Na. Borisova et al., DEVELOPMENT OF THE TUBEROINFUNDIBULAR SYSTEM IN RATS - BIRTH-DATES OFTHE TYROSINE HYDROXYLASE-IMMUNOPOSITIVE NEURONS, Developmental brain research, 73(2), 1993, pp. 173-176
The present study has attempted to determine the birthdates of the tyr
osine hydroxylase (TH)-immunopositive neurons in the arcuate nucleus (
AN) of rats, thus evaluating the time of the last mitotic divisions of
their cell precursors. For this aim, 'long-survival' [H-3]thymidine a
utoradiography was used in combination with immunocytochemistry of TH,
the first enzyme of catecholamine synthesis. According to our data, s
ome TH-immunopositive neurons in the AN were born as early as the 13th
fetal day. At day 14, the number of double-labeled neurons almost tri
pled while reaching a maximum at day 15 of the intrauterine developmen
t. The fraction of the double-labeled neurons dropped on the following
day, and practically disappeared by fetal day 17, showing cessation o
f the production of the TH-immunopositive neurons. The birth of the TH
-immunopositive neurons is considered as the onset of the development
of the tuberoinfundibular dopaminergic system.