By: A. Riasi (PhD in Animal Nutrition & Physiology) riasi.iut.ac.ir

2. Isfahan University of Technology, Isfahan, Iran Advanced Reproductive Physiology (part 2) By: A. Riasi (PhD in Animal Nutrition & Physiology) http://riasi.iut.ac.ir

3. Reproductive system in male animal: The primary sex organs Testes Secondary sex organs Epididymis, Vas deferens and Penis Accessory sex organs Prostate gland, Seminal vesicles, Bulbourethral glands Gamete production in male animals

4. The testes have two compartments: Interstitial compartment (interstitial tissue) Leydig cells Blood vessels and neurons Leukocytes Fibroblastes Germinal compartment (seminiferous tubules) Gamete production in male animals

5. Seminiferous tubules composed of: Sertoli cells (SCs) Maturing germ cells Peritubular myoid cells One layer in rodents More layer in large animals Gamete production in male animals

6. Gamete production in male animals Adapted from Fijak and Meinhardt, 2006

7. The interstitial compartment: The leydig cells Secretion of testicular testosterone Secretion of insulin like factor 3 (INSL3) Gamete production in male animals

8. Gamete production in male animals • Different type of leydig cells: • Stem Leydig cells as founder cell • Progenitor Leydig cells as a committed stem cell • Fetal Leydig cells as a terminally differentiated cell in the fetus • Adult Leydig cells as the terminally differentiated Leydig cell

9. The interstitial compartment also contains cells belonging to the immune system: Macrophages, probably influence the function of leydig cells: Proliferation Differentiation Steroid production Lymphocytes Gamete production in male animals

10. Spermatogenesis takes place in the tubular compartment: Germ cells Somatic cells The peritubular cells Sertoli cells Gamete production in male animals

11. Peritubular cells produce several factors that are involved in cellular contractility Panactin Desmin Gelsolin Smooth muscle myosin and actin Gamete production in male animals

12. These cells secrete extracellular matrix and factors typically expressed by connective tissue: Collagen Laminin Vimentin Fibronectin Growth factors Fibroblast Gamete production in male animals

13. The cytoplasm of sertoli cells contains: Eendoplasmic reticulum Smooth type Rough type A Prominent Golgi apparatus Lysosomal granules Microtubuli and intermediate filaments Gamete production in male animals

14. Sertoli cells synthesize and secrete a large variety of factors: Proteins Cytokines Growth factors Opioids Steroids Prostaglandins Modulators of cell division Gamete production in male animals

15. Another important functions of Sertoli cells: Final testicular volume Support for sperm production Gamete production in male animals

16. Gamete production in male animals Localization of the BTB/SC barrier and cellular components of the testis. Testis interstitium consists of Leydig cells, macrophages (MΦ), tolerogenic DCs, T cells and blood vessels. The seminiferous tubules are composed of SCs and maturing germ cells surrounded by peritubular myoid cells. Tight junctions between adjacent SCs along with the body of the SCs form the BTB/SC barrier, which divides the tubules into the basal and adluminal compartments Adapted from G. Kaur et al., 2014

17. Gamete production in male animals (TGF-β, IDO, galectin-1, activin A) Adapted from G. Kaur et al., 2014

18. Gamete production in male animals SCs inhibit proliferation of NK, B and T cells by expressing/secreting immunosuppressive factors. SCs also inhibit IL-2 production by T cells resulting in reduced proliferation. SCs express several apoptosis and complement inhibitors to prevent NK and T cell-mediated death, and complement-mediated lysis, respectively. Blue triangles, immune suppressive factors. Adapted from G. Kaur et al., 2014

19. Gamete production in male animals Adapted from M. Kathrins and C. Niederberger, 2016

20. Gamete production in male animals • The endocrine control of spermatogenesis is governed by hypothalamic-pituitary-testicular axis. • The GnRH: • Characteristically secreted in pulsatile manner • Acts via the transmembrane GnRH receptor

21. Gamete production in male animals • The gonadotropins (FSH and LH) are secreted in a pulsatile fashion in response to GnRH. • Relatively, and in general, the pulsatile LH release is robust and similar to that of GnRH. • The pulsatile release of FSH is rather sluggish.

22. Gamete production in male animals • At the level of the testis, FSH and LH mediate their actions via specific transmembrane receptors: • FSH-R • LH-R

23. Gamete production in male animals • Predominantly, FSH-R is expressed in the Sertoli cells within the seminiferous tubules. • The LH-R is expressed in the interstitial Leydig cells.

24. Gamete production in male animals • The gonadotropins exert their actions on spermatogenesis: • FSH (directly) • LH (indirectly via testosterone-androgen receptor [AR])

25. Gamete production in male animals Adapted from Grinspon and Rey, 2010

26. Gamete production in male animals Adapted from Grinspon and Rey, 2010

27. Gamete production in male animals • Two major endocrine signals are produced from the testis: • Testosterone, which is secreted in a pulsatile fashion • A non-steroidal hormone (inhibin), produced by the Sertoli cells in response to FSH signaling and secreted in a non-pulsatile manner.

28. Approximately 15% of the adenohypophysealcells produce gonadotropins. It is believed that the same cells type secrete both gonadotropins. Pituitary gonadotropes are often found in close connection with prolactin cells. Gamete production in male animals

29. In male testosterone is major hormone controlling GnRH secretion. Testosterone can act as such or after metabolism to DHT or estradiol. Gamete production in male animals

30. During spermatogenesis gonadotropes regulate testicular function. Testosterone and FSH affect the seminiferous tubules and enhance spermatogenesis FSH causes the seminiferous tubules growth and affect spermiation. LH affect the release of sperm from germinal epithelium (spermiation) Gamete production in male animals

31. Gamete production in male animals Seminiferous tubules growth FSH Spermiation Spermatogenesis Testosterone secretion LH Spermiation

32. Gamete production in male animals Adapted from: Liji Thomas, MD

33. Other hormones may affect testicular function: Prolactin Insulin Thyroid hormones PGE2 Glucocorticoids Progesterone and estradiol GH and IGF-I Testicular GnRH Aldosterone Gamete production in male animals

34. Androgens are essential for: The development and function of testes Maturation of secondary sexual characteristics Masculinization of the bone-muscle apparatus Libido Stimulation of spermatogenesis Gamete production in male animals

35. Physiological effects of androgens depend on: Number of androgen molecules Distribution of androgens and their metabolites inside the cell Interaction with the receptors Polyglutamine number of the amino acid sequence in the androgen receptor Receptor activation Gamete production in male animals

36. In turn, androgen concentrations in the blood depend on: The synthesis rate Balanced by metabolic conversion and excretion Gamete production in male animals

37. Different andro-compounds and their effects: Androstenediol may refer to: 5-Androstenediol which is an endogenous weak androgen and estrogen and is a pro-hormone of testosterone. 1-Androstenediol which is a pro-hormone of DHT and hence an androgenic-anabolic steroid. Gamete production in male animals

38. Leydig cells are the main site of androgen production. Leydig cells cannot store androgens. LH as the central regulatory factor controls both steroidogenesis and Leydig cell cholesterol homeostasis in vivo. Gamete production in male animals

39. Gamete production in male animals

40. Cholesterol is stored in cytoplasmic lipid droplets. The number of lipid droplets is inversely related to the rate of androgen synthesis in the Leydig cell. Gamete production in male animals

41. Testosterone moves from the leydig cells into: Blood vessel Lymphatic vessel Seminiferous tubules Gamete production in male animals

42. Testosterone also give rise to two other potent androgens: Dihydrotestosterone (DHT) 5α-androstenediol Gamete production in male animals

43. Gamete production in male animals

44. Circulating testosterone is found in three forms: Free Bounded with a liver-drived sex steroid-binding globulin (SSBG) Bounded with albumin and other proteins Gamete production in male animals

45. Testosterone is excreted by urine: As glucronide 1% of daily production of testosterone 17-ketosteroids products Gamete production in male animals

46. Gamete production in male animals Testosterone (T) is synthesized in the testis. After entering the target cells (in the hypothalamus, pituitary, testis and wolffian duct) T is directly bound to the androgen receptor (AR) and the complex T-AR binds to specific DNA sequences and regulates gene transcription, which can result different works.

47. Gamete production in male animals Specific actions of Dihydrotestosterone (DHT). After entering the T to target cells (in the urogenital sinus, urogenital tubercle, and several additional androgen target tissues) T is metablized to 5α-Dihydrotestosterone (DHT) by the enzyme 5α-Reductase type 2. DHT binds directly to the androgen receptor (AR) and the complex DHT-AR interacts to specific DNA sequences and regulates gene transcription, which can result in differentiation and development of the prostate, the external genitalia and at puberty in several secondary male characteristics.

48. The major role of testosterone: Stimulates of differentiation of the wolffian ducts into the epididymis, vas deferens and seminal vesicles. With or without DHT causes enlargement of the penis and seminal vesicles. Causes enlargement of the larynx and thickening of the vocal cords. Gamete production in male animals

49. The major role of testosterone: Local hormone required for initiation and maintenance of spermatogenesis. Cessation of linear growth by closure of the epiphyseal growth center. Enlargement of the muscle mass during puberty. Important effect on lipid metabolism. Gamete production in male animals

50. The major role of testosterone: Initiation of sexual drive. Suppression of mammary gland growth. Stimulation hematopoiesis. Stimulation of renal sodium reabsorption. Stimulation of aggressive behavior Suppression of hepatic synthesis of SSBG, cortisol-binding globulin and thyroxin-binding globulin. Gamete production in male animals