Myogenesis within the human gubernaculum: histological and immunohistochemical evaluation.
BACKGROUND
The presence of varying amounts of smooth muscle (SM) in the patent processus vaginalis suggests that SM plays a role in the descent of the testis. Myogenesis within the gubernaculum (representing primitive mesenchymal tissue) has been evaluated.


METHODS
Bilateral gubernacula of ten male and five female fetuses were obtained. Sections were stained with hematoxylin-eosin, van Gieson and Gomori trichrome. Expressions of human muscle actin, desmin, vimentin, alpha-smooth muscle actin, human myosin, fast myosin, slow myosin, and Myo-D were determined through immunohistochemistry. The structural alterations and expressions according to the fetal ages were determined within the gubernacula of both sexes.


RESULTS
Gubernacula revealed striated muscle at twelve weeks of age. Despite expression of actin and desmin, those muscles did not express Myo-D. Actin and desmin expressing striated muscles ceased to exist until 22 weeks of age. Both vascular SM and cremaster muscle (CM) expressed Myo-D during the 22nd and 23rd weeks. CM additionally expressed alpha-smooth muscle actin. Detection of myofibroblasts in the 22nd week was followed by appearance of the SM in the 27th week in the gubernacula of male fetuses. The same alterations were encountered among the female fetuses at later time points.


CONCLUSIONS
Both smooth muscle and CM develop within the gubernaculum. CM may have transdifferentiated from the vascular SM. If the gubernaculum represents primitive mesenchymal tissue, it ceases to exist after the development of muscles.
Department of Pediatric Surgery, Hacettepe University, Faculty of Medicine, 06100 Ankara, Turkey. ctanyel@hacettepe.edu.tr
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Tanyel
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Talim
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Atilla
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Müftüoğlu
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Kale
D000199:Actins / Q000378:metabolism; D002454:Cell Differentiation; D003238:Connective Tissue / Q000196:embryology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008648:Mesoderm / Q000502:physiology*; D024510:Muscle Development / Q000502:physiology; D009130:Muscle, Smooth / Q000196:embryology* / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000196:embryology / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D013737:Testis / Q000196:embryology
D000199:Actins; D009218:Myosins