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Formation and ultrastructure of the micropylar apparatus in Bombyx mori ovarian follicles
Author(s) -
Yamauchi Hideo,
Yoshitake Narumi
Publication year - 1984
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1051790106
Subject(s) - biology , ultrastructure , anatomy , bombyx mori , vitelline membrane , microbiology and biotechnology , oocyte , embryo , biochemistry , gene
The formation of the micropylar apparatus during oogenesis in the silkworm, Bombyx mori , has been studied using light and transmission electron microscopy. The micropylar apparatus is formed by three types of cells: the micropylar channel‐forming cells (MCFCs), the micropylar orifice‐forming cells (MOFCs), and the micropylar rosette‐forming cells (MRFCs). During the formation of the vitelline membrane and the chorion, each of the MCFCs extends a cytoplasmic projection serving as the mold of a micropylar‐channel into the egg envelopes. The detachment and collapse of the projections takes place at the end of choriogenesis. The micropylar channels possess a common external orifice on the chorion and several internal orifices within the vitelline membrane. The MOFCs interact closely with the MCFCs and contribute to the formation of the external micropylar orifice. A petal‐like rosette surrounding the orifice is imprinted on the outer chorionic surface by the MRFCs which enclose a group of the MCFCs and MOFCs.