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Anatomy > 2.Gametogenesis > Flashcards

2.Gametogenesis Flashcards

1
Q

No.of Chromosomes present in nucleus of each cell is

A

23 pairs (22pairs of autosomes + 1 pair of allosomes (sex chromosomes) )

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2
Q

Primordial germ cells (PGC) are….

A

The first sex cells of the body

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3
Q

Primordial germ cells (PGC) develop from

A

Epiblast cells

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4
Q

Primordial germ cells migrates towards…?

A

Genital ridge (abdomen region) to form gametes.(gametogenesis)

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5
Q

Aberrant migration of PGC results in

A

GERM CELL TUMOURS

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6
Q

Teratoma is a______? and have____?

A

Is a GERM CELL TUMOUR and have all three germ layers.

      1. ECTODERM
      2. ENDODERM
      3. MESODERM

As PGC is a PLEURIPOTENT cell

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7
Q

Mitosis is_____and Meoisis is______

A

Mitosis is Equational division (No change in no.of chromosomes).

Meoisis is REDUCTION DIVISION. (chromosome number changes).

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8
Q

Oropharyngeal teratoma occurs if…

A

PGC migrates to oropharynx instead of genital ridge.

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9
Q

Sacrococcygeal teratoma occurs if…

A

Primitive streak is persistant as PGCs will be present.

Usually primitive streak disappears

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10
Q

Order of formation of gametes

A

Epiblast cells—PGCs—gametogonia—primary gametocyte(spermatocyte/oocyte)—mature spermatocyte/oocyte—zygote

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11
Q

Which structures enter meoisis-1

A

Primary spermatocyte and primary occyte

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12
Q

Which enter meoisis-1 early. Primary spermatocyte or primary occyte…???

A

Primary oocyte entere meiosis-1 quite early than spermatocyte.

Spermatogenesis begins after puberty.
Oogenesis begins before birth.
(In-utero)

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13
Q

Mitosis occurs in______, meiosis occurs in_____?

A

Mitosis-somatic cells like skin, hair, bone and muscle cells in 1 sequence.

Meiosis occurs in germ cells in 2 sequences. (Meiosis-1 & meiosis-2)

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14
Q

Drugs acting on Metaphase (M PHASE) of mitosis

A

Paclitaxel-microtubule inhibitors-Hyperstabilize polymerized microtubules so that mitotic spindle cannot break down. (Anaphase cannot occur).

Vinblastine, vincristine (vinca alkaloids that bind beta-tubulin and inhibit its polymerization into microtubules Prevents mitotic spindle formation.
(M-phase arrest).

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15
Q

Events occurring in PROPHASE of MITOSIS

A
  1. Condensation of chromosomes.
  2. Nuclear envelope breaks down.
  3. Sister chromatids bound at the centromere.
  4. Spindle fibres grows from centrioles.
  5. Centrioles migrate to opposite poles of cells.
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16
Q

Events occurring in METAPHASE of MITOSIS

A
  1. Chromosomes arrange at equator(midline).
  2. Some spindle fibres attach to kinetochores.
  3. Fibres of aster attach to plasma membrane.
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17
Q

Events occurring in ANAPHASE of MITOSIS

A
  1. Centromere splits.
  2. SISTER CHROMATIDS SEPERATE FROM EACH OTHER.
  3. Each pole has an identical set of genes.
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18
Q

Events occurring in TELOPHASE of MITOSIS

A
  1. Two daughter cells are formed.
  2. Chromosomal number is similar to parent cells.
  3. Daughter cells are similar to parent cells.
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19
Q

Which structure enters meoisis-1?

A.Primary spermatocyte/oocyte
B.Secondary spermatocyte/oocyte
C.Spermatids/Mature oocyte
D.Gametogonia

A

A. Primary Gametocytes (primary spermatocyte / primary oocyte)

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20
Q

Stages of mitosis

A

Prophase-metaphase/anaphase-telophase

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21
Q

Stages of prophase-1

A

Leptotene—zygotene—pachytene—diplotene

22
Q

Chromosome condensation occurs in which stage of prophase-1

A

Leptotene

23
Q

Homologous chromosomes appears as BIVALENT in

A

Zygotene

24
Q

Chromosomes appears as tetrad and Sister chromatids are evident in

A

Pachytene

25
Q

Chiasma( cross-over) (exchange of genetic material) is seen in

A

Pachytene

26
Q

Primary oocyte is arrested in___and why?

A

Diplotene stage (prophase-1) of meiosis-1. (DICTYOTENE is the resting stage of oocyte at the end of diplotene)

Due to OMI (OOCYTE MATURATION INHIBITOR).
1. More cAMP causing prophase arrest.

LH AT PUBERTY REDUCES cAMP

27
Q

Primary occyte turns into secondary oocyte after..?

A

LH surge and completes meiosis-1 which results in formation of SECONDARY OOCYTE and FIRST POLAR BODY.

28
Q

Secondary oocyte is arrested in ?

A

Metaphase 2 of meoisis-2

29
Q

DNA duplication or replication occurs in

A

S ( synthetic) phase of Interphase or resting phase.
DNA REPLICATION
|
PGC———Oogonium———-primary
(2n,2N) (2n,2N). oocyte(2n,4N)
(Sisterchromatids)

30
Q

Materal & paternal chromosomes (Homologous chromosomes) seperation occurs in

A

Diplotene (prophase-1) (Meiosis-1)

31
Q

In meiosis separation of sister chromatids occurs in

A

Meoisis-2- Anaphase

32
Q

Which stage of oocyte is ovulated and menstruated?

A

Secondary oocyte which is arrested in metaphase of Meoisis-2.

33
Q

When Second polar body is released?

A

If Fertilization occurs then secondary oocyte which is arrested in metaphase of meiosis-2 will complete meiosis-2 and becomes Mature oocyte (ovum) (fertilized oocyte) and second polar body is released.

34
Q

In Females ratio of primary and final cells in oogenesis is 1:1 and male ratio is 1:4

A

If we start with one primary oocyte finally one mature oocyte is present and three polar bodies will be discarded/degenerated.

In males one primary spermatocyte gives 4 spermatids finally.

35
Q

Primary oocytes at birth, at 5th month and how many undergoes ovulation?

A

5th month of Intra uterine life(IUL)= 7 million.

At birth= 1-2 million

Undergoes ovulation= 400-500

36
Q

Oogenesis follows which law?

A

Independent assortment because during meiosis-1 where homologous chromosomes are separated there is 50% chance of that chromosome to be maternal or 50% chance for that chromosome to be paternal in daughter cell.

37
Q

Testis at birth has

A

Only primordial germ cells because they remain dormant till puberty in males and spermatogenesis begins only after puberty.

38
Q

How many days does spermatogenesis and oogenesis takes place

A

Spermatogenesis takes 74 days
i.e., from PGC to spermatocyte.

Oogenesis takes years for completion.

39
Q

Largest cell in spermatogenesis and oogenesis is

A

Primary spermatocyte is largest cell which undergoes meiosis-1 resulting in secondary spermatocyte which enters meiosis-2 and results in 4 spermatids.

In meiosis-1 Homologous chromosomes are separated whereas in meiosis-2 sister chromatids are separated.

In OOGENESIS Primary oocyte is the largest cell.

40
Q

When First polar body is released ?

A

First polar body is released at LH PEAK which occurs 12 hrs before ovulation. (Usually we will tell after LH Surge) (Before ovulation).

LH SURGE OCCURS 36 hrs before ovulation

LH peak occurs 12 hrs before ovulation (1st polar body is released).

41
Q

Fertilization should occur within..?

A

24 hrs of ovulation. If not degeneration of secondary oocyte occurs=MENSTRUATION

42
Q

WINDOW PERIOD FOR FERTILIZATION?

A

Females=24 hrs
Males=48 hrs

Sperms survival time in FEMALE= 5-10 days.

43
Q

Fertile peroid is

A

12th —15th day [ 3 days ]

44
Q

In case of no organic cause of infertility

LH KIT POSITIVE INDICATES?

A

Ovulation.
So advice for copulation.
Will have maximum chance of feetilization.

45
Q

In case of organic cause of infertility like Bilateral tubal blockage what are indicated for Fertilization?

A

ART (assisted reproductive techniques)

Like INVITRO FERTILIZATION

46
Q

In ART (INVITRO FERTILIZATION) ovary is hyper stumulated by whcih drug?

A

Clomiphene citrate

47
Q

Which stage is aspirated in INVITRO FERTILIZATION when ovary is hyper stimulated and when?

A

GRAFFIAN FOLLICLE. Just before ovulation.

SECONDARY OOCYTE IS RETRIEVED

48
Q

In INVITRO FERTILIZATION Trans vaginal insertion into uterus is done at which celled stage?

A

8 celled stage—Natural protocol

Some experts done it at 32 celled stage

49
Q

Drug used for infertility due to ANOVULATION? (Example PCOS)

A

CLOMIPHENE

Antagonist at oestrogen receptors in hypothalamus.

Prevents normal feedback inhibition and INCREASE the release of LH and FSH from pituitary which stimulates OVULATION.

SERMs (SELECTIVE OESTROGEN RECEPTOR MODULATOR) can cause hot flushes, ovarian enlargement, multiple simultaneous pregnancies and visual disturbances.

50
Q

SERMs (SELECTIVE OESTROGEN RECEPTOR MODULATOR) can cause ?

A

Hot flushes, ovarian enlargement, multiple simultaneous pregnancies and visual disturbances.

51
Q

Conceptus reaches uterine cavity on which day in which stage?

A

4th day in 16- 64 cell stage.

If options are 
A. 1 cell
B. 2 cell
C. 16 cell
D. 32 cell

Then go for D. 32 cell stage

Anatomy (3 decks)

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