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BIOM3200 > reproduction - March 5th & 7th > Flashcards

reproduction - March 5th & 7th Flashcards

1
Q

What are the four phases of Gametogenesis?

A
  1. Extraembryonic primordial germ cells (PGCs) and their migration to the gonads
  2. Increase in # of PGCs by mitosis
  3. Decrease in chromosomal material by meiosis
  4. Structural and function maturation of gametes (oogenesis and spermatogenesis)
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2
Q

What are Primordial Germ Cells (PGCs)?

A
  • Earliest recognizable precursors of gametes
  • originate outside of the gonads in the hindgut
  • migrate into gonads during early embryonic development
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3
Q

What is the function of spermatogenesis?

A

spermatozoa produced from male PGCs by meiosis and mitosis

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4
Q

Where does spermatogenesis occur?

A

in the testes

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5
Q

how many gametes are produced per cycle of spermatogenesis?

A

4

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6
Q

What are the intitial cells of spermatogenesis called?

A

spermatogonia

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7
Q

What are the cells called after mitosis of spermatogonia in spermatogenesis?

A

primary spermatocytes

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8
Q

Are spermatogonia haploid or diploid?

A

diploid

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9
Q

Spermatogonia give rise to two daughter cells, what happens to them?

A
  • one daughter cell remains at the basement membrane as a stem cell
  • second daughter cell (primary spermatocyte) moves toward the tubule lumen for further division
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10
Q

Describe the steps of spermatogenesis

A
  • 1st meiosis: DNA duplicates and daughter cell (primary spermatocyte) splits into 2 new, haploid daughter cells (secondary spermatocytes)
  • 2nd meiosis: sister chromatids in secondary spermatocytes are split into 4 daughter cells (spermatids)

Primary spermatocyte undergoes 2 meiotic divisions to form 4 haploid spermatids

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11
Q

What is Spermatocytogenesis?

A
  • from spermatogonium to primary and then secondary spermatocyte
  • Phase 1: spermatogonial phase (type A dark (Ad) spermatogonia are stem cells of the seminiferous epithelium ; Type A pale (Ap) spermatogonia are committed to differentiation ; Type B spermatogonia are differentiated from Type A)
  • Phase 2: Each primary diploid spermatocyte duplicates its DNA and divides into two haploid, secondary spermatocytes by meiosis 1
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12
Q

What is Spermatidogenesis?

A

From secondary (haploid) spermatocyte to spermatid (haploid)

brevity of this stage meawns that secondary spermatocytes are rarely seen in histological studies

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13
Q

What is Spermiogenesis?

A

from spermatid to mature, immotile spermatozoon

  • spermatids form tail by growing microtubules (axoneme) on one of the centrioles (basal body)
  • Anterior part of tail (midpiece) thickens due to mitochondrial arrangement (energy supply)
  • DNA undergoes condensation
  • Tightly-packed chromatin transcriptionally inactive
  • Golgi apparatus surrounds condensed nucleus forming the acrosome
  • Testosterone removes remaining extra cytoplasm and organelles (residual bodies phagocytosed by Sertoli cells)
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14
Q

What is Spermiation?

A

from mature, immotile spermatozoon to mature, motile spermatozoon

  • release of mature spermatozoa from Sertoli cells into the lumen of the seminiferous tubule
  • mature immotile spermatozoa transported to the epidiymis in testicular fluid secreted by Sertoli cells with the aid of peristaltic contractions
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15
Q

What do the Sertoli Cells do?

A
  • maintain environment and protect spermatids from immune system (blood-testis barrier & FAS-ligand that triggers apoptosis of T-cells thus preventing immune attack on developing sperm
  • phagocytose residual cytoplasm
  • secrete: supporting testicular fluid, sibstances that initiate meiosis, ABP (concentrates testosterone close to developing gametes), hormones affecting pituitary gland in control of spermatogenesis
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16
Q

Describe the steps of sperm transport in the male reproductive tract

A
  • non-motile infertile spermatozoa passively transported via testicular fluid from seminiferous tubules to caput of epididymis
  • 4-12 days in epididymal duct where biochemical maturation takes place
  • upon ejaculation, spermatozoa pass through ductus deferns and mix with secretions from the seminal vesicles
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17
Q

Describe the steps of sperm transport in the female reproductive tract

A
  • sperm deposited in upper vagina (rapid elevation of pH)
  • passage through cervix
  • passage through uterus
  • entry into uterine tubes
  • passage up uterine tube by flagellar movement and contractions of tube

composition and buffering capability of seminal fluid protect spermatozoa from acidity of upper vagina. Buffering only lasts a few minutes which is enough for sperm to approach the cervix at the optimal pH for sperm motility

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18
Q

Massive numbers of spermatozoa get trapped in ________ in the female reproductive tract

A

mucosal folds of cervical crypts

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19
Q

slow release of spermatozoa through cervial mucus ensures what?

A

continued availability of spermatozoa to enter oviduct for fertilization

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20
Q

The ovum secretes ____ that helps sperm transport

A

chemoattractant

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21
Q

The oviduct has a unique function of conveying spermatozoa and eggs in the ____ directions almost _______

A

opposite ; simultaneously

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22
Q

The frequency and amplitude of oviductal contractions are regulated by:

A
  • ovarian hormones
  • components of seminal plasma
  • prostaglandins
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23
Q

Sperm have a ____ lifespan after ejaculation

A

limited

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24
Q

While migrating in the genital tract, sperm are rapidly seperated from ____ and resuspended in _____

A

seminal plasma ; female gential fluid

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25
Q

most sperm are eliminated at ____ and ______

A

cervix ; uterotubal junction

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26
Q

What is capacitation?

A
  • process of physiological changes occurring in mammalian spermatozoa during passage through female reproductive tract that enables them to penetrate ovum membrane
  • alteration of glycoprotein surface of spermatozoa under influence of female tissue secretions within the reproductive tract
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27
Q

The ____ of the oocyte facilitates sperm binding and serves as a protective membrane

A

zona pellucida

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28
Q

the ____ of an oocyte delivers protein (support)

A

corona radiata

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29
Q

fertilization usually occurs in the ____ area of the uterine tube

A

ampullary

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30
Q

____ emanating from the acrosome of sperm head may play a role in penetration

A

hyaluronidase

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31
Q

The zona pellucida allows only sperm of the same ____ to enter the ovum

A

species

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31
Q

Sperm ____ plays a major role in penetration of corona radiata

A

motility

32
Q

Which layer surrounding an oocyte prevents the premature implantation of an embryo?

A

zona pellucida

33
Q

what is the acrosomal reaction?

A
  • orderly fusion of the spermatozoa plasma membrane and outer acrosomal membrane
  • release of acrosomal enzymes allows spermatozoon to digest its way through the zona pellucida
  • acrosomal reaction releases hyaluronidase and acrosin
34
Q

What are the mechanisms that prevent polyspermy?

A
  1. Fast Block: rapid depolarization of ovum’s plasma membrane, occuring 2-3s after fusion
  2. Slow Block: cortical reaction; calcium wave from site of sperm-ovum fusion, cortical granules fuse with plasma membrane and release hydrolytic enzymes and polysaccharides into perivitelline space, content of cortical granules hydrolyzes sperm receptors in the zona
35
Q

What is oligospermia

A
  • <20M sperm/mL
  • Decreased Fertility
36
Q

Spermatozoa can survive for ____ after ejaculation

A

~80 hrs.

37
Q

Female ____ helps maintain metabolic requirements of spermatozoa

A

cervical mucus

38
Q

What is artificial insemination

A

sperm washed and injected into uterus

39
Q

What is in-vitro fertilization

A

oocytes harvested and fertilized in a lab and then re-implanted into uterus

40
Q

an erection is a largely ____ event

A

hemodynamic

41
Q

What happens during an erection?

A
  • parasympathetic nerve-induces vasodilation of arterioles through relaxation of smooth muscle
  • allows blood to flow into corpus cavernosum
  • veins contract (less blood outflow)
  • increased intracavernosal pressure results in erection
42
Q

Which neurotransmitter mediates erections?

A

nitric oxide (NO)

43
Q

What is the role of NO in erection?

A
  • acts on vascular smooth muscle cell, activating guanylate cyclase which catalyzes conversion of GTP to cGMP
  • cGMP causes Ca2+ channels in vascular smooth muscle cell to close (cytoplasmic Ca2+ conc. decreases)
  • vascular sooth muscle cell relaxes resulting in vasodilation of penis and engorgement of erectile tissue
44
Q

What was the Sildenafil (Viagra) initially supposed to treat?

A

angina (chest pain)

45
Q

Viagara inhibits ____ that catalyzes ____ resulting in _____

A

phosphodiesterase (PDE) ; breakdown of cGMP, increase of cGMP availability promoting erection

46
Q

Each mammary gland contains _______

A

7-10 lobes

47
Q

Lobes in mammary glands are further subdivided into ______

A

lobules

48
Q

Lobules in mammary glands contain ____ which secrete milk into ______

A

alveoli ; secondary tubules

49
Q

Describe the movement of mil in the mammary glands starting from the secondary tubules

A

secondary tubules -> mammary ducts -> lactiferous duct -> nipple

50
Q

The ____ secretes ____ and ____ which stimulates growth and decelopment of mammary glands and ducts

A

placenta ; estrogen ; progesterone

51
Q

After birth, estrogen secretion ____ and prolactin secretion ______

A

decreases ; increases

52
Q

milk production is under the control of the hormone ____ from the ______

A

prolactin ; anterior pituitary

53
Q

Milk release is under control of the hormone ____ from the _____

A

oxytocin ; posterior pituitary

54
Q

Prolactin release is stimulated by:

A

suckling stimulus

55
Q

oxytocin release is stimulated by;

A

suckling stimulus, visual/auditory cues, thought of child

56
Q

The ____ gene is a sex determining gene (thought to be important for male determination) located on the ____ chromosome

A

SRY ; Y

57
Q

In the presence of SRY embryonic gonads become ____, in the absence of SRY, embryonic gonads become ____

A

testes ; ovaries

58
Q

In the presence of testosterone ____ is made from Sertoli cells which maintains the ____ and degenerates the ____ in a ten week old fetus

A

Mullerian inhibition factor; woffian duct; mullerian duct

59
Q

In the absence of testosterone there is no ____ the ____ degenerates and the ____ is maintained in a 10 week old fetus

A

Mullerian inhibition factor; Wolffian duct; Mullerian duct

60
Q

The Wolffian duct becomes:

A
  • seminal vesicle
  • vas deferens
  • epididymis
61
Q

The Mullerian duct becomes:

A
  • fallopian tube
  • uterus
  • vagina
62
Q

How do the external genetalia of males and females compare during the first 6 weeks of development?

A

essentially identical; urogential sinus, genital tubercle, urethral folds, labioscrotal swellings

63
Q

in females the labioscrotal swellings form the ____, in males they form the ____

A

labia majora ; scrotum

64
Q

in females the genital tubercle forms the ____, in males it forms the ____

A

clitoris ; penis

65
Q

How can an XX male occur?

A

They inherit the SRY gene on an X chromosome that’s been recombined with Y

65
Q

How can an XY female occur?

A

They don’t inherit the SRY gene on the Y chromosome because it’s been recombined with the uninherited X chromosome from the father

66
Q

Testes determination requires ____ receptor family

A

insulin

67
Q

what is true hermaphroditism?

A

intersex condition where individuals have both ovary and testis tissue

68
Q

What is pseudohermaphroditism?

A

individual has external genitalia of one sex and internal sex organs of the other sex

69
Q

Puberty has earlier and more obvious signs in:

A

females

70
Q

during puberty there is coupling of interactions between the ____ and _____

A

nervous system ; gonadal steroid hormones

71
Q

At birth FSH and LH levels are ____ and remain this way until the first six months of postnatal life. The levels then____ until puberty.

A

high ; decline

72
Q

puberty is triggered by ____ secretion of the hormone _____

A

pulsatile ; LH

73
Q

____ stimulates the release of LH

A

GnRH

74
Q

LH results in increased _____

A

sex hormones, estradiol in females, testosterone in males

75
Q

Increased sex hormone secretion results in the development of ________ characteristics

A

secondary sex

76
Q

What happens in children with a GnRH deficiency?

A

They fail to sexually mature

77
Q

What is precocious puberty?

A

very early onset of puberty

BIOM3200 (12 decks)

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