Fertilization of ovum normally occurs in which part of fallopian tube?
Ans. c (Ampulla) (Ref. Dutta Obstetrics, 6,h/pg. 21; Shaw's Gynecology, 14th/pg.l77)# Fertilization is the process of fusion of the spermatozoon with the mature ovum. It begins with sperm collision and ends with production of a mononucleated single cell called zygote.# Almost always, fertilization occurs in the ampullary part of the uterine tube.# Its objectives are: To initiate embryonic development of the egg and to restore the chromosome number of speciesFertilization related Important factsQ. Ans.1Number of oogonia reaches its maximum at20th approximately 7 millions.2Total numbers of oocyte at birth are1 million.3Total number of oocyte at puberty is 4, 00,000 out of which400 are likely to ovulate.4Fertilization (useful) life-span of oocyte is 12 hours and rarely up to 24 hours, whereas that of the sperm is limited to24 hours.5Sperm takes60 minutes to travel6Ovulation occurs soon after the formation ofsecondary oocyte.7Ovulation occurs approximately16-24 hours after LH surge.8A fully mature ovumIs largest cell in the body (130 microns diameter).9Ovum is surrounded by a cell membrane called vitelline membrane, there is also transparent mucoprotein envelope known asZona pellucida10Time required for spermatogonium to develop into mature spermatozoa is about61 days.11Capacitation of spermTakes 2-6 hours and only the capacitated sperms can penetrate the zona pellucida.12Out of hundred millions of sperms deposited in vagina at single ejaculation, only thousands capacitated spermatozoa enter the uterine tube whileOnly 300-500 reach the ovum. The tubal transport is facilitated by muscular contraction and aspiration action of the uterine tubes.13 It takes about 60 minutesFor the sperm to reach the fallopian tube (ampulla), i.e to cover the intervening distance of 20 cm.15 Usually fertilization occurs inAmpulla.Also know;Sequence of maturation of ovarian primordial follicle after Primary follicle stage is:Primordial follicle (Single layered)Spermatogonium (diploid, 2N)||Primary folliclePrimary spermatocyte (diploid, 2N)||Secondary follicle (Antral follicle)Secondary spermatocyte (haploid, 2N)||0Graafian follicleSpermatid (haploid, N)|(Spermatogenesis begins with spermatogonia.Corpus luteumFull development takes 2 months. It occurs in seminiferous tubules).| Corpus albicans
Isthmus
Intramural part
Ampulla
Fimbria
Uterine Tubes