This investigation was supported by Public Health Service Research Grant CA-05493 from the National Cancer Institute.
The transmural passage of blood cells into myeloid sinusoids and the entry of platelets into the sinusoidal circulation; a scanning electron microscopic investigation†
Article first published online: 3 FEB 2005
Copyright © 1976 Wiley-Liss, Inc.
American Journal of Anatomy
Volume 145, Issue 2, pages 183–205, February 1976
How to Cite
Becker, R. P. and De Bruyn, P. P. H. (1976), The transmural passage of blood cells into myeloid sinusoids and the entry of platelets into the sinusoidal circulation; a scanning electron microscopic investigation. Am. J. Anat., 145: 183–205. doi: 10.1002/aja.1001450204
- Issue published online: 3 FEB 2005
- Article first published online: 3 FEB 2005
- Manuscript Accepted: 8 AUG 1975
Scanning electron microscopic observations of rat bone marrow reveal that the sinusoidal wall is continuous and has no permanent patent apertures allowing free communication between the extravascular and intravascular myeloid compartments. Blood cells migrate into the sinusoids by perforating the endothelial cell body.
Platelets are derived from long intrasinusoidal “proplatelet” processes which originate from the cell body of extravascularly located megakaryocytes. Proplatelet processes frequently occur in clusters, with the probability that all processes in a cluster arise from a single megakaryocyte. The release of platelets into the circulation may be initiated by local constriction along these processes, at which places either individual platelets or larger segments of proplatelet cytoplasm are pinched off. The larger segments may subsequently undergo further fragmentation into individual platelets.