Human Reproduction: Class 12 Biology Chapter 2 Hinglish mein

Yeh page padhne wala har insaan ek single cell se shuru hua tha, jo lagbhag ek millimetre ka dasvaan hissa chauda tha. Yeh cell tab bana jab father ka ek sperm mother ke ek egg se fuse hua. Woh cell divide hua, mother ke uterus ki wall mein jaakar baith gaya aur lagbhag nau mahine mein baby ban gaya. Humans sirf sexually reproduce karte hain, aur kyunki hamare bachche mother ke body ke andar develop hote hain aur zinda paida hote hain, hum viviparous hain.

Yeh chapter is kahani ko order mein follow karta hai. Pehle hum un organs se milenge jo males aur females mein gametes banate aur le jaate hain, phir un cell divisions se jo sperms aur eggs banate hain. Uske baad aata hai woh monthly cycle jo aurat ke body ko pregnancy ke liye taiyaar karta hai, sperm aur egg ka milna, uterus mein life, birth aur breastfeeding. Yeh sab puberty ke baad hi shuru hota hai. Ek contrast poore chapter mein chalta hai: aadmi budhaape tak sperms banata rehta hai, jabki aurat ki ovaries lagbhag pachaas saal ki umar mein eggs release karna band kar deti hain.

2.1 Male Reproductive System

Male reproductive organs lower abdomen, yaani pelvic region, mein hote hain, aur kuch parts uske bahar latakte hain. Inke chaar groups hain: ek pair testes, jo sperms aur hormones banate hain; accessory ducts, jo sperms ko store karti aur le jaati hain; accessory glands, jo fluid jodti hain; aur external genitalia. Fig. 2.1 system ki ek side ko shuru se aakhir tak follow karta hai.

Testes (वृषण) body ke bahar kyun latakte hain, jahan woh khule lagte hain? Sperm production body temperature se thoda kam par sabse achha hota hai, aur scrotum, yaani abdomen ke neeche skin ki ek thaili, unhe body core se 2–2.5 °C thanda rakhta hai. Har adult testis lagbhag 4–5 cm lamba aur 2–3 cm chauda oval hota hai, jo ek mazboot fibrous coat mein band hota hai.

Andar se testis kuch-kuch santre ki phaankon jaisa bata hota hai: partitions lagbhag 250 testicular lobules banate hain, aur har lobule mein ek se teen seminiferous tubules lipti hoti hain, yahi asli sperm factories hain.

Ab seminiferous tubule ki wall par zoom karo (Fig. 2.2). Isko do tarah ke cells line karte hain. Male germ cells, yaani spermatogonia, bahari boundary se sate rehte hain; har sperm inhi mein se kisi ek se shuru hota hai. Lambe Sertoli cells boundary se khokhle centre, yaani lumen, tak phaile hote hain. Develop hote sperms unki sides par pockets mein baithe hote hain, aur Sertoli cells unhe nutrients dete hain.

Phir tubules ke beech dekho. Yeh packing tissue, yaani interstitial space, mein patli blood vessels phaili hoti hain aur kuch immune cells hote hain, lekin iske khaas residents Leydig cells (interstitial cells) ke clusters hain, jo testis ki hormone factory hain. Yeh male sex hormones, yaani androgens, khaas taur par testosterone, blood mein release karte hain.

Ek sperm ko bahar jaate hue follow karo (Fig. 2.1, doosra step):

1. Apni seminiferous tubule ke lumen se yeh rete testis mein jaata hai, jo channels ka ek jaal hai.
2. Kuch patli tubes, yaani vasa efferentia, ise testis se bahar le jaati hain.
3. Yeh epididymis mein intezaar karta hai, jo testis ke peeche ki taraf padi ek lambi, lipti hui tube hai, jahan sperms store hote hain.
4. Vas deferens ise upar abdomen mein aur urinary bladder ke upar se le jaati hai.
5. Bladder ke peeche seminal vesicle ki duct isse mil jaati hai; yahan se tube ejaculatory duct kehlati hai, jo prostate ke andar se guzarti hai.
6. Yeh urethra mein jaata hai, jo bladder se penis ki poori length tak jaati tube hai, aur uske opening, yaani urethral meatus, se bahar nikalta hai.

Urethra urinary system ke saath share hoti hai: doosre time par yeh urine le jaati hai, lekin kabhi bhi urine aur semen ek saath nahi. Penis, yaani external genital organ, mein spongy erectile tissue hota hai jo arousal ke dauraan blood se bhar jaata hai aur insemination ke liye organ ko stiff kar deta hai. Skin ki ek dheeli fold, foreskin, uske gol tip, yaani glans penis, ko dhakti hai.

Raaste mein teen tarah ki accessory glands fluid jodti hain: ek pair seminal vesicles, bladder ke theek neeche urethra ke chaaron taraf lipti ek single prostate, aur prostate ke neeche ek pair matar jitni bulbourethral glands. Inka mila hua secretion seminal plasma kehlata hai. Yeh fructose deta hai, ek sugar jise sperms energy ke liye jalate hain, saath mein calcium aur kai enzymes, aur bulbourethral glands ek chikna fluid jodti hain jo penis ko lubricate karta hai.

2.2 Female Reproductive System

Aurat mein eggs banane aur pregnancy sambhalne wale organs pelvis ke andar hote hain: do ovaries, do oviducts, apni gardan, yaani cervix, ke saath uterus, aur vagina, jo external genitalia ke beech bahar khulti hai. Inke kaam relay race ki tarah ek ke baad ek aate hain: egg release karna, sperms ko usse milne ki jagah dena, baby ko sambhaalna aur phir use deliver karna. Chest mein do mammary glands newborn ko doodh pilakar aakhri leg poori karti hain.

Ovaries (अंडाशय) se shuru karo, jo primary female sex organs hain. Har ek 2–4 cm lambi badaam jaisi shape ki body hoti hai, jo ligaments se pelvis ki side wall aur uterus ke beech latki hoti hai. Ovary ek saath do kaam karti hai: yeh female gamete, yaani ovum, ko pakaati hai, aur ek endocrine gland ki tarah ovarian hormones, estrogens aur progesterone, release karti hai. Section mein, epithelium ki ek patli skin ovarian tissue, yaani stroma, ko gherti hai. Iska bahari zone, cortex, alag-alag stages ke follicles se bhara hota hai; iska andar wala zone, medulla, blood vessels le jaata hai.

10–12 cm lambi ek oviduct (fallopian tube) ko uterus se bahar ki taraf trace karo. Pehla hissa, isthmus, ka raasta patla hota hai. Yeh chauda hokar ampulla banta hai, jo sabse lamba aur sabse chauda hissa hai, aur yahin normally sperm aur egg milte hain. Tube ek funnel, yaani infundibulum, par khatam hoti hai, jo ovary se juda nahi hota: uske kinaare par ungliyon jaise fimbriae ovary ki surface par ghoomte hain aur ovulation ke baad egg ko andar kheench lete hain. Oviducts, uterus aur vagina milkar female accessory ducts banate hain.

Uterus (womb) ek single, muscular, khokhla organ hai, lagbhag ulte naashpaati ke size aur shape ka, jo ligaments se pelvis mein tika rehta hai. Iska patla neeche wala end, cervix, vagina mein nikla hota hai; cervix ke andar ka raasta (cervical canal) aur vagina milkar woh route banate hain jisse baby birth ke time bahar aata hai, yaani birth canal. Uterine wall ko kaato to teen layers milti hain (Fig. 2.3, aakhri step). Sabse andar endometrium hai, woh glandular lining jo har cycle mein dobara banti aur girti hai. Uske chaaron taraf myometrium hai, smooth muscle ki ek moti layer jiske powerful contractions birth ke time baby ko bahar dhakelte hain. Ek patli membrane, perimetrium, bahar se lipti hoti hai.

External genitalia, jinhe milakar vulva kehte hain, yahan aage aur bahar se andar ki taraf list kiye gaye hain.

• Mons pubis: pubic bone ke upar fat ka ek gol pad, jiske upar skin aur puberty ke baad baal hote hain.
• Labia majora: vaginal opening ke dono taraf skin folds ka bahari pair.
• Labia minora: folds ka andar wala, patla pair.
• Clitoris: aage ki taraf ek chhota, bahut sensitive organ, jahan andar wale folds milte hain, urethral opening ke upar.
• Hymen: vaginal opening par ek patli, aksar adhoori membrane.

Hymen ke baare mein ek aam belief ko sudhaarna zaroori hai. Bahut log maante hain ki iski haalat se pata chalta hai ki aurat ne intercourse kiya hai ya nahi. Aisa nahi hai. Iski shape alag-alag logon mein bahut alag hoti hai, yeh cycling, horse riding, girne ya tampon use karne se khinch ya phat sakti hai, aur intercourse ke baad bhi intact reh sakti hai. Isliye hymen virginity ka reliable sign nahi hai, aur iske basis par kisi ko judge karne ka koi scientific basis nahi hai.

Mammals ka naam inhi glands se aaya hai: har female mammal apne bachchon ko apni mammary glands ke doodh se pila sakti hai. Har breast mein fat hota hai, jiski amount alag-alag auraton mein bahut alag hoti hai, aur doodh banane wala glandular tissue hota hai jo 15–20 mammary lobes mein bata hota hai. Har lobe mein chhoti-chhoti thailiyon, yaani alveoli, ke clusters hote hain, jinke cells apne khokhle centre mein doodh secrete karte hain. Doodh tubes ke ek branching set se bahta hai (Fig. 2.4): alveoli, mammary tubules, har lobe ke liye ek mammary duct, ek chaudi mammary ampulla, phir ek lactiferous duct jo nipple par khulti hai.

2.3 Gametogenesis

Gametogenesis gametes banane ka process hai: testes mein sperms aur ovaries mein ova, jo primary sex organs hain. Dono raaste meiosis use karte hain, woh division jo chromosome number ko aadha kar deta hai, isliye har human gamete mein body cell ke 46 ($2n$) ki jagah 23 chromosomes (haploid number, $n$) hote hain. Sperm aur ovum ke fusion se phir 46 ho jaate hain.

Spermatogenesis

Spermatogenesis puberty se budhaape tak seminiferous tubules ke andar bina ruke chalta hai (Fig. 2.2). Isme ek cell ko track karo (Fig. 2.8):

1. Multiply. Spermatogonia, jo diploid ($2n=46$) hain, tubule wall par baithe mitosis se divide hote rehte hain, isliye stock kabhi khatam nahi hota.
2. Commit. Beech-beech mein ek spermatogonium badhkar primary spermatocyte ($2n$) ban jaata hai, woh cell jo meiosis se guzrega.
3. Halve. Meiosis I, yaani reduction division, ise do barabar secondary spermatocytes mein baant deta hai, har ek haploid ($n=23$).
4. Split again. Meiosis II inmein se har ek ko divide karta hai, isliye ek primary spermatocyte se aakhir mein chaar barabar, haploid spermatids bante hain.

Spermatids gol cells hote hain jo abhi tair nahi sakte. Unka spermatozoa (sperms) mein badalna, jise spermiogenesis kehte hain, ek head, middle piece aur tail banata hai aur zyadatar cytoplasm hata deta hai; yeh sab tab hota hai jab sperm heads Sertoli cells mein dhanse hote hain. Taiyaar hone par sperms tubule ke lumen mein chhod diye jaate hain, is release ko spermiation kehte hain.

Hormones jo ise on karte hain

Sperm production puberty ka intezaar kyun karta hai? Kyunki yeh ek hormone relay par depend karta hai jo tabhi chalu hota hai (Fig. 2.5). Shuruaati signal hypothalamus se aane wala gonadotropin-releasing hormone (GnRH) hai, jiska output puberty par tezi se badhta hai. GnRH anterior pituitary tak pahunchta hai aur use do gonadotropins release karne ko kehta hai. Ek, luteinising hormone (LH), Leydig cells ko target karta hai, jo jawab mein androgens banate hain, aur androgens hi spermatogenesis ko chalate hain. Doosra, follicle-stimulating hormone (FSH), Sertoli cells ko target karta hai, jo phir aise substances secrete karte hain jo spermiogenesis ko support karte hain.

Sperm ki structure

Sperm ko sirf ek delivery kaam ke liye halka banaya gaya hai: ek haploid nucleus ko egg tak pahunchana (Fig. 2.6). Ise ek engine wala payload samjho. Payload, jo head mein hai, ek lamba haploid nucleus hai. Iske aage acrosome fit hota hai, enzymes se bhari ek cap jo egg ki coverings mein raasta digest karegi. Ek chhoti neck head ko middle piece se jodti hai, jispar mitochondria lipte hote hain, yahi power supply hai. Unki energy tail ko chalati hai, jiski chaabuk jaisi beating sperm ko aage badhati hai, aur jo sperm tair nahi sakta woh fertilise nahi kar sakta. Ek single plasma membrane chaaron regions ko lapete rehti hai.

Semen sperms plus seminal plasma hai. Tubule se abhi-abhi nikla sperm fertilise nahi kar sakta: yeh ducts se guzarte hue mature hota hai aur tairne ki taaqat paata hai, jismein epididymis, vas deferens, seminal vesicles aur prostate ke secretions madad karte hain, aur yeh sab tabhi kaam karte hain jab androgens maujood hon. Jab doctors kisi aadmi ki fertility check karte hain to woh teen figures dekhte hain: ek ejaculation mein normally lagbhag 200–300 million sperms hote hain, jinmein se kam se kam 60 per cent normal dikhne chahiye (sahi size aur form) aur kam se kam 40 per cent tezi se tairne wale hone chahiye.

Oogenesis

Oogenesis, yaani egg banna, spermatogenesis se bilkul alag timetable par chalta hai. Iski kahani umar ke hisaab se sabse achhe se samajh aati hai (Fig. 2.7).

• Birth se pehle. Female foetus ki ovaries kareeb do million egg mother cells, yaani oogonia, banati hain; birth ke baad koi naya nahi judta. Yeh meiosis shuru karte hain lekin prophase I mein ruk jaate hain, aur primary oocytes ban jaate hain. Har ek ko jaldi hi granulosa cells ki ek single layer mil jaati hai aur tab woh primary follicle kehlata hai.
• Birth se puberty tak. Zyadatar follicles khatam ho jaate hain, isliye puberty tak ek ovary mein sirf lagbhag 60 000–80 000 primary follicles bachte hain.
• Puberty ke baad har cycle mein. Kuch follicles phir se badhna shuru karte hain. Granulosa ki extra layers aur ek bahari coat, theca, milkar secondary follicle banate hain. Phir fluid se bhari ek jagah, antrum, khulti hai, aur theca theca interna (andar) aur theca externa (bahar) mein bant jaata hai: yeh tertiary follicle hai.
• Tertiary follicle ke andar. Primary oocyte, jo saalon ya decades se ruka tha, bada hota hai aur aakhirkaar meiosis I poora karta hai. Yeh split ek-tarfa hota hai: haploid secondary oocyte lagbhag saara khane se bharpoor cytoplasm rakh leta hai, jabki first polar body ko lagbhag kuch nahi milta.
• Ovulation se theek pehle. Follicle ab ek mature Graafian follicle hai, aur uske andar secondary oocyte ek glycoprotein coat, zona pellucida, mein band hai.11Zona pellucida asal mein kaafi pehle, badhte primary oocyte ke chaaron taraf banna shuru ho jaati hai, aur follicle ke develop hone ke saath moti hoti jaati hai.
• Ovulation. Graafian follicle phat jaata hai aur secondary oocyte ovary se bahar nikal jaata hai: yahi ovulation hai. Release hua cell meiosis II shuru kar chuka hota hai lekin phir ruk jaata hai, aur use tabhi poora karta hai jab koi sperm andar aaye (Section 2.5).

Dono ko compare karna

Dono processes ek hi tarah ke divisions se guzarte hain, lekin timing aur results bahut alag hote hain. Fig. 2.8 ko step by step dekho aur dono ko cell by cell compare karo, phir uske baad wali table use karo.

2.4 Menstrual Cycle

Puberty se lagbhag pachaas saal tak, aurat ka body ek repeat hone wala programme chalata hai jo lagbhag har mahine pregnancy ki taiyaari karta hai aur pregnancy shuru na hone par woh taiyaari hata deta hai. Yahi menstrual cycle hai, ek pattern jo humans doosre primates jaise monkeys aur apes ke saath share karte hain. Ek cycle bleeding ke pehle din se agli bleeding ke pehle din tak gina jaata hai aur average lagbhag 28–29 din chalta hai; puberty par sabse pehli bleeding ko menarche kehte hain. Cycle ke beech ke aas-paas normally ek ovum release hota hai. Fig. 2.9 ek cycle ko ghadi ki tarah ghoom kar follow karta hai.

Menstrual phase (lagbhag days 1–5). Cycle ki shuruaat wali bleeding purane endometrium ka hatna hai: lining aur uski blood vessels toot jaati hain, aur bana hua fluid 3–5 dinon mein vagina se bahar nikalta hai. Yeh isliye hota hai kyunki pichhla cycle bina fertilised ovum ke khatam hua. To jab period nahi aata, to pregnancy ek possibility hai, lekin stress, bimaari aur kharab nutrition bhi wajah ho sakte hain.

Follicular phase (lagbhag days 6–13). Do cheezein ek saath badhti hain. Ovary mein, pituitary se dheere-dheere badhte FSH aur LH follicles ke ek batch ko develop hone ke liye push karte hain, aur unmein se ek mature Graafian stage tak pahunchta hai. Badhte follicles estrogen nikaalte hain, aur estrogen cell division se endometrium ko dobara banata hai, isiliye is hisse ko proliferative phase bhi kehte hain.

Ovulatory phase (lagbhag day 14). Jab pake follicle se estrogen peak par hota hai, to pituitary jawab mein LH ka ek burst deta hai, yaani LH surge, saath mein FSH ka ek chhota peak. Lagbhag ek din ke andar yeh surge Graafian follicle ko phaad deta hai aur woh apna secondary oocyte release kar deta hai.

Luteal phase (lagbhag days 15–28). Khaali follicle bekaar nahi jaata: yeh bhar kar corpus luteum ban jaata hai, ek temporary gland jo bahut zyada progesterone release karta hai. Progesterone endometrium ko apni jagah banaye rakhta hai aur uski glands ko on kar deta hai, taaki woh embryo ko receive karne ke liye taiyaar ho; yeh uterus ka secretory phase hai. Aage kya hoga, yeh fertilisation par depend karta hai. Agar embryo implant hota hai, to corpus luteum chalta rehta hai, lining bani rehti hai, aur poori pregnancy ke liye cycling ruk jaati hai. Agar nahi, to corpus luteum sookh jaata hai, progesterone girta hai, bina support ki lining toot jaati hai, aur bleeding agle cycle ka day 1 hoti hai.

Lagbhag pachaas saal ki umar mein, menopause par, cycles hamesha ke liye band ho jaate hain. Menarche aur menopause ke beech ke saal aurat ka reproductive phase hain, aur is dauraan regular cycles achhi reproductive health ka sign hain. Neeche diye explorer se cycle ko din-ba-din dekho aur dekho ki embryo implant hone par kya badalta hai.

2.5 Fertilisation aur Implantation

Fertilisation ke liye milna zaroori hai, aur timing hi sab kuch hai. Insemination mein sexual intercourse (coitus) ke dauraan semen vagina mein deposit hota hai. Phir sperms ko lamba tairna padta hai: cervix se hokar, uterus ke paar aur ek oviduct mein upar ampulla tak. Isi beech egg ko fimbriae usi tube mein kheench lete hain aur woh ampulla ki taraf badhta hai. Ovulation ke baad egg sirf lagbhag ek din tak fertilise ho sakta hai, jabki sperms female tract mein kuch din zinda reh sakte hain. Jab tak dono ek saath ampulla mein na hon, fertilisation nahi hota, isliye har intercourse se pregnancy nahi hoti.

Fertilisation (निषेचन) ek sperm aur ek ovum ka milna hai, aur yeh ek fixed order mein hota hai (Fig. 2.11):

1. Contact. Kai sperms egg tak pahunch sakte hain, lekin jo pehla uske glycoprotein coat, zona pellucida, ko chhoota hai, woh egg ki coverings mein changes shuru kar deta hai.
2. Entry. Us sperm ke acrosome se nikle enzymes zona pellucida mein raasta digest karte hain; phir sperm egg ki plasma membrane se fuse hota hai aur uska nucleus cytoplasm mein chala jaata hai.
3. Lock-out. Contact par shuru hue changes coverings ko band kar dete hain, isliye normally sirf ek sperm andar aata hai.
4. Meiosis II. Sperm ka andar aana secondary oocyte ke liye apna second meiotic division poora karne ka signal hai. Phir se split unequal hota hai: ek haploid ovum, yaani ootid, aur ek chhoti si second polar body.
5. Fusion. Sperm ka haploid nucleus aur ovum ka haploid nucleus paas aakar fuse hote hain aur ek diploid nucleus bante hain. Ab yeh cell ek zygote hai.

Baby ka sex

Zygote ladki banega ya ladka, yeh fertilisation par hi tay ho jaata hai, aur faisla sperm karta hai (Fig. 2.12). Aurat ke body cells mein do X chromosomes hote hain; aadmi ke cells mein ek X aur ek Y. Aurat ka banaya har egg uske do Xs mein se ek paata hai, isliye har egg mein X hota hai. Jab aadmi ke testes sperms banate hain, to meiosis X ko aadhe sperms mein aur Y ko baaki aadhe mein bhejta hai. X-bearing sperm se fertilise hua egg XX banta hai aur ladki ki tarah develop hota hai; Y-bearing sperm se fertilise hua egg XY banta hai aur ladke ki tarah develop hota hai. Isliye bachche ke sex ke liye mother ko blame karne ka koi scientific basis nahi hai. Chapter 4 mein sex determination par phir se baat hogi.

Cleavage aur implantation

Zygote safar karte hue divide hota hai (Fig. 2.14). Tube ke beat karte cilia aur halki muscular waves use isthmus ke saath uterus ki taraf dhakelti hain, aur yeh mitosis se 2, phir 4, 8, 16 … cells mein bantta hai, jinhe blastomeres kehte hain. Yeh divisions, jinhe cleavage kehte hain, zygote ko lagaataar chhote cells mein kaat dete hain, lekin poora embryo bada nahi hota. 8–16 blastomeres par embryo ek solid ball hota hai jise morula kehte hain.

Uterus ke andar morula divide hota rehta hai aur khokhla hokar blastocyst ban jaata hai. Ab iske cells do groups mein bant jaate hain jinka future bilkul alag hai: ek patla bahari shell, trophoblast, jo mother se contact banata hai, aur shell ki andar wali side par ek gucchha, inner cell mass, jo khud embryo banega. Trophoblast endometrium se chipak jaata hai; uske paas ke uterine cells tezi se multiply hote hain aur blastocyst ke upar tak badh jaate hain, jab tak woh lining mein dab nahi jaata. Is dabne ko implantation kehte hain, aur isi ke saath pregnancy shuru hoti hai.

2.6 Pregnancy aur Embryonic Development

Implant hone ke baad embryo ko ek supply line chahiye. Trophoblast ungliyon jaise chorionic villi aas-paas ke uterine tissue mein bhejta hai, jahan woh mother ke blood ke pools mein doobe rehte hain. Villi aur uterine tissue ek doosre mein aise badhte hain jaise ungliyan aapas mein phansi hon, aur milkar placenta (अपरा) banate hain, ek organ jo embryo (baad mein foetus kehlata hai) aur mother milkar banate hain (Fig. 2.15).

Villi ki patli walls ke aar-paar foetus ka blood mother ke blood se oxygen aur nutrients leta hai aur carbon dioxide aur doosre wastes wapas deta hai; dono bloodstreams khud normally kabhi nahi milte. Umbilical cord, jismein foetus ki blood vessels hoti hain, use placenta se jodti hai.

Placenta ek hormone factory bhi hai. Iske do products, human chorionic gonadotropin (hCG) aur human placental lactogen (hPL), pregnancy ke bahar kabhi nahi milte, aur yeh estrogens aur progestogens bhi banata hai. Sirf pregnancy wala ek teesra hormone, relaxin, baad ke mahino mein ovary se aata hai aur birth ke liye pelvic ligaments ko dheela karne mein madad karta hai. Inke upar, mother ke blood mein estrogens, progestogens, cortisol, prolactin aur thyroxine normal se kai guna zyada hote hain. Hormones ka yeh surge foetus ki growth ko badhata hai, mother ke metabolism ko adjust karta hai aur pregnancy ko jaldi khatam hone se rokta hai.

Isi beech inner cell mass organise hota hai (Fig. 2.16). Ismein stem cells hote hain, unspecialised cells jo koi bhi tissue ya organ bana sakte hain, aur woh layers mein bantna shuru karte hain: pehle bahari ectoderm aur andar wala endoderm, phir unke beech ek middle mesoderm. Adult body ka har tissue in teen germ layers mein se kisi ek se aata hai.

Human pregnancy lagbhag nau mahine chalti hai, jise aksar lagbhag teen-teen mahine ke teen trimesters mein baanta jaata hai. Timeline development ke kuch milestones dikhati hai.

2.7 Parturition aur Lactation

Lagbhag nau mahine, yaani gestation period, ke baad baby paida hota hai. Birth, yaani parturition (प्रसव), uterus ke powerful contractions se foetus ko bahar nikalna hai, aur ise nerves aur hormones milkar control karte hain, yaani ek neuroendocrine mechanism (Fig. 2.17).

Kamaal ki baat yeh hai ki shuruaati signal baby khud deta hai. Jab foetus poori tarah develop ho jaata hai, to usse aur placenta se aane wale signals uterus ke halke contractions shuru karte hain, jise foetal ejection reflex kehte hain. In contractions se aane wale nerve messages mother ki pituitary se oxytocin release karwate hain. Oxytocin uterine muscle ko aur zor se nichodne par majboor karta hai, aur zyada zor ke contractions aur bhi oxytocin release karwate hain. Kyunki har step agle ko badhata hai, jise positive feedback kehte hain, contractions tab tak badhte rehte hain jab tak baby birth canal se bahar na aa jaaye. Thodi der baad aur contractions placenta, yaani afterbirth, ko bahar nikaalte hain.

Doodh banna, yaani lactation, pregnancy ke dauraan taiyaar hota hai, jab mammary glands aur develop hoti hain, aur pregnancy ke end ki taraf shuru hota hai. Pituitary se aane wala prolactin alveoli se doodh banwata rehta hai, aur oxytocin, jo labour ka hormone hai, baby ke doodh peene par use bahar nichodta hai. Pehla doodh, colostrum, gaadha aur halka peela hota hai aur antibodies se bharpoor hota hai jo newborn ko infection se bachati hain jab tak uska apna immune system taiyaar nahi hota. Isiliye doctors salah dete hain ki birth ke jaldi baad baby ko breast se lagao aur lagbhag pehle chhe mahine sirf breast milk do.