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Micromere lineages in the glossiphoniid leech HelobdellaIn leech embryos, segmental mesoderm and ectoderm arise from teloblasts by lineages that are already relatively well characterized. Here, we present data concerning the early divisions and the definitive fate maps of the micromeres, a group of 25 small cells that arise during the modified spiral cleavage in leech (Helobdella robusta) and contribute to most of the nonsegmental tissues of the adult. Three noteworthy results of this work are as follows. (1) The c"' and dm' clones (3d and 3c in traditional nomenclature) give rise to a hitherto undescribed network of fibers that run from one end of the embryo to the other. (2) The clones of micromeres b" and b"' (2b and 3b in traditional nomenclature) die in normal development; the b" clone can be rescued to assume the normal c" fate if micromere c" or its clone are ablated in early development. (3) Two qualitative differences in micromere fates are seen between H. robusta (Sacramento) and another Helobdella sp. (Galt). First, in Helobdella sp. (Galt), the clone of micromere b" does not normally die, and contributes a subset of the cells arising exclusively from c" in H. robusta (Sacramento). Second, in Helobdella sp. (Galt), micromere c"' makes no definitive contribution, whereas micromere dm' gives rise to cells equivalent to those arising from c"' and dm' in H. robusta (Sacramento).
Document ID
Document Type
Reprint (Version printed in journal)
Huang, Francoise Z.
(University of California Berkeley, CA 94720-3200, United States)
Kang, Dongmin
Ramirez-Weber, Felipe-Andres
Bissen, Shirley T.
Weisblat, David A.
Date Acquired
August 21, 2013
Publication Date
February 1, 2002
Publication Information
Publication: Development (Cambridge, England)
Volume: 129
Issue: 3
ISSN: 0950-1991
Subject Category
Life Sciences (General)
Distribution Limits
Non-NASA Center
NASA Discipline Evolutionary Biology

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