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Staging of middle and late embryonic development in the medicinal leech, Hirudo medicinalis
Author(s) -
Reynolds Shirley A.,
French Kathleen A.,
Baader Andreas,
Kristan William B.
Publication year - 1998
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19981214)402:2<155::aid-cne2>3.0.co;2-8
Subject(s) - hirudo medicinalis , leech , embryogenesis , embryo , biology , anatomy , zoology , microbiology and biotechnology , computer science , world wide web
We present a description of the last half of embryonic development in the European medicinal leech, Hirudo medicinalis , based entirely on externally visible morphological features, and establish reliably observable stages during that development. Embryogenesis, from the time fertilized eggs are deposited in an eggcase (called a cocoon) to the emergence of juveniles from the cocoon, takes approximately 4 weeks at room temperature. The stages described in this paper extend from the completion of segmentation to the appearance of the final bands of pigmentation. Developmental stages are expressed as percentages of total embryonic developmental time. This staging table was constructed for embryos kept at 20°C. In addition, the development of animals kept at 17°C or at 24°C was compared with those held at 20°C. Development proceeds more quickly at higher temperatures. Because development in embryos held at higher or lower temperatures was linearly related to the stages determined for embryos held at 20°C, the rate of development at any intermediate temperature can be predicted from the staging table at 20°C by simple multiplication. J. Comp. Neurol. 402:155–167, 1998. © 1998 Wiley‐Liss, Inc.