Neuron-specific enolase as a marker of hypothalamo-neurohypophyseal development in postnatal Monodelphis domestica (Marsupialia).

In the newborn Monodelphis domestica, pituitary and brain are far from their definite shape and structural organization. The presumptive neurohypophysis appears as a mass of proliferating cell immunonegative for neuron-specific enolase (NSE) in the newborn, while perikarya positive for NSE are present in the rostroventral area of the hypothalamus. At the same time, the periventricular areas of the brain, consisting of proliferating cells, are non-reactive for NSE. In the 2.5-day-old specimens of this study, the neurohypophysis displays anti-NSE reactions in the peripheral regions. In animals 8-10 days of age, the amount of reaction product in the neurohypophysis has reached highest levels. This dramatic increase parallels the increase of NSE expression in perikarya of the rostroventral and caudoventral hypothalamus as well as the formation of a band-like reaction zone between the respective hypothalamic areas and the neurohypophysis.