Gametogenesis, implantation,

Question 1

what is gametogenesis?

Answer 1

•The process of meiosis and cytodifferentiation converting germ cells to mature male and female gametes or sex cells

Question 2

where do the germ cells originally differenciate?

Answer 2

the wall of the yolk sac (endoderm in origin- that grows outside of the developing embryo)- then they migrate back into the developing embryo and end up on the psoterior wall

Question 3

what is the term for gametogenesis in men and women?

Answer 3

Males = spermatogensis

Female = oogenesis

Question 4

when do the oogonia begin meiosis?

Answer 4

they begin meiosis by the 5th month

Question 5

Under what condition does meiosis complete in the ova?

Answer 5

meiosis does not complete unless fertilization occurs

Question 6

what is the result of oogenesis?

Answer 6

•Results in one mature oocyte (viable) and three polar bodies

Question 7

what is the result of spermatogenesis in men?

Answer 7

Spermatogenesis

•Primordial cells differentiate into spermatagonia

Produce in 4 spermatids

Question 8

describe the order of spermatogenesis in men?

Answer 8

first spermatogenesis

then spermiogenesis (

• Spermatids undergo dramatic changes to convert them to mature sperm
• Formation of acrosome
• Condensation of nucleus
• Formation of neck, middle piece and tail
• 64 days spermatagonia sprematids spermatazoa)

Question 9

how long is the process of spermatogenesis?

Answer 9

64 days

Question 10

Describe the 3 main phases from fertilization til birth

Answer 10

–The first 3 weeks = pre-embryonic period

–Weeks 4 to 8 = embryonic period

–Week 9 until birth = fetal period

Question 11

where does fertilization occur in the fillopian tube?

Answer 11

normally in the ampulla (widest part) - however it can occur anywhere in the tube

Question 12

Describe the stages of the ova after it is fertilized

Answer 12

Question 13

Describe the blastocyst stage of development

Answer 13

Question 14

At what point doe the blastocyst emerge from the zona pellucida and begin to adhere to the uterine wall

Answer 14

Day 6

Question 15

the first differentiation of the inner cell mass is into what types of cells?

Answer 15

ectoderm and endoderm (aka the epiblast and hypoblast)

Question 16

What is the purpose of syncytiotrophoblast?

Answer 16

They are Highly invasive - they eat into the uterine wall

Question 18

What type of cells form the yolk sac?

Answer 18

endoderm

Question 19

What layers form the placenta?

Answer 19

the trophoblast and extraembryonic mesoderm (from mother) along with the inner layer of the endometrium will develop into the placenta

Question 20

What are the stages of endometrial change during menstrual cycle

Answer 20

• Proliferative
• Ovulation
• Then secretory

Question 21

What occurs to the endometrium when no implantation?

Answer 21

• After ovulation
• Endometrium - maximum thickness
• Glands - corkscrew shape & producing glycogen.
• No implantation spasmodic constriction of spiral arterioles & degeneration and loss of functional layer = menses

Question 22

invasion of the corionic villi cause what?

Answer 22

it causes breakdown of the spiral arteries - allowing for pools of maternal blood (lacunae) that are closely associated with the chorionic villi - therefore nutrients can pass from the mother to the developing baby

Question 23

are cytotrophoblasts or syncytiotrophoblasts closer to the baby?

Answer 23

Cytotrophoblast

Question 24

What are the functions of the placenta

Answer 24

• Exchange of gasses
• Exchange of nutrients & electrolytes
• Maternal IgG

Endocrine functions – amongst others

•Secretes hCG – NB to maintain progesterone output

»And for pregnancy test

•Secretes oestrogens & progesterone

Question 25

as the pregnancy continues, what layer becomes predominant?

Answer 25

the syncytiotrophoblast

Question 26

Know the various structures in this picture

Question 27

do the fetal and maternal blood circulations mix?

Answer 27

no - there is an endothelial barrier -

however, if there is rupture of the villi - then you have Rhesus incompatibility

Question 28

as the pregnancy progresses, what layer begins very thin?

Answer 28

the trophoblastic layer

Question 29

Where is there intricate development of the chorionic villi?

Answer 29

at the chorion frondosum

Question 30

which cavity decreases in size as the baby gets larger?

Answer 30

the chorionic cavity

Question 31

as the embryo grows , what happens tothe decidual capsularis?

Answer 31

the decidua capsilaris attaches to the opposite side of the uterus - eliminating the uterine cavity - so now you have the amnion and chorion fused - these two membranes rupture during labor

Question 32

what is the umbilical cord composed of?

Answer 32

3 blood vessels - 2 arteries and 1 vein - embedded in loose connective tissue = Wharton’s Jelly

Question 33

What is a Hydatidifom mole?

Answer 33

implantation occurs - but the problem is that two spermatazoa pass through and they fuse together- this forms a diploid paternal cell which undergoes mitosis and develops - only develops the trophoblastic layer - which is highly invasive and can become cancerous -

Question 34

where can abnormal implantation occur?

Answer 34

normally occurs on the anterior/posterior wall of uteris but it can implant all the way down at the internal os - which is a challenge b/c during labor the blood supply to the baby is cut off and then the baby is in distress