Development and loss of early projections in a sexually dimorphic rat spinal nucleus.

摘要: The spinal nucleus of the bulbocavernosus (SNB) contains 3-4 times more motoneurons in adult male rats compared to females. This large dimorphism motoneuron number is produced perinatally by an androgen-regulated cell death. To determine if early projections SNB its target musculature may be involved creation this sexual dimorphism, and how these might interact with androgens, HRP tracing techniques were used retrogradely label during prenatal postnatal development males, females, masculinized labeling revealed that formation males females comparable. increases through day before birth all groups, increase, labeled cells can seen outside SNB, which we hypothesize are process migrating into from lateral column. Postnatally, declines, especially 10 has been established. These results indicate although masculine androgen levels critical determining survival, they not necessary for initial axon outgrowth motoneurons. However, androgens regulation migration stabilization peripheral SNB. Both female axons present at their muscles time sex differences develop, suggesting interaction targets could dimorphic survival.