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A general Embryo (Lecturio) > 1. Gametes, fertilization, cleavage and blastulation > Flashcards

1. Gametes, fertilization, cleavage and blastulation Flashcards

1
Q

This is scale of prenatal development.

  1. Weeks that embryogenesis occur?
  2. Weeks that fetal development (fetus) occur?
A
  1. 3rd → 8th weeks: embryogenesis
  2. 9th → 40th weeks: fetal development (fetus)
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2
Q

What is Zona Pellucida (ZP_?

A

specialized extracellular matrix (ECM) which is produced by the oocyte and follicular granulosa cells

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3
Q

What are main glycoproteins of Zona Pellucida (ZP)?

A

ZP1, ZP2, ZP3, ZP4

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4
Q

6 general functions of Zona Pellucida (ZP)?

A
  1. protection
  2. transport
  3. sperm binding
  4. prevention of polyspermy
  5. support of blastocyst development
  6. prevention of early implantation
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5
Q

2 Functions of ZP1, ZP3 and ZP4

A
  1. bind to the capacitated human spermatozoa
  2. induce acrospmal reaction
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6
Q

2 functions of ZP2

A
  • sperm recognition receptor (It is cleaved by ovastacin released from cortical granules after fertilization and other sperm can not bind to the oocyte)
  • plays an important role in defence against polyspermy.
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7
Q

What is gametogenesis?

A

The conversion of germ cells into male and female gametes

→ It happens in order to reduce the number of chromosomes and to complete their maturation

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8
Q

What are Prenatal events?

A

Primordial germ cells develop from epiblast during the second week and appear in the wall of the yolk sac at the end of the 3 rd week of development.

Germ cells migrate from the yolk sac toward the developing gonads (primitive sex glands). They arrive at the end of the 4 th or the beginning of the 5 th week.

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9
Q

Gametogenesis → Prenatal events

  • Primordial germ cells develop from (1)____ during the (2)____ week and appear in the wall of the yolk sac at the end of the (3)____ week of development.
  • Germ cells migrate from the yolk sac toward the (4)____. They arrive at the end of the (5)___ week or the beginning of the (6)___ week.
A
  1. epiblast
  2. second
  3. third
  4. developing gonads (primitive sex glands)
  5. fourth
  6. fifth
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10
Q

Gametogenesis → Prenatal events

  • (1)____ develop from epiblast during the second week and appear in (2)___ at the end of the 3 rd week of development.
  • Germ cells migrate from (3)____ toward the developing gonads (primitive sex glands). They arrive at the end of the 4 th or the beginning of the 5 th week.
A
  1. Primordial germ cells
  2. the wall of the yolk sac
  3. the yolk sac
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11
Q

What is spermatogenesis?

A

the sequence of events by which spermatogonia are transformed into mature gametes: sperm (spermatozoa).

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12
Q

3 events of spermatogenesis

A
  1. Spermatocytogenesis : asymmetric division of spermatogonia. Some of them remain „stem cell”, others start the differentiation process.
  2. Meiosis: meiotic division of spermatocytes (I and II)
  3. Spermio (histo)genesis: spermatids are transformed to sperm that can fertilize eggs
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13
Q

Sequences of formation of spermatids

A

SPERMACYTOGENESIS AND MEIOSIS

Spermatogonia

→ mitosis, growth

→ primary spermatocytes

→ first meiotic division

→ second spermatocytes

→ second meiotic division

→ spermatids

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14
Q

What is Spermio(histo)genesis?

A

Transformation of spermatids into spermatozoa

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15
Q

4 events happening during Spermio(histo)genesis?

A

(a) Formation of acrosome cap (lysosome-hydrolytic enzymes for acrosomal reaction of fertilization)
(b) Condensation and elongation of the nucleus
(c) Development of flagellum (formation of neck, middle piece and tail)
(d) Shedding of most of the cytoplasm

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16
Q

During spermatogenesis

→ The supporting cells are derived from the (1)___ and become (2)____

A

surface epithelium of the testis

Sustentacular/Sertoli Cells

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17
Q

Just before puberty, the sex cords acquire lumen and become the ____

A

Seminiferous Tubules

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18
Q

Just before puberty, ___ acquire lumen and become the Seminiferous Tubules

A

the sex cords

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19
Q

Just before puberty, the sex cords acquire lumen and become the Seminiferous Tubules

→ At the same time PGCs give rise to ___

A

Spermatogonial cells

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20
Q

What is Type A Spermatogonia?

A

Type A spermatogonia, derived from the spermatogonial stem cell population, represent the first cells in the process of spermatogenesis.

→ undergo a limited number of divisions to clone themselves

(with the last division producing Type B Spermatogonia)

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21
Q

Type B Spermatogonia divide to form ____ which stay in prophase for ~22 days

A

Primary Spermatocytes,

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22
Q

___ divide to form Primary Spermatocytes, which stay in prophase for ~22 days

A

Type B Spermatogonia

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23
Q

Type B Spermatogonia divide to form Primary Spermatocytes, which stay in prophase for ~22 days

→ After completing Meiosis 1, these cells form (1)___

→ During Meiosis 2, (2)___ are formed

A
  1. Secondary Spermatocytes
  2. haploid Spermatids
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24
Q

Spermatogonia and Spermatids are embedded in deep recesses of ____ while they develop

A

Sertoli cells

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25
Q

Spermatogenesis is regulated by ___ by the Pituitary Gland

A

LH (Luteinizing hormone) production

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26
Q

Spermatogenesis is regulated by LH (Luteinizing hormone) production by ___

A

the Pituitary Gland

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27
Q

Spermatogenesis is regulated by LH production by the Pituitary Gland

o LH binds to (1)___ -> stimulates testosterone production -> binds to Sertoli cells -> promotes (2)___

FSH binds to Sertoli cells -> stimulates (3)___

A
  1. Leydig cells
  2. spermatogenesis
  3. testicular fluid & intracellular androgen receptor production
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28
Q

Spermatogenesis is regulated by LH (Luteinizing hormone) production by the Pituitary Gland

  • (1)___ binds to Leydig cells -> stimulates testosterone production -> binds to (2)___ -> promotes spermatogenesis
  • (3)___ binds to Sertoli cells -> stimulates testicular fluid & intracellular androgen receptor production
A
  1. LH (Luteinizing hormone)
  2. Sertoli cells
  3. The follicle stimulating hormone (FSH)
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29
Q

Fully formed Spermatozoa enter (1)___

→ they are pushed toward the (2)___

A
  1. the lumen of the Seminiferous tubules
  2. Epididymis (where they will gain full motility)
30
Q

In the first stage of meiosis, (1)___ are divided

In the second stage of meiosis, (2)___ are divided.

A
  1. the homologous chromosomes
  2. the chromatids
31
Q

Spermatocyte meiosis occurs in ____ in the testes and results in four gametes (spermatids) of equal size.

A

the convoluted seminiferous tubules

32
Q

Spermatocyte meiosis occurs in the convoluted seminiferous tubules in the testes and results in __

A

four gametes (spermatids) of equal size.

33
Q

Ejaculate (semen, seminal fluid) is composed of __ (2 parts)

A

a cellular part and a fluid part.

34
Q

Ejaculate (semen, seminal fluid) is composed of a cellular part and a fluid part.
→ What does the cellular part consist?

A

The cellular component consists mainly of spermatozoa, as well as sloughed-off epithelial cells from the genital tract.

35
Q

Ejaculate (semen, seminal fluid) is composed of a cellular part and a fluid part.
→ What does the fluid part consist?

A

The fluid component of semen, known as seminal plasma, consists of fluid secreted in the epididymis and accessory sex glands (prostate, seminal vesicle)

36
Q

After migration, sperm cells undergo (1)___, a process that is also assisted by (2)___ (which hormone?).

A
  1. capacitation
  2. estrogen
37
Q

What is Capacitation?

A

A biochemical and physiological “maturation process” that allows the sperm cell to penetrate an egg cell.

→ The resulting changes to the plasma membrane of the spermatozoa are necessary for the subsequent acrosome reaction.

38
Q

What is Oogenesis?

A

Oogenesis is the process whereby oogonia differentiate into mature oocytes.

39
Q

What are contraceptive pills?

A

combination of estrogen and progesteron or progesteron only (mini pills)

40
Q

3 events that Contraceptive pills inhibit?

A

(i) the release of FSH and LH from the pituitary gland → inhibition of ovulation (but permit menstruation)

(ii) preparation of the lining of the uterus for implantation and

(iii) changing the uterine mucus to avoid sperm penetration into the egg.

41
Q

4 events of oogenesis

A
  1. Primary Oocyte Formation
  2. Folliculogenesis
  3. Follicular Growth & Development
  4. Follicular Atresia
42
Q

When will oogenesis begin?

A

Before BIRTH

43
Q

How is primary oocyte formed?

A

In the female, PGCs form oogonia.

→ After repeated mitotic divisions, some of these arrest in prophase of meiosis I to form primary oocytes.

44
Q

In the female, PGCs form oogonia.

→ After ____, some of these arrest in prophase of meiosis I to form primary oocytes.

A

repeated mitotic divisions

45
Q

In the female, PGCs form oogonia.

→ After repeated mitotic divisions, some of these arrest in ___ to form primary oocytes.

A

prophase of meiosis I

46
Q

OOGENESIS

By the seventh month, many oogonia have become (1)____

→ only (2)___ remain surrounded by a layer of follicular cells derived from the surface epithelium of the ovary

A
  1. atretic
  2. primary oocytes
47
Q

OOGENESIS

By the (1)___ month, many oogonia have become atretic

→ only primary oocytes remain surrounded by a layer of (2)____ derived from the surface epithelium of the ovary

A
  1. seventh
  2. follicular cells
48
Q

Oogenesis

By the seventh month, many oogonia have become atretic

→ only primary oocytes remain surrounded by a layer of follicular cells derived from ___

A

the surface epithelium of the ovary

49
Q

Oogenesis at puberty

→ describe

A

At puberty, a pool of growing follicles is recruited and maintained from the finite supply of primordial follicles.

50
Q

3 stages that follicles must pass to mature

A

(1) primary or preantral
(2) vesicular or antral
(3) mature vesicular or graafian follicle.

51
Q

The primary oocyte remains in prophase of the first meiotic division until ___

A

the secondary follicle is mature.

52
Q

The primary oocyte remains in prophase of the first meiotic division until the secondary follicle is mature.

→ At this point, a surge in ___ stimulates preovulatory growth

A

luteinizing hormone (LH)

53
Q

a surge in luteinizing hormone (LH) stimulates preovulatory growth: (1)____ is completed, and (2)_____ (2 things) are formed.

A
  1. Meiosis I
  2. secondary oocyte and polar body
54
Q

What is ovulation?

A

The process in which Ovum enlarges and follicle ruptures then shed from ovary

55
Q

With each (1)____, a number of primary follicles begin to grow, but usually only one reaches full maturity, and only one oocyte is dis- charged at (2)___

A
  1. ovarian cycle
  2. ovulation
56
Q

What happen during ovulation?

A

The oocyte, in metaphase of meiosis II, is discharged from the ovary together with a large number of cumulus oophorus cells.

→ Follicular cells remaining inside the collapsed follicle differentiate into lutein cells.

57
Q

Ovulation

→ What is stigma?

A

avascular area appears over most convex point of follicle

58
Q

What is the role of the corpus luteum?

A
  • To produce hormones (progesterone, estrogen) essential for preparing the uterus for pregnancy and then for maintaining that pregnancy until the placenta becomes fully functional (approximatelythe beginning ofthe fourth month).
  • The corpus luteum originates from the theca interna (derived from ovarian stromal cells) and from granulosa cells that remain in the ovary after ovulation.
59
Q

What is the origin of the corpus luteum?

A
  • The corpus luteum originates from the theca interna (derived from ovarian stromal cells) and from granulosa cells that remain in the ovary after ovulation.
60
Q

What happen during capacitation

A

Capacitation, during which time a glycoprotein coat and seminal plasma proteins are removed from the spermatozoon head

61
Q

During fertilization, the spermatozoon must penetrate ___ (3 things)

A
  1. The corona radiata
  2. The zona pellucida
  3. The oocyte cell membrane (Fig. 3.5)
62
Q

What are the 3 phases of fertilization?

A
  • Phase 1*: Penetration of the corona radiata
  • Phase 2*: Penetration of the zona pellucida
  • Phase 3*: Fusion of the oocyte and sperm cell membranes
63
Q

Fertilization

What happen during Phase 1: Penetration of the corona radiata?

A

Capacitated sperm penetrates the barrier corona radiata by „the corona radiata penetrating enzyme”, hyaluronidase, phosphatase and acrosine .

→ The enzymes are released from the plasma membrane of the sperm, that break apart the cell junctions and ECM.

64
Q

Fertilization

Phase 1: Penetration of the corona radiata

Capacitated sperm penetrates the barrier corona radiata by „the corona radiata penetrating enzyme”, which are ___ (3 enzymes)

→ The enzymes are released from the plasma membrane of the sperm, that break apart the cell junctions and ECM.

A

hyaluronidase, phosphatase and acrosine .

65
Q

Fertilization

Phase 1: Penetration of the corona radiata

Capacitated sperm penetrates the barrier corona radiata by „the corona radiata penetrating enzyme”, which are hyaluronidase, phosphatase and acrosine .

→ The enzymes are released from (1)___, that break apart (2)___

A
  1. the plasma membrane of the sperm
  2. the cell junctions and ECM.
66
Q

Fertilization

What happen during Phase 2: Penetration of the zona pellucida

A

The outer membrane of the sperm binds to ZP proteins (ZP1, ZP3 and ZP4 of the ZP)

→ (acrosomal reaction begins) formation of composite membrane

→ release of enzymes (neuramidase and acrosine)

→ breaking down ZP

→ sperm reaches the vitelline membrane of the oocyte

67
Q

Fertilization

Phase 1: Penetration of the zona pellucida

The outer membrane of the sperm binds to (1)____

→ (acrosomal reaction begins) formation of composite membrane

→ release of enzymes which are (2)___

→ breaking down ZP

→ sperm reaches the (3)____

A
  1. ZP proteins (ZP1, ZP3 and ZP4 of the ZP)
  2. neuramidase and acrosine
  3. vitelline membrane of the oocyte
68
Q

Fertilization

What is cortical reaction?

A

When fertilin (on the head of the fastest sperm) connects to integrin of the oocyte vitellin membrane, Ca2+-influx (depolarization) increases and then exocytosis of cortical granules (CG) occurs.

→ Enzymes released from the CG cleave ZP molecules and inhibit the docking of other sperm. Other peptides from CG facilitate the increase of osmotic pressure → the periveitelline space takes up water and expands. The structural composition of the membrane changes. These events prevent polyspermy.

69
Q

Fertilization

CORTICAL REACTION

When (1)____ connects to integrin of the oocyte vitellin membrane, (2)____ increases and then exocytosis of (3)___ occurs.

A
  1. fertilin (on the head of the fastest sperm)
  2. Ca2+-influx (depolarization)
  3. cortical granules (CG)
70
Q

Fertilization

CORTICAL RACTION

When fertilin (on the head of the fastest sperm) connects to integrin of the oocyte vitellin membrane, Ca2+-influx (depolarization) increases and then exocytosis of cortical granules (CG) occurs.

→ Enzymes released from the CG cleave (1)___ and inhibit (2)____.

→ Other peptides from CG facilitate the increase of (3)___

→ the periveitelline space takes up water and expands.

→ The structural composition of the membrane changes.

→ These events prevent (4)___.

A
  1. ZP molecules
  2. the docking of other sperm
  3. osmotic pressure
  4. polyspermy
71
Q

Cleavage

What are blastomere?

A
  1. tissues of the embryo proper
  2. the trophoblast
  3. placenta

A general Embryo (Lecturio) (10 decks)

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