In humans, at the end of the first meiotic division, the male germ cells form

$A$ : Blastocyst undergoes gastrulation to produce the three germinal layers.
$R$ : This involves cell movements (morphogenetic movement) that eventually help to attain new shape and morphology of embryo

Tertiary egg membrane is

In rabbit, the uterus is

In the development of the human body, the ectoderm is responsible for the formation of