Reproductive physiology

1. Reproductive Physiology
Development of Reproductive System
Puberty
Male Reproduction
Female Reproduction
Menstrual cycle
Fertilization
Menopause

2. Sexual differentiation
Testis determining gene (TDG)
• The gene on the short arm of Y-chromosome is SRY
gene, ( Sex Determining Region of Y Chromosome),
• some times it is called H-Y Ag (= Histocompatibility
of Y antigen), and codes for SRY protein
• SRY protein is a DNA binding transcription factor
which induces transcription of cascades of genes
including
– MIF, eventually inducing the indifferent gonad to
differentiate into male gonadal sex

6.  In the male, as a result of these factors the
following events will happen:
Mullerian duct degenerate by (MDIF), act locally
and unilaterally
Wolfian duct develops into (Androgenic effect)- and
eventually, it differentiates to:
– Epididymis
– Vas deferens
– Seminal vesicles
Prostate and seminal vesicle develops (5α-
Reductase effect)
Musculine brain develops (Estrone effect)

7. Differentiation of external genitalia
(Genital, Phenotypic Sex)
External genitalia is
indifferent until 8th
week
It is hormonally
determined
The male is an induced
sex whereas the
female is a default sex

8. 8
Onset of Puberty
• Withdrawal of sensitivity of hypothalamic to NFB
inhibition to circulating sex steroids allowing LH and
FSH secrtion (before puberty, the negative feed back
mechanism of steroids was inhibited, i.e. even if
concentration of steroids is low, they could not have
negative feed back to the hypothalamus).
• Increased responsiveness of gonadotrophs to GnRH
• Removal of inhibition by pineal gland

9. 9
of onset of puberty

10. 10
of onset of puberty

11. The Male reproductive system
The testis
•Functions
•Secrete hormones
•Spermatogenesis
•Size
•4-6 cm long
•2-3 cm wide

12. •Component
•Seminiferous tubules
•Rete testis
•Efferent ductuli
•Epididymus

15. Semineferous tubules cont…
• Components
Connective tissue
Smooth muscles
Sertoli cells
Spermatogonia
Between seminferous tubules are
Leydig cells

16. Sertolic cells
•Provide nutrients
•Help sperm maturations
•Germ cells are embeded with in and
between sertoli cells

18. 18
Scheme of Spermatogensis
At puberty, spermatogonia migrate
along Sertoli cells towards its lumen
while proliferating (requires FSH)
Those that cross Sertoli barrier
enlarge and begin Meiosis-I (primary
spermatocytes, largest cells in ST)
During their growth primary
Spermatocytes duplicate their DNA
(diploid), Meiosis-I continues,
homologous chromosomes separate,
and 2nd spermatocytes form (2n)
Meiosis-II occurs in secondary
spermatocytes to convert them to
spermatids, sister chromatids
separate to form haploid (n)
spermatid
Spermatid differentiate into mature
sperm cells, by spermiogenesis

19. Spermatozoa
•Mature spermatozoa are released
into lumen of Seminiferous tubules
•Slowly advance to rete testis
•Stored in tail of epididymus

20. Physiological roles of androgens
Roles of testicular androgens
•Prepubertal
Wolffian duct differentiation and growth
Growth of penis and scrotum
•Pubertal
Musculine body growth and physique
Enhanced protein synthesis

21. •Epiphyseal cartilage plate closure
•Deepening of voice
•Hair growth
•Bitemporal hair loss
•Sebaceous gland growth
•Sertoli cell maturation
•Synthesis of Androgen Binding protein
•Increased sexual activity (libido)- CNS effect
•NFB control of HPG axis

22. Female reporductive organs

23. Female reproduction
Hierarchy of Female Hormonal System
1.Hypothalamic releasing hormone,
gonadotropin-releasing hormone
(GnRH)
2. The anterior pituitary sex hormones,
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH),
3. The ovarian hormones,
Estrogen
Progesterone,

24. Hormonal cycles

25. Ovarian cycle
• Follicular phase
– Follicular recruitment
– Follicular growth
– Dominance
– Maturation
• Ovulation
• Luteal phase

26. Stage of follicular growth

27. 27
Follicular hormonogesis

28. 28
i. Uterus:
– Epithelium & Stromal cells: ↑Proliferation, ↑Vascularity
– Endometrial glands: maintain their straight shape.
– Myometrium: ↑ Contractile proteins (Actin, Myosin) → ↑
Excitability → ↑Action Potential (↑spontaneous muscular
contractions)
• ↑ Sensitivity to oxytocin
• ↑ Progesterone receptors in uterus
ii. Fallopian tubes:
– ↑ Secretion of mucosa & ↑ motility of muscle &
cilia to propel ovum to uterus.
The effect of estrogen

29. 29
• iii. Cervix:
– cervical glands: Copious, thin watery mucus, alkaline
secretions

30. 30
IV. Vagina:
– ↑Proliferation & cornification of epithelium & glycogen
deposition
v. Breasts
– Tubular duct growth
– ↑ Pigmentation of the areolas.

31. 31
• vi. Bone:
– ↑ Osteoblastic activity →↑ Rate of bone growth → Epiphyseal closure in
long bones → cessation of linear growth
– ↑ Bone matrix, ↑ Ca2+ & P deposition
– Oval/roundish shape of the pelvic inlet, narrow shoulders

32. 32
• viii. Liver:
– ↑ Plasma proteins (↑angiotensinogen (↑hypertension),
– ↓ Lipoproteins: ↓ VLDL, ↓ Cholestrol, ↓ LDL, ↑HDL, + ↑NO (problems
of coronaries less common), ↑Cholesterol in bile and ↑risk of
cholelithiasis
• ix. Adipose Tissue:
– ↑Deposition of fat in the subcutaneous tissues (breasts,
buttocks, thighs)
• x.. Skin:
– ↓ Sebaceous gland secretion →↑ fluidity of sebaceous gland
→inhibition of acne.
– Induce soft, smooth and worm (vascular) texture of the skin)
– ↑pigmentation of the face augmented by solar rays (Chloasma)

33. 33
Function of progesterone
i. Uterus:
– ↑Secretory activity (change) (↑ endometrial glands- become
elongated & coiled)
– ↑ Vascularization of the uterus (↑differentiation of the
stratum functionale)
– (Needs priming action of Estrogen, prepares uterus for
implantation of blastocyst)
ii. Myometrium:
– ↓ Excitability (↑RMP, ↓ spontaneous electrical activity)
– ↓ Sensitivity to oxytocin
– ↓ Estrogen receptors in the endometrium

34. 34
• iii. Cervix:
– ↓ Mucus (thick and viscid → ↓ sperm penetration)
• iv. Vagina:
– Further maturation & proliferation of epithelium, ↓
cornified cells, ↑ pH
• V. Breast: Promote development of the lobule
and alveoli of the breast causing breast to swell.

35. Ovulation
– Shortly before ovulation primary oocyte enlarge
– Complete first meiotic division resulting in
secondary oocyte and first polar body
– During ovulation secondary oocyte completes
first and begins second meiotic division and stop
in metaphase
– If fertilization occurs, metaphase completes with
second polar body and the ovum

36. Mechanism of ovulation

37. Uterine cycle
Menstual phase
Proliferative phase
Secretory phase
Ischemic phase

39. 39
Menstrual phase (1-5 d)
– Coincides with early follicular phase of ovary
– Functional layer (Compact and Spongy layer) is shed
– Basal layer (stroma and glandular) regenerates
Uterine cycle

40. 40
Proliferative phase (6-14)
– Estrogen phase
– Coincides with growth of ovarian follicle and
ovulation
– Epithelial cells regenerate from glands
– Endometrial stoma proliferate (4 mm)
– Uterine gland elongate and become tortuous
– Blood vessels grow up and become spiral

41. 41
• Secretory phase (luteal) (15-28)
– Progesterone dominated (preparation for implantation)
– Coincides with formation and growth of corpus
luteum
– Progesterone of corpus luteum causes
• Epithelial secretion rich in glycogen (viscid)
• Large, wide tortuous, secretory glands in uterus
• Thicker endometrium (6mm)
• Coiled arteries
– By 20 day implantation is expected

42. 42
• Ischemic (premenstrual phase: 24-28d)
– Reduced hormone secretion following programmed
deterioration of luteal cells
• Intermittent contraction of spiral artery
• Localized deficiency of blood and nutrient to functional
layer
• Loss of hormonal (progesterone) stimulation of uterus
• Glandular secretion stops
• Loss of interstitial fluid and endometrium shrink
• Pale endometrium
Necrosis

43. 43
Fertilization and Pregnancy
• Presence of developing offspring in the uterus
• Transport of sex cells
– 300-500 million germ cells deposited near the
cervix
– Movements of sperm in thin watery secretions,
– Aided by uterine contractions and seminal PGs
– Accompanied by capacitation few hundreds reach
2o oocyte at the ampulla's of the fallopian tubes 
– Fertilization

44. 44
Steps of fertilization
• Secondary oocytes
– Survive for only 12-24 hrs
– Germ cells survive up to 72 hrs in female genital tract
1. Capacitation reaction
2. Acrosome reaction
3. Penetration of corona radiata
4. Penetration of zona pellucida
5. Fusion of sperm membrane with egg cell membrane
6. Cortical reaction occurs hardening zona pellucida
7. Entrance of sperm nucleus into secondary oocyte
8. Resumption of completion of second meiotic division

45. Menopause
Cessation of functional state of the ovary, uterus,
menstrual blood flow, and ovarian hormone
Back pain, joint pain and muscle pain
Osteoporosis
Depression
Fatigue
Irritability
Loss of memory
Mood and sleep disturbances
Atherosclerosis