Embryology and Pregnancy Lecture

Comprehensive flashcards covering the stages of pregnancy, hormonal regulation, germ layer development, and the labor process based on the lecture material.

Luteinizing Hormone (LH)

A hormone that skyrockets for the last three hours for ovulation to occur within $48$ hours.

Corpus luteum

A mature follicle remnant in the ovaries that releases progesterone to signal the hypothalamus to stop releasing gonadotropia releasing hormone.

Corpus albicans

A white, scar-like tissue that the corpus luteum becomes if fertilization does not occur.

Embryonic period

The developmental stage from fertilization to the eighth week.

Fetal period

The developmental stage that starts in week $9$ and continues until birth.

Zygote

A diploid cell with $46$ chromosomes (joint genetic material from male and female) created during the first week of development.

Morula

A solid ball of $16$ cells formed by the third or fourth day after fertilization; it is still protected by the zona pellucida.

Blastocyst

A structure formed by day $5$ consisting of an embryoblast (inner muscle mass) and a trophoblast outer layer.

Trophoblast

The outer layer of the blastocyst that nourishes the embryoblast and eventually becomes the fetal portion of the placenta.

Syncytiotrophoblast

A cell layer derived from the trophoblast that secretes enzymes to promote implantation and releases human chorionic gonadotropin hormone.

Human chorionic gonadotropin (hCG)

A hormone used to maintain the corpus luteum; if the corpus luteum does not receive this, it disintegrates into corpus albicans.

Amnion

A protective layer that secretes fluid to act as a shock absorber, prevent desiccation, and prevent the fetus's skin from adhering to surroundings.

Yolk sac

A structure that serves as the source for blood cells and primordial germ cells (stem cells) for the gametes.

Chorion

A structure that creates the maternal-embryonic barrier and later becomes the placenta.

Placenta

The organ of exchange between the mother and fetus for nutrients and waste; it also protects the fetus from maternal immune responses.

Human placental lactogen (hCS)

A hormone that increases protein synthesis, decreases the mother's use of glucose, and makes more glucose available for the fetus.

Corticotropin releasing hormone (CRH)

A placental hormone that establishes the timing of birth and increases secretion beginning at week $12$.

Ectoderm

The primary germ layer that gives rise to almost all nervous tissue, the epidermis, hair follicles, and the lens/cornea of the eye.

Mesoderm

The primary germ layer that forms skeletal and cardiac muscle, cartilage, bone, blood, the adrenal cortex, and the dura mater.

Endoderm

The primary germ layer that forms the epithelial lining of most internal organs and the GI tract.

Neurulation

The formation of the central nervous system from the neural plate during the third week of development.

Organogenesis

The stage beginning in the fourth week where organs begin to form and the heart starts to work.

Relaxin

A hormone produced by the corpus luteum and placenta that increases the flexibility of the pubic symphysis and dilates the cervix during labor.

Prolactin

A hormone that increases by the end of pregnancy to induce the making of milk.

Oxytocin

A hormone from the posterior pituitary that stimulates uterine contractions during labor and the ejection of milk during lactation.