Embryology

Question 1

What are unique vertebrate characteristics?

Answer 1

Endoskeleton.
Cranium.
Vertebral column.

Question 2

What are the two reproductive strategies?

Answer 2

R-selected: large number of small young, no parental care.

K-selected: small number of large young, lots of parental care.

Question 3

What are the three amounts of yolk an egg can have?

Answer 3

Microlecithal.
Mesolecithal.
Macrolecithal.

Question 4

What is cleavage?

Answer 4

A series of mitotic divisions that take the zygote to a mass of smaller cells, the blastula/blastocyst/blastoderm.

Question 5

What are the two types of cleavage?

Answer 5

Holoblastic: full cleavage, isolecithal, micro/mesolecithal.
Meroblastic: partial cleavage, telolecithal, macrolecithal.

Question 6

What kind of cleavage do amphibians have?

Answer 6

Mesolecithal, radial and holoblastic cleavage.

Question 7

What kind of cleavage do mammals have?

Answer 7

Microlecithal, rotational, holoblastic cleavage.

Question 8

What kind of cleavage do birds have?

Answer 8

Macrolecithal, discoidal, meroblastic cleavage.

Question 9

What is gastrulation?

Answer 9

Rearrangement of cells by migration and division resulting in the formation of the three embryonic germ layers, endoderm, mesoderm and ectoderm. Cells moving into cell make up endoderm and mesoderm. Cells on outside make ectoderm.

Question 10

What is it called when the ectoderm covers the embryo?

Answer 10

Epiboly.

Question 11

What is neurulation?

Answer 11

Folding process to form neural tube which becomes the spinal cord and CNS.

Question 12

What does the ectoderm become during neurulation?

Answer 12

Skin, hair, lining of nose, mouth and NS.

Question 13

What does the endoderm become during neurulation?

Answer 13

Digestive tract, respiratory tract, liver and pancreas.

Question 14

What does the mesoderm become during neurulation?

Answer 14

Muscles and skeleton.

Question 15

What do extra-embryonic layers do?

Answer 15

Prevent embryo dehydration and protect it.
Provide nutrition.
Sequester waste products.
Exchange respiratory gases.

Question 16

What is the first extra-embryonic layer?

Answer 16

Yolk sac.

Question 17

What extra-embryonic layers do the mesoderm and ectoderm form?

Answer 17

Chorion and amnion.

Question 18

What do the mesoderm and endoderm form?

Answer 18

Allantois.

Question 19

What extra-embryonic layers have blood vessels?

Answer 19

Yolk sac and allantois.

Question 20

What is organogenesis?

Answer 20

Series of organised integrated processes that transforms an amorphous mass of cells into a complete organ in developing embryo.

Question 21

What does the ectoderm form in organogenesis?

Answer 21

Nervous System.
Ectoderm.
Epithelia of eye, nose and ear.

Question 22

What does mesoderm form in organogenesis?

Answer 22

Connective tissue.
Urogenital system.
Circulatory system.

Question 23

What does HPG mean in HPG axis?

Answer 23

Hypothalamus Pituitary Gonadal

Question 24

What does the hypothalamus do?

Answer 24

Direct signals to pituitary.
Releases/inhibits.
Thermoregulation, food intake, thirst and activity.

Question 25

What does the pituitary do?

Answer 25

Master gland. Produces many hormones. Metabolism, growth, sexual maturation.

Question 26

What is the oestrous cycle?

Answer 26

Main reproductive cycle of non-primitive vertebrates.

Question 27

What are the two types of ovulators?

Answer 27

Spontaneous and induced (ovulate upon mating).

Question 28

What does polyoestrous mean?

Answer 28

Many oestrous cycles throughout the year.

Question 29

What does monoestrous mean?

Answer 29

One cycle a year.

Question 30

What does oestrogen do?

Answer 30

Dominates follicular phase. Permits copulation and ova release. Promotes fertilisation.

Question 31

What does progesterone do?

Answer 31

Levels high in luteal phase. Progesterone produced by corpus luteum. Maintains uterine lining.

Question 32

What does the placenta do?

Answer 32

Takes over production of progesterone and oestrogen. Progesterone prevents womb contraction. Oestrogen stimulates uterine growth.

Question 33

What do prostaglandins do?

Answer 33

Stimulate cervical ripening, breaks down cervical connective tissue. Promotes further corticotrophin-releasing hormone.

Question 34

What does oxytocin do?

Answer 34

Feelings of motherhood. Triggered by oestrogen. When oxytocin-receptor concentration reaches a critical threshold, labour begins. Causes regular contractions. Causes milk to be squeezed out of alveoli into ducts and out of nipple.

Question 35

Where does prolactin get produced?

Answer 35

Produced in pituitary. Produced in uterus and breasts. Regulated by oestrogen.