Embryology 2

What is implantation?

Attachment of the developing embryo to the uterine endometrium, leading to placenta formation.

What are the two broad categories of placenta?

Choriovitelline (yolk sac placenta) and chorioallantoic (definitive placenta in domestic mammals).

Which placenta type is definitive in domestic mammals?

Chorioallantoic placenta.

What defines histologic placental classification?

The number of maternal tissue layers between fetal and maternal blood.

What is an epitheliochorial placenta and which species has it?

Chorionic epithelium contacts maternal epithelium; found in horses, donkeys, and pigs.

What is a synepitheliochorial placenta and which species has it?

Fused fetal and maternal epithelial layers; found in ruminants.

What is an endotheliochorial placenta and which species has it?

Chorionic epithelium contacts maternal capillaries; found in dogs, cats, and elephants.

What is a hemochorial placenta and which species has it?

Chorionic epithelium contacts maternal blood directly; found in rodents and primates.

What defines morphologic placental classification?

Shape and distribution of chorionic villi attachment to the endometrium.

What species has a diffuse placenta?

Horses and pigs.

What species has a cotyledonary placenta?

Ruminants (e.g. cows, sheep).

What species has a zonary placenta?

Dogs and cats.

What species has a discoidal placenta?

Rodents and primates.

What is the embryologic origin of the heart?

Paired cardiac tubes that fuse medially.

What are the three layers of the myocardium?

Endocardium (inner), myocardium (middle), epicardium (outer).

What are the three neural tube vesicles?

Prosencephalon, mesencephalon, and rhombencephalon.

What does the prosencephalon give rise to?

Telencephalon (cerebrum) and diencephalon (thalamus, hypothalamus).

What does the mesencephalon give rise to?

Tectum and tegmentum.

What does the rhombencephalon give rise to?

Brainstem (myelencephalon) and cerebellum (metencephalon).

What structures make up the ventricular system?

Four ependymal-lined brain cavities and the central canal of the spinal cord.

What lines the ventricles and central canal?

Ependymal cells.