Everything about Embryonic Diapause totally explained
Embryonic diapause or
Delayed implantation is a reproductive strategy used by close to 100 different
mammals in seven different
orders. In embryonic diapause, the
embryo (
blastocyst) doesn't immediately implant in the
uterus, but is maintained in a state of
dormancy. No development takes place as long as the embryo remains unattached to the uterine lining. As a result, the normal
gestation period is extended, sometimes up to a year.
While much of the molecular regulation involved in activating dormant blastocysts has been characterized, little is still known about entry into diapause, and the conditions which enable a blastocyst to remain dormant.
Some mammals that undergo embryonic diapause include
rodents,
bears,
mustelids (for example
badgers), and
marsupials, (for example
kangaroos). Some groups only have one species that undergoes embryonic diapause, such as the
roe deer in the
order Artiodactyla.
Types
Two types of embryonic diapause have been identified.
Facultative diapause
Facultative diapause is a mechanism that's associated with metabolic stress, normally
lactation. If a female
copulates while still lactating for her original
offspring, the sucking stimulus will cause the embryos to enter into diapause. This is known to occur in some
rodents,
insectivores and
marsupials.
Facultative diapause can also be referred to as facultative arrest. Another example of diapause associated with metabolic stress associated is that exhibited by the
brine shrimp,
Artemia franciscana. The adult female which usually gives birth to live offspring (
nauplii) desists and instead produces encysted embryos in the fall season which is characterized by low temperature and high salinity. These embryos are known to have very low metabolic activities and can survive up to 17 months of anoxia (complete lack of oxygen).
In favorable conditions, the 'cysts' will hatch and release nauplii to continue their life cycle.
Obligate diapause
Obligate diapause is a mechanism that allows mammals to time the birth of their offspring for favorable environmental conditions. This mechanism occurs as a regular part of the reproductive cycle in many of the
pinnipeds,
mustelids,
ursids,
armadillos, one species of
fruit bat, and the
roe deer.
Obligate diapause can also be referred to as obligate arrest.
For example, Roe Deer mate in July or August and don't give birth until May or June the following year, usually to twins of opposite sexes.
Remarks
The term
Diapause is also used to refer to the temporary partial or complete metabolic suspension in various life stages of
insects and
plants.
Further Information
Get more info on 'Embryonic Diapause'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://embryonic_diapause.totallyexplained.com">Embryonic diapause Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
