Kuehn - Gamete Development/Fertilization Flashcards Preview

► Med Misc 28 > Kuehn - Gamete Development/Fertilization > Flashcards

Flashcards in Kuehn - Gamete Development/Fertilization Deck (42):
1

How is an oocyte transported to the ampulla?

after rupturing the outer epithelium of the ovary, enters peritoneal cavity, cumulus oophorus is hooked by cilia and pulled into infundibulum, via peristalsis is then pulled into ampulla

2

How long can an oocyte remain in the ampulla?

12-24hrs

3

How do sperm enter the ampulla after being deposited in birth canal?

combination of uterine peristaltic movements and sperms own chemotaxis(motility) towards oocyte

4

What part of the oocyte degrades in the ampulla?

the cumulus oophorus degrades into corona radiata

5

When does fertilization begin?

sperm reaches corona radiata of oocyte, passes through and attaches to Zona Pellucida

6

What glycoproteins help the sperm to bind to Zona Pellucida?

ZP3

7

What does the sperm release from its acrosome?

enzymes that digest Zona Pellucida

8

What happens once the sperm has penetrated Zona Pellucida?

fusion of sperm and oocyte membranes occurs

9

What makes Zona penetration by a second sperm unlikely?

when zona is penetrated there is a release of cortical granules from oocyte preventing a second intruder (Ca++ mediated)

10

What occurs in order for pronuclei to fuse into a single nucleus?

oocyte completes second meiotic division = female pronucleus
sperm nucleus becomes male pronucleus

11

The fused pronuclei are now technically what?

a zygote

12

What is the acrosome of a sperm?

the head which contains digestive enzymes that aide in oocyte fertilization

13

What contains the sperms haploid DNA (N) in condensed form?

the nucleus within the head

14

What contains the mitochondria of the sperm?

the Mid-piece

15

What does the mitochondria do for the sperm?

powers the flagellum for motility

16

What part of the sperm contains microtubules for motility?

the tail

17

What cell does spermatogenesis begin with and they only divide by which method?

begins with stem cell - Type Ad spermatogonium
ALL spermatogonia divide by mitosis

18

What is the product of Type Ad spermatogonium division?

1 - Type Ad spermatogonium
1 - Type Ap spermatogonium

19

Type Ap spermatogonium further divide by mitosis and differentiate into what?

Type B spermatogonia (terminal differentiation) which divide by mitosis into primary spermatocytes

20

How do the primary spermatocytes form into secondary spermatocytes?

they divide by meiosis in Division I (reduction division)

21

What is formed when the secondary spermatocytes undergo Division II of meiosis?

Spermatids (round cells) are formed! (genetically mature gametes - not physically mature)

22

What occurs after morphological differentiation of spermatids (spermiogenesis)?

nucleus condenses and Normal sperm forms = mature Spermatozoan

23

What triggers the spermatids to mature?

a response to Bcl2-family gene products

24

What are follicles?

they contain oocytes, throughout their development, and follicular cells

25

When do oogonia complete differentiation into primary oocytes?

oogonia is only found in fetus and completes differentiation by birth

26

When does the primary oocyte begin to form a secondary oocyte?

it remains in Prophase of Division I until a signal initiates further development

27

Where are the secondary oocytes found?

only in final stage of Graffian follicle, just before ovulation (1 day or so)

28

What is a primordial follicle?

only one thin layer of follicular cells

29

What is a primary follicle?

cuboidal layer of follicular cells

30

What is a secondary follicle?

a growing follicle with primary oocyte

31

What is a mature/antral/graffian follicle?

it contains antrum and primary/secondary oocyte

32

After fertilization what occurs in the zygote?

cells rapidly manufacture new proteins(microtubules, histones, and enzymes) and the DNA replicates

33

When does the zygote move into the uterine tube?

after about 30 hours and undergoes first cleavage into two blastomeres

34

What happens to the blastomeres after first cleavage?

cells synchronously divide until LAST stage of 8 cells and are surrounded by Zona Pellucida

35

What is the ball of 12-32 cells still bound in Zona Pellucida called and how long since fertilization is it?

MORULA and it is now 3 days after fertilization

36

What happens to the cells in the morula at ~ day 4 of fertilization?

cells shrink and migrate to the edge leaving a cavity in the center (blastocyst cavity) - called early blastocyst

37

Describe the parts of the early blastocyst?

whole surrounded by zona pellucida, trophoblast cells surround embryoblast/epiblast (inner cell mass) and hypoblast

38

What happens in humans on day 5 after fertilization?

zona pellucida breaks open and blastocyst squeezes out, exposed receptors on trophoblast will attach to uterus

39

Timing is everything! What can happen if timing of blastocyst attachment is wrong?

blastocyst will implant on any surface, errors in timing result in extopic attachment (ovary, mesenteries, uterine tube)

40

What does the blastocystic cavity become?

it becomes the exocelomic cavity

41

What does the exocelomic cavity become?

becomes the yolk sac cavity

42

what becomes the bilaminar embryonic disc?

the epiblast and hypoblast together make up the embryonic disc