NEURON-SPECIFIC ENOLASE AS A MARKER OF HYPOTHALAMONEUROHYPOPHYSEAL 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 neu rohypophysis appears as a mass of proliferating cells immunonegative f or neuron-specific enolase (NSE) in the newborn, while perikarya posit ive 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 s pecimens of this study, the neurohypophysis displays anti-NSE reaction s in the peripheral regions. In animals 8-10 days of age, the amount o f reaction product in the neurohypophysis has reached highest levels. This dramatic increase parallels the increase of NSE expression in per ikarya of the rostroventral and caudoventral hypothalamus as well as t he formation of a band-like reaction zone between the respective hypot halamic areas and the neurohypophysis.