Embryo transfer (ET) — select the most accurate description of donor and recipient genetics and the direction of embryo movement.

Introduction / Context:
Embryo transfer (ET) is widely used in animal breeding to multiply the offspring of genetically superior females. Donor cows or ewes are superovulated and inseminated; resulting embryos are flushed and placed into synchronized recipients that serve as gestational carriers.

Given Data / Assumptions:

• Objective: increase genetic gain by using high-merit donors.
• Recipients need not be genetically elite; they provide the uterine environment.
• Synchronization of estrous cycles between donor and recipients is required.

Concept / Approach:

Genetic merit is captured at the embryo stage. ET allows one elite female to produce many calves or lambs in a season, while recipients—of average or lower genetic merit—carry the pregnancies, leveraging reproductive capacity without diluting genetics of the embryo.

Step-by-Step Solution:

Verification / Alternative check:

Breeding program manuals describe donor-superovulation → embryo flush → transfer to synchronized recipients as the standard ET workflow.

Why Other Options Are Wrong:

(b) Inverting donor/recipient defeats the purpose. (c) No transfer is not ET. (e) IVF embryos are commonly transferred; “never transferred” is false.

Common Pitfalls:

Confusing ET with cloning or IVF; conflating “recipient quality” with pregnancy success rather than genetic merit.

Final Answer:

Fertilized ova are collected from a genetically superior female and transferred to an inferior recipient