摘要:

Gross and histological analyses of the reproductive tracts from 72 multiparous females, 12 nulliparous females, and 28 non-pregnant females, taken pelagically in the eastern Pacific and on the Pribilof Islands between 1959 and 1961, have been used to determine the histology and physiology of the estrus cycle, the age of sexual maturity, and certain causes of prenatal mortality.The ovaries alternate in function, one ovary ovulating in one breeding season, the opposite ovary ovulating in the next. An undetermined factor suppresses follicular development in the ovary containing a corpus luteum of pregnancy; suppression maintains for 6 months after parturition. Graafian follicular development is greatest in June, with an average of 15 follicles in the ovary destined to ovulate. About four of these will enlarge abruptly in July; one will reach ovulation size (10 mm or greater in diameter) and rupture; the rest will become atretic.Ovulation occurs spontaneously 3–5 days after parturition in mid July. If fertilization is accomplished, the resulting blastocyst remains free in the uterus until early or mid November, when it implants in the mucosa.The newly formed corpus luteum is actively secretory for a month after ovulation. During this time, follicular development is suppressed in both ovaries, and the uterine mucosa prepares for implantation. From the middle of August, the corpus luteum regresses; the luteal cells are vacuolated, and secretion is minimal. This is reflected in a recrudescence of follicular activity in the ovary containing the corpus luteum, and regression of the associated uterine mucosa. Immediately prior to implantation the corpus luteum resumes secretion, and the mucosa is prepared for implantation. Placentation is established during December. Luteal degeneration begins in January and is progressive until parturition, when the corpus luteum appears to be non-secretory. Luteal degeneration has no effect on the pregnant uterine horn; it is assumed that the placenta secretes hormones sufficient to replace the luteal hormones.A nulliparous female ovulates for the first time in late August or September,months later than subsequent ovulations. On the basis of gross reproductive examination, approximately 70% of females ovulate for the first time at 4 years of age. Since the pregnancy rate of 5-year-olds is consistently about 50%, probably a number of 4-year-olds do not mate, either because ovulation occurs after the breeding season, or because breeding males are not available.Prenatal mortalities take 3 forms: "missed" pregnancies, abortions, and resorptions. On the basis of histological examinations, "missed" pregnancies are ultimately due to failure of implantation. Three conditions are responsible: failure of fertilization, failure of implantation, or malfunction of the reproductive tract which precludes pregnancy. Abortion results in the expulsion of a conceptus from the uterus before term; resorption is a gradual process of dissolution of the conceptus within the uterus. On the basis of histological evidence, three causative agents of abortion and resorption are apparent: degeneration of the corpus luteum after implantation, malfunction of the uterine mucosa, and inter-uterine mortality of the conceptus.

ISSN:0706-652X    

DOI:10.1139/f64-070

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Storage studies of iced irradiated scallops (Placopecten magellanicusGmelin) have shown that treatment with a dose of 75,000 rads of gamma radiation increases the useful storage life at 0 °C with negligible changes in odour and texture. The raw scallops remained acceptable for 28 days, while the scallops assessed after cooking remained unchanged for 35 days and did not become unacceptable until 43 days storage. Doses of gamma radiation greater than 75,000 rads caused undesirable changes in texture and odour with a consequent loss of quality. Neither irradiated nor fresh iced scallops rated as high organoleptically as frozen control scallops which had been rapidly frozen in a pre-rigor condition and immediately stored at −26 °C.

ISSN:0706-652X    

DOI:10.1139/f64-071

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Studies of the storage life of iced haddock (Melanogrammus aeglefinus) fillets after treatment with doses of gamma radiation of 75,000, 150,000, and 250,000 rads, have shown that a useful extension of the storage life is made possible by irradiation. The fillets irradiated with the 75,000-rad dose and assessed after cooking became unacceptable after about 25 days at 0 °C. The unirradiated control became unacceptable after 12 days. Fillets irradiated at the two higher levels were of lower quality initially than the fillets irradiated at the 75,000-rad level but showed no significant decrease in acceptability up to 27 days storage in ice. Raw fillets developed an objectionable odour and appearance just prior to becoming unacceptable to the taste panel.

ISSN:0706-652X    

DOI:10.1139/f64-072

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f64-073

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f64-074

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f64-075

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f64-076

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f64-077

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f64-078

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f64-079

出版商:NRC Research Press    

年代:1964

数据来源: NRC