1-Gametogenesis

8/7/2019 1-Gametogenesis

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SpermatogenesisSpermatogenesis


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DEFINITIONDEFINITION

It is the process of

formation of sperms

in the seminiferous

tubules of the testis.


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AIM:AIM:

Reduce the number of

chromosomes from 46 to 23.

Change the shape of the male

germ cell to become ready forfertilization.


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STAGES:STAGES:

SPERMATO-CYTOGENESIS:

SPERMIOGENESIS


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STAGES:STAGES:

1-SPERMATO-

CYTOGENESIS:


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STAGES:STAGES:

2-SPERMIOGENESIS


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SpermiogenesisSpermiogenesis


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SpermSperm


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SpermSperm

Head:

Neck:

Body (middle piece):

Tail:

Principle piece:

Its terminal piece:


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SpermSperm

Head:formed of condensed nucleus &

acrosomal cap covering its

anterior 2/3.

Neck:

a constriction behind the head.

contains the 2 centrioles.


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SpermSpermBody (middle piece):

Plasma membrane.

Mitochondrial sheath.

9 bundles of microfilaments.

Tail:

Principle piece: has fibrous sheath. Its terminal piece:has no fibrous

sheath


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In form:In form:

Giants (too big).

Dwarfs (too small).

With two heads (bicephalic).

With two tails (bicaudal).


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Abnormal form of spermAbnormal form of sperm


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In number:In number:

Azospermia: is absence of

sperms in the semen.

Oligospermia: is the

presence of few

sperms.


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yNecrospermia

:

is thepresence of dead sperms.


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OogenesisOogenesis


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OogenesisOogenesis


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Definition:Definition:

It is theprocessof

productionofamatureovumin thecortexofthe

ovary.


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Aim:Aim:

Reduce thenumberof

chromosomesfrom 46 to23.

Increase thesizeoftheovumfrom 30 to 120 .


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PRENATALDEVELOPMENT:PRENATALDEVELOPMENT:--11

Duringintra-uterinelife, the

ovarycontainsonlyoogonia,

Then themajorityoftheoogoniadegenerate, while

thesurvivingonestransformedinto 1ryoocytes.


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PRENATALDEVELOPMENT:PRENATALDEVELOPMENT:--11

Each 1ryoocyteissurroundedbyalayerofflat

epithelialcellscalledfollicularcells.

1ryoocyte, togetherwith thefollicularcells,is knownasa

primordial follicle.


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OogenesisOogenesis


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Post natalPost natal

1ry oocyte (44 + XX) undergoes 1st

meioticdivision togiverise:

1st polarbody (22+X):asmallcellasit receivesalittleof

cytoplasm.

2ryoocyte (22+X):alargecellasit receivesmost ofthecytoplasm.


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Post natal:Post natal:

2ry oocyte (44 + XX) undergoes

2ndmeioticdivision togiverise

Ovum.2ndpolarbody.


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Growing folliclesGrowing follicles


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11ry folliclery follicle

Thefollicularcells then

deposit zona pellucida & the

follicularcellsarenow calledgranulosa cells


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22ry folliclery follicle

Smallirregularspaces

appearbetween the

granulosacells, which laterjoineach othertoformone

largespacecalled thefollicular cavity (antrum)


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Growing folliclesGrowing follicles


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Graffian follicleGraffian follicle

Thefollicularcellssurrounding theoocytearecalledcumulus oophorus.

Thestromacellsofthecortexofovary

differentiateinto:

Aninnervascularlayercalledtheca

interna.

Anouterfibrouslayercalledtheca

externa.


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2ry oocyte: (120 )

Zona pellucida:

surrounds theoocyte.

Cumulusoophorus:follicularcells

surroundingoocyte.


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Follicular antrum: fills thematurefollicle & islinedbystratumgranulosa.

Thestromacellsoftheovarydifferentiateinto:

Aninnervascularlayer

calledtheca interna.Anouterfibrouslayercalledtheca externa.


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After ruptureAfter rupture


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Date post:	08-Apr-2018
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1-Gametogenesis

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