2 Game to Genesis E-learning

8/3/2019 2 Game to Genesis E-learning

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GametogenesisGametogenesis

&&Female Reproductive CycleFemale Reproductive Cycle


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Cell DivisionCell Division

2 Types:

Mitosis: somatic cell division

2 cells with same number of chromosomes (46)

Meiosis: reproductive cell division

4 cells with half number of chromosomes (23)

2 subdivision:

1st. Reduction division2nd. Cromosomes division


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MitosisMitosis

Prophase:Coiling & condensing of replicatedDNA to form chromosomes (?)

Break down of??

Metaphase

Arrangement of chrom. Inmetaphase plane (equatorial)

AnaphaseSplitting of centromeres &movement of chrom. to the poles

Telophase & CytokinesisUncoiling of chromosomes to ??

Formation of??


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MeiosisMeiosis

Reduction Division:Prophase I

Metaphase I

Anaphase I

Telophase I

Chromosomal division:

(Mitosis)

Prophase II

Metaphase II

Anaphase II

Telophase II


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GametogenesisGametogenesis

The process offormation (meiosis) & development of gametes(male or female)

- Spermatogenesis: definition?

starts at puberty (13-16y)

- Oogenesis: definition?

starts during fetal period

but never completed until ?


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Spermatocytogenesis & MeiosisSpermatocytogenesis & Meiosis

Spermatogonia (primitive cells):Present during fetal period

After pubertyJmitosis J in # in size

Primary spermatocytes:Largest germ cell in

Seminiferous tubules (2n)

Secondary spermatocytes:

number of chromosomes (1n) size of 1o

Spermatids: (1n)

size of 2o


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SpermiogenesisSpermiogenesis

The transformation (change in shape) of spermatids into

elongated sperms (spermatozoa)

- Condensation of nucleus

- Formation ofacrosome:

a vesicle containing hydrolytic enzymes

- Loss of most of cytoplasm

- Arrangement of Mitochondria

- Tail development


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Spermatogenesis process requires b2 months (64 days)

After spermatogenesis:

sperms move to epididymis:

1. stored

2. mature (functionally)

Normal human male usually ejaculates 2-5 ml of semen

Normal sperm count= 50 100 million sperms/ml of semen

b20 million/ml adequate

10 million/ml poor (50 millionintotalspecimen)


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Mature SpermMature Sperm

Head:

nucleus & acrosome

Neck

Tail:

middle piece: mitochondria

principal piece

end piece


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OogenesisOogenesis

During fetal life:

oogonia divides & grow 1o Oocytes

After puberty:

1

o

Oocyte

reduction division= 2

oOocyte + 1st polar body

* unequal division of cytoplasm

After ovulation:

2o Oocyte chromosomal division= Mature Oocyte + 2nd polar body


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- Oocytes within the ovary are surrounded by a protectingfollicle

(formed by follicular cells)

- Ovulated 2o Oocytes are surrounded by:

Zona pellucida:

amorphus material

Corona radiata:

remaining follicular cells


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An infant female usually have b 2 million 1o

Oocytes

At puberty b 40, 000

During fertility period:

b 400 ovulated

* Contraceptive pills preventOvulation thenumberis greatlyreduced


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Female ReproductiveFemale Reproductive

CycleCycle


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Female Reproductive CycleFemale Reproductive Cycle

2 cycles (mirrors)2 cycles (mirrors)

Ovarian cycle:

ovariesovulation

Menstrual cycle:uterusuterine lining

Thesecycles arecontrolledbyhormonalsecretions from:

hypothalamus

pituitary gland


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Hormones Regulating Female CycleHormones Regulating Female Cycle

(Ovarian)(Ovarian)

Gonadotropin Releasing Hormone (GnRH):

hypothalamus

enhance pituitary gland to release FSH & LH

Follicular Stimulating Hormone (FSH):

stimulates growth of follicles

enhances secretion of Estrogen

Luteinizing Hormone (LH):

triggers ovulation & formation of??

stimulates progesterone secretion


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The Ovarian CycleThe Ovarian Cycle

1. Menstrual Phase:

Primordial follicles grow 1o 2o follicle

~ 5 days

2. Preovulatory (Follicular) Phase:

follicular cells start to secrete Estrogen

Secondary follicle mature1

ooocyte divides 2

ooocyte

~ 9 days (highly variable)

3. Ovulation:

rupture of mature follicle & release of 2

o

oocyteusually ~ day 14

4. Postovulatory (Luteal) Phase:

Formation of corpus luteum

Secretion of progesterone


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Hormones Regulating Female CycleHormones Regulating Female Cycle

(Menstrual)(Menstrual)

Estrogen:

Ovarian follicles

develop. & growth of functional layer (endo. bed)

Progesterone:

Corpus Luteum (?)

1. maintenance of functional layer

2. enhance secretion of endo. Glands

Human Chorionic Gonadotropin H. (HCG):

Implanted blastocyst (Syncytiotrophoblast)

maintain endocrine activity of Corpus Luteum


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The Menstrual CycleThe Menstrual Cycle

4 Phases:4 Phases:

1. Menstrual Phase:

fxnal. Layer is sloughed off

& discarded with menstrual flow

5 days (1-5)

2. Proliferative Phase:

growth & develop. ofnew fxnal. Layer

(endo. 2-3 times)under control of estrogen

9 days (6-14)


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3. Secretory Phase:

endo. Bed (fxnal. layer) is readyendo. Glands are secreting uterine fluids

under control of progesterone (mainly)

13-14 days (15-27/28)

4. Ischemic Phase:

If fertilization does NOT occur

Corpus Luteum degeneratesprogesterone

1 day (28/29)


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If fertilization occurs:

HCG progesterone secretory phase continues & No menstruation

Pregnancy Phase

Menstrual cycle usually range between 23 35 days

hormonaldisturbances

psychologicalconditions:

stress & depression


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Contraceptive PillsContraceptive Pills

Contents:

combination of estrogen & progesterone like

hormones (COCPCOCP)

Method of Application:

A woman takes the pills for21 days, followed by 7

days of no pills. Then the cycle starts again.


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Contraceptive PillsContraceptive Pills

Mechanism ofMechanism ofActionAction

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