Oogenesis Reproductive Cycle & Fertilization

EMBRYOLOGY

OOGENESIS Defination:Sequence of events by which oogonia are transformed into mature oocytes. •Begins before birth and is completed after puberty and continues to menopause. 1)Prenatal maturation of oocytes.

Prenatal Maturation Of Oocyte • Oogonia enlarged to from primary oocytebefore birth • Primary oocyte get surrounded by flattened cell– primordial follicle

Amorphous acellular glycoprotein material –Zona pellucida surrounds primary oocyte ●

Primary follicle with more than one

• Primary Oocyte begin first meiotic division before birth but remains suspended prophase till puberty

Postnatal maturation of oocyte • Begins during puberty –one follicle matures each monthovulation • No primary oocytes form after birth in females • Primary oocyte completes first meiotic division just before ovulation,cytoplasm division unequal

At ovulation nucleus of secondary oocyte starts second meiotic divisonArrest in metaphase ●

• Fertilization –second meiotic divison completes

FEMALE REPRODUCTIVE CYCLE • Commencing at puberty & continuing throughout the reproductive years , monthly reproductive cycles • These monthly cycles prepare the reproductive system for pregnancy. • Consists of 1)Ovarian cycle 2)Endometrial

Ovarian Cycle • Each cycle-FSH, LH • Follicular development • One will mature and ruptures through the surface of the ovary ( Ovulation) • Copus luteum

Follicular Development •Growth and differentiation of primary oocyte •Proliferation of follicular cells •Formation of zona pellucida •Development of the theca folliculi

Transportation of gamets • Oocyte transport • Sperm transport

MATURATION OF SPERMS & ACROSOME REACTION •Freshly ejaculated sperms are unable to fertilize oocytes •Sperms undergo a period of conditioning(7 hrs) in the uterus or uterine tube.- Capacitation •Glycoprotein coat and seminal proteins are removed from the surface of the sperms acrosome.

FERTILIZATION Defination:is a complex sequence of coordinated moleculer events that begin with contact between the sperm and oocyte and ends with the intermingling of paternal & maternal chromosomes at the metaphase of first mitotic division of the zygote ,a unicellular embryo. •Time taken: 24 hrs

PHASES OF FERTILIZATION Fertilization is a complex sequence of coordinated events. •Passage of sperm through corona radiata. •Penetration of zona pellucida &Zona reaction •Fusion of plasma membranes of the oocyte and the sperm •Completion of second meiotic division of the oocyte& formation of female pronucleus.

FERTILIZATION •Fusion of male & female pronuclei to form a diploid

SIGNIFICANCE OF FERTILIZATION •Restoration of diploid number of chromosomes in the zygote •Variation of the human species through mingling of maternal& paternal chromosomes. •Determination of sex of the embryo.

chromosomal

•Initiation of cleavage

Applied aspects • • • •

Mittelschmerz Anovulation Vasectomy Tubal ligation

ASSISTED REPRODUCTIVE TECHNIQUES

Hormonal treatment Female

Basic Principle of

Harvest the ovum Mature Ova Mix in a test tube Motile sperms

Keep to develop embryo

Collect semen

Natural ejaculation

Male

Transfer to mother

ICSI Stands for intracytoplasmic sperm injection. This process is used to inject a single sperm into each egg before the fertilized eggs are put back into the woman's body. The procedure may be used if the male has a low sperm count.

Cryopreservation of Ova, Sperm and Embryo

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