Fertilization

FertilizationFertilization

• FertilizationFertilization – – fusion of egg and fusion of egg and sperm into a single sperm into a single diploid cell, the diploid cell, the zygotezygote..– ExternalExternal– InternalInternal

External FertilizationExternal Fertilization

– Sperm spread over egg cellsSperm spread over egg cells•Requires waterRequires water

•Most aquatic animalsMost aquatic animals– Examples: most fish, corals, starfishExamples: most fish, corals, starfish

• InefficientInefficient

– Spermatophore – sperm packaged Spermatophore – sperm packaged into capsuleinto capsule•Some terrestrial animalsSome terrestrial animals

– Examples: salamanders, scorpions, octopusExamples: salamanders, scorpions, octopus

Internal FertilizationInternal Fertilization

• Requires copulationRequires copulation

• Most common method for terrestrial Most common method for terrestrial animalsanimals

• Less sperm and eggs neededLess sperm and eggs needed

PHASES OF FERTLIZATIONPHASES OF FERTLIZATION

1.1. Passage of sperm through the corona radiata Passage of sperm through the corona radiata of the oocytes by the use of hyaluronidase of the oocytes by the use of hyaluronidase which is released by the acrosome of the which is released by the acrosome of the sperm and movement of the tailsperm and movement of the tail

2.2. Penetration of Zona Pellucida- helped by the Penetration of Zona Pellucida- helped by the enzymes esterase, enzymes esterase, acrosin,acrosin, and and neuraminidaseneuraminidase

Once penetration occurs there is a Once penetration occurs there is a biochemical zona reaction that causes the biochemical zona reaction that causes the egg to become impermeable to other sperm.egg to become impermeable to other sperm.

PHASES OF FERTLIZATIONPHASES OF FERTLIZATION

3. Fusion of the plasma membranes of 3. Fusion of the plasma membranes of the oocyte and spermthe oocyte and sperm

4. Completion of second meiotic 4. Completion of second meiotic division of the oocyte and formation division of the oocyte and formation of the female pronucleusof the female pronucleus

5. Formation of the male pronucleus5. Formation of the male pronucleus

PHASES OF FERTLIZATIONPHASES OF FERTLIZATION

6. Breakdown of pronuclear 6. Breakdown of pronuclear membranes, condensation of membranes, condensation of chromosomes, and arrangement of chromosomes, and arrangement of chromosomes for mitotic cell divisionchromosomes for mitotic cell division

FertilizationFertilization• Acrosome Acrosome

discharges enzymes discharges enzymes to digest zona to digest zona pellucidapellucida

• Once single sperm Once single sperm enters eggenters egg

• Egg releases Egg releases enzymes that enzymes that harden zona harden zona pellucida preventing pellucida preventing other sperm from other sperm from enteringentering

• Sperm nucleus Sperm nucleus enters egg and fuses enters egg and fuses with egg nucleuswith egg nucleus

Figure 7.8(1) Figure 7.8(1) Events Leading to the Fusion of Egg and Sperm Plasma MembranesEvents Leading to the Fusion of Egg and Sperm Plasma Membranes

Recognition of egg and sperm;Recognition of egg and sperm;

1. Chemoattraction of the sperm to the egg by soluble molecules1. Chemoattraction of the sperm to the egg by soluble molecules

2. The exocytosis of the acrosomal vesicle to release its enzyme2. The exocytosis of the acrosomal vesicle to release its enzyme

3. The binding of the sperm to the extracellular envelop of the egg3. The binding of the sperm to the extracellular envelop of the egg

4. The passage of the sperm through this envelop4. The passage of the sperm through this envelop

5. Fusion of egg and sperm cell membrane5. Fusion of egg and sperm cell membrane

The Entry of Sperm into Sea Urchin The Entry of Sperm into Sea Urchin EggsEggs

Entry of Sperm into Golden Hamster Egg

Entry of Sperm into Golden Hamster Entry of Sperm into Golden Hamster EggEgg

Formation of the Fertilization Formation of the Fertilization EnvelopeEnvelope and Removal of Excess Sperm and Removal of Excess Sperm

The slow block to polyspermy;Cortical granule fuse with egg cell memb;-release contents; -protease; clips off the binding receptor and sperm attached-mucosaccharides; osmotic gradient that cause water to rush into the space btwn mem and vitelline envelp– envelop expanding and becomes the fertilization envelop.-peroxidase; hardens the fertilization envelop by crosslinking Tyr rsidues am adjacent proteins-hyalin; forms a coating around the egg; ; hylain layer

In mammals; the cortical granule reaction—Enzymes; modify the ZP sperm receptor; no longer binding

Cortical Granule Cortical Granule ExocytosisExocytosis

Wave of Calcium Release across Sea Wave of Calcium Release across Sea Urchin Eggs During FertilizationUrchin Eggs During Fertilization

The calcium as the initiator of the cortical reaction

Intracellular free Ca increase-the cortical granule memb fusion-release contents ( Ca from intracelluar (ER); wave of Ca)

Postulated Pathway of Egg Activation in the Sea Postulated Pathway of Egg Activation in the Sea UrchinUrchin

The activation of egg metabolism to the sperm

The Roles of Inositol Phosphates in Releasing Calcium from theThe Roles of Inositol Phosphates in Releasing Calcium from theER and the Initiation of DevelopmentER and the Initiation of Development

Possible Mechanisms of Egg ActivationPossible Mechanisms of Egg Activation

Possible Mechanisms of Egg ActivationPossible Mechanisms of Egg Activation

Possible Mechanisms of Egg ActivationPossible Mechanisms of Egg Activation

Nuclear Events in the Nuclear Events in the Fertilization Fertilization of the Sea Urchinof the Sea Urchin

Fusion of the genetic material

The sperm nucleus, centriole Mito and flagellar disintegrate inside egg;Mitochondrial DNA from egg , not from sperm

Sperm nucleus undergo dramatic changes;--nulcear lamin breakage--pronucleus --cAMP-dependent protein kinase phosphorylate the sperm specific Histone --decondensation- sperm specific Histone are replaced by histone from egg--

Reorganization of Cytoplasm in the Newly Fertilized Reorganization of Cytoplasm in the Newly Fertilized Frog EggFrog Egg

PROSES FERTILISASI TERDIRI DARI PROSES FERTILISASI TERDIRI DARI 2 ASPEK:2 ASPEK:

• EMBRIOLOGISEMBRIOLOGIS– PENGAKTIFAN SEL TELURPENGAKTIFAN SEL TELUR

• GENETISGENETIS– PENURUNAN UNSUR KEBAKAAN PENURUNAN UNSUR KEBAKAAN

(DNA) DARI PEJANTAN(DNA) DARI PEJANTAN

UNSUR-UNSUR YANG BERPERAN:UNSUR-UNSUR YANG BERPERAN:– SEL TELUR YANG MATANGSEL TELUR YANG MATANG– SPERMA DEWASASPERMA DEWASA

• TEMPATTEMPAT : KAUDA AMPULA (1/3 TF): KAUDA AMPULA (1/3 TF)

• WAKTUWAKTU : TERGANTUNG SPESIES: TERGANTUNG SPESIES

SEL TELUR TERDIRI DARI:SEL TELUR TERDIRI DARI:

• INTI.INTI.

• SITOPLASMA (PROTEIN, BUTIR-SITOPLASMA (PROTEIN, BUTIR-BUTIR LEMAK, ENZIM).BUTIR LEMAK, ENZIM).

• MEMBRAN PLASMA (MENGATUR MEMBRAN PLASMA (MENGATUR ALIRAN ION-ION, TERUTAMA ALIRAN ION-ION, TERUTAMA WAKTU FERTILISASI).WAKTU FERTILISASI).

SPERMATOZOA :SPERMATOZOA :• KEPALA KEPALA INTI, AKROSOMINTI, AKROSOM• LEHER LEHER CENTRIOLE CENTRIOLE• EKOREKOR

KAPASITASI : SERANGKAIAN KAPASITASI : SERANGKAIAN PERUBAHAN YANG TERJADI GUNA PERUBAHAN YANG TERJADI GUNA MEMPERSIAPKAN SPERMA UNTUK MEMPERSIAPKAN SPERMA UNTUK BERTEMU DAN BERINTERAKSI BERTEMU DAN BERINTERAKSI DENGAN OVUM PADA SAAT DENGAN OVUM PADA SAAT FERTILISASI.FERTILISASI.

• TEMPAT : DI BAGIAN BAWAH ISMUSTEMPAT : DI BAGIAN BAWAH ISMUS

KAPASITASI PENTING, KARENA :KAPASITASI PENTING, KARENA :• MENGEMBANGKAN MOTILITAS YG MENGEMBANGKAN MOTILITAS YG

HIPERAKTIFHIPERAKTIF• MENGANTARKAN PENETRASI MENGANTARKAN PENETRASI

SPERMA KE CUMULUS OOPHORUSSPERMA KE CUMULUS OOPHORUS• MEMPERSIAPKAN SPERMA MEMPERSIAPKAN SPERMA

MENJALANI REAKSI AKROSOMEMENJALANI REAKSI AKROSOME

REAKSI AKROSOME :REAKSI AKROSOME :• TERJADI PERUBAHAN MEMBRAN TERJADI PERUBAHAN MEMBRAN

KEPALA SPERMA KEPALA SPERMA STRUKTUR LIPID STRUKTUR LIPID • ALBUMIN ALBUMIN COATING FACTOR COATING FACTOR

ASPEK-ASPEK DALAM PROSES ASPEK-ASPEK DALAM PROSES KAPASITASI :KAPASITASI :

• MORFOLOGISMORFOLOGIS

• FISIOLOGISFISIOLOGIS

• BIOKIMIABIOKIMIA– PERUBAHAN LIPIDPERUBAHAN LIPID– PERUBAHAN PROTEINPERUBAHAN PROTEIN

• REGULASI ION-ION REGULASI ION-ION Ca2+Ca2+ >>>>

JALUR JELAJAH SPERMATOZOAJALUR JELAJAH SPERMATOZOA

DALAM SALURAN KELAMIN JANTAN :DALAM SALURAN KELAMIN JANTAN :TUB. SEM (SPERMA INMOTIL) TUB. SEM (SPERMA INMOTIL) RETE TESTIS RETE TESTIS

DUKT. EFERENDUKT. EFEREN EPIDIDIMIS (KAPUT, EPIDIDIMIS (KAPUT, KORPUS, KAUDA (PENDEWASAAN) :KORPUS, KAUDA (PENDEWASAAN) :

- [ ] - [ ] - MENGKERUT- MENGKERUT

DUKT. DEFDUKT. DEF - AKROSOM <- AKROSOM <- MOTIL- MOTIL

URETRAURETRA

EJAKULASI EJAKULASI SEMEN SEMEN (SPERMA + PLASMA (SPERMA + PLASMA SEMEN)SEMEN)

DALAM SALURAN KELAMIN BETINADALAM SALURAN KELAMIN BETINA

VAGINA : MAMALIAVAGINA : MAMALIA SERVIK : BABISERVIK : BABI UTERUS : KUDAUTERUS : KUDA TRANSPOR :TRANSPOR :1. AKTIF 1. AKTIF GERAKAN SPERMA GERAKAN SPERMA2. PASIF 2. PASIF KONTRAKSI OTOT UTERUS KONTRAKSI OTOT UTERUS

UTJ UTJ BARRIER BARRIER MENGHALANGI MENGHALANGI PERJALANAN SPERMA KE TEMPAT PERJALANAN SPERMA KE TEMPAT FERTILISASIFERTILISASI

LAPISAN SEL TELUR YANG HARUS LAPISAN SEL TELUR YANG HARUS DILEWATI SPERMA :DILEWATI SPERMA :

1. SEL-SEL KUMULUS 1. SEL-SEL KUMULUS EZM. EZM. HYALORONIDASEHYALORONIDASE

2. ZONA PELUSIDA 2. ZONA PELUSIDA ZONA ZONA LIZINLIZIN

3. SELAPUT VITELIN3. SELAPUT VITELIN

AKTIVITAS UTAMA YANG TERJADI PADA AKTIVITAS UTAMA YANG TERJADI PADA PROSES FERTILISASI :PROSES FERTILISASI :

1. PENGENALAN SPERMA DAN SEL TELUR1. PENGENALAN SPERMA DAN SEL TELUR– TERJADI PERLEKATAN KEPALA SPERMA DAN TERJADI PERLEKATAN KEPALA SPERMA DAN

SEL TELUR SEL TELUR RESEPTOR Z. P. RESEPTOR Z. P.– MENCEGAH PERLEKATAN MENCEGAH PERLEKATAN ANTIBODI ANTIBODI

ANTI ZONA / TRYPSINANTI ZONA / TRYPSIN– SPERMA : ANTIBODI ANTI SPERMASPERMA : ANTIBODI ANTI SPERMA

2. PENETRASI SPERMA KE DALAM SEL 2. PENETRASI SPERMA KE DALAM SEL TELURTELUR

- - KAPASITASI KAPASITASI REAKSI AKROSOME : REAKSI AKROSOME : -ZONALYSIN / AKROSIN-ZONALYSIN / AKROSIN -MOTILITAS SPERMA-MOTILITAS SPERMA

3. 3. FUSI GAMETFUSI GAMETSPERMA SPERMA MENEMBUS Z. P.MENEMBUS Z. P.

KEPALA KONTAK M. KEPALA KONTAK M. VITELINVITELIN

ROTASIROTASI

FUSI MEMBRANFUSI MEMBRAN

M. PLASMA SPERMA LEPASM. PLASMA SPERMA LEPAS

INTI : DEKONDENSASI INTI : DEKONDENSASI PRONUKLEUS PRONUKLEUS

JANTANJANTAN

SPERMASPERMA M. VITELIN M. VITELIN REDUKSI II REDUKSI II PB II PB II

1. POLY SPERMA BLOCK :1. POLY SPERMA BLOCK :

• PERUBAHAN RESEPTOR ZONA PELUSIDAPERUBAHAN RESEPTOR ZONA PELUSIDA SPERMA MENEMBUS Z. P. SPERMA MENEMBUS Z. P. RESEPTOR RESEPTOR MODIFIKASI MODIFIKASI Z. P. BERUBAH Z. P. BERUBAH TIDAK DIKENALI SPERMA LAINTIDAK DIKENALI SPERMA LAIN

2. 2. SLOW BLOCK POLYSPERMA/REAKSI SLOW BLOCK POLYSPERMA/REAKSI KORTEKSKORTEKS

M. VITELIN M. VITELIN BUTIR KORTEK BUTIR KORTEK LEPAS LEPAS RONGGA PERIVITELIN RONGGA PERIVITELIN