The migrating gubernaculum grows like a "limb bud".
BACKGROUND
The gubernaculum is crucial for testicular descent, and in the second, or inguinoscrotal, phase of descent it has no caudal attachments. Cranially, it is attached to the testis, but its caudal free tip migrates to the scrotum controlled by the genitofemoral nerve. Recent studies show active proliferation in the tip. We hypothesized that the gubernacular tip may grow like a limb bud.


METHODS
We performed whole-mount in situ hybridization studies on male and female fetal mice (ages, E14.5-E18.5; n = 162) looking for limb bud regulatory factors.


RESULTS
Our results showed that a member of the fibroblast growth factor (Fgf) family, Fgf10, and Hoxa10 were both expressed in the male gubernaculum at E14.5, and Hoxa10 was also expressed in the E16.5 mice. Weak staining was seen in the female gubernaculum for Hoxa10 on days E14.5 and E16.5, whereas no staining for Fgf10 was seen in the female gubernaculums.


CONCLUSIONS
These studies, although preliminary, suggest limb bud regulators are essential for gubernacular growth. Hox genes and Fgfs may be fruitful areas of research to unravel the molecular control of gubernacular migration during testicular descent.
Nightingale
Sophie S
SS
Department of General Surgery, Royal Children's Hospital, Melbourne 3052, Australia.
Western
Patrick
P
Hutson
John M
JM
D000818:Animals; D003456:Cryptorchidism / Q000196:embryology* / Q000235:genetics; D005260:Female; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D005819:Genetic Markers / Q000235:genetics; D017403:In Situ Hybridization; D007264:Inguinal Canal / Q000196:embryology / Q000254:growth & development; D018878:Limb Buds / Q000196:embryology / Q000254:growth & development; D008297:Male; D051379:Mice; D023421:Models, Animal; D011247:Pregnancy; D011270:Pregnancy, Animal; D012611:Scrotum / Q000196:embryology* / Q000254:growth & development; D012680:Sensitivity and Specificity; D013737:Testis / Q000196:embryology* / Q000254:growth & development*; D046509:Tissue Culture Techniques
D005819:Genetic Markers; D005346:Fibroblast Growth Factors