placentation

Placentation refers to the development and attachment of the placenta, a vital organ that connects the developing fetus to the uterine wall. This process is crucial for providing nourishment, oxygen, and waste removal for the fetus during pregnancy.1

In mammals, placentation involves the interaction between maternal and embryonic tissues. The placenta forms from the trophoblast (an outer layer of embryonic cells) and the uterine lining. This structure allows for the exchange of nutrients and gases between the mother and the embryo, while also acting as a barrier against certain intrusions.2

Different types of placentas exist across the animal kingdom, varying in their structure and the degree of intimacy between maternal and fetal tissues. For example, some mammals have an epitheliochorial placenta, where fetal and maternal tissues are closely pressed, while others have more invasive types like hemochorial placentas.3

Placentation is also a term used in botany to describe the arrangement of ovules within a plant ovary.4