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Pediatr Surg Int (2011) 27:12551265 DOI 10.1007/s00383-011-2983-4
REVIEW ARTICLE
The role of cremaster muscle in testicular descent in humans and animal models
Gabrielle Lie John M. Hutson
Accepted: 19 September 2011 / Published online: 30 October 2011 Springer-Verlag 2011
Abstract Testicular descent is a complex developmental process involving anatomical and hormonal regulation. The gubernaculum undergoes a swelling reaction during the transabdominal phase and is mainly under the control of Insulin-Like Peptide 3 (INSL-3) and Mullerian Inhibitory Substance/Anti-Mullerian Hormone (MIS/AMH). The second phase of testicular descent is regulated by androgens and calcitonin gene-related peptide (CGRP) release from the sensory nucleus of the genitofemoral nerve (GFN). In rodents, the active proliferation of the gubernacular tip and cremaster muscle, its rhythmic contraction, as well as the chemotactic gradient provided by the CGRP result in eventual migration of the testis into the scrotum. This review illustrates the structural aspects and hormonal control of cremaster muscle development to better understand the mechanism of testicular descent in normal rodents and humans, compared to diseased rodent models. The analysis showed the cremaster muscle is formed from mesenchymal differentiation of the gubernacular tip and is not a direct passive extension of internal oblique muscle. Cremaster muscle matures slower than other body muscles,
and the persistence of immature myogenic proteins seen in cardiac muscle allows rhythmic contraction to guide the testis into the scrotum. Finally, remodelling of the cre-master muscle enables gubernacular eversion. Further understanding of the molecular regulators governing the structural and hormonal changes in the cremaster muscle may lead to new advances in the treatment of undescended testes.
Keywords Testicular descent Cremaster muscle
Overview of testicular descent
Biphasic model
The phylogeny of testicular descent began as early as 1762, with Hunters description of the gubernaculum as a brous ligament that is attached to the testis and epididymis proximally and the caudal end initially xed to the inguinal muscles [1]. Today, testicular descent can generally be accepted as a two-stage model with different anatomy and hormonal regulation. The rst or transabdominal phase occurs at gestational age 815 weeks in humans and embryonic days (E) 1419 in rats [2]. Before transabdominal migration occurs, the testes are initially held high up in the abdominal cavity by two opposing forces. The cranial suspensory ligament (CSL)...