Embryology

Question 1

Name 2 events in gamete production that creates genetic variability

Answer 1

Crossing over between segments of homologous chromosomes and independent assortment of chromosomes during meiosisFirst card

Question 2

Define oogenesis

Answer 2

Development of female gamete which begins during fetal life and is completed only after fertilization

Question 3

Put the following stages into their correct order: Secondary follicle, primary oocyte, mature follicle with antrum, primary follicle, ovulated ovum with zona pellucida and corona radiata

Answer 3

Primary oocyte → primary follicle → secondary follicle → mature follicle with antrum → ovulated ovum with zona pellucida and corona radiata

Question 4

Approximately how long is the ovum fertilizable?

Answer 4

24 hours

Question 5

Approximately how long are sperm viable in the female reproductive tract?

Answer 5

6 days

Question 6

What cell contains an acrosome and what is its function?

Answer 6

a. Sperm

b. Contains enzymes that help penetrate the corona radiata and the zona pellucida

Question 7

What cell contains cortical granules and what is their function?

Answer 7

a. Ova
b. To “toughen” the zona pellucida and block polyspermy, to protect the zygote until it reaches the uterus for implantation, to help hold dividing cells together

Question 8

Put the following steps into the correct order: Two cell stage, blastula, zygote (fusion of male and female pronuclei), morula, implantation

Answer 8

a. Zygote (fusion of male and female pronuclei) → two cell stage → morula → blastula (the blastula is the first cavity that forms) → implantation

Question 9

At one week the embryo consists of what two cell types?

Answer 9

a. Embryoblast (1st cells that will form the embryo) and the trophoblast

Question 10

At 2 weeks what changes have occurred in the embryo?

Answer 10

a. Epiblast and hypoblast
b. The uterine wall has closed over the embryo and implantation is “complete.” The cranial-caudal axis is being set by the primitive streak. The amniotic cavity is first formed.

Question 11

At 3 weeks, how many layers are there in the embryo? What are their names?

Answer 11

a. Three

b. Ectoderm, mesoderm, endoderm

Question 12

By what process do the three germ layers form?

Answer 12

a. Gastrulation

Question 13

By what process does the embryo begin to take its three-dimensional shape?

Answer 13

a. Lateral body folding and cranial-caudal body folding

Question 14

Name the derivatives of ectoderm

Answer 14

a. Skin and its “decorations” (hair, nails, sweat and sebaceous glands), CNS, and neural crest cells

Question 15

Name the derivatives of endoderm

Answer 15

a. The lining epithelium of the GI and Respiratory systems, also lower portion of the urinary system

Question 16

Name the regions of the mesoderm

Answer 16

a. Notochord, paraxial (somites), intermediate, lateral plate (somatic and splanchnic)

Question 17

Name the derivatives of mesoderm

Answer 17

a. Connective tissue (bone, tendon, ligaments, fascia, fat), Muscle (3 kinds), blood vessels and cells, lymphatic vessels and organs, upper urinary system, and internal reproductive organs

Question 18

Name the three regions of the somite

Answer 18

a. Sclerotome, dermatome, and myotome

Question 19

What three layers make up the chorion?

Answer 19

a. Syncytiotrophoblast, cytrophoblast, and extraembryonic mesoderm

Question 20

What can be exchanged between maternal and fetal blood? What cannot?

Answer 20

a. Gases, nutrients, steroid hormones, immunoglobins, viruses, and some bacteria and protozoans can cross the placenta
b. Blood cells and protein hormones do not cross the barrier very easily, if at all

Question 21

What structures grow from the embryo through the connecting stalk of extraembryonic mesoderm to invade the placenta?

Answer 21

a. Two umbilical arteries and one umbilical vein

Question 22

The umbilical arteries/vein grow into a mesodermal core of a _______________?

Answer 22

a. Chorionic villus

Question 23

Why are chorionic villi clinically 23) Why are chorionic villi clinically important?

Answer 23

a. One of the safest fetal tissues to sample for genetic analysis

Question 24

How many pharyngeal arches are there?

Answer 24

a. Five: numbered 1,2,3,4,6

Question 25

What is the name of the first pharyngeal arch?

Answer 25

a. Maxillary and mandibular processes

Question 26

What bones will the first pharyngeal arch (maxillary and mandibular processes) produce?

Answer 26

a. Maxilla, mandible, palate, zygoma, part of the temporal bone (“bones of mastication”), and the incus and malleus of the inner ear

Question 27

What is the function of muscles derived from the first pharyngeal arch?

Answer 27

a. Muscles of mastication

Question 28

Which cranial nerve supplies the muscles of mastication?

Answer 28

a. The trigeminal nerve, mandibular division V3

Question 29

What is the name of the second pharyngeal arch?

Answer 29

a. Hyoid arch

Question 30

What bone will the second pharyngeal arch (hyoid arch) produce?

Answer 30

a. Hyoid bone

Question 31

What is the function of the muscles derived from the second pharyngeal arch (hyoid arch)?

Answer 31

a. Muscles of facial expression

Question 32

Which cranial nerve supplies the muscles of facial expression?

Answer 32

a. The facial nerve (VII)

Question 33

What is the cranial nerve that belongs to the third branchial arch?

Answer 33

a. The glossopharyngeal nerve (IX)

Question 34

What is the cranial nerve that belongs to the 4th and 6th pharyngeal arches (and wanders elsewhere, too!)?

Answer 34

a. The vagus nerve (X)