Abstract
Hatching of decapod crustaceans is characterized by the sudden rupture of the egg case. This study focused on the following two issues regarding the hatching mechanism of the estuarine terrestrial crab Sesarma haematocheir: (1) dissolution of the egg case, and (2) the site where the egg case breaks. The egg case comprises three layers: the outer two (E1 and E2) layers and the inner (E3) thin layer (0.2 μm in thickness). The outer layers showed no morphological changes upon hatching, but the inner layer (E3) was markedly digested. The digestion of this layer would enable the embryo to absorb ambient water via reverse peristalsis of the intestine, resulting in an increase of the volume. The egg case always ruptured perpendicular to the longitudinal axis of the embryo. In addition, breakage of the egg case occurred at the dorsal thorax of the embryo. The three major organs positioned at this area were (1) a sharp projection (dorsal spine), (2) an assemblage of muscles, and (3) a pair of secretory glands, each of which was about 30 μm in diameter. The dorsal projection is soft before hatching, and it is clear that the egg case does not break with the posterior expansion of this projection. The rupture instead appears to be caused by the expansion of the muscles arranged perpendicular to the body axis. In addition, some (unknown) factor might weaken the egg case just before hatching. The secretory glands may be a kind of rosette gland, but the role that this gland plays at hatching is not known. As a duct comes out from the center and enters the dorsal projection, some active substance may be released at the tip of this projection. However, immunochemical studies are not consistent with this substance being an ovigerous hair stripping substance (OHSS). (C) 2000 Wiley-Liss, Inc.
| Original language | English |
|---|---|
| Pages (from-to) | 510-523 |
| Number of pages | 14 |
| Journal | Journal of Experimental Zoology |
| Volume | 287 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - Dec 1 2000 |
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ASJC Scopus subject areas
- Animal Science and Zoology
Cite this
Hatching of an estuarine crab, Sesarma haematocheir : From disappearance of the inner (E3) layer to rupture of the egg case. / Saigusa, Masayuki; Terajima, Michihiro.
In: Journal of Experimental Zoology, Vol. 287, No. 7, 01.12.2000, p. 510-523.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Hatching of an estuarine crab, Sesarma haematocheir
T2 - From disappearance of the inner (E3) layer to rupture of the egg case
AU - Saigusa, Masayuki
AU - Terajima, Michihiro
PY - 2000/12/1
Y1 - 2000/12/1
N2 - Hatching of decapod crustaceans is characterized by the sudden rupture of the egg case. This study focused on the following two issues regarding the hatching mechanism of the estuarine terrestrial crab Sesarma haematocheir: (1) dissolution of the egg case, and (2) the site where the egg case breaks. The egg case comprises three layers: the outer two (E1 and E2) layers and the inner (E3) thin layer (0.2 μm in thickness). The outer layers showed no morphological changes upon hatching, but the inner layer (E3) was markedly digested. The digestion of this layer would enable the embryo to absorb ambient water via reverse peristalsis of the intestine, resulting in an increase of the volume. The egg case always ruptured perpendicular to the longitudinal axis of the embryo. In addition, breakage of the egg case occurred at the dorsal thorax of the embryo. The three major organs positioned at this area were (1) a sharp projection (dorsal spine), (2) an assemblage of muscles, and (3) a pair of secretory glands, each of which was about 30 μm in diameter. The dorsal projection is soft before hatching, and it is clear that the egg case does not break with the posterior expansion of this projection. The rupture instead appears to be caused by the expansion of the muscles arranged perpendicular to the body axis. In addition, some (unknown) factor might weaken the egg case just before hatching. The secretory glands may be a kind of rosette gland, but the role that this gland plays at hatching is not known. As a duct comes out from the center and enters the dorsal projection, some active substance may be released at the tip of this projection. However, immunochemical studies are not consistent with this substance being an ovigerous hair stripping substance (OHSS). (C) 2000 Wiley-Liss, Inc.
AB - Hatching of decapod crustaceans is characterized by the sudden rupture of the egg case. This study focused on the following two issues regarding the hatching mechanism of the estuarine terrestrial crab Sesarma haematocheir: (1) dissolution of the egg case, and (2) the site where the egg case breaks. The egg case comprises three layers: the outer two (E1 and E2) layers and the inner (E3) thin layer (0.2 μm in thickness). The outer layers showed no morphological changes upon hatching, but the inner layer (E3) was markedly digested. The digestion of this layer would enable the embryo to absorb ambient water via reverse peristalsis of the intestine, resulting in an increase of the volume. The egg case always ruptured perpendicular to the longitudinal axis of the embryo. In addition, breakage of the egg case occurred at the dorsal thorax of the embryo. The three major organs positioned at this area were (1) a sharp projection (dorsal spine), (2) an assemblage of muscles, and (3) a pair of secretory glands, each of which was about 30 μm in diameter. The dorsal projection is soft before hatching, and it is clear that the egg case does not break with the posterior expansion of this projection. The rupture instead appears to be caused by the expansion of the muscles arranged perpendicular to the body axis. In addition, some (unknown) factor might weaken the egg case just before hatching. The secretory glands may be a kind of rosette gland, but the role that this gland plays at hatching is not known. As a duct comes out from the center and enters the dorsal projection, some active substance may be released at the tip of this projection. However, immunochemical studies are not consistent with this substance being an ovigerous hair stripping substance (OHSS). (C) 2000 Wiley-Liss, Inc.
UR - http://www.scopus.com/inward/record.url?scp=0034566029&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034566029&partnerID=8YFLogxK
U2 - 10.1002/1097-010X(20001201)287:7<510::AID-JEZ7>3.0.CO;2-G
DO - 10.1002/1097-010X(20001201)287:7<510::AID-JEZ7>3.0.CO;2-G
M3 - Article
C2 - 11110165
AN - SCOPUS:0034566029
VL - 287
SP - 510
EP - 523
JO - Journal of Experimental Zoology Part A: Comparative Experimental Biology
JF - Journal of Experimental Zoology Part A: Comparative Experimental Biology
SN - 0022-104X
IS - 7
ER -