Human Reproduction
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SUMMARY ****Humans are sexually reproducing and viviparous. The male reproductive system is composed of a pair of testes, the male sex accessory ducts and the accessory glands and external genitalia.
Each testis has about 250 compartments called testicular lobules, and each lobule contains one to three highly coiled seminiferous tubules. Each seminiferous tubule is lined inside by spermatogonia and Sertoli cells.
The spermatogonia undergo meiotic divisions leading to sperm formation, while Sertoli cells provide nutrition to the dividing germ cells.
The Leydig cells outside the seminiferous tubules, synthesise and secrete testicular hormones called androgens. The male external genitalia is called penis.
The female reproductive system consists of a pair of ovaries, a pair of oviducts, a uterus, a vagina, external genitalia, and a pair of mammary glands.
The ovaries produce the female gamete (ovum) and some steroid hormones (ovarian hormones).
Ovarian follicles in different stages of development are embedded in the stroma.
The oviducts, uterus and vagina are female accessory ducts.
The uterus has three layers namely perimetrium, myometrium and endometrium.
The female external genitalia includes mons pubis, labia majora, labia minora, hymen and clitoris.
The mammary glands are one of the female secondary sexual characteristics.
Spermatogenesis results in the formation of sperms that are transported by the male sex accessory ducts.
A normal human sperm is composed of a head, neck, a middle piece and tail.
The process of formation of mature female gametes is called oogenesis.
The reproductive cycle of female primates is called menstrual cycle. Menstrual cycle starts only after attaining sexual maturation (puberty).
During ovulation only one ovum is released per menstrual cycle. The cyclical changes in the ovary and the uterus during menstrual cycle are induced by changes in the levels of pituitary and ovarian hormones.
After coitus, sperms are transported to the junction of the isthmus and ampulla, where the sperm fertilises the ovum leading to formation of a diploid zygote.
The presence of X or Y chromosome in the sperm determines the sex of the embryo.
The zygote undergoes repeated mitotic division to form a blastocyst, which is implanted in the uterus resulting in pregnancy.
After nine months of pregnancy, the fully developed foetus is ready for delivery.
The process of childbirth is called parturition which is induced by a complex neuroendocrine mechanism involving cortisol, estrogens and oxytocin.
Mammary glands differentiate during pregnancy and secrete milk after child-birth.
The new-born baby is fed milk by the mother (lactation) during the initial few months of growth.
Each testis has about 250 compartments called testicular lobules, and each lobule contains one to three highly coiled seminiferous tubules. Each seminiferous tubule is lined inside by spermatogonia and Sertoli cells.
The spermatogonia undergo meiotic divisions leading to sperm formation, while Sertoli cells provide nutrition to the dividing germ cells.
The Leydig cells outside the seminiferous tubules, synthesise and secrete testicular hormones called androgens. The male external genitalia is called penis.
The female reproductive system consists of a pair of ovaries, a pair of oviducts, a uterus, a vagina, external genitalia, and a pair of mammary glands.
The ovaries produce the female gamete (ovum) and some steroid hormones (ovarian hormones).
Ovarian follicles in different stages of development are embedded in the stroma.
The oviducts, uterus and vagina are female accessory ducts.
The uterus has three layers namely perimetrium, myometrium and endometrium.
The female external genitalia includes mons pubis, labia majora, labia minora, hymen and clitoris.
The mammary glands are one of the female secondary sexual characteristics.
Spermatogenesis results in the formation of sperms that are transported by the male sex accessory ducts.
A normal human sperm is composed of a head, neck, a middle piece and tail.
The process of formation of mature female gametes is called oogenesis.
The reproductive cycle of female primates is called menstrual cycle. Menstrual cycle starts only after attaining sexual maturation (puberty).
During ovulation only one ovum is released per menstrual cycle. The cyclical changes in the ovary and the uterus during menstrual cycle are induced by changes in the levels of pituitary and ovarian hormones.
After coitus, sperms are transported to the junction of the isthmus and ampulla, where the sperm fertilises the ovum leading to formation of a diploid zygote.
The presence of X or Y chromosome in the sperm determines the sex of the embryo.
The zygote undergoes repeated mitotic division to form a blastocyst, which is implanted in the uterus resulting in pregnancy.
After nine months of pregnancy, the fully developed foetus is ready for delivery.
The process of childbirth is called parturition which is induced by a complex neuroendocrine mechanism involving cortisol, estrogens and oxytocin.
Mammary glands differentiate during pregnancy and secrete milk after child-birth.
The new-born baby is fed milk by the mother (lactation) during the initial few months of growth.
Transport of sperm: -
Seminiferous tubules → Rete testis → Vasa efferentia → Epididymis → Vas deferens → Ejaculatory duct → Urethra → Urethral meatus
Spermatids : spermatogonia (meiosis) → immature male gametes
Sperm cells: mature male reproductive cells capable of fertilizing an egg cell.
Spermatogenesis: spermatogonium → motile spermatozoa
Spermiogenesis: spermatids → spermatozoa
Spermiation: release of sperms from seminiferous tubules
MCQs
3. The shared terminal duct of the reproductive and urinary system in the human male is
a. urethra, b. ureter, c. vas deferens, d. vasa efferentia
Ans. a
4. The Leydig's cells as found in the human body are the secretory source of
a. progesterone, b. intestinal mucus, c. glucagon, d. androgens
Ans. d
5. If for some reason, the vasa efferentia in the human reproductive system get blocked, the gametes will not be transported from
a. testes to epididymis, b. epididymis to vas deferens, c. ovary to uterus, d. vagina to uterus
Ans. a
6. The testes in human are situated outside the abdominal cavity inside a pouch called scrotum. The purpose served is for
a. maintaining the scrotal temperature lower than the internal body temperature
b. escaping any possible compression by the visceral organs
c. providing more space for the growth of epididymis
d. providing a secondary sexual feature for exhibiting the male sex.
Ans. a
7. Sertoli cells are found in
a. ovaries and secrete progesterone, b. adrenal cortex and secret adrenaline, c. seminiferous tubules and provide nutrition to germ cells, d. pancreas and secret cholecystokinin
Ans. c
8. Vasa efferntia are the ductules leading from
a. testicular lobules to rete testis, b. rete testis to vas deferens, c. vas deferens to epididymis, d. epididymis to urethra
Ans. b
9. Seminal plasma in human males is rich in
a. fructose and calcium, b. glucose and calcium, c. DNA and testosterone, d. ribose and potassium
Ans. a
10. Secretions from which one of the following are rich in fructose, calcium and some enzymes?
a. Male accessory glands, b. liver, c. Pancreas, d. salivary glands
Ans. a
11. Seminal plasma in humans is rich in
a. fructose and calcium but has no enzymes, b. glucose and certain enzymes but has no calcium, c. fructose and certain enzymes but poor in calcium, d. fructose, calcium and certain enzymes
Ans. d
13. Male hormone is produced in the testis by cells of
a. Sertoli, b. Epithelial cells, c. Spermatocytes, d. Leydig
Ans. d
14. Location and secretion of Leydig's cells are
a. liver-cholesterol, b. ovary-estrogen, c. testis - testosterone,
d. pancreas - glucagon
Ans. c
15.Hysterectomy is surgical removal of
a. vas deferens, b. mammary glands, c. uterus, d. prostate glands
Ans. c
17. The part of fallopian tube closest to the ovary is
a. isthmus, b. infundibulum, c. cervix, d. ampulla
Ans. b
18. Bartholin's glands are situated
a. on the sides of the head of some amphibians, b. at the reduced tail end of birds, c. on either side of vagina in humans, d. on either side of vas deferens in humans.
Ans. c
19. Meiotic division of the secondary oocyte is completed
a. prior to ovulation, b. at the time of copulation, c. after zygote formation, d. at the time of fusion of a sperm with an ovum.
Ans. d
20. The difference between spermiogenesis and spermiation is
a. in spermiogenesis spermatids are formed, while in spermiation spermatozoa are formed
b. in spermiogenesis spermatozoa are formed, while in spermiation spermatids are formed
c. in spermiogenesis spermatozoa from sertoli cells are released into the cavity of seminiferous tubules, while in spermiation spermatozoa are formed
d. in spermiogensis spermatozoa are formed, while in spermiation spermatozoa are released from sertoli cells into the cavity of seminiferous tubules
Ans. d
21. Which of the following layer in an antral follicle is acellular?
a. Stroma, b. Zona pellucida, c. Granulosa, d. Theca interna
Ans. b
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