Gametogenesis and fertilisation

Question 1

why’d o we study human embryology? (5)

Answer 1

• to understand our parental origin
• understanding birth defects or congenital abnormalities
• foundational knowledge for obstetrics and paediatrics specialities
• understanding illness or disease with development origin
• knowledge for patients on issues relating to reproduction, birth defects and prenatal development, in-vitro fertilisation, stem cell and cloning

Question 2

how many trimesters are there in the prenatal period?

Answer 2

3

Question 3

which weeks do most morphogenic abnormalities develop?

Answer 3

3-7 weeks

Question 4

when does the CNS and heart begin to develop?

Answer 4

middle week 6

Question 5

when do the arms and legs develop

Answer 5

week 8

Question 6

when do the eyes begin to develop

Answer 6

middle of week 8

Question 7

when do the external genitals develop

Answer 7

weeks 9-38

Question 8

what is gametogenies

Answer 8

the process of the production of male and female gamete or sex cells (sperm and egg) from the primordial germ cells via meiotic cell division in the gonads (testes and ovaries)

Question 9

what do gametes develop from

Answer 9

the primordial germ cells

Question 10

what kind of cell division forms the gametes

Answer 10

meiotic

Question 11

what are the gonads

Answer 11

the testes and the ovaries

Question 12

what are PGCs

Answer 12

primordial germ cells - specialised stem cells that give rise to the germ line and are formed a generation earlier when the parents were embryos

( we are handed over reproductive ability by parents before we were born)

Question 13

stem cell

Answer 13

an undifferentiated cell that has the ability to form specialised cell types - embryonic or adult stem cells

Question 14

embryonic stem cells are

Answer 14

pluripotent

Question 15

adult stem cells are

Answer 15

multipotent

Question 16

pluripotent cells

Answer 16

have the ability to form all mature cell types in the body except placental and extra embryonic cells - cannot form the whole organism

Question 17

what can pluripotent cells NOT form

Answer 17

placental and extra embryonic cells

Question 18

multipotent cell

Answer 18

ability to form more that one closely related mature cell types in the body but not as varied as pluripotent

eg - cord, blood/bone marrow stem cells from erythrocyte, leucocyte, platelet.

Question 19

totipotent cell

Answer 19

has ability to form all differentiated cell types in the body including the placental and extraembryonic membrane cells. It could form a whole organism

Question 20

which is the most undifferentiated stem cell.

Answer 20

totipotent

Question 21

errors in gametogenesis can lead to

Answer 21

chromosomal abnormalities that could result to birth defects or spontaneous abortions.

Question 22

errors in spermatogenesis can lead to

Answer 22

a number of spermatozoa morphological abnormalities that could affect male fertility – Sperm count clinical investigation.

Question 23

what does a sperm count show

Answer 23

number/quality - viability and agility

Question 24

what do basic contraceptive methods target?

Answer 24

physiological processes and anatomical framework relating to release of gametes – hormonal induction of hostile environment

Question 25

male infertility could result from

Answer 25

the quality and quantity of spermatozoa ejaculated.

Question 26

Female infertility could result from

Answer 26

a number of causes including physiological and anatomical factors

Question 27

Infertility in both male and female could be treated with

Answer 27

Infertility in both male and female could be treated with

Question 28

when totipotent cells split in the womb

Answer 28

monozygotic twins

Question 29

what % f birth are twins in natural fertilisation

Answer 29

3%

Question 30

How are monozygotic twins (identical) twins formed

Answer 30

Form by splitting of a single fertilized zygote at various stages of development.

Question 31

what % of natural births are monozygotic twins

Answer 31

0.4%

Question 32

Monozygotic (Identical) twins

Answer 32

Monozygotic (Identical) twins

Question 33

what are fraternal twins

Answer 33

dizygotic twins - not genetically identical

Question 34

when do dizygotic twins occur

Answer 34

Form when two separate oocytes are produced simultaneously in the same menstrual cycle and are fertilized by different spermatozoa.

Question 35

what % of natural births are dizygotic twins

Answer 35

1.2%

Question 36

are dizygotic twins always going o be the same sex

Answer 36

no, they may or mayn’t be the same sex

Question 37

6 methods of assisted reproductive technologies for infertility treatment

Answer 37

• In vitro fertilisation (IVF)
• gamete intrafallopian transfer (GIFT)
• artificial insemination by donor (AID)
• Zona drillin (ZD)
• Subzonal insemination (SUZI)
• intracytoplasmic sperm injections (ICSI)

Question 38

In Vitro Fertilization (IVF)

Answer 38

Sperm and eggs are placed in a laboratory dish to fertilize.

Question 39

Gamete Intrafallopian Transfer (GIFT)

Answer 39

Sperm and eggs are injected into the uterine tube to fertilize

Question 40

Artificial Insemination by Donor (AID):

Answer 40

Sperm is injected into the cervix or uterus or uterine tube

Question 41

Zona Drilling (ZD):

Answer 41

A microsurgical technique that facilitates sperm penetration into the egg with the use of acid tyrode’s solution or enzyme such as trypsin or pronase. Fertilized egg is transferred into the uterus.

Question 42

Subzonal Insemination (SUZI)

Answer 42

A procedure where spermatozoa are injected into the perivitelline space that surrounds the egg membrane. The fertilized egg is later implanted into the uterus.

Question 43

Intracytoplasmic Sperm Injection (ICSI):

Answer 43

A procedure where a single sperm is directly injected into an egg. The fertilized egg is then implanted into the uterus.