The narrow middle part of the epididymis is called

$A$ : 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

The mother germ cells are transformed into a mature follicle through series of steps. Provide the missing steps in the blank boxes.

$\boxed{{\text{Oogonia}}}$ $\to $ $\boxed{\text{A}}$ $\to $ $\boxed{{\text{Primary follicle}}}$ $\to $ $\boxed{\text{B}}$ $\to $$\boxed{\text{C}}$ $\to $ $\boxed{{\text{Mature or Graafian follicle}}}$

Location and secretion of leyding cells are

The stroma of the ovary consists of nerves, blood vessels, muscle fibres and a type of protein called

Which of the following cannot pass through the placenta into the foetus