1. Game to Genesis I-My Lecture

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Gametogenesis

DR. Amany El-Agawany

Ass. Prof. of Anatomy


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5/4/12Copyright 2002 Pearson Education, Inc., publishing as Benjamin Cummings

Male Reproductive System


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Male Reproductive System

Testes:

Seminiferoustubules:

Contain 2 typesof cell:spermatogonia and

Sertoli cells.

InterstLeydigcells:

Present inbetween theseminifroustubules.

Insert fig. 20.12


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Overview of Gross Anatomy of Male Reproductive System:

Testis

Male sex gland, Located in the Scrotum.Produce Sperm and Androgens.

Have also the interstitial cells (leydeg cells) that produce male sexhormone (testosterone)

Seminiferous tubules is the structural unit of testes., it have thedevelopmental phases of sperms in addition to Sertoli cells.

Epididymis

Sperm Storage

Complete of sperm maturation.

Vas Deferens

Duct that transports the Sperm from the Scrotum to theProstate Gland

Seminal Vessicle

Secrets Fluid, rich in Fructose, to Semen


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Prostate Gland (Ejaculatory Duct)

Contributes Milky Alkaline Fluid that assists

Sperm Activation.Urethra (Penis)


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Female reproductivesystem


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Female Genital System

The Ovary: female sex gland, produce ova.

The Uterus: in which the fetus develop.


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Gametogenesis


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Aim. Formation of sperms

with haploid number ofchromosomes 23X or 23Y .

Site. In the seminiferoustubules of the testis

Duration. From puberty tilldeath .

Steps;

1- proliferation:Means increase in the

number of the cells.

Spermatogonia which have

diploid number ofchromosomes 46XY, divided

Spermatogenesis


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46 46

46 46

46 46 4646

46 46 46 46

4646

46 46

4646

Cell division continues bymitosis, so all the cells willcontain 46 chromosomes early embryo

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2-Growth:

The daughterspermatogonia enlarge insize only forming primaryspermatocytes .

3-Maturation:

a- The primaryspermatocytes divides bymeiosis into two secondaryspermatocytes

( haploid =23X or 23Y).

b- The secondary

spermatocytes divides by2nd meiosis into two


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4-Transformation:spermiogenesis:

Nucleus = head.

Golgi = acrosamal cap.

Centeriols = axialfilament.

Mitochonderia = helicalsheath.

The sperms undergomaturation in theepididymis, then storedin the ampulla of vasdefferens. If notejaculated, they die

and become absorbed.


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Total length=60 Formed of:

1- head: contains the a- nucleus with

haploid number of chromosomes whichcarry the genetic characters.

b. Acrosomal cap. Secretes enzymes whichfacilitate penetration of the ovum.

2- neck.3- body or meddle piece. Contain

mitochondrial sheath which produceenergy for motility.

4- Tail .

The sperm.


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Aim: formation of ovum ( single large and haploid)

Site: in the ovary . Each ovary produce one ovumevery 2 month.

Duration :from puberty till menopause.

Steps:

v I. Two prenatal stages. Occur in intra uterine life .

A- proliferation

Oogonia with diploid number of chromosomes 46XXdivided by mitosis giving daughter oogonia.

O0genesis


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B-Growth.

The daughter oogonia enlarge formingprimary oocytes . Each primary oocytebecome surrounded by follicular cells forminga primordial follicle, further changes arearrested till puberty by meiosis inhibitoryfactor(MIF) secreted by follicular cells.

v II- After puberty. the third stage of oogenesisoccur which is maturation .


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C- Maturation :occur once per month

5-15 primordial follicles begins to grow , one onlycontinues maturation and the rest degenerateforming atretic follicles.

1- first maturation division

the 1ry oocyte divided by meiosis giving 2ryoocyte and first polar body .

2- second maturation division , occur afterovulation , and only if fertilization occur.

the 2ry oocyte divided by 2nd meiosis into matureovum and second polar body which extruded to theperivitelline space and degenrate.

N.B: one primary oocyte gives rise to one mature


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Atpuberty

1


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23

46

46

23

23

23

2

3

2

3

2

3 46

spermmothercell

ovummothercell

sperms producedby meiosis

fertilization

zygote

ova produced by meiosisbut only one develops to

maturity

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1. Game to Genesis I-My Lecture

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