Clinically Differentiated Abnormalities of the Architecture and Expression of Myosin Isoforms of the Human Cremaster Muscle in Cryptorchidism and Retractile Testis

Abstract

Aim: To describe architecture and expression of myosin isoforms of the human cremaster muscle (CM) and to individuate changes in clinically differentiated abnormalities of testicular descent: cryptorchidism or undescended testis (UDT) and retractile testis (RT). Background: The CM is a nonsomitic striated muscle differentiating from mesenchyme of the gubernaculum testis. Morphofunctional and molecular peculiarities linked to its unique embryological origin are not yet completely defined. Its role in abnormalities of testicular descent is being investigated. Subjects and Methods: Biopsy samples were obtained from corrective surgery in cases of cryptorchidism, retractile testis, inguinal hernia, or hydrocele. Muscle specimens were processed for morphology, histochemistry, and immunohistology. Results and Conclusions: The CM differs from the skeletal muscles both for morphological and molecular characteristics. The presence of fascicles with different characterization and its myo-sinic pattern suggested that the CM could be included in the specialized muscle groups, such as the extrinsic ocular muscles (EOMs) and laryngeal and masticatory muscles. The embryological origin from the nonsomitic mesoderm is, also for the CM, the basis of distinct molecular pathways. In UDT, the histological alterations of CM are suggestive of denervation; the genitofemoral nerve and its molecular messengers directed to this muscle are likely defective. Compared with the other samples, RT has a distinct myosinic pattern; therefore, it has been considered a well-defined entity with respect to the other testicular descent abnormalities.

The Cremaster in Undescended Testis

“…Molinaro et al’s [1] study elegantly confirms the hypothesis of an impaired innervation of cremaster as a causative role in the pathogenesis of undescended testis. We believe it is worth better defining whether the altered innervation in cremaster of undescended affected patients is at corticospinal or at nucleus level of the genitofemoral nerve and, then, the role of innervation on the abnormal arrangement of the cytoskeleton of CM cells in these patients [4].…”

“…We read and truly appreciated the recent interesting article written by Molinaro et al [1], focusing on histomorphometric changes and immunoexpression of myosin isoforms in cremasteric muscle (CM) of pediatric patients affected by undescended and retractile testis. Even if still unclear, the role of CM in the pathogenesis of undescended testis has been appreciably investigated in the last few years.…”

“…Even if still unclear, the role of CM in the pathogenesis of undescended testis has been appreciably investigated in the last few years. CM is characteristically composed of both smooth muscle and striated cells, the latter featuring multifocal innervation by multiple neuromuscular innervations [1]. In their study, authors documented a thinning of CM fibers, whose statistical significance increases with age of patients affected by undescended testis, and an immunohistological pattern of “hybrid fiber” co-expressing multiple MyHC isoforms, both suggesting muscular denervation [1].…”

“…We believe it is worth better defining whether the altered innervation in cremaster of undescended affected patients is at corticospinal or at nucleus level of the genitofemoral nerve and, then, the role of innervation on the abnormal arrangement of the cytoskeleton of CM cells in these patients [4]. Finally, we would like to congratulate Molinaro et al [1] for their remarkable article, highlighting the obscure pathogenesis of undescended testis.…”

Gubernaculum and Epididymo-Testicular Descent: Review of the Literature

“…Both gubernaculum and cremaster muscle are a derivative of mesenchyme and have a distinct myosinic pattern [ 24 ]. The epididymis exhibits spontaneous contractions along the epididymal duct through cAMP-mediated smooth muscle contractions [ 25 ].…”