Document Detail

Quantitative differences in the pineal ultrastructure of perinatal and adult harp (Phoca groenlandica) and hooded seals (Cystophora cristata).
MedLine Citation:
PMID:  12932203     Owner:  NLM     Status:  MEDLINE    
Seals are unique among mammals in that newborns have a large pineal gland and extremely high plasma levels of melatonin at birth. Melatonin levels are also high in the seal fetus but decline rapidly during the first few days of life. The aim of the present study was to provide quantitative information about the ultrastructure of the seal pineal gland using fetal, newborn, and adult hooded seals (Cystophora cristata), and newborn and adult harp seals (Phoca groenlandica). The relative and absolute volumes of pinealocytes (Pi), arteries and veins, nerves, connective tissue, capillaries and glial cells, as well as mitocondria and lipid droplets in Pi, were calculated by use of point count analysis. Whereas the pineal ultrastructure was similar in fetuses and newborns, both seal species showed a pronounced and particular reduction in the volume of Pi and a similar reduction in pinealocyte mitochondria. There was also a shift from unmyelinated to myelinated pineal nerves in adults compared with fetal/newborns. The selective and marked reduction of Pi may explain the zonated pineal structure typical of the adult seal. The results demonstrate that the fetal gland is as large and active as that of the newborn seal and support the notion that the large size and high activity of the pineal gland in the newborn seal is a fading consequence of its prenatal condition.
Jo Jorem Aarseth; Karl-Arne Stokkan
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of pineal research     Volume:  35     ISSN:  0742-3098     ISO Abbreviation:  J. Pineal Res.     Publication Date:  2003 Oct 
Date Detail:
Created Date:  2003-08-22     Completed Date:  2004-05-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8504412     Medline TA:  J Pineal Res     Country:  Denmark    
Other Details:
Languages:  eng     Pagination:  188-95     Citation Subset:  IM    
Department of Arctic Biology and Institute of Medical Biology, University of Tromsø, Tromsø, Norway.
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MeSH Terms
Fetus / ultrastructure
Mitochondria / metabolism
Pineal Gland / metabolism,  ultrastructure*
Seals, Earless / anatomy & histology*

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