TY  - JOUR
TI  - The ascidian egg envelope in fertilization: structural and molecular features 
AU  - Honegger, ThomasG.
AU  - Koyanagi, Ryo
T2  - The International Journal of Developmental Biology
AB  - In this report, unpublished and recent findings concerning the structure and function of the ascidian egg coat are compiled in context with fertilization. In the initial stage of ascidian fertilization, sperm interact with a complex egg investment that consists of a layer of follicle cells attached to an acellular vitelline coat. Increasing evidence exists that ascidian sperm are activated at their encounter with the follicle cells. The molecular basis of sperm-follicle cell interactions is discussed in context with sperm binding, membrane proteins and sperm bound glycosidase. The model that suggests a block to polyspermy established by glycosidase released from the follicle cells on fertilization is evaluated and compared with assured facts. Although a number of questions remain to be answered, our recent findings that a cloned beta-hexosaminidase from P. mammillata binds exclusively to the follicle cells of unfertilized but not fertilized eggs, indicates that the follicle cells participate in the block to polyspermy. A dual function, mediating sperm activation and a block to polyspermy attributes to the ascidian follicle cells a key position in fertilization.
PY  - 2008
DO  - 10.1387/ijdb.072547th
VL  - 52
IS  - 5-6
SP  - 527
EP  - 533
J2  - Int. J. Dev. Biol.
LA  - en
SN  - 0214-6282
SN  - 1696-3547
UR  - https://ijdb.ehu.eus/article/072547th
Y2  - 2024/04/28/05:39:38
ER  -