells become intermingled with other tissue elements amongst which they lie dormant with their inherent power of proliferation in abeyance.
At a later date in the life of the individual, by some unknown stimuli, they resume their active power of proliferation and so give rise to new growths.
The mesoderm seems to be formed entirely from the proliferation of the cells of the mesoblastic somites.
They may at some later date become active in some way, and so give rise to a cellular proliferation that may imitate the structure in which they grow, so giving rise to new growths.