· There are two types of reproduction: asexual and sexual reproduction.
A. Asexual reproduction
· It involves only one parent so reproduction occurs without the formation and fusion of gametes.
· It produces genetically identical offspring.
· Cell divisions are only mitosis.
· It is a faster mode of reproduction found usually in lower organisms.
· It involves only one parent so reproduction occurs without the formation and fusion of gametes.
· It produces genetically identical offspring.
· Cell divisions are only mitosis.
· It is a faster mode of reproduction found usually in lower organisms.
B. Sexual reproduction (Gametic reproduction)
· It involves two parents of opposite sexes like male and female. They produce gametes and there occurs fusion of gametes.
· Gametes are formed by meiosis and the zygote undergoes mitotic division.
· Offspring are not genetically identical.
· It is a much slower mode of reproduction found in higher invertebrates and all vertebrates.
· Humans are unisexual i.e. male and female reproductive organs are found in separate individuals.
· There is distinct sexual dimorphism.
· Humans are unisexual i.e. male and female reproductive organs are found in separate individuals.
· There is distinct sexual dimorphism.
· Besides, male and female reproductive organs differ anatomically and physiologically. So, reproductive systems are dealt with separately.
· Actually, the reproductive system starts to function effectively only after puberty.
· Reproductive system consists of reproductive organs and the physiology of reproduction.
· Actually, the reproductive system starts to function effectively only after puberty.
· Reproductive system consists of reproductive organs and the physiology of reproduction.
MALE REPRODUCTIVE SYSTEM
· It consists of the following organs:1. 2 Testes
2. 2 Epididymides
3. 2 Vas deferens
4. 2 Ejaculatory ducts
5. 1 Urethra
6. 1 Penis
7. Accessory glands [Seminal vesicles (2), Prostate gland (1), Cowper’s glands (2)]
1. Testes
· Testes are a pair of pinkish, oval bodies and lie inside the scrotum.
· They are about 4 cm long, 2-3 cm wide and 3 cm thick and are suspended in the scrotum by a band of connective tissue called gubernaculum or spermatic cords.
· Successful spermatogenesis occurs at a temperature about 3°C below the normal body temperature.
· Testes are a pair of pinkish, oval bodies and lie inside the scrotum.
· They are about 4 cm long, 2-3 cm wide and 3 cm thick and are suspended in the scrotum by a band of connective tissue called gubernaculum or spermatic cords.
· Successful spermatogenesis occurs at a temperature about 3°C below the normal body temperature.
· So, testes are situated outside the abdominal cavity and the thin outer covering of the scrotum has very little insulating fat.
· The scrotal sac and abdominal cavity are communicated with each other by the inguinal canal.
· The scrotal sac and abdominal cavity are communicated with each other by the inguinal canal.
Covering of the Testis:
· The testis is surrounded by 3 layers. They are:
a. Tunica vaginalis - It is the outer covering of the testis. It is a double membrane structure.
b. Tunica albuginea - It is the fibrous covering around the testis. It lies below tunica vaginalis.
c. Tunica vasculosa - It is the innermost layer, supported by delicate connective tissue. It consists of a network of blood capillaries.
· The testis is surrounded by 3 layers. They are:
a. Tunica vaginalis - It is the outer covering of the testis. It is a double membrane structure.
b. Tunica albuginea - It is the fibrous covering around the testis. It lies below tunica vaginalis.
c. Tunica vasculosa - It is the innermost layer, supported by delicate connective tissue. It consists of a network of blood capillaries.
Microscopic Structure of a Testis
· Internally, each testis is divided into 200-300 lobules called testicular lobules by septa.
· Each lobule of the testis is composed of 1-4 coiled seminiferous tubules.
· These seminiferous tubules open in straight tubules called tubuli recti which forms a network of small capillaries called rete testis.
· Seminiferous tubules are lined with germinal epithelial cells that produce sperms by spermatogenesis and few, tall, columnar cells, the Sertoli cells.
· Sertoli cells that lie between the germinal epithelial cells provide nourishment to the developing sperms.
· Between the seminiferous tubules, there are groups of round interstitial cells or cells of Leydig, discovered by Franz Von Leydig.
· Cells of Leydig secrete the hormone testosterone after puberty which promotes the development of male accessory glands (seminal vesicles, prostate gland and Cowper's glands) and stimulates the secondary sexual characteristics in males such as the formation of moustache, beard, deepening of the voice, broadening of the shoulders, body hair etc.
· Seminiferous tubules are lined with germinal epithelial cells that produce sperms by spermatogenesis and few, tall, columnar cells, the Sertoli cells.
· Sertoli cells that lie between the germinal epithelial cells provide nourishment to the developing sperms.
· Between the seminiferous tubules, there are groups of round interstitial cells or cells of Leydig, discovered by Franz Von Leydig.
· Cells of Leydig secrete the hormone testosterone after puberty which promotes the development of male accessory glands (seminal vesicles, prostate gland and Cowper's glands) and stimulates the secondary sexual characteristics in males such as the formation of moustache, beard, deepening of the voice, broadening of the shoulders, body hair etc.
· Sperms are produced in the seminiferous tubules and mature as they pass through long and convoluted epididymis, where they are stored.
· Sperms produced inside the testis are transferred into epididymis through vasa efferentia.
· Sperms produced inside the testis are transferred into epididymis through vasa efferentia.
· Sperms have 3 parts: head, body and tail.
· The Head has DNA and enzymes to penetrate the outer layer of the ovum and fuse with its nucleus.
· The body of sperm is packed with mitochondria that provide energy for the propelling action of the tail into female reproductive tracts.
2. Epididymis
· Epididymides are a pair of very long and highly convoluted tubes of about 4-6 m length each which lie outside and partially encircling the testis.
· Epididymides are a pair of very long and highly convoluted tubes of about 4-6 m length each which lie outside and partially encircling the testis.
· Epididymis has three parts:
a. Caput epididymis:
· It is a highly convoluted and broad anterior part and is connected to the end of the testis.
· It is embedded in a thick mass of a fat body and is connected with the dorsal abdominal wall by the inguinal canal.
b. Corpus epididymis:
· It is a narrow middle part lying in the inner lateral margin of the testis.
· It connects the caput epididymis with cauda epididymis.
c. Cauda epididymis:
· It is the posterior part of the epididymis which connects the posterior end of the testis to the scrotal sac by a thick elastic tissue called the gubernaculum.
· Epididymis functions as a storage organ of sperms and secretes a fluid that nourishes the sperms.
· Epididymis functions as a storage organ of sperms and secretes a fluid that nourishes the sperms.
3. Vas deferens or Ductus deferens
· Cauda epididymis opens into a thick-walled muscular tube, the vas deferens or sperm duct.
· It is about 45 cm long.
· It makes a loop around the urinary bladder and then joins with the seminal vesicle to form the ejaculatory duct.
· It transports sperms from epididymis to the ejaculatory duct.
· It transports sperms from epididymis to the ejaculatory duct.
4. Ejaculatory ducts
· These are two short tubes measuring about 2 cm long and are formed by the union of the seminal vesicle and vas deferens.
· They are lined by simple columnar epithelium.
· They carry the mixture of sperms and secretions of the seminal vesicles.
5. Urethra
· It is a long tube of about 20 cm arising from the urinary bladder.
· It is a common tube for the discharge of semen and urine so-called urinogenital duct.
· It consists of three parts: the prostatic urethra, the membraneous urethra and the penile urethra.
· The prostatic urethra passes through the prostate gland originating from the urethral orifice of the bladder.
· The membranous urethra is the shortest and narrowest part that extends from the prostate gland to the bulb of the penis.
· The penile urethra lies within the corpus spongiosum of the penis and terminates in the external urethral orifice of the glans penis.
· It is a long tube of about 20 cm arising from the urinary bladder.
· It is a common tube for the discharge of semen and urine so-called urinogenital duct.
· It consists of three parts: the prostatic urethra, the membraneous urethra and the penile urethra.
· The prostatic urethra passes through the prostate gland originating from the urethral orifice of the bladder.
· The membranous urethra is the shortest and narrowest part that extends from the prostate gland to the bulb of the penis.
· The penile urethra lies within the corpus spongiosum of the penis and terminates in the external urethral orifice of the glans penis.
6. Penis
· It is an erectile, cylindrical, fibrio- muscular, male copulatory organ.
· It has three columns of erectile tissues.
· Two lateral corpora cavernosa and the column lying between them containing the urethra is the corpus spongiosum.
· At its tip, it is expanded into a triangular structure called a Glans penis.
· At its tip, it is expanded into a triangular structure called a Glans penis.
· It is covered by a fold of skin called prepuce or foreskin.
· The tip of the glans penis is pierced by the end of the urethra as a vertical slit
· The function of the penis is the deposition of semen into the vagina and the excretion of urine.
· The tip of the glans penis is pierced by the end of the urethra as a vertical slit
· The function of the penis is the deposition of semen into the vagina and the excretion of urine.
6. Accessory glands:
· They include:
a. Seminal vesicles
· They lie on the posterior side of the urinary bladder.
· Each seminal vesicle opens into an ejaculatory duct.
· Seminal vesicles secrete yellowish and slightly alkaline fluid containing fructose and prostaglandins.
· Fructose provides energy to sperm during their journey through the female reproductive tract and prostaglandins stimulate vaginal contraction which helps in the fusion of gametes.
a. Seminal vesicles
· They lie on the posterior side of the urinary bladder.
· Each seminal vesicle opens into an ejaculatory duct.
· Seminal vesicles secrete yellowish and slightly alkaline fluid containing fructose and prostaglandins.
· Fructose provides energy to sperm during their journey through the female reproductive tract and prostaglandins stimulate vaginal contraction which helps in the fusion of gametes.
b. Prostate gland
· It is a single gland present behind the urinary bladder.
· Its secretion is directly discharged into the urethra.
· It gives a milky appearance to the semen and adds alkaline secretion.
· It prevents sperms from the acid present in the female vagina.
c. Cowper’s glands (Bulbourethral glands)
· The paired Cowper's glands, below the prostate gland and on either side of the urethra, secrete thick and slippery fluid (mucus) and serve as lubricant for the lumen of the urethra.
Semen
· The fluid ejaculated at insemination is called semen.
· It contains sperms and secretions of seminal vesicles, prostate gland and Cowper's glands.
· Amount of semen ejaculated at a time varies from 2.5- 3.5 ml containing about 40- 100 spermatozoa per ml.
b. If the number of sperms falls below 20 million, the person becomes infertile.
c. Oligospermia: reduced number of sperms in the ejaculate.
d. Azoospermia: lack of sperms.
e. Whales and elephants have abdominal testes due to their low body temperature. Cooling of the testis is not required for them.
f. In Kangaroo, the scrotum is present in front of the penis.
g. In Bats, Rodents (Rats), Moles etc. testes descend to scrotal sacs only during the breeding season.
h. Castration: Removal of testes or ovaries.
i. Orchidectomy: Surgical removal of testes.
j. Vasectomy: Removal of vas deferens.
k. Alkalinity of semen helps to neutralize the acidity of the urethra left from the passage of urine and protects the sperm from the acidity of the vagina.
l. Urethra consists of 4 parts- urinary, prostatic, membranous and penile.
m. It is physically impossible for a man to urinate and ejaculate at a time because just prior to ejaculation, the internal sphincter closes off the opening of the urinary bladder. The sphincter does not relax until the ejaculation is completed.
n. Closing of the internal sphincter prevents urine from entering the urethra and also prevents the backflow of ejaculatory fluid into the urinary bladder.
o. Scrotal sacs have dartos muscles that constantly contract or relax the loose scrotal skin. This helps to keep the testicular temperature at 35°C.
· The fluid ejaculated at insemination is called semen.
· It contains sperms and secretions of seminal vesicles, prostate gland and Cowper's glands.
· Amount of semen ejaculated at a time varies from 2.5- 3.5 ml containing about 40- 100 spermatozoa per ml.
Did you know?
a. Once ejaculated, sperm in the semen lives only 24-42 hours outside the body.b. If the number of sperms falls below 20 million, the person becomes infertile.
c. Oligospermia: reduced number of sperms in the ejaculate.
d. Azoospermia: lack of sperms.
e. Whales and elephants have abdominal testes due to their low body temperature. Cooling of the testis is not required for them.
f. In Kangaroo, the scrotum is present in front of the penis.
g. In Bats, Rodents (Rats), Moles etc. testes descend to scrotal sacs only during the breeding season.
h. Castration: Removal of testes or ovaries.
i. Orchidectomy: Surgical removal of testes.
j. Vasectomy: Removal of vas deferens.
k. Alkalinity of semen helps to neutralize the acidity of the urethra left from the passage of urine and protects the sperm from the acidity of the vagina.
l. Urethra consists of 4 parts- urinary, prostatic, membranous and penile.
m. It is physically impossible for a man to urinate and ejaculate at a time because just prior to ejaculation, the internal sphincter closes off the opening of the urinary bladder. The sphincter does not relax until the ejaculation is completed.
n. Closing of the internal sphincter prevents urine from entering the urethra and also prevents the backflow of ejaculatory fluid into the urinary bladder.
o. Scrotal sacs have dartos muscles that constantly contract or relax the loose scrotal skin. This helps to keep the testicular temperature at 35°C.
FEMALE REPRODUCTIVE SYSTEM
It consists of the following parts:a. External genitalia (Vulva) [Mons pubis, Labia majora, Labia minora, Hymen, Vestibule, Clitoris]
b. Internal genitalia
i. Vagina (1)
ii. Uterus (1)
iii. Fallopian tubes or uterine tubes or oviducts (2)
iv. Ovaries (2)
c. Accessory glands- Vestibular glands (Bartholin’s glands) and Mammary glands.
A. External genitalia (Vulva)
i. Mons pubis
· It is a pad of subcutaneous tissue in front of the pubis.
· It is the anterior portion consisting of pubic hair at puberty.
ii. Labia majora
· They are two large folds of skin made up of adipose tissue and smooth muscle which form the boundary of the vulva.
· They are covered with coarse hair on their external lateral surface but are devoid of hair on their inner surface.
iii. Labia minora
· These are two smaller folds of skin lie between labia majora containing sebaceous glands.
· The area between the right and left labia minora is called the vestibule.
· Vagina, urethra and vestibular glands open into vestibule.
· It is a thin layer of the mucus membrane that partially occludes the opening of the vagina in the virgins.
v. Clitoris
· It is an erectile tissue, corresponds to the penis in males and sensory in function.
B. Internal genitalia
· It consists of the vagina, uterus, fallopian tubes and ovaries.
1. Vagina
· It is a fibrio-muscular tube whose interior wall is about 7.5 cm long and posterior wall about 9cm long and extends from the cervix to the external genitalia.
· Vagina has three layers: an outer covering of the areolar tissue, a middle layer of the smooth muscle and an inner lining of the stratified squamous epithelium.
· It consists of the vagina, uterus, fallopian tubes and ovaries.
1. Vagina
· It is a fibrio-muscular tube whose interior wall is about 7.5 cm long and posterior wall about 9cm long and extends from the cervix to the external genitalia.
· Vagina has three layers: an outer covering of the areolar tissue, a middle layer of the smooth muscle and an inner lining of the stratified squamous epithelium.
· It contains bacteria Lactobacillus acidophilus which secretes lactic acid to inhibit the growth of the microbes that may enter the vagina from the perineum.
· It is adapted for:
a. receiving the male’s penis during copulation
b. allowing menstrual cycle and
c. serving as a birth canal.
· It is adapted for:
a. receiving the male’s penis during copulation
b. allowing menstrual cycle and
c. serving as a birth canal.
The well-labelled sketch of female reproductive organs is given below:
2. Uterus (Womb)
· It is a large, hollow, muscular, pear-shaped, highly elastic medium specialized for the development of the embryo.
· It is about 7.5 cm long, 5 cm wide and its wall are about 2.5 cm thick.
· It weighs from 30-40 grams.
· It is a large, hollow, muscular, pear-shaped, highly elastic medium specialized for the development of the embryo.
· It is about 7.5 cm long, 5 cm wide and its wall are about 2.5 cm thick.
· It weighs from 30-40 grams.
· It lies between the urinary bladder and rectum.
· It is smaller in a nulliparous woman (not given birth) and larger in a multiparous woman (who has borne 2 or more children).
· Highly vascular wall of the uterus is made up of 3 layers– Perimetrium (outer), myometrium (middle) and endometrium (inner).
· It is smaller in a nulliparous woman (not given birth) and larger in a multiparous woman (who has borne 2 or more children).
· Highly vascular wall of the uterus is made up of 3 layers– Perimetrium (outer), myometrium (middle) and endometrium (inner).
· The endometrium is richly supplied with blood vessels.
· Endometrium is divided functionally into the upper functional layer that is shed during menstruation if an ovum is not fertilized and the lower basal layer from which the fresh functional layer is regenerated during each cycle.
· Endometrium is divided functionally into the upper functional layer that is shed during menstruation if an ovum is not fertilized and the lower basal layer from which the fresh functional layer is regenerated during each cycle.
· Uterus consists of the following three regions:
a. Fundus: It is an upper wide, dome-shaped structure and lies above the openings of the uterine tubes.
b. Body: It is the main large part into which oviducts open. It narrows posteriorly at the internal os where it is continuous with the cervix.
c. Cervix: It is the narrow circular portion that communicates above with the body of the uterus by an aperture, the internal os or internal orifice of the uterus and with the vagina, by an opening, the external os or external orifice of the uterus.
a. Fundus: It is an upper wide, dome-shaped structure and lies above the openings of the uterine tubes.
b. Body: It is the main large part into which oviducts open. It narrows posteriorly at the internal os where it is continuous with the cervix.
c. Cervix: It is the narrow circular portion that communicates above with the body of the uterus by an aperture, the internal os or internal orifice of the uterus and with the vagina, by an opening, the external os or external orifice of the uterus.
3. Fallopian tubes or Uterine tubes or Oviducts
· These are tubes of about 10 cm long and extend from the uterus between the body and fundus.
· It consists of four parts:
a. Infundibulum: It is the funnel-shaped posterior end and lies near the ovary. Its end bears finger-like structures called fimbriae. Ovum is collected by fimbriae.
b. Ampulla: It is the expanded, widest and curved path and is the site of fertilization.
c. Isthmus: It is the narrow and straight part of the fallopian tube. It lies between the ampulla and uterus.
d. Uterine part: The part very close to the uterus is called the uterine part.
4. Ovaries
· Ovaries or female gonads are almond-shaped bodies, 2.5- 3.5 cm long, 2 cm wide and 1 cm thick.
· Each ovary is attached to the uterus by an ovarian ligament.
· Ovary is also attached to the dorsal body wall by peritoneal fold, the mesovarium.
· Internally each ovary has 3 parts:
a. Outer germinal epithelium
b. Tunica albuginea– below the germinal epithelium
c. Stroma- innermost mass divided into a highly cellular outer cortex and inner medulla consisting of richly vascularized loose connective tissue
· Cortex has about 40,000 ovarian follicles which are developed from germinal epithelial cells.
· A fully matured ovarian follicle is called Graafian follicle.
· Outer covering of graafian follicle is membrana granulosa. It covers the follicular cavity.
· Inside the follicular cavity, an ovum is situated.
· Ovum is surrounded by transparent layers- zona pellucida and zona radiata (corona radiata).
· A maturing egg is contained in a cellular sac called a follicle.
· A maturing egg is contained in a cellular sac called a follicle.
· Zona pellucida is surrounded by membrana granulosa.
· Membrana granulosa cells, later, become elongated to form corona radiata.
· Membrana granulosa is separated from thecal layer via the basement membrane.
· The thecal layer consists of theca externa (fibrous) and theca interna (granular).
· At ovulation, Graafian follicle ruptures to release an ovum (secondary oocyte).
· Corona Radiata and remaining structures form corpus luteum.
· It secretes Progesterone and activates uterus and mammary glands for their development.
· Corona Radiata and remaining structures form corpus luteum.
· It secretes Progesterone and activates uterus and mammary glands for their development.
5. Accessory Sex Glands
· It consists of vestibular glands and mammary glands.
a. Vestibular glands (Bartholin’s glands)
· Two pea-shaped vestibular glands lie on either side of the vaginal orifice.
· They secrete mucus that keeps the vulva moist.
b. Mammary glands
· They are compound tubule-alveolar glands.
· Externally, each breast has a projection called nipple surrounded by a circular pigmented area of skin called Areola.
· On the surface of the areola, there are numerous sebaceous glands called areolar glands.
· Internally, the mammary gland consists of glandular tissue, connective tissue and fat.
· They are compound tubule-alveolar glands.
· Externally, each breast has a projection called nipple surrounded by a circular pigmented area of skin called Areola.
· On the surface of the areola, there are numerous sebaceous glands called areolar glands.
· Internally, the mammary gland consists of glandular tissue, connective tissue and fat.
· Glandular tissue has about 15-20 lobes in each breast.
· Each lobe is composed of a number of lobules.
· Each lobule is made up of grape-like structures called alveoli.
· Each lobe is drained by its own lactiferous duct leading directly to the nipple, where it opens onto its surface.
· Before reaching the nipple, each of the ducts is dilated to form a lactiferous sinus for milk storage and then narrows before passing through the nipple.
· Connective cells support the alveoli and ducts.
· Fat cells found between the lobes determine the size of the breasts.
· Milk production (secretion) is stimulated by the prolactin hormone.
· Each lobe is drained by its own lactiferous duct leading directly to the nipple, where it opens onto its surface.
· Before reaching the nipple, each of the ducts is dilated to form a lactiferous sinus for milk storage and then narrows before passing through the nipple.
· Connective cells support the alveoli and ducts.
· Fat cells found between the lobes determine the size of the breasts.
· Milk production (secretion) is stimulated by the prolactin hormone.
· Milk ejection is stimulated by the oxytocin hormone.
· The first milk after the parturition is called colostrum.
· It contains protein, WBCs and antibodies and thus increases the immunity power of the newly born baby.
· Due to this, it is very much essential for the newborn.
Menstrual cycle or Ovarian cycle or Menstruation
· It is the cyclic changes in the reproductive tract of female primates (monkeys, apes and man).· The fertility period of women ranges from 13-15 to 45-55 years.
· This period is marked by a characteristic event repeated almost every month (28 days with minor variation).
· It involves the discharge of endometrial glands, endometrial cells, blood from broken down capillaries and the unfertilized ovum.
· It is also called weeping of the uterus for lost ovum.
· The period of the menstrual cycle can be divided into the following four phases.
a) Menstrual phase (Days 1-5)
b) Proliferative or follicular phase (Days 6-13 or 14)
c) Ovulatory phase (Day 14)
d) Secretory or luteal phase (Days 15-28)
a) Menstrual phase (Days 1-5)
b) Proliferative or follicular phase (Days 6-13 or 14)
c) Ovulatory phase (Day 14)
d) Secretory or luteal phase (Days 15-28)
A. Menstrual phase (Days 1-5)
· If an ovum is not fertilized, corpus luteum degenerates and becomes non-functional about 14 days after ovulation so progesterone and oestrogen levels fall.
· Due to this, the endometrium of the uterus is shed off.
· Due to this, bleeding or menstrual flow occurs containing the secretions from the endometrial glands, endometrial cells, blood from broken down capillaries and the unfertilized ovum.
· Low levels of progesterone and oestrogen in blood lead to resumed anterior pituitary activity, rising FSH levels and initiation of the next cycle.
· Low levels of progesterone and oestrogen in blood lead to resumed anterior pituitary activity, rising FSH levels and initiation of the next cycle.
B. Proliferative or follicular phase (Days 6-13 or 14)
· This period lasts 6-13 or 14 days in a 28-day cycle.
· In this phase, the FSH secreted by the anterior lobe of the pituitary stimulates the primordial follicles to develop into mature or Graafian follicles so it is called the follicular phase.
· Graafian follicle secretes oestrogen that stimulates the proliferation of the functional layer of the endometrium of the uterine wall in preparation for the reception of the fertilized ovum.
· Now, the endometrium thickens, becomes very vascular and is rich in mucus-secreting glands i.e. endometrium rebuilds.
· It ends when ovulation occurs and oestrogen secretion by follicle declines.
C. Ovulatory phase (Day 14)
· On the 14th day, both LH and FSH attain a peak level.
· On the 14th day, both LH and FSH attain a peak level.
· LH induces the rupturing of Graafian follicle and release of ovum called ovulation.
· The finger-like projections at the end of the fallopian tube draw the ovum from the ovary into the fallopian tube.
· Egg resides in the ampulla of the fallopian tube for about 8 hours waiting for spermatozoa.
· Egg resides in the ampulla of the fallopian tube for about 8 hours waiting for spermatozoa.
D. Secretory or luteal phase (Days 15-28)
· It lasts for 15-28 days and is the period between ovulation and onset of menstruation.
· The remaining cells of ovarian follicles are stimulated by LH to develop the corpus luteum.
· Corpus luteum secretes progesterone and some oestrogen.
· Progesterone stimulates the endometrial glands of the uterus to secrete an increased amount of the watery mucus.
· Progesterone stimulates the endometrial glands of the uterus to secrete an increased amount of the watery mucus.
· It allows the passage of the spermatozoa through the uterus to uterine tubes where the ovum is usually fertilized.
· Uterine glands and vaginal glands also secrete mucus that lubricates the vagina. Progesterone also maintains the endometrium.
· Uterine glands and vaginal glands also secrete mucus that lubricates the vagina. Progesterone also maintains the endometrium.
· It is essential for the implantation of the fertilized ovum and other events of pregnancy.
· If an ovum is fertilized, there is no breakdown of the endometrium and no menstruation.
· If an ovum is fertilized, there is no breakdown of the endometrium and no menstruation.
· The fertilized ovum or zygote travels through the uterine tube to the uterus where it gets implanted at about 9 days of fertilization and secretes HCG (human chorionic gonadotrophin).
· It keeps the corpus luteum intact that secretes progesterone and oestrogen for the first 3-4 months of pregnancy, inhibiting the maturation of further ovarian follicles.
· By that time, the placenta develops and produces progesterone, oestrogen and gonadotrophins.
· In the absence of fertilization, the corpus luteum degenerates and there is disintegration (degeneration) of the endometrium leading to menstruation making a new cycle.
Menopause
· Menopause is the phase in a woman’s life when ovulation and menstruation cease.
· It occurs between the ages of 45-55 years, marking the end of the childbearing period.
· The ovaries become less responsive to FSH and LH, and the ovulation and the menstrual cycle become irregular and gradually cease.
· So in menopause, female loses the ability to reproduce.
· Several other phenomena may occur at the same time like:
· Vasodilation, sweating, palpitation
· Irritability, mood change
· Shrinkage of breasts
· Axillary and pubic hair become sparse
· Loss of bone mass
· Gradual thinning of the skin
· Slow increase in blood cholesterol level
· Several other phenomena may occur at the same time like:
· Vasodilation, sweating, palpitation
· Irritability, mood change
· Shrinkage of breasts
· Axillary and pubic hair become sparse
· Loss of bone mass
· Gradual thinning of the skin
· Slow increase in blood cholesterol level
Note: First menstrual is called menarche.
· Dysmenorrhoea- Painful menses
· Menorrhagia- Excessive menstruation
· Amenorrhoea- Non-occurrence of menses
· Oligomenorrhoea- Irregularity of menstrual cycle