Basics (L1-L4)

Question 1

What is fertilisation?

Answer 1

Fertilisation is a complex sequence of coordinated molecular events that begin with contact between a sperm and an oocyte, and ends with the intermingling of maternal and paternal chromosomes at metaphase of the 1st mitotic division of the zygote, a unicellular embryo.

Question 2

List the phases of fertilisation

Answer 2

1. Passage of sperm through corona radiata
2. Penetration of zona pellucida
3. Fusion of cell membranes of oocyte and sperm, where head and tail of the sperm enters the oocyte cytoplasm, but the sperm’s cell membrane and mitochondria remains behind
4. Completion of the 2nd meiotic division of oocyte and formation of female pronucleus
5. Formation of male pronucleus
6. As the pronuclei fuse into a single diploid aggregation of chromosomes, the ootid becomes a zygote

Question 3

Site of fertilisation

Answer 3

ampulla of uterine tube

Question 4

What does the acrosome of a capacitated sperm bind to?

Answer 4

A glycoprotein, ZP3, on the zona pellucida

Question 5

What gives rise to the embryo?

Answer 5

Embryoblast - a group of centrally located blastomeres

Question 6

When and where does implantation occur?

Answer 6

6 to 10 days after ovulation, completed by the 2nd week.

Implantation occurs in the middle/upper dorsal wall of the uterine

Question 7

Define gastrulation

Answer 7

Formation of germ layers

Question 8

Define neurulation

Answer 8

Formation of neural tube

Question 9

What happens to:

• Epiblast
• Hypoblast

Answer 9

Epiblast becomes the ectoderm;

Hypoblast becomes the endoderm

Question 10

What forms the mesoderm?

Answer 10

Cells that come out from the primitive streak to fill the space between the epiblast and hypoblast

Question 11

What does embryonic ectoderm give rise to?

Answer 11

Epidermis, CNS, PNS, eyes, int. ear, neural crest cells

Question 12

What does embryonic endoderm give rise to?

Answer 12

Source of epithelial linings of the respiratory and alimentary tracts, including the glands that open into the GI tract and glandular cells of associated organs such as liver and pancreas

Question 13

What does the embryonic mesoderm give rise to?

Answer 13

All skeletal muscles, blood cells, lining of blood vessels, visceral smooth muscle coats, serosal linings of all body cavities, ducts and organs of the reproductive and excretory systems + most of CVS system

Question 14

List some neural crest derivatives

Answer 14

• Schwann cells and meninges
• Dorsal root ganglion
• Autonomic ganglia
• Blood & Connective tissue of craniofacial structures
• Melanocytes
• Chromaffin cells (of adrenal medulla)
• Odontoblasts

Question 15

What does each pharyngeal arch consist of?

Answer 15

• Core of mesenchyme
• Neural crest cells (skeletal components of face)
• Cranial nerve component
• Artery

Question 16

What does connective tissue and bone cartilage develop from?

Answer 16

Mesenchyme

Question 17

Define instructive (wrt tissue interaction)

Answer 17

The ability of one tissue to determine specific patterns of morphogenesis and differentiation that will develop in an associated tissue

Question 18

Define permissive (wrt tissue interaction)

Answer 18

The ability of an interacting tissue to provide certain conditions that is necessary for its committed partner tissue to progress to full expression of its pre-determined phenotype

Question 19

Define organogenesis

Answer 19

Organogenesis refers to the production and development of the organs of animals (or plants)