## Abstract To examine the biological significance of thyroid hormones contained in eggs, the hormones were depleted from eggs by treating the mother fish with thiourea. Constantly spawning medaka (__Oryzias latipes__) were reared in fresh water containing 0.03% thiourea. The plasma thyroxine (T4)
Spiral patterns in the micropylar wall and filaments on the chorion in eggs of the medaka,Oryzias latipes
β Scribed by Iwamatsu, Takashi ;Nakashima, Seiko ;Onitake, Kazuo
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- English
- Weight
- 882 KB
- Volume
- 267
- Category
- Article
- ISSN
- 0022-104X
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β¦ Synopsis
Abstract
The relationship between spiral patterns in the inner wall of the micropyle and attaching and nonβattaching filaments on the chorion was investigated by electron microscopy in eggs of the medaka, Oryzias latipes. There were both rightβ and leftβhanded spiral patterns of attaching filaments that arose from the chorion at the vegetal pole area. In the majority of eggs examined, however, the prominent folds in the inner wall of the micropylar vestibule descended toward the micropylar canal in a leftβhanded spiral. This spiral pattern in the micropyle may reflect surface indentations in the cytoplasmic extension of the micropylar cell during formation of the micropyle apparatus. The present observations suggest that the patterns of these spiral structures of the chorion are casused by the rotation of the oocyte due to the movement of follicular cells during oogenesis. Β© 1993 WileyβLiss, Inc.
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The measurement of cellular DNA content by DNA microfluorometry revealed that medaka embryos that were fertilized with normal sperm and exposed to heat shock (41Β°C for 3 min) or hydrostatic pressure (700 kg/cm2 for 10 min) at 85-95 min after insemination were tetraploid. Embryos fertilized with norm
## Abstract To clarify the effect of exogenous estradiolβ17Ξ² (E~2~) on sex differentiation, the E~2~ content of developing eggs of __Oryzias latipes__ was measured by radioimmunoassay. Endogenous E~2~ was present in lower concentrations in ovulated, mature eggs in the ovarian cavity than in intrafo
Carotenoids were introduced into the egg yolk of the medaka by either injection or feeding. Carotenoids for injection were dissolved in either olive oil, a mixture of olive oil and castor oil or Tween 80. Capsanthin, lutein and canthaxanthin were readily transferred from the yolk to the larval xanth
## Abstract A cDNA for furin was cloned from the ovary of the medaka, __Oryzias latipes__, by a combination of cDNA library screening, 5';βrapid amplification of cDNA ends (RACE), and 3'β RACE. The cDNA sequence codes for a protein of 814 amino acid residues highly homologous to other vertebrate fu