Gametogenesis Ms. Mayuri Patel Sandra Shroff ROFEL College of Nursing, vapi

Gametogenesis

The process involved in the maturation of the two highly specialized cells, spermatozoon in male and ovum in the female before they unite to form zygote, is called gametogenesis.

Oogenesis

The process involved in the development of a mature ovum is called oogenesis.

From yock sac – Primitive germ cells at 3rd week

GERM CELLS

OOGENIA First meiotic division

PRIMARY OOCYTES

46,XX

7 million at 20 weeksMitosis

Arrest 1st meiotic

division upto puberty

Maturation of graafian follicle

Secondary oocytes

23, X

1st Polar body23, X

OVULATION

Not fertilized Fertilized

Degeneration within 24 hours

Completion of second meiotic division

Female pronucleus 23,X

Second polar body 23, X

Spermatogenesis

The process involved in the development of spermatids from the primorbadial male germs and their differentiation into spermatozoa is called spermatogenesis.

GERM CELLS

SPERMATOGONIA

First meiotic division

PRIMARY OOCYTES

46,XY

7 million at 20 weeksMitosis

1st meiotic division

Secondary Spermatocytes

23, X 23, Y

Second Meiotic Division

23, X

Morphological Changes To Spermatozoa

SPERMATIDS

23, Y

23, Y

23, X

OVULATION

OVULATION

OOCYTE TRANSPORT At the time of ovulation, the fimbriae

move over the ovary and sweep the ovulatory mass containing secondary oocyte, into the infundibulum.

The ovulatory mass is then guided into the ampulla through the movements of cilia, and by muscular contraction of uterine tube wall (Tubal Peristalsis).

It has been estimated that the ovulatory mass takes about 25 minutes to reach the site of fertilization.

SPERM TRANSPORT Usually 200 to 500 million sperms are

deposited. Sperms pass by movements of their tails

through uterus & tubes; assisted by muscular contraction.

Prostaglandins present in the seminal plasma may stimulate uterine motility at the time of intercourse.

It is not known how long it takes sperms to reach the fertilization site but the time of transport is short 5-45minutes.

FERTILIZATION1. Penetration of the Corona Radiata2. Penetration of Zona Pellucida3. Penetration of Oocyte Cell

Membrane and Formation of Zygote

Contact And Fusion Of The GemetsPenetration of the zona pellucida

Releasing of Hyaluronize from acrosomal cap

Sperm touches oolema

Zona reaction & oolema block

Release Of Cortical Granules

From Oocytes

Sperm & ovum met

Completion of secondary meiotic division

Female pronucleous 23, X

Second polar body 23, X

23, X 23, Y

ZYGOTE

Sex of child determine by pattern of sex chromosome supplied by spermatozoon.

FERTILIZATION

Morula

Mitotic DivisionResembling like

Mulberry

30 hours after

fertilization

Morula spend 3days in the uterine tube enter the uterine cavity through the narrow uterine ostium on 4th day in the 16-64 cell stage.

TRANSPORT

Slow process Controlled by muscular contraction

Movement of cilia

Form embryo

Form protective &

nutritive membranes of

embryo