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Fallopian Tube Uterus \ } Endometrium —— Myometrium Cervix —[ \ ) A j Cervical Canal Vagina During copulation, semen is released by the penis into the vagina. It is called insemination. bankofbiology.com FERTILIZATION AND IMPLANTATION nd ba ‘ Land Coal * Fertilization happens only if ovum & sperms are transported simultaneously. So all copulations do not lead to fertilization & pregnancy. A sperm contacts with It induces changes in the membrane that block the entry of additional sperms. The secretions of the help sperm to enter the egg cytoplasm via zona pellucida and plasma membrane. This causes second meiotic division of the secondary oocyte to form an and The haploid nuclei of the sperm and ovum fuse y fr | , together to form a EG CYTOPLASIA Corncal granule bankofbiology.com => . > @- Zygote Two-cell stage Four-cell stage Eight-cell stage 16-cell stage Blastocyst ¢ The embryo with 8-16 blastomeres is ¢ Morula continues to divide and « Zygote undergoes mitotic division starts as it moves through the isthmus towards the uterus and forms 2, 4, 8, 16 daughter cells called called a transforms into bankofbiology.com FERTILIZATION AND IMPLANTATION \o& \ } = | Endometrium Uterine cavity \% JQ } r 1 F 1 1 ; Oy +— Uterine mucosa cells Endometrium grows over and surrounds the embryo The blastocyst digests the uterine mucosa ¢ After attachment, uterine cells divide rapidly and cover the blastocyst. ¢ As aresult, the blastocyst becomes embedded in the endometrium. This is called implantation. bankofbiology.com bankofbiology.com PREGNANCY AND EMBRYONIC EAA TE aN Chorionic villi Uterine artery and vein , Maternal blood \, > / Ora x2 y |_— Placenta ; — Yolk sack -— Uterus ¢ After implantation, finger-like projections (chorionic villi) appear on trophoblast. ¢ They are surrounded by uterine tissue and maternal blood. bankofbiology.com PREGNANCY AND EMBRYONIC DEVELOPMENT Umbilical vein. — Umbilical artery Placenta ¢ The chorionic villi & uterine tissue are interdigitated to form placenta. ¢ Placenta is a structural and functional unit b/w embryo (foetus) & maternal body. bankofbiology.com —=— PREGNANCY AND EMBRYONIC DEVELOPMENT Kime >) Functions of placenta _ | 1. Acts as ‘ier between the foetus & mother. 2. Supply O,, nutrients etc. from mother to foetus. 3. Remove 2 & excretory wastes from foetus. 4. Acts as ane rine | It secretes Relaxin is also secreted by ovary. ~ —_— banxofbiology.com PREGNANCY AND EMBRYONIC DEVELOPMENT a | | * During pregnancy, Placenta etc. are also increased in maternal blood. \ = * They support the fetal x | VV Uterus growth, metabolic = 1¢ changes in the mother and maintain pregnancy. Umbilical Fetus bankofbiology.com PREGNANCY AND EMBRYONIC DEVELOPMENT <> =a 2, ow * Human pregnancy (gestation period) lasts Placenta \ ~ ‘ ‘ Umbilical 9 months. : cord \ Fe S - For cats: 2 months. \ “ Dogs: 2 months. SS PB WV Uterus Elephants: 21 months. bankofbiology.com PREGNANCY AND EMBRYONIC DEVELOPMENT, Changes in embryo during pregnancy h: Heart is formed. sec h: Limbs and digits are developed. n f 12 wee '): Major organs (limbs, external genital organs etc.) are well developed. ur yf First movement of foetus and ppectance: of hair on the head. Body is covered with fine hair, eyelids separate and eyelashes are formed. ths: Ready for delivery. banxofbioloyy.com Oo. 7g",2 Parturition (labour) 80 Process of giving birth to young ones. It is induced by The signals from the foetus and placenta induce mild uterine contractions This causes the release of from maternal pituitary. banxofbioloyy.com PARTURITION AND LACTATION F 7 Parturition (labour) “27% * Oxytocin causes stronger uterine muscle contractions which in turn stimulate further secretion of oxytocin. * This process is continued leading to expulsion of the baby out of the uterus through the birth canal. banxofbioloyy.com 
