RRC ID 35470
Author Ishikawa Y, Inohaya K, Yamamoto N, Maruyama K, Yoshimoto M, Iigo M, Oishi T, Kudo A, Ito H.
Title The Parapineal Is Incorporated into the Habenula during Ontogenesis in the Medaka Fish.
Journal Brain Behav Evol
Abstract The parapineal is present in many teleost families, while it is absent in several others. To find out why the parapineal is absent at adult stages in the latter families, the development of the epithalamus was examined in the medaka fish (Oryzias latipes). For this purpose, a green fluorescent protein-transgenic medaka line, in which the pineal complex (pineal and parapineal) is visible fluorescently, was used. We found that a distinct parapineal was present in the roof plate at early developmental stages. Subsequently, however, the parapineal and the associated roof plate began to be incorporated into the habenula between embryonic stages 28 and 29. Between embryonic stages 29 and 30, the entire parapineal was incorporated into the habenula. That is, the parapineal became a small caudomedial region (termed the 'parapineal domain') within the left habenula in the majority of embryos, resulting in the left-sided asymmetry of the epithalamus. Thereby the left habenula became larger and more complex than its right counterpart. In the minority of embryos, the parapineal was incorporated into the right habenula or into the habenulae on both sides. In the majority of embryos, the parapineal domain projected a fiber bundle to a subnucleus (termed the 'rostromedial subnucleus') in the left habenula. The rostromedial subnucleus sent axons, through the left fasciculus retroflexus, to the rostral region of the left half of the interpeduncular nucleus. We further found that the ratio of the left-sided phenotype was temperature dependent and decreased in embryos raised at a high temperature. The present study is the first demonstration that the supposed lack of a distinct parapineal in adult teleost fishes is due to ontogenetic incorporation into the habenula.
Volume 85(4)
Pages 257-70
Published 2015-1-1
DOI 10.1159/000431249
PII 000431249
PMID 26184391
MeSH Animals Animals, Genetically Modified Axons / physiology Epithalamus / anatomy & histology Epithalamus / embryology Epithalamus / growth & development* Habenula / anatomy & histology* Habenula / embryology Habenula / growth & development* Microscopy, Fluorescence Neurons / cytology Oryzias / anatomy & histology Oryzias / embryology Oryzias / growth & development* Pineal Gland / anatomy & histology Pineal Gland / embryology Pineal Gland / growth & development
IF 1.542
Times Cited 7
Medaka Cab-Tg(FoxD3-GFP)2 (TG1068) Cab inbred strain HO4C (IB180)