Male Reproductive Physiology • SRY gene • Puberty • Spermatogenesis • Cells in testis • Semen • Hormones Female Reproductive Physiology • Two cell two gonadotrophin theory • Oogenesis • Menstrual cycle • Endometrial changes • Cervical and vaginal changes • Hormones • Lactation

1. ZOOLOGY
2021
• Name: Aditya Arya
• B.Sc. B.Ed. (CBZ) 6th Semester
Topic:
Physiology of Reproduction

2. Physiology
Physiology is a branch of biology that deals with the
functions and activities of life or of living matter (such
as organs, tissues, or cells) and of the physical and
chemical phenomena involved.
Or
Physiology is the science of life. It is the branch of
biology that aims to understand the mechanisms of
living things, from the basis of cell function at the
ionic and molecular level to the integrated behaviour
of the whole body and the influence of the external
environment 2

3. Male Reproductive
Physiology
• SRY gene
• Puberty
• Spermatogenesis
• Cells in testis
• Semen
• Hormones

4. 4
✓ For development of male gonads, presence of SRY gene is mandatory.
✓ SRY gene:
▪ Sex determining region of Y chromosome
▪ Present on short arm of Y chromosome
▪ Codes for a transcription factor known as Testis determining gene product
✓ The embryo exhibits gender bipotential.
▪ Around week seven of fetal development the SRY (Sex-determining region of Y
chromosome) gene becomes activated.
✓ The SRY directs the bipotential gonads.
▪ The absence of this on the X chromosome causes the gonads to develop into
ovaries:
- Ovaries then produce further gender biased hormones.
▪ The presence of this gene and its products causes the gonads to descend and
develop into testes
- Testes then produce further gender based hormones.
SRY gene

5. “
5

6. Puberty
▪ Gonadotropin-releasing hormone (GnRH) secreted by hypothalamus
▪ GnRH is secreted continuously before puberty. This inhibits release of FSH and LH
▪ Most important event marking onset of puberty :-
▪ Before puberty, pulsatile release of GnRH is inhibited by GABA and Melatonin
▪ At puberty Pulsatile secretion is activated by Kisspeptin
▪ Kisspeptin receptor on GnRH neuron is called GPR 54
(G-Protein coupled receptor)

7. Puberty
▪ Peripheral signal :-
Adequate body fat stores
Leptin
Kisspeptin
Puberty
▪ This action of leptin is called the permissive action

8. Spermatogenesis:
8
❖ Occurs in seminiferous tubules of testis
❖ Takes 74 days.
Stem cell Spermatogonia
Divides into type A and type B stem cells
Type B stem cells form primary spermatocyte by mitosis
Primary spermatocyte diploid- 2n
Form 2 secondary spermatocytes
meiosis reduction division
each secondary spermatocyte gives rise to two spermatids
each spermatid forms one mature sperm (spermiogenesis)

9. 9
❖ At the end of cycle, 4
spermatids (haploid) are
formed.
❖ Spermatids then develop
into spermatozoa.
❖ Release of mature sperm:
Spermiation

10. 10
Cells in testis
❖ Sertoli cells :
➢ Regulated by LH
➢ Release testosterone
❖ Leydig cells :
➢ Provide nutrition to developing sperms ; called nurse
cells
➢ Involved in formation of blood testis barrier
- For adequate protection and development of sperm
- Blood testis barrier is formed by adjacent sertoli cells
➢ Produce Androgen binding Protein (ABP)
➢ Secrete anti-mullerian hormone
➢ Secrete aromatase Form estrogen
➢ Inhibin FSH
➢ Phagocytic cells : Phagocytose dead sperms

11. 11
Semen
❖ undergoes capacitation i.e. undergoes acrosome reaction
Can then penetrate the zona pellucida of ovum
Can fertilize the ovum
❖ Capacitation occurs in female genital tract.
❖ Has sperms and fluid component
❖ pH : 7.4
❖ Sperm : Normal count - 90-120 million /ml
❖ Acquires motility in the epididymis i.e. Sperm acquires a
calcium channel called Catsper

12. 12
Semen
❖ Fluid component of Semen:
1. Seminal vesicle secretion:
a. Fructose : For nutrition of sperm { Transported by
GLUT- 5 }
b. Anti-oxidant : Vitamin C
c. Prostaglandins
d. Phosphoryl choline:- used in the detection of
seminal stains by Florence test
2. Prostate gland secretion
a. Fibrinolysin cause liquefaction of semen
b. Acid phosphatase
c. Spermine: Identified by Barberio's test for
detection of seminal stains.
2. Buffers : Bicarbonate, Phosphate

13. 13
Hormones
Hypothalamus
GnRh
Anterior Pituitary
Follicle Stimulating
Hormone
Luteinizing
Hormone
Sertoli Cells
Androgen Binding
Protein
Spermatogenesis
Interstitial Cells
Testosterone
1. Testosterone:
➢ major male sex steroid
➢ Receptor : Androgen receptor
➢ In circulation, it is bound to sex hormone
binding globulin (SHBG)
➢ SHBG binds to 65% of
circulating testosterone
and 35% of circulating
estrogen.
➢ Fall in SHBG levels-
Testosterone is affected
more.

14. 14
➢ Action of testosterone:
a. During development
Leydig cells
Secrete testosterone
Wolffian stimulation
b. Development of internal genital organs.
c. Increase muscle mass
d. Increase bone growth
e. Increase RBC
2. Dihydrotestosterone:
❖ Testosterone is
converted to DHT
by 5- α - reductase.
❖ DHT levels inerease
during puberty
❖ Function of DHT:
Growth of
external genital
organs
❖ Prostate growth:- In conditions
like benign prostatic
hyperplasia, 5- α - reductase
inhibitors (Finasteride) is used,
for treatment

15. Female Reproductive
Physiology
• Two cell two gonadotrophin theory
• Oogenesis
• Menstrual cycle
• Endometrial changes
• Cervical and vaginal changes
• Hormones
• Lactation

16. 16
Gonadotropin-releasing hormone
Stimulates anterior pituitary
LH FSH
Theca cells Granulosa cells
Androstenedione
Androstenedione
Estrogen
Aromatase enzyme
❖ Androstenedione secreted by theca cells is converted into estrogen by the
action of aromatase enzyme which is secreted by granulosa cells.

17. 17
❖ In the ovarian cortex, a process called oogenesis (formation of egg) occurs to
develop a mature ovum
❖ Before birth :
* Several million of primordial oocytes exist in the ovaries: most of them
spontaneously degenerate
❖ At birth:
* only 1 million primordial oocytes are left
❖ By puberty (age 10-11) :
*only 400,000 remain in the ovaries
❖ From puberty to menopause:
*Some of these primordial oocytes (containing 46 chromosomes) undergo DNA
replication:
primary oocytes (with 46 pairs of chromosomes ).

18. 18
❖ Oogenesis now is arrested
* where the ovary discharges a mature secondary oocyte into the uterine tube (in a
process called ovulation) .
* Meiosis II is reactivated when this secondary oocyte is fertilized by a sperm dividing
the 46 chromosomes into
-23 (inside the second polar body) and
-another 23 will be united with the 23 chromosomes released from the sperm
* if no fertilization:
-secondary oocyte is discarded along with the menstrual flow
❖ Primary oocytes
*undergo "crossing - over" to shuffle their genes, and meiosis I will occur to
divide the cells into:
- secondary oocytes (containing 46 unique chromosomes) and
-the first polar bodies (also containing 46 unique chromosomes ; but will be degenerated) .

19. 19
Menstrual Cycle
19
❑ Cyclical changes in ovary (ovarian cycle), endometrium, cervix and vagina.
❑ Ovarian cycle :- 3 phases:
❖ Follicular phase
❖ Ovulation - on 14 day of cycle
❖ Luteal phase - always constant
Follicular phase :-
❖ Controlled by follicle-stimulating hormone (FSH)
First hormone to rise in menstrual cycle
❖ FSH stimulates 15-20 follicles 1 follicle becomes dominant
❖ Dominant follicle:-
Also called Graafian follicle, will have maximum number of FSH receptors, Have high aromatase
activity, Produce highest levels of estrogen.
❖ Estrogen:-
Second hormone to rise in the cycle, Highest level seen: Just before ovulation.

20. 20
Ovulation :-
❖ Increase in estrogen Increase in LH, This is Known as positive
feedback mechanism.
❖ LH Surge- 3 hours before ovulation
❖ LH peak -8-10 hours before ovulation
❖ Ovulation occurs on 14th day of cycle
❖ Ovulation also requires FSH Surge to lyse follicular wall and release
ovum .
❖ Body temperature rises by o.5 - 1°F around the time of ovulation
❖ LH is the third hormone to rise in the cycle .
Luteal phase :-
❖ Following ovulation, graafian follicle wall is filled with blood called
corpus hemorrhagicum.
❖ Blood eventually clots and is replaced by luteal cells (yellow colored
cells formed under the influence of luteinizing hormone).
❖ It is now corpus luteum.
❖ Increased LH Stimulates corpus luteum which Secretes
progesterone (fourth hormone to rise.
❖ 1o days after ovulation (Day 24 of cycle), if ovum is not fertilized then
Corpus luteum degenerates

21. 21
Menstrual
Cycle

22. 22
Endometrial Changes
1) Proliferative phase (6th – 14th day)
2) Secretory phase (15th – 28th day)
3) Menstrual phase (1st – 5th day)
Proliferative phase:
✓ Endometrial thickness increases
✓ Uterine glands lengthen
Secretory phase
✓ Endometrial thickness highest
✓ Uterine glands secrete a clear fluid
Menstrual phase:
✓ Superficial 2/3rd of endometrium is shed
Supplied by spiral arteries
✓ Constriction and degeneration of spiral
arteries due to PGF2-α Blood loss
3 Phases:-
Cervical & Vaginal Changes
Cervical mucus :-
➢ Becomes thin under the influence of estrogen
(facilitates smooth transport of sperms)
➢ Mucus thinnest at the time of ovulation
➢ Mucus is thickest under the in influence of
progesterone.
Vaginal cell changes :-
Superficial cells when estrogen is high
Intermediate cells when progesterone is high

23. 23

24. 24
Hormones
Female Sex Hormones
Steroids Protein Hormones
1) Estrogen (Major)
2) Progesterone
1) Inhibin B
2) Activin
3) Relaxin

25. 25
Estrogen
Estradiol (Eα) Estriol (Eβ) Estrone(Eγ )
In a
reproductive
age group
During
Pregnancy
Following
Menopause

26. 26
Action of estrogen:-
1. On uterus:
Estrogen-primed uterus:
❑ Increased contractility
❑ More excitable
❑ Increase gap junctions
❑ In normal labor : Estrogen increases sensitivity of uterus to oxytocin.
2. On breast
Increase ductal growth of breast called growth hormone of breast
3. Estrogen is responsible for secondary sexual characteristics in female
4. On bone :-
Prevents bone resorption hence called the bone-friendly hormone in reproductive
age group females
5. On Kidney:-
Cause sodium water retention

27. 27
❑ C21 steroid
Action of progesterone:-
1. On uterus:-
Anti-estrogen action i.e. Decreases contractility & excitability
2. On breast:-
Lobular and alveolar growth
3. On CNS:-
Progesterone is a CNS depressant
4. Thermogenic action:-
Increases body temperature by 0.5-01°F during ovulation
5. On Kidney:-
Sodium-water excretion (exception to usual action of steroid
hormones, Progesterone induces diuresis

28. 28
1. Inhibin B
❖ Major source ; granulosa cells
❖ Decreases FSH (negative feedback)
2. Activin
❖ Increases FSH
3. Relaxin
❖ Relaxes pubic symphysis
❖ Dilates & softens cervix
Helps during delivery of foetus
{PARTURITION}

29. 29
Lactation
1. Mammogenesis :-
Breast development
❖ Estrogen for growth of ducts
❖ Progesterone for growth of alveoli and lobules
2. Lactogenesis :- .
Milk production
❖ Function of Prolactin
3. Galactokinases:-
Ejection of milk
❖ Suckling, increases oxytocin which causes ejection of milk.
❖ Known as milk-ejection reflex (type of neuro-endocrine reflex).

30. Thanks!
30
Name: Aditya Arya
B.Sc. B.Ed. (CBZ) 6th Semester