Ultrastructural and immunohistochemical evidence of in situ differentiation of mononuclear phagocyte system cells in the interstitium of human fetal testis.
Ultrastructural and immunohistochemical studies were made of the testicular interstitial tissue from eight human fetuses of 15 to 27 weeks gestation. Three cell types developed in mesenchymal cells: Leydig cells and peritubular cells, as already reported, and cells of the mononuclear phagocyte system (MPS), which are located in the intermediate area of the interstitial tissue. Located at the periphery of Leydig cells, these gradually differentiate between 16 and 20 weeks and later acquire the ultrastructural characteristic of histiocytes during the involution phase of the fetal testis. Immunohistochemical studies using monoclonal antibodies (Mo Ab) to antigens of human myelomonocytic cells isolated a cell subpopulation in the interstitial tissue that is distinct from the peritubular (fibroblastic) and the Leydig cells. This subpopulation expressed all or some of these antigens according to their stage of differentiation; all cells are labelled by MY7 Mo Ab which is directed against myelomonocytic cells, including stem cell. Using monoclonal antibodies directed against more mature cells (MY4, MO1 and MO2), the number of labelled cells decreased in this mesenchymal population. MY4 Mo Ab, which detect myelomonocytic cells excluding stem cell, label fewer than MY7 Mo Ab. MO1 MO Ab and MO2 Mo Ab, respectively, directed against antigens of more mature or mature monocytic cells, label less number of mesenchymal cells, which are histiocytes after 20 weeks. These ultrastructural and immunohistochemical findings suggest that cells of the MPS differentiate within the interstitium.
Dechelotte
P
P
Department of Pathology, CHU/Hotel-Dieu, Clermont Ferrand, France.
Chassagne
J
J
Labbe
A
A
Afane
M
M
Scheye
T
T
De Laguillaumie
B
B
Boucher
D
D
D000911:Antibodies, Monoclonal / Q000032:analysis; D000943:Antigens, Differentiation / Q000032:analysis; D002454:Cell Differentiation; D005333:Fetus / Q000033:anatomy & histology*; D006801:Humans; D007985:Leydig Cells / Q000276:immunology / Q000648:ultrastructure*; D008297:Male; D008854:Microscopy, Electron; D010586:Phagocytes / Q000276:immunology / Q000648:ultrastructure*; D013737:Testis / Q000166:cytology* / Q000276:immunology / Q000648:ultrastructure
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation