Embrology Chapter 2

Front 1

Which division of meiosis reduces the the number of chromosomes?

Back 1

the first meiotic division
(reduction division)
reduced to haploid

Front 2

What is the "physical basis of segregation"?

Back 2

the separation of paired homologous chromosomes in the 1st mitotic division

separation of allelic genes

Front 3

what step is skipped in the 2nd mitotic division?

Back 3

Interphase

(no DNA replication)

Front 4

What are the 3 reasons why meiosis is important?

Back 4

provides constancy of chromosome number from generation to generation

allows random assortment

"shuffles" genes by crossing over of chromosome segments

Front 5

What is a common abnormality that results from a disturbances of meiosis? (nondisjunction)

Back 5

Down syndrome

Front 6

What is spermatogenesis?

Describe its processes.

Back 6

The process by which spermatogonia are transformed into mature sperms.

spermotogonia--> primary spermatocytes--> first meiotic division--> secondary spermatocytes--> secondary mieotic division--> spermatid

Front 7

Spermatogonia remain dormant from the fetal period until puberty in what gland?

Back 7

prostate
(seminiferous tubules)

Front 8

What are the largest germ cells in the seminiferous tubules?

Back 8

primary spermatocytes

Front 9

What is the process in which spermatids develop into mature sperm?

Back 9

spermiogenesis

(This stage is in included in spermatogenesis)

Front 10

Approx how long does the entire process of spermiogenesis take?

Back 10

2 months

Front 11

When spermiogenesis is complete, sperms enter the ________ of the seminiferous tubules.

Back 11

lumina

Front 12

What are the cells that line the seminiferous tubules that support and nurture the germ cells?

Back 12

sertoli cells

Front 13

What is the name of the tube that transfers the sperm from the epididymis to the urethra?

Back 13

ductus (vas) deferns

Front 14

What region is the acrosome of the sperm developed in?

Back 14

The golgi region

Front 15

What is shed from the from the spermatids during spermiogenesis?

Back 15

residual cytoplasm

Front 16

What does the acrosome of a mature sperm contain?

Back 16

enzymes that are released at the beginning of fertilization to assist in dispersion of the follicular cells of the corona radiata and penetration of the zona pellucida

Front 17

What are the 3 segments of the tail of the sperm?

Back 17

middle piece
principal piece
end piece

Front 18

Which segment of the tail of the sperm contain the mitochondria?

Back 18

middle piece of the tail

Provides the tail with ATP

Front 19

Recent studies have shown that proteins of the Bcl-2 family are involved in what in spermatogenesis?

Back 19

maturation of germ cells as well as their survival at different stages

Front 20

Is the Y chromosome essential for normal spermatogenesis?

Back 20

YES

Front 21

What is oogenesis?

Back 21

The process in which oogonia are transformed into mature oocytes

(process begins before birth, and ends after puberty)

Front 22

What is menopause?

Back 22

permanent cessation of the menses

Front 23

Oogonia enlarge to form primary oocytes. When does this process occur?

Back 23

Before birth

Front 24

What is a primordial follicle?

Back 24

a primary oocyte enclosed by a single layer of flattened, follicular epithelial cells

Front 25

What is a primary follicle?

Back 25

stage of oogenesis at puberty
follicular epithelial cells become cuboidal and then columnar

This is where you see the zona pelicula (amorphous acellular layer of glycoprotein material)

Front 26

When does prophase of the 1st meiotic division of primary oocytes occur?

Back 26

begins before birth and ends in adolescense

Front 27

What is oocyte maturation inhibitor and what secretes it?

Back 27

believed to keep the meiotic process of the oocyte arrested from birth to adolescence

secreted by follicular cells

Front 28

At ovulation, the nucleus of the secondary oocyte begins the second meiotic division, but only makes it to what pahse by itself?

Back 28

metaphase

If sperm penetrates it, the second division will be complete

Front 29

Approx how many primary oocytes are in the ovaries of a newborn female?

Back 29

2 million

Front 30

About how many primary oocytes remain in the ovaries during adolescence?

Back 30

40,000

Front 31

Describe the 2 kinds of normal sperm and the 1 kind of a normal secondary oocyte

Back 31

Sperm: 23 X and 23 Y

Secondary oocyte: 23 X

Front 32

What is the ideal maternal age for reproduction in females?

Back 32

18-35

Front 33

Approx how many sperms in an ejaculate are abnormal?

Back 33

approx 10%

(have 2 heads)

It is believed that these sperm will not fertilize the egg due to their lack of normal motility

Front 34

What is the average length of a uterus?

Back 34

7-8 cm in length

5-7 cm in width at its superior part
2-3 cm in wall thickness

Front 35

Where are the internal and external os located?

Back 35

the internal os communicates with the cavity of the uterine body

the external os communicates with the vagina

Front 36

What are the 3 layers of the wall of the uterus?

Back 36

perimetrium (thick outer layer)
myometrium (thick SM layer)
endometrium (thin internal layer)

Front 37

During the menstrual cycle, 3 layers of the endometrium are evident. What are they?

Back 37

compact layer
spongy layer
basal layer

usually 4-5 mm thick at the peak of its development

Front 38

Which layer of endometrium has it's own blood supply and is not sloughed off during mestruation?

Back 38

basal layer

Front 39

What are the spongy and compact layer of endometrium referred to as collectively?

Back 39

functional layer

Front 40

What are the 4 parts of the uterine tube?

Back 40

infundibulum
ampulla (fertilization site)
isthmus
uterine part

Front 41

What are the ovaries responsible for producing?

Back 41

oocytes
estrogen
progesterone

Front 42

Where is GRH synthesized?

Back 42

hypothalmus

(carried by the hypophysical portal system to the anterior lobe of the pituitary)

Front 43

What does gonadotropin-releasing hormone stimulate the release of in the pituitary?

What do these hormones do?

Back 43

FSH- stimulates development of follicles and the production of estrogen by follicular cells

LH- "trigger" for ovulation (release of secondary oocyte). Also stimulates follicular cells and corpus luteum to produce progesterone

Both induce growth of endometrium

Front 44

FSH usually promotes the growth of how many primordial follices?

Back 44

Usually 5-12

But only one primary follicle develops into a mature follicle

Front 45

What are the 2 layers of the theca folliculi?

Back 45

internal vascular (theca interna)
glandular layer (theca externa)

Front 46

What do theca cells produce that promotes growth of blood vessels in the theca interns?

Back 46

angiogenesis factor

Front 47

What is the name for the fluid-filled cavity inside the folllicle?

Back 47

antrum

(contains follicular fluid)

Front 48

In a histology slide, what is the indication that the follicle is now secondary?

Back 48

when the antrum has been formed

Front 49

What is the name for the mound of follicular cells that surrounds the oocyte in a secondary follicle?

Back 49

cumulus oophorus

Front 50

What hormone do growing follicles produce?

Back 50

estrogen

Front 51

What is the function of theca interna?

Back 51

produces androgens in response to LH which is later converted by follicular cells to estrogen

Also produce follicular fluid

Front 52

What is the interstitial gland of the ovary?

Back 52

scattered groups of stromal secretory cells that also produce estrogen in the follicle

Front 53

What is the stigma of the ovary?

Back 53

a small avascular spot that appears as a result of the follicle swelling right before it bursts out

Front 54

Which hormone surge results in ovulation?

Back 54

LH

Usually follows the LH peak by 12-24 hours

Front 55

What triggers the LH surge?

Back 55

High estrogen levels in the blood

Front 56

What causes the oocyte to burst out?

Back 56

Intrafollicular pressure

possible contraction of the smooth muscle of theca externa

enzymatic digestion of the follicular wall

Front 57

What does the LH surge also do regarding the oocyte?

Back 57

It induces resumption of the first meiotic division of the primary oocyte

Front 58

What are the 2 glycoproteins that make up the zona pellucida

Back 58

ZPA
ZPB
ZPC

Front 59

What is mittelschmerz?

Back 59

Abdominal pain associated with slight bleeding into the peritoneal cavity as a result of ovulation

German
Mittel=mid
schmerz=pain

Front 60

What is anovulation?

Back 60

cessation of ovulation because of inadequate release of gonadotropins

Front 61

What 2 hormones are produced by the corpus luteum?

Back 61

estrogen and progesterone

(if the oocyte is fertilized, the corpus luteum enlarges to form a corpus luteum of pregnancy and bumps up its hormone production)

Front 62

Degeneration of the corpus luteum is prevented by .....

What is this hormone secreted by?

Back 62

human chroionic gonadotropin

secreted by the syncytiotrophoblast of the blastocyst

Front 63

How long during pregnancy does the corpus luteum remain active?

Back 63

During the first 20 weeks

At 20 weeks, the placenta takes over its job

Front 64

If there is no fertilization, how long will it take the corpus luteum to degenerate?

Back 64

10-12 days after ovulation

(then called the corpus luteum of menstruation)

Front 65

What is the name of the white scare that remains as a result of the degeneration of the corpus luteum?

Back 65

corpus albicans

Front 66

What are the age ranges of menopause?

Back 66

48-55

Front 67

What is climacteric?

Back 67

The endocrine, somatic, and psychological changes that occur during menopause

Front 68

What is happening during day 1 of the menstrual cycle?

Back 68

menstrual flow begins

Front 69

What are the 3 phases of the menstrual cycle?

Back 69

Mestrual
Proliferative
Luteal (spiral arteries grow into compact layer in this phase)

Front 70

What is the ischemic phase of the menstrual cycle?

Back 70

Occurs when oocyte is not fertilized
spiral arteries constrict as a result of decreases hormones
blood supply is reduced
venous stasis and patchy ischemic necrosis
torn arteries bleed

Front 71

How much blood is lost during menstration?

Back 71

20-80mL

Front 72

If fertilization occurs, when does the blastocyst begin to implant in the endometrium?

Back 72

Approx the 6th day of the luteal phase

(day 20 of the 28 cycle)

Front 73

What is peristalsis?

Back 73

movements characterized by alternate contraction and relaxation that moves the oocyte or sperm through the tubes

Front 74

How many sperms are usually deposited around the external os of the uterus and fornix of the vagina?

Back 74

200 to 600 million

Front 75

What is the purpose of the enzyme vesiculase?

Back 75

it coagulates some of the semen or ejaculate and forms a vaginal plug that may prevent backflow of the semen into the vagina.

* produced by seminal galnds

Front 76

What are the 2 parts of the reflex ejaculation of semen?

Back 76

Emission (sympathetic response)
Ejaculation

Front 77

How are prostoglandins help the process of fertilization?

Back 77

They are thought to stimulate uterine motility at the time of intercourse and assist in the movement of sperms

Front 78

What is the energy source of sperm and what secretes it?

Back 78

Fructose
seminal glands

Front 79

What is the usual volume of sperm ejaculated?

Back 79

3.5 mL with a range of 2-6 mL

These sperm move 2-3 mm per minute (varies with pH of environment)

Front 80

Are the sperm motile or nonmotile during storage in the epididymis?

Back 80

nonmotile

Front 81

Where do sperm start to move more quickly?

Back 81

They are slow in the acidic environment of the vagina, and move more quickly in the alkaline environment of the uterus

Front 82

How many sperms actually reach the fertilization site?

Back 82

200

Front 83

What is capacitation and how long does it take?

Back 83

Process in which a glycoprotein coat and seminal proteins are removed. Occurs in the uterus or tubes
7 hours

Front 84

What is the acrosome reaction?

Back 84

where the acrosome of the sperm binds to glycoprotein (ZP3) on the zona pellicula

enzymes hyaluronidase and acrosin from the acrosome facilitate fertilization

Front 85

What is the percentage of sperm in semen?

Back 85

less than 10%

Front 86

What is dispermy?

Back 86

The process of 2 sperms participate in fertilization

Front 87

What is triploidy?

Back 87

result of dispermy
69 chromosomes
nearly always abort
If birthed, die shortly after

Front 88

How long does the oocyte have to be fertilized after ovulation?

Back 88

24 hours until it degeneralted

Front 89

Which 2 enzymes appear to assist in the dispersal of the follicular cells of the zona radiata?

Back 89

hyaluronidase
tubal mucosal

Front 90

Which enzymes appear to cause lysis of the zona pellucida?

Back 90

esterases
acrosin (most important)
neuraminidase

Front 91

What is the zona reaction?

Back 91

a change in properties (after one sperm penetrates) of the zona pelludica making it impermeable to other sperm

Front 92

What is the name for the oocyte that contains 2 indistinguishable haploid pronuclei? (one from the female and one from the male)

Back 92

ootid

Front 93

How is the zygote formed?

Back 93

by fusion of the pronuclei into a single diploid aggregation of chromosomes

Front 94

What is early pregnancy factor?

Back 94

an immunosuppressant protein secreted by trophoblastic cells within 24-48 hours of fertilization

Front 95

Statistically, are more boys or more girls born?

Back 95

105 boys per 100 girls

Front 96

During in vitro fertilization, when is the zygote ready to be implanted into the uterus?

Back 96

After 4-8 cell stages are reached from cleavage

Front 97

What is cryopreservation?

Back 97

The freezing of zygotes after they reach the 4-8 cell stage

Front 98

What is intracytoplasmic sperm injection?

Back 98

When sperm is injected directly into the cytoplasm of a mature oocyte

Front 99

What is gamete intrafallopian transfer?

Back 99

laparoscopic placement of several oocytes and sperms into the uterine tubes to allow fertilization in it's normal location

Front 100

When and where does the division of the zygote begin?

Back 100

30 hours after fertilization
as it is passing down through the fallopian tubes

Front 101

What is a mosaic?

Back 101

an individual with numerical mosaicism
nondisjunction occurs during an early cleavage division of the zygote

Front 102

How is the blastocytic cavity formed as the morula enters the uterus?

Back 102

fluid passes from the uterine cavity through the zona pelllucida

Sep

Front 103

What are the 2 parts of a blastocyst?

Back 103

trophoblast (thin outer cell layer)
Gives rise to the placenta

Inner cell mass or embryoblast (group of centrally located blastomeres)
Gives rise to the embryo

Front 104

When does the zona pellucida of the blastocyst degenerate and why?

Back 104

2 days after the blastocyst has been free floating in the uterine cavity

shedding of this layer permits the hatched blastocyst to increase rapidly in size

Front 105

What side of the blastocyst attaches to the wall of the uterus?

Back 105

embryonic pole

Front 106

After attachment to the uterine wall, what 2 layers do the trophoblast form at the embryonic pole?

Back 106

cytotrophoblast
syncytiotrophoblast

Front 107

Approx what day does the processes of the syncytiotrophoblast extend through the endometrial epithelium and invade the connective tissue?

Back 107

day 6

Front 108

approx what day does the hypoblast cell layer form on the surface of the embryoblast facing the cavity?

Back 108

day 7