The zygote is the fertilized egg cell, formed by the union of a sperm and an egg, marking the beginning of human development.

Cleavage is the initial series of cell divisions that occur in the zygote, resulting in the formation of blastomeres.

The ectoderm is the outermost germ layer and is responsible for the development of the nervous system, skin, and some sensory organs.

Organogenesis is the process by which individual organs develop from the embryonic tissues and germ layers.

Progesterone is the dominant hormone during pregnancy, playing a crucial role in maintaining the uterine lining and preparing the body for the developing fetus.

The placenta facilitates gas exchange, nutrient transport, waste removal, and hormone production, supporting the growth and development of the fetus.

Synaptogenesis is the process of synapse formation between neurons, which occurs extensively during early brain development, establishing neural circuits and networks.

Neonatal refers to the period immediately after birth, while embryonic and fetal are stages of prenatal development.

Cell migration is the directed movement of cells from one location to another during embryonic development, contributing to the formation of tissues and organs.

Neuroderm is not a germ layer in human embryonic development. The three primary germ layers are ectoderm, mesoderm, and endoderm.

Histogenesis is the process by which tissues are formed from embryonic cells, involving cell differentiation and organization.

Oxytocin is the hormone responsible for stimulating uterine contractions during labor and childbirth.

Cytogenesis refers to the process of cell maturation and specialization, involving the acquisition of specific functions and characteristics.

The yolk sac is not an extraembryonic membrane in human development. The three extraembryonic membranes in humans are the amnion, chorion, and allantois.

Morphogenesis is the process by which the overall shape and external features of the embryo are formed, involving the coordinated growth and differentiation of tissues and organs.