How does preprgancy effect egg cells in mice?

[Calvin P]

I'm currently a student learning about genetic engineering and one thing that I didn't quite understand is before extracting an egg cell from a female, the female mouse must first perform coitus with a vasectomized male mouse.  Does anybody know why or how this is related to the female mouse releasing an egg cell?

[StringJunky]

Quote

4.3.2 The estrus cycle
The normal estrus cycle of a laboratory mouse is 4-6 days in length. The cycle has been divided into four phases which are distinguished by changes in physiology, morphology, and behavior. (1) The proestrus portion of the cycle begins when a new batch of eggs reach maturity within ovarian follicles that are ripe and large. External examination of the female will usually show a bloated vulva with an open vagina. (2) Estrus begins with the ovulation of fully mature oocytes. The vulva remains in an extended state with an open vagina, and females are maximally receptive to male advances. When mice are maintained on a standard light-dark cycle, the estrus phase will usually begin soon after midnight and last for 6-8 hours. (3) The metestrus phase follows, when mature eggs move through the oviducts and into the uterus. The vulva is no longer bloated, and the vagina is now closed.

At the end of metestrus, a physiological branch point occurs with the direction to be taken dependent on whether a successful copulation has occurred. The act of successful copulation induces hormonal changes that prepare the uterus for a pregnancy which will ensue under normal circumstances. However, a sterile copulation — one that does not lead to fertilization — can induce a state of pseudopregnancy (see Section 6.2.3). A pseudopregnancy can extend the metestrus phase by as long as 10-13 days.

(4) If pregnancy does not occur, the metestrus phase is ultimately followed by the last phase of the estrus cycle, diestrus. Unfertilized eggs are eliminated, the vagina and vulva are at a minimum size, and new follicles begin to undergo a rapid growth for the next ovulation. (The proestrus and estrus phases together constitute the follicular phase; the metestrus and diestrus phases together constitute the luteal phase.)

http://www.informatics.jax.org/silver/chapters/4-3.shtml

I presume they are collected at the elimination stage.

Edited April 25, 2020 by StringJunky

[Calvin P]

Much appreciated @StringJunky by any chance would you know any ebooks or papers I can read to improve my knowledge on this?

[StringJunky]

3 hours ago, Calvin P said:

Much appreciated @StringJunky by any chance would you know any ebooks or papers I can read to improve my knowledge on this?

@CharonY may well know.