Differentiation of the suprachiasmatic nucleus in fetal @entity35 anterior XXXX transplants in oculo.

@entity35 @entity8943 @entity2339 @entity1640
The capacity of the @entity35 anterior @entity2339 , and particularly the suprachiasmatic nucleus (SCN), to develop and differentiate when removed from its normal environment was examined in this study using light and electron microscopy. The @entity2339 from fetuses ranging in age from embryonic day 12 (E 12) to E 16 was transplanted to the anterior chamber of the eye of adult @entity35 . In initial experiments, we found that transplants from E 15 fetuses and older routinely differentiated into fields of neurons with extensive neuropil with an appearance similar to the anterior @entity1640 area. Groups of small, compactly organized neurons were observed only occasionally in this tissue. Ultrastructural analysis of these transplants typically revealed well-differentiated neuronal perikarya and neuropil with a complex synaptic organization similar in appearance to the normal @entity35 anterior @entity1640 area. Occasionally both mature and immature tissue coexisted in some of the transplants. Tissue from young embryos (E 12-14) frequently showed development of a compact, small neuron nucleus with the cytoarchitectonic appearance of the SCN. At least 45 days were required after transplantation for the successful differentiation to occur in this situation. The @entity8943 in these transplants displayed vasoactive intestinal polypeptide-immunoreactive cells and fibers surrounded by vasopressin-immunoreactive cells and fibers, similar to the pattern observed in the normal adult SCN. Our results indicate that the anterior @entity2339 will differentiate normally in oculo and that the phenotypic specification of the SCN occurs prior to the birthdate of its component neurons.
