Male Reproductive System Physiology PDF

10/29/2024 physiology of Male Reproductive System By Assistant Prof. Omar Abd-Alhakeem Ammar Assistant Professor of Cell Biology and Histology Director of Quality Assurance U...

10/29/2024 physiology of Male Reproductive System By Assistant Prof. Omar Abd-Alhakeem Ammar Assistant Professor of Cell Biology and Histology Director of Quality Assurance Unit Intended Learning Outcomes (ILOs) Identify structure and function of sperm. Discuss fertilization, spermatogenesis process, pathway of the sperm, puberty, and, male infertility. Identify physical and psychological maturity changes. Detect hormonal control of the testes. 1  10/29/2024 What is sperm? Function: To move and carry genetic information Head to the egg. Body ❑ Sperm production begins at puberty (10 to 14 years of From the side age), and millions of sperm are formed each day in the From above testes. Sperms mature at the rate of about 300 million per day and once released cannot survive more than 48 Tail hours within female reproductive tract. A sperm cell is composed of head, a mid-piece and tail. ❑ Sperms mature in the epididymis. 2  10/29/2024 What is sperm? Structure: Head: The large head region of the sperm that contains DNA (23 chromosomes) (22 autosomes + 1X or 1Y chromosome) and a lysosome like structure called acrosome which contains enzymes hyaluronidase and proteinases that help in penetration of sperms in the female egg. What is sperm? Structure: Midpiece: The narrow middle part of the cell that contains mitochondria provides ATP energy for movement of sperms in female reproductive tract. Tail: The wavelike motion of the flagellum propels the sperm forward. 3  10/29/2024 What is sperm? ❑ Sperm Count: average range of sperms is about 50 to 100 million per mL of semen. Fertilization ❑ Defined: Fusion of egg and sperm to create zygote. ❑ Semen Pathway: - Epididymis → vas deferens → urethra - 50-500 million sperm released. ❑ only 1 sperm cell gets through to egg. ❑ enzymes help get in. ❑ instant biochemical change (no more sperm can enter). 4  10/29/2024 Spermatogenesis ❑ Defined: Production of sperm cells. ❑ Meiosis forms sperm as gametes. Four haploid sperm cells at a time. 23 chromosomes in each. ❑ Location: sperm forms in testes. Spermatogenesis ❑ Spermatogenesis is the formation of sperm cells. ❑ It takes place in the seminiferous tubules. ❑ Spermatogonia are the cells from which sperm cells arise The spermatogonia divide by mitosis One daughter cell remains a spermatogonium and the other becomes a primary spermatocyte. 5  10/29/2024 Spermatogenesis ❑ Diploid cells that begin the process are located near the outer wall of the tubules. ❑ Diploid cells multiply constantly by mitosis, and each day about 3 million of them differentiate into primary spermatocytes, the cells that undergo meiosis. Spermatogenesis ❑ Meiosis I of a primary spermatocyte produces secondary spermatocytes, each with the haploid number of chromosomes (n=23). ❑ The cells are still in their duplicated state, each consisting of two identical chromatids. 6  10/29/2024 Spermatogenesis ❑ Meiosis II then forms four cells, each with the haploid number of single-chromatid chromosomes. ❑ A sperm cell develops by differentiation of each of these haploid cells and gradually pushed toward the center of the seminiferous tubule. ❑ From there, it passes into the epididymis, where it matures, becomes motile, and is stored until ejaculation. 7  10/29/2024 Spermatogenesis Spermatogenesis process: ❑ Each testis is covered by a capsule of connective tissue called the tunica albuginea, which extends inward to form a series of compartments called lobules. ❑ Each lobule contains one to three convoluted seminiferous tubules in which spermatogenesis occurs. 8  10/29/2024 Spermatogenesis process: ❑ Spermatogenesis begins from spermatogonia. It divided to form primary spermatocytes. ❑ Primary spermatocytes divided to form secondary spermatocytes that develop into spermatids. ❑ Spermatids develop into mature sperm cells (or spermatozoa). Spermatogenesis process: ❑ In the lobules, sertoli cells supply nutrients to the developing sperm cells. ❑ Leydig cells produce the male sex hormone testosterone. 9  10/29/2024 Pathway of the sperm: ❑ The pathway of the sperm in the male reproductive system are the following: 10  10/29/2024 Puberty: ❑ Puberty is the development of secondary sexual characteristics in male at age of 14-15 years due to increased secretion of: Gonadotropin-releasing hormone (GnRH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Ttestosterone hormone. Puberty: Physical and psychological maturity changes are as follows: ❑ Increase in rate of production and maturation of sperms in the testes i.e. spermatogenesis. ❑ Enlargement of testes and penis. ❑ Increased in size of prostate gland, seminal vesicles and bulbourethral gland. ❑ Enlargement of the larynx and thickening of the vocal cords results in a deep voice. ❑ Growth of hairs on face (beard), chest, underarm, abdomen and pubis. ❑ Growth of the muscle & bone and marked increased in height and weight. 11  10/29/2024 Hormonal Control of the Testes: ❑ At puberty certain hypothalamic neurosecretory cells increase their secretion of gonadotropin-releasing hormone (GnRH). ❑ GnRH in turn stimulates gonadotrophs in the anterior pituitary to increase their secretion of the two gonadotropins: I. Luteinizing hormone (LH). II. Follicle stimulating hormone (FSH). ❑ LH stimulates Leydig cells, which are located between seminiferous tubules, to secrete the hormone testosterone. ❑ FSH acts indirectly to stimulate spermatogenesis. Male infertility ❑ Infertility is an inability to fertilize a secondary oocyte when the sperm count falls below 20 million per mL of semen in the male. Then male is considered to be infertile. ❑ Male fertility requires production of adequate quantities of normal sperm count by testes, transportation of sperms through the ducts and satisfactory deposition in the vagina. The main causes of male infertility include: ❑ X-rays, infections, malnutrition, significantly higher than normal temperature of scrotum. These factors may cause degenerative changes and produce male infertility. 12  10/29/2024 Question # The mitochondrion is located in which part of the sperm cell? a) Head b) Midpiece c) Tail d) Acrosome Question # The mitochondrion is located in which part of the sperm cell? b) Midpiece 13  10/29/2024 Question # Arrange the following organs in the correct sequence for the travel of sperm: epididymis, testis, urethra, vas deferens. a) Testis - urethra - epididymis - vas deferens b) Epididymis - testis - urethra - vas deferens c) Testis - epididymis - vas deferens - urethra d) Epididymis - vas deferens - testis - urethra Question # Arrange the following organs in the correct sequence for the travel of sperm: epididymis, testis, urethra, vas deferens. c) Testis - epididymis - vas deferens - urethra 14 10/29/2024 15