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Microanatomy > Gametogenesis and Fertilization > Flashcards

Gametogenesis and Fertilization Flashcards

1
Q

primordial germ cells

A
  • progenitors of gametes

- from yolk sac endoderm, migrate to genital ridge and become indifferent gonad

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2
Q

intermediate mesoderm

A

-urogenital organs: leydig cells, sertoli cells, follicular cells, ovary, testis, ducts, uterus

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3
Q

urogenital sinus endoderm

A

-terminal internal parts of genital organs: vesicular, prostate and bulbourethral glands

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4
Q

Mullerian (paramesonephric) ducts

A
  • develop into fallopian tubes, uterus, cervix

- in male they disappear under the influence of anti-paramesonephric duct hormone

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5
Q

prepuberal testis

A
  • seminiferous cords consisting of: sertoli cells, primordial germ cells (stem cells for spermatogenesis-stay dormant until puberty)
  • inactive interstitial cells of leydig
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6
Q

cryptochidism

A

testes fail to descend into scrotum, inherited as a sex-limited autosomal recessive trait

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7
Q

types of cryptorchidism

A
  • unilateral

- bilateral: sterile but has normal sexual behavior

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8
Q

scrotal hernia

A

type of inguinal hernia=congenital weakness in the abdominal wall

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9
Q

primitive sex cells

A

spermatogonia, oogonia- have complete DNA complement.

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10
Q

spermatogonia and oogonia Mitosis

A

results in more spermatoginia and oogonia

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11
Q

spermatocye and oocyte meiosis

A

insure variation and provide 1/2 of chromosomes (haploid number) both in male (1N) and female (1N) sex cells (gametes)

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12
Q

fertilization

A

joining of sex cells, create zygote, restores DNA complement (2N) initiates cleavage

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13
Q

mitosis

A

results in formation of 2 daughter cells each having DIPLOID set of chromosomes, same number as in the mother cell

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14
Q

Meiosis

A

comprised of 2 meiotic divisions, results in daughter cells which have half the parental number of chromosomes (haploid), called gametes

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15
Q

goals of meiosis

A
  • reduction of diploid set chromosomes into haploid gametes
  • exchange of genetic material between male and female chromatids in prophase of meiosis (crossing over)
  • results in 4 daughter cells with 4 different genetic makeups
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16
Q

common features of gametogenesis

A
  • multiplication of spermatogonia and oogonia
  • meiosis
  • extensive morphological differentiation
  • incapacity of surviving for long if ferrtiization does not occur
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17
Q

characteristics of sperm

A
  • continually renewed
  • one spermatocyte produces 4 sperm
  • initial large cell results in small cells
  • motile cells
  • x or y sex chromosomes
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18
Q

characteristics of ovum

A
  • all oocytes present at birth
  • one oocyte produces 1 ovum and 2-3 polar bodies
  • initial small cell grows to large cell
  • immobile
  • x chromosome only
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19
Q

oogenesis

A

occur in ovary
1. oogonia-prenatal mitosis and differentiation
2. all are primary oocytes (4N) arrested in meiosis 1 until puberty
-at ovulaton, meiosis 1 is completed except in dogs and mares
3. secondary oocyte awaits fertilization in uterine tubes
-meiois 2 completed on sperm contact
result is ovum (1N) and 2nd polar body (2N)

20
Q

ovulation

A

results from hormone influence on folliculogenesis at puberty

21
Q

folliculogenesis: primordial (resting) follicles

A

oocyte1 + single layer of squamous follicular cells

22
Q

folliculogenesis: primary follicles

A

activated or growing follicles, zona pellucida forms

23
Q

folliculogenesis:secondary follicles

A

secretory/antral follicles, fluid filled spaces are formed among the granulosa cells

24
Q

folliculogenesis: tertiary mature (Graafian) follicle

A

one antrum containig liquor folliculi, have eccentric cumulus oophorus, contain primary oocyte

25
Q

zona pellucida

A

acts as immunologic protective barrier for developing egg and early embryo

26
Q

corpus hemorrhagicum

A

after ovulation the follicular space fills with blood and clots, will be replaced by luteal calls and become corpus luteum

27
Q

corpus luteum

A

yellow body, produces progesterone and some estrogen

  • granulosa luteal cells: large
  • theca luteal cells: small
28
Q

progesterone

A

helps maintain the pregnancy, stimulate mammary development, and locally down regulates the immune system

29
Q

corpus albicans

A

corpus luteum regresses during diestrus, connective tissue scar

30
Q

atrectic follicle

A

follicle that is not selected to complete maturation, undergo programmed destruction, common

31
Q

ovulation

A

oocyte departs the ovary and leave behind corpus hemorrhagicum that becomes the corpus luteum of thecal and granulosa cells

32
Q

spermatogenesis

A
  • spermatogonium mitosis: differentiate
  • primary spermatocyte: meiosis 1 (crossover)
  • 2 secondary spermatocytes: meiosis 2
  • 4 sermatids do not divide but undergo spermiogenesis (metemorphosis)
  • 4 spermatozoa
33
Q

functions of sertoli cells

A
  • activated by FSH
  • secrete AMH during fetal development to inhibit uterus formation
  • secrete inhibin and activins after puberty to regulate FSH secretion from pituitary
  • secrete androgen binding protein (ABP) to bind testosterone increase concentration in seminiferous tubules and stimulate spermatogenesis
34
Q

sperm cell maturation

A

spermatogonia (2N) –> spermatocytes: primary (4N) undergo st meiosis to secondary (2N) undergo 2nd meiosis–>spermatids (1N) undergo metamorphosis to spermatozoa

35
Q

round spermatid

A

undergoes metamorphosis to elongated spermatids

36
Q

sperm head

A

nucleus and acrosome

37
Q

sperm head shape

A
  • ruminants: disc like
  • man, stallion: pear shaped
  • rodents: hook like
  • guinea pig: spoon like
  • birds: filiform
38
Q

axonema

A

core of cilia & sperm flagellum (tail)

39
Q

structure of axonema

A

-derived from modified centriole
-pair of central microtubles
+ outer ring of 9 doublets with dynein arms
-each doublet has a microtuble A with dynein arms + an incomplete microtubule B

40
Q

characteristics of spermatogenesis

A
  • continuous process: throughout the year except for seasonal breeders
  • highly organized process, fixed length of time
  • takes place in orderly waves
  • very sensitive to: temperature, x ray irradiation, nutrition, infection & non-infectious diseases, stress, drugs
41
Q

spermatogenesis vs oogenesis: sperm

A
  • spermatogonia remain dormant until puberty, the proliferate by mitotic division
  • meiosis completed within testis
  • each spermatogonium give rise to multiple
  • spermatids undergo metamorphosis
  • spermatogenesis may continue throughout the whole life of the animal
42
Q

spermatogenesis vs oogenesis: oogenesis

A
  • complete their proliferation in the early embryonic stage
  • by birth all oogonia entered meiosis 1 but development arrested until puberty
  • one oocytes give rise to one ovum
  • ova do not undergo metamorphosis
  • meiosis is completed in fallopian tube
  • oogenesis stops after overy exhausted of germ cells
43
Q

fertilization-sperm

A

-capacitation: occurs in uterine environment, gain ability to fertilize the oocyte
-acrosome reaction: release acrosomal enzymes to digest through zona pellucida
sperm contacts oocytes
-fusion of sperm plasma membrane with plasma membrane of oocyte

44
Q

capacitation and acrosome reaction

A

plasma membrane over acrosome is destabilized and breaks down together with outer acrosomal membrane, acrosomal enzymes are released

45
Q

fertilization-ovum

A
  • cortex of oocytes below oolemma contains cortical granules
  • sperm contact with oocyte plasma membrane causes release of proteases which modifies zona pellucida
  • zona pellucida is then a barrier to other sperm penetration
46
Q

pronuclei

A

nuclear material of sperm and ootid

47
Q

syngamy

A

union of male and female pronuclei

Microanatomy (3 decks)

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