Blood Cells - Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems - page 166

Table 3.39. Tissue macrophages and dendritic cells (Source: [ 304 ]; NA: not applicable). During
conduit formation, macrophages reside along collagen fibers of the stroma immediately adjacent to
the growing terminal end bud, where they contribute to collagen fibrillogenesis, as well as within
these multilaminate bulbous termini, where they phagocytose dead epithelial cells that occur during
lumen formation. Macrophages that produce Wnt7b participate in the regulation of angiogenesis
during wound healing. Macrophages phagocytose dead endothelial cells (due to angiopoietin-2
released from adjoining pericytes that antagonizes survival angiopoietin-1) for vascular regression
and proper vessel patterning.

Tissue Cell name Function

Bone Osteoclast Bone remodeling, stem cell niche

Bone marrow macrophage Erythropoiesis

(degradation of ejected nucleus)

Brain Microglial cell Neuronal survival

Neuronal connectivity (hypotha-
lamic-pituitary-gonadal axis)
Tissue damage repair

Epidermis Langerhans cell Immune surveillance

Eye NA Vascular remodeling

Intestine Crypt macrophage Immune surveillance

Kidney NA Duct development

Liver Kupffer cell Debris clearance

Tissue damage repair

Mammary gland NA Duct outgrowth and branching

Muscle NA Regeneration

Ovary NA Steroid hormone production

Pancreas NA Islet development

Testis NA Steroid hormone production

Uterus Uterine dendritic cell Angiogenesis

Uterus wall decidualization

Uterine macrophage Cervical ripening

constitute a distinct splenic cell subset that is involved in removing senescent red
blood cells. 174
Macrophages are also involved in the clearance of cell debris after apoptosis.
Macrophage receptors for homeostatic clearance include scavenger, phosphatidyl
serine, thrombospondin, and complement receptors, as well as integrins [ 299 ].
On the other hand, removal of cellular debris after cell necrosis modifies
macrophage function with production of cytokines and pro-inflammatory mediators
and change in plasmalemmal protein expression. Macrophages detect debris of

174 Transcription factors spleen focus-forming virus (SFFV) proviral integration proto-oncogene
product SPI1, or PU1, and C/EBP α are involved in myelomonocytic development. The SPI1-
related transcription factor SPIc controls selectively the development of red pulp macro-
phages [ 305 ]. Factor SPIc of the SPI subfamily of ETS transcription factor family (SPI1, SPIb,
and SPIc) is highly expressed in red pulp macrophages, but not monocytes, dendritic cells or other
tissue macrophages.