Biology 30 - Unit 3 Booklet 2: Development (Terms)

Zygote

The first embryonic stage that appears as a recently fertilized egg in the fallopian tube that will undergo mitosis to become a morula

Cleavage

The process by which a zygote undergoes mitosis where the cell divides equally without increasing in size

Morula

The embryonic stage in which a zygote has undergone 8 cleavages in the fallopian tube

Blastocyst

The embryonic stage in which a morula that has differentiated into different layers and has moved to the uterus

Fetus

The embryonic stage in which a blastocyst has developed from a cell-like structure into a human-like structure with all major adult parts (week 8 of embryonic development)

Embryo

An unborn offspring that will go through stages of development to become a fetus

hCG (Human Chorionic Gonadotropin)

A hormone released by the chorion and placenta targeting the corpus luteum in the ovary that prevents the corpus luteum from degeneration for 3 months and stimulates the production of estrogen and progesterone

Chorion

The outermost extra-embryonic membrane that secretes hCG, part of it will intermingle with the endometrium to form the placenta

Placenta

A disc-shaped organ formed 3 months post fertilization from the part of the chorion that intermingles with the endometrium containing maternal and fetal blood vessels that allows for the diffusion of gases, nutrients, and wastes from mother to embryo and continues the production of hCG, estrogen, and progesterone

Amnion

The innermost extra-embryonic membrane appearing as a sac filled with amniotic fluid that protects the embryo from trauma and temperature fluctuations as well as allowing freedom of movement

Allantois

The end of the umbilical cord that helps the embryo exchange gases and handle liquid waste as well as provides umbilical blood vessels to placenta

Umbilical Cord

The cord providing a connection between the mother and embryo that carries the embryo’s blood to and from the placenta

Yolk Sac

The site of early red blood cell formation that contributes to the primitive digestive tract

Gastrulation

The process of the embryonic cells in a blastocyst starting to produce three layers

Ectoderm

The outer layer of cells formed from gastrulation that will become the skin and nervous system (including brain)

Mesoderm

The middle layer of cells formed from gastrulation that will become the skeleton, muscles (including heart), and reproductive structures

Endoderm

The inner layer of cells formed from gastrulation that will become the digestive and respiratory lining and endocrine glands

Partuition

The act of a mature fetus being pushed out from the mother at around 40 weeks from conception

Relaxin

A hormone released by the placenta targeting the ligaments of the pelvis that loosen the pelvic ligaments during childbirth to produce a larger passageway for the baby

Colostrum

The first fluid formed by the mammary glands that is thick, lacks fat, and contains antibodies

Prolactin

A hormone released by the anterior pituitary targeting the mammary that stimulates milk production

Oxytocin

A hormone released by the posterior pituitary targeting the uterus and mammary that stimulates uterine contracts and milk secretion

Ultrasound

A non-invasive procedure that uses sound waves to detect body structures used for diagnostic testing during pregnancy

Amniocentesis

A procedure in which a long needle is used to remove a sample of amniotic fluid from the amnion containing fetal cells that are cultured for 2-4 weeks followed by a karyotype that is used to analyze for genetic disorders

CVS (Chorionic Villi Sampling)

An intensive procedure in which a small sample of tissue of chorionic villi is taken followed by a karyotype that is used to analyze for genetic disorders

In Vitro Fertilization

A process in which ova can be surgically removed from a woman whose oviducts are blocked and fertilized in a Petri dish in a lab, resulting in an embryo that can be inserted into a woman/surrogate mother’s uterus. Used to combat infertility

Vasectomy

A process in which an incision is made through the scrotum and the vas deferens is cut off and sealed so that sperm is produced but cannot get out, used as a form of birth control. 99-100% effective but hard to reverse and provides no protection against STIs

Tubal Ligation

A process in which an oviducts are severed so that the movement of the egg from the ovary to the uterus is stopped, used as a form of birth control. 99-100% effective but hard to reverse and provides no protection against STIs

Birth Control Pill

A pill consisting of a combination of estrogen and progesterone taken for 21 days of the 28 day cycle that acts as negative feedback of GnRH and subsequently FSH and LH production so that follicles do not develop, used as a form of birth control. Provides no protection against STIs but has hormonal side effects

Condom

A barrier that fits over the penis or in the vagina that prevents semen from entering the female used as a form of birth control. Provides protection against STIs and has no hormonal side effects

Diaphragm

A barrier that fits over the cervix and prevents semen from entering the uterus used as a form of birth control. Provides no protection against STIs and has no hormonal side effects

IUD (Inter-Uterine Device)

A device placed in the uterus by a physician that prevents implantation of a blastocyst in the endometrium used as a form of birth control. Provides no protection against STIs and may have hormonal side effects if device contains hormones

STI (Sexually Transmitted Infection)

Infections commonly but not exclusively transmitted through sexual contact that can cause dangerous conditions if untreated