CYTO-EMBRYOLOGICAL STUDIES OF SEA URCHINS. III. ROLE OF THE SECONDARY MESENCHYME CELLS IN THE FORMATION OF THE PRIMITIVE GUT IN SEA URCHIN LARVAE
Open Access
- 1 February 1956
- journal article
- research article
- Published by University of Chicago Press in The Biological Bulletin
- Vol. 110 (1) , 29-42
- https://doi.org/10.2307/1538890
Abstract
1. The first half of the gastrulation process in sea urchins begins with an in toto invagination of the endodermal plate, followed by its stretching. 2. In the second half of the process, pseudopodia are sent out by the secondary mesenchyme cells toward the animal pole. These pseudopodia attach to the blastular wall and pull the archenteron up toward that pole. 3. The pulling capacity of the pseudopodia is shown by the displacement toward the secondary mesenchyme cells of oil droplets injected in the blastocoel. 4. When the pseudopodial connection is artificially severed by one of the following methods, exogastrulae result: a) Blastocoelic expansion after sucrose treatment (Mespilia globulus, Clypeaster japonicus). b) Ca-low treatment (Clypeaster, Pseudocentrotus depressus). c) Pancreatin treatment (Mespilia). 5. Abnormal invagination in various degrees brought about by the above treatments can be accounted for by differences in their effects on the pseudopodia formation. 6. Pseudopodia of the secondary mesenchyme cells are indispensable in the latter half of the gastrulation process in order to produce normal embryos.This publication has 0 references indexed in Scilit: