Male Reproductive Anatomy PDF

Male Reproductive System Hamza Abu Hilail M.Sc. Physiology  The male reproductive system The reproductive system becomes active after puberty. During puberty the reproductive organs mature to create a fertile individual capable of reproducing. The primary sex organs p...

Male Reproductive System Hamza Abu Hilail M.Sc. Physiology  The male reproductive system The reproductive system becomes active after puberty. During puberty the reproductive organs mature to create a fertile individual capable of reproducing. The primary sex organs produce the sex cells (egg/sperm) and sex hormones. The accessory sex organs are all the components involved in maintaining the sex cell and assisting in the process of fertilization.  The male reproductive system This system is simpler than the female reproductive system. 1. Scrotum: a sac located outside of the abdominal cavity, made up of a thin layer of smooth and skeletal muscle and skin.  It is divided into left and right by a septum to form different compartments for the testicles.  The scrotum keeps the testicles outside the body so they can be 3 degrees cooler than normal core temperature.  The muscles of the scrotum contract to bring the testicles closer to the body in cooler conditions.  In warm conditions they relax to allow the skin to stretch and maximize cooling. The male reproductive system 2. Testes: Oval shape organs made up of thousands of seminiferous tubules where the sperm is produced. It responds to follicle stimulating hormone that signals sperm production. When the sperm is in its last stages of maturation it moves to the epididymis.  The male reproductive system 2. Seminiferous tubules and spermatogenesis: The seminiferous tubules consist of a thick stratified epithelium surrounding a lumen. The epithelium has spermatogenic cells that mature into sperm. At puberty the seminiferous tubules begin to produce about 400 million sperm.  The male reproductive system Spermatogenesis: these are the stages involved in sperm formation. Stage 1: formation of spermatocytes:  spermatogonia divide by mitosis to produce two daughter cells, one remains in the germ line (to continue regeneration of more spermatogonia) and the other one goes on to become sperm. Stage 2: Meiosis:  this is a reduction division that takes a cell through two rounds of division.  At the end four genetically distinctive cells (spermatids) are created which will each mature into a sperm.  The male reproductive system Stage 3: Spermiogenesis:  spermatids mature into sperm  the cell develops a long flagella  mid piece with high mitochondria  Head filled with DNA= the nucleus.  At the tip of the head lies a sac filled with digestive enzymes called the acromosome. Other cells in the testicles perform jobs like assisting the cells to mature and exit the scrotum (referred to as nurse cells), produce male androgen (like testosterone) muscular cells that cause tiny contractions to push the sperm out of the testes. When sperm leaves the seminiferous tubules it travels down the efferent tubules towards the epididymis.  Reproductive duct system is males the tubules through which sperm travel to exit the body. 1. Epididymis:  organ that arches over the posterior lateral side of the testis.  If you uncoil the epididymis is can be as long as 6meters  During the twenty days the sperm spend here they complete maturation and gain the ability to swim and fertilize.  During ejaculation smooth muscle contracts to send mature sperm to the ductus deferns.  Reproductive duct system is males 2. Ductus deferens: also known as the vas deference, it runs superior to the testicles, enters the abdominopelvic cavity, form the ejaculatory duct, and finally leads into the prostatic urethra. 3. Spermatic cords: a tube of fascia holding blood vessels, nerves, and the ductus deference. 4. Urethra : in men carries both sperm and urine. Urethral glands along the spongy urethra secrete a lubricating solution before ejaculation  Accessory glands These glands produce substances that increases the chances of sperm survival once it is outside the body. These secretions in addition to sperm form semen. 1. Seminal vesicles: During ejaculation smooth muscle contract to help secrete a fluid that contains fructose (sugar), nutrients, prostaglandins to stimulate the urethra to contract, enzymes the enhance sperm mobility, and enzymes that thicken the ejaculate.  Accessory glands 2. Prostate gland:  Secrete a milky white fluid that has substances to enhance sperm mobility and thicken ejaculate.  It is susceptible to tumors and sexually transmitted diseases (STDs). 3. Bulbourethral glands:  secrete a mucus substances that lubricates and neutralizes the acid from urine in the male urethra.  Penis Designed to deliver semen into the female reproductive tract. The penis contains erectile bodies: 1.corpora spongiosum 2.corpora cavernosa 3.smooth muscle and connective tissue.  Penis erectile bodies a spongy network surrounded by a high amount of blood vessels that dilate during arousal and engorge the spongy tissues with blood. The veins that normally drain the penis are pressured shut by the expanding spongy tissue. The parasymphatetic branch causes the penis to become erect by stimulating vasodilation. The symphatetic branch cause ejaculation by stimulating contraction of smooth muscle along the reproductive tract Female Reproductive System Hamza Abu Hilail M.Sc. Physiology  The Female Reproductive System II. The female reproductive system: These organs produce the ova (eggs) and sex hormones provide an environment for internal fertilization and development of the fetus. They undergo changes according to the menstrual cycle. Mammary glands are considered part of this system because they nourish the infant.  The Ovaries The ovaries: paired organ is suspended by mesenteries and ligaments. It is surrounded by a fibrous capsule and can be divided into a cortex and medulla.  The cortex houses the developing ova  The medulla holds vascular tissue. The ovary is the site of oogenesis and female sex hormone production.  The Ovaries It responds to follicle-stimulating hormone (FSH) that signals the maturation of an ovum. Typically only one egg is released from an ovary every month, the ovaries alternate in releasing the egg. Hormones that affect the menstrual cycle and female sex organs are also released by the ovaries; estrogen and progesterone.  Ovarian Cycle Ovarian cycle: Females are born with all the potential ova they can produce in a life time. the primordial follicles which consist of a single immature oocyte and a single layer of follicular cells.  These cells respond to FSH and being the maturation of an oocyte. 1. Follicular phase: during the first two weeks of the menstrual cycle one follicle matures up until the stage when it is able to release an oocyte.  Ovarian Cycle Other primordial follicles may get activated but die out along the way. The primordial follicle becomes the primary follicle and continues to develop until it becomes the vesicular follicle. At this point the oocyte is surrounded by follicle cells that the form a fluid filled cavity.  Ovarian Cycle 2. Ovulation (midpoint) phase: at about the mid cycle LH is release to signal the follicle to rupture and release the oocyte from the ovary. The ovum is surrounded by a group of cells that continue to nourish it, they are called the corona radiata. When the egg cell is released it enters the peritoneal cavity but is swept into the fallopian/uterine tubes by fimbriae.  Ovarian Cycle 3. Luteal phase: after ovulation and during the last two weeks of the cycle the follicle that held the oocyte becomes the corpus luteum, it is now considered an endocrine gland that releases progesterone. If no implantation occurs it becomes the corpus albicans (now scar tissue).  Oogenesis 2. Oogenesis in females oogenesis takes several years. During fetal development oocytes undergo: 1. meiosis I but do not complete it; at this point they are called primary oocytes.  At ovulation the primary oocyte completes meiosis I and begins meiosis II 2. meiosis II which is completed only if fertilization occurs.  At the completion of meiosis II the oocyte is called an ovum.  Uterine tubes Uterine tubes: also called fallopian tubes, they take the oocyte and provide a site for fertilization. The tube is lined with ciliated epithelium that gently guides the oocyte towards the uterus. There are also peristaltic waves caused by smooth muscle contraction to aide the movement of the oocyte. There are also non-ciliated cells the nourish the oocyte or embryo on its way to the uterus. sometimes a fertilized egg can implant in a uterine tube and cause a life threatening ectopic pregnancy.  The Uterus The uterus: a thick muscular pouch about the size of a pear that lies in the pelvic cavity superior to the bladder. The function of the uterus is to receive an embryo and provide an environment for its development. During pregnancy it stretches to accommodate the growth of the fetus. When there is no pregnancy the cavity within the uterus is small. The opening of the uterus is at the cervix, during child birth it dilates to allow the child to pass by.  The Uterus The Uterus: The cervix tissue may become infected by HPV human papillomavirus. It can cause abnormal tissue growth including cervical cancer. Uterine wall: composed of three layers: 1. Perimetrium 2. Myometrium 3. Endometrium The thick layer called stratum functionalis (above myometrium) undergoes most of the changes during the uterine cycle.  Uterine cycle Uterine cycle: also called the menstrual cycle, it relates to changes occurring in the endometrium of the uterus that are induced by female sex hormones. Menstrual phase: (days 1-5) during this phase the endometrium is shed  Uterine cycle Proliferative phase: (days 6-14) During this phase the endometrium builds a new stratum functionalis as it responds to rising estrogen levels. As the layer thickens glands release a clear sticky mucus secretion that assist the sperm in finding the egg.  Secretory phase Secretory phase: (days 15-28) during this point the stratum functionalis is highly vascularized and there is secretion of glycoproteins to support a developing embryo in case fertilization occur. These changes are a response to progesterone released by the corpus luteum in the ovary. If there is no fertilization the progesterone levels drop signaling changes that cause death of the stratum functionalis. The arteries constrict cutting out blood supply and suddenly open again but the weak capillaries fragment and the menstrual phase begins again.  The vagina The vagina: also known as the birth canal. It is the opening that leads into the cervix It is located anterior to the anus but posterior to the clitoris and urethral opening. The vagina is also the site where sperm is deposited. This canal is very flexible and it composed of three layers: 1. Adventitia 2. Muscularis 3. Mucosa  The vagina It also has ruggae to stimulate the penis during intercourse and stretch out during childbirth. The mucosa secretes glycogen to maintain healthy beneficial bacteria that produce lactic acid. This creates an acidic environment that is not beneficial to other bacteria or sperm.  External genitalia External genitalia also called the vulva It includes the 1. mons pubis 2. labia majora 3. the clitoris (erectile tissue analogous to the penis) 4. vestibule associated structures( the vaginal and urethral orifice and vestibule glands). 5. labia minora (the mucus membrane sheathes protect the vestibule)  Mammary glands Mammary glands: modified sweat glands that are active in pregnant females to produce milk for the infant. These first appear as rudimentary structures in both men and women. When females reach puberty the ducts grow but the glands do no fully develop; the mas of the breast is mostly adipose.  Mammary glands Mammary glands: During pregnancy glandular alveoli form and produce milk shortly after childbirth. The breast include the nipple and the areola (ring around nipple). The glands consist of lobes that drain into the nipple by lactiferous ducts and lactiferous sinuses where milk accumulates during breast feeling. Lymph vessels drain into the parasternal and axillary lymph nodes.