scholarly journals New Insights in Canine Reproduction

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 2021
Author(s):  
Monica De los Reyes ◽  
Nucharin Songsasen
Keyword(s):  
Reproductive Cycle ◽  
Immature Oocytes

Reproduction in canids has been characterized by having some peculiar aspects, such as the extended reproductive cycle and ovulation of immature oocytes [...]

The reproductive cycle in winter flounder, Pseudopleuronectes americanus (Walbaum)

1984 ◽  
Vol 62 (12) ◽  
pp. 2563-2567 ◽  
Author(s):  
M. P. Burton ◽  
D. R. Idler
Keyword(s):  
Reproductive Cycle ◽  
Winter Season ◽  
Winter Flounder ◽  
Reproductive Status ◽  
Reproductive Capacity ◽  
Pseudopleuronectes Americanus ◽  
Fish Stocks ◽  
Immature Oocytes ◽  
Vitellogenic Stage ◽  
Summer Feeding

The reproductive status of winter flounder was analyzed in individuals collected at regular intervals throughout the year. Although spawning occurred in May–June, sperm could be activated in January, and male gonadosomatic indices in November were approximately twice those recorded immediately before spawning. Oocyte recruitment occurs close to spawning, and oocyte changes are compatible with a 3-year cycle. Vitellogenesis of the oldest year class of oocytes is initiated during the summer feeding season and maintained over the nonfeeding winter season. Some females after spawning do not enter the vitellogenic stage but overwinter with two year classes of immature oocytes. This nonreproductive phase in females in related to condition rather than age. Nonreproductive males also occur in the population sampled and in the fall there was a trend towards an increased number with advancing age. The protracted gametogenesis in winter flounder demonstrates the need for caution when assessing spawning condition and reproductive capacity of some fish stocks.

Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser
Keyword(s):  
Predation Risk ◽  
Reproductive Cycle ◽  
Perceived Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Size Variation ◽  
Egg Laying ◽  
Offspring Size ◽  
Natural Predation ◽  
Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

Mechanisms underlying pituitary microvascular remodelling in thoroughbred horses during the annual reproductive cycle

2014 ◽  
Author(s):  
Angus Yeomans ◽  
Nichol Thompson ◽  
Jennifer Castle-Miller ◽  
David O Bates ◽  
Domingo Tortonese
Keyword(s):  
Reproductive Cycle ◽  
Annual Reproductive Cycle ◽  
Thoroughbred Horses
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