AbstractThe gubernaculum is a mesenchymal tissue that connects the gonads to the inguinal abdominal wall in the mammalian embryo. During gestation in the male, differential development of the gubernaculum and regression of the cranial suspensory ligament coordinate the first phase of testicular descent. As many as 1–3% newborn boys show impaired testicular descent, in part due to problems in gubernacular development. Little is known about the signaling molecules and cascades that are required for the development and differentiation of the gubernaculum. Protein tyrosine kinases comprise a large class of proteins that play important roles in proliferation, differentiation, and many aspects of cell–cell signaling in tissues. To date, no information on the existence of members of tyrosine kinase family in gubernaculum is available. We used a reverse transcription‐polymerase chain reaction approach to identify 25 individual members of cytoplasmic and receptor tyrosine kinase classes in the developing male gubernaculum. The analysis of cellular distribution suggests that each tyrosine kinase examined may play a unique role in gubernacular development and differentiation. Developmental Dynamics 230:660–665, 2004. © 2004 Wiley‐Liss, Inc.