MB 551 Human Anatomy & Physiology • 4 Hours • MSc Medical Microbiology Semester II
Detailed study of the male and female reproductive organs, their gross and microscopic anatomy, functions, reproductive physiology and important clinical correlations.
The reproductive system is the group of organs responsible for reproduction, production of gametes, secretion of reproductive hormones, fertilization and, in females, support of pregnancy, fetal development and childbirth. Unlike many other body systems, the reproductive system is not primarily necessary for the survival of an individual, but it is essential for continuation of the species.
The reproductive system consists of both primary reproductive organs (gonads) and accessory reproductive organs. The male gonads are the testes, whereas the female gonads are the ovaries. The gonads perform two major functions: they produce reproductive cells or gametes and secrete reproductive hormones. The testes produce spermatozoa and mainly secrete testosterone, while the ovaries produce ova and secrete estrogen and progesterone.
The accessory reproductive organs provide pathways for transport, maturation and delivery of gametes. In females, the reproductive tract also provides the site for fertilization, implantation, pregnancy and parturition. Therefore, the reproductive system has both anatomical and endocrine functions.
| System | Primary Organ/Gonad | Major Accessory Organs | Main Hormones |
|---|---|---|---|
| Male | Testes | Epididymis, vas deferens, ejaculatory ducts, urethra, seminal vesicles, prostate, bulbourethral glands and penis | Testosterone, inhibin B |
| Female | Ovaries | Uterine tubes, uterus, cervix, vagina and external genitalia | Estrogen, progesterone, inhibin, AMH |
The male reproductive system consists of the testes, a system of ducts, accessory reproductive glands and external genitalia. The testes are the primary male reproductive organs and are responsible for sperm production and secretion of testosterone.
The sperm produced within the seminiferous tubules pass through a series of ducts before reaching the exterior. The epididymis provides an important site for sperm maturation and storage. The vas deferens transports sperm toward the pelvic cavity. The seminal vesicles, prostate and bulbourethral glands contribute secretions that combine with sperm to form semen.
The penis acts as the organ of copulation and provides a passage for semen during ejaculation. The male urethra serves as a common passage for urine and semen, although the two are not normally expelled simultaneously.
Testis — sperm production and testosterone secretion.
Epididymis — maturation, concentration and storage of sperm.
Vas deferens and ejaculatory ducts transport sperm.
Seminal vesicles, prostate and bulbourethral glands contribute seminal fluid.
The testes are paired male gonads located within the scrotum. The scrotal position keeps the testes at a temperature slightly below core body temperature, which is important for normal spermatogenesis.
Each testis is approximately oval in shape and is covered by several protective layers. The outer covering includes the tunica vaginalis and a dense connective tissue capsule called the tunica albuginea. The tunica albuginea sends connective tissue septa into the testis and divides it into numerous testicular lobules.
Each lobule contains one or more highly coiled seminiferous tubules. These tubules converge toward the mediastinum testis and ultimately connect with the duct system that carries sperm to the epididymis.
The testis is composed mainly of seminiferous tubules and interstitial tissue. The seminiferous tubules are lined by a specialized germinal epithelium containing developing germ cells and Sertoli cells.
Between the seminiferous tubules is interstitial connective tissue containing the Leydig cells. These endocrine cells produce testosterone under the influence of luteinizing hormone (LH).
| Cell | Location | Main Function |
|---|---|---|
| Spermatogenic cells | Seminiferous epithelium | Develop into mature spermatozoa. |
| Sertoli cells | Seminiferous tubules | Support developing germ cells, form the blood-testis barrier, secrete inhibin B and produce androgen-binding protein. |
| Leydig cells | Interstitial tissue | Secrete testosterone. |
Seminiferous tubules are the functional sites of sperm production within the testis. Their walls contain a specialized stratified germinal epithelium. Spermatogenic cells are arranged from the basement membrane toward the lumen according to their stage of development.
Sertoli cells extend from the basement membrane toward the lumen and provide nutritional and structural support to developing germ cells. Tight junctions between Sertoli cells contribute to the blood-testis barrier, which separates developing germ cells from many components of systemic circulation.
Spermiogenesis is the transformation of spermatids into structurally specialized spermatozoa. During this process, the nucleus becomes condensed, the acrosome develops, excess cytoplasm is removed and the flagellum develops. The resulting spermatozoa are released into the lumen of the seminiferous tubules.
| Part | Main Features | Function |
|---|---|---|
| Head | Nucleus and acrosome | Contains paternal genetic material; acrosome contains enzymes involved in fertilization. |
| Neck | Connects head and middle piece | Structural connection. |
| Middle piece | Contains numerous mitochondria | Provides ATP for sperm movement. |
| Tail | Flagellum | Produces motility. |
The epididymis is a long, highly coiled duct attached to the posterior aspect of each testis. Anatomically it is divided into the head, body and tail. The head receives sperm from the efferent ductules, while the tail continues into the vas deferens.
The epididymis is lined mainly by pseudostratified columnar epithelium with stereocilia. The stereocilia are long non-motile microvilli that increase surface area and participate in absorption and modification of luminal fluid. Smooth muscle surrounds the duct and contributes to movement of sperm.
The vas deferens, or ductus deferens, is a thick muscular tube that carries sperm from the epididymis toward the ejaculatory duct. It passes through the spermatic cord and inguinal canal before entering the pelvic cavity.
The wall of the vas deferens consists of a mucosa lined by pseudostratified columnar epithelium, a thick muscular layer and an outer connective tissue layer. The prominent smooth muscle allows powerful peristaltic contractions during ejaculation.
Its principal function is rapid transport of sperm from the epididymis toward the ejaculatory duct during ejaculation. The thick muscular wall is particularly important because sperm must be transported efficiently over a relatively long distance.
Each ejaculatory duct is formed by the union of the duct of the seminal vesicle with the ampulla of the vas deferens. It passes through the prostate and opens into the prostatic urethra.
The ejaculatory ducts therefore provide a short final pathway for the mixture of sperm and seminal vesicle secretion before it enters the urethra.
The male urethra is a common passageway for urine and semen. It extends from the urinary bladder through the prostate and penis.
| Part | Location | Important Feature |
|---|---|---|
| Prostatic urethra | Within prostate | Receives ejaculatory ducts and prostatic ducts. |
| Membranous urethra | Through external urethral sphincter region | Short and surrounded by skeletal muscle. |
| Spongy urethra | Within penis | Longest portion; surrounded by corpus spongiosum. |
The seminal vesicles are paired accessory reproductive glands located posterior to the urinary bladder. Their ducts join the vas deferens to form the ejaculatory ducts.
The secretion of the seminal vesicles contributes a substantial portion of seminal plasma. It is rich in fructose, which provides an energy source for sperm. The secretion also contains substances that support sperm function and contribute to the appropriate environment for sperm transport.
The seminal vesicle has a highly folded mucosa, producing an irregular luminal appearance. It is lined mainly by pseudostratified columnar epithelium and contains a muscular wall that helps expel its secretion during ejaculation.
The prostate is a single accessory reproductive gland located inferior to the urinary bladder and surrounding the proximal part of the urethra. It contributes an important component of seminal fluid.
The prostate is a firm glandular organ located at the base of the bladder. Its position around the urethra has important clinical significance because prostatic enlargement can narrow the urethral lumen and interfere with urinary flow.
The prostate consists of numerous tubuloalveolar glands embedded in fibromuscular stroma. The glandular epithelium varies from simple to pseudostratified columnar epithelium. Prostatic secretions enter the urethra through multiple ducts.
The bulbourethral glands are paired small accessory glands located below the prostate. Their ducts open into the proximal spongy urethra.
They produce a clear mucus-rich secretion that contributes to lubrication of the urethra and helps provide a suitable environment for passage of semen. Their secretion is released mainly before ejaculation.
The penis is the male external copulatory organ and also provides the distal passage for the urethra. It contains erectile tissue that becomes engorged with blood during sexual arousal.
The penis consists of a root, shaft and glans penis. Its erectile tissues include paired corpora cavernosa and a single corpus spongiosum. The corpus spongiosum surrounds the spongy urethra and expands distally to form the glans.
Erection is primarily a vascular event. Parasympathetic stimulation promotes relaxation of smooth muscle in erectile tissue and increases arterial inflow. Blood fills the vascular spaces of erectile tissue, while venous outflow is partly compressed, maintaining rigidity.
| Function | Organ/Structure Mainly Involved | Description |
|---|---|---|
| Sperm production | Seminiferous tubules | Production of male gametes through spermatogenesis. |
| Sperm maturation | Epididymis | Sperm acquire functional maturity and motility. |
| Sperm transport | Vas deferens and ducts | Moves sperm toward the urethra. |
| Seminal fluid production | Seminal vesicles, prostate and bulbourethral glands | Provides fluid, nutrients and supportive substances. |
| Hormone secretion | Leydig and Sertoli cells | Testosterone and inhibin B contribute to reproductive regulation. |
| Copulation | Penis | Deposits semen within the female reproductive tract. |
The female reproductive system consists of the ovaries, uterine tubes, uterus, cervix, vagina and external genitalia. The ovaries are the primary female gonads. They produce oocytes and secrete reproductive hormones, particularly estrogen and progesterone.
The uterine tubes receive the ovulated oocyte and provide the usual site of fertilization. The fertilized ovum then travels toward the uterus, where implantation occurs. The uterus supports development of the embryo and fetus during pregnancy.
The cervix forms the lower portion of the uterus and connects it with the vagina. The vagina serves as the copulatory canal and forms part of the birth canal.
The ovaries are paired female gonads located in the pelvic cavity. They are oval structures situated on either side of the uterus. Each ovary is attached to surrounding structures by supporting ligaments and mesovarian tissue.
The ovary has two major anatomical regions: an outer cortex and an inner medulla. The cortex contains ovarian follicles at different stages of development, whereas the medulla contains connective tissue, blood vessels, lymphatics and nerves.
The ovarian cortex contains follicles consisting of an oocyte surrounded by follicular cells. Follicles develop through primordial, primary, secondary and mature stages. Following ovulation, the remaining follicular tissue forms the corpus luteum.
The medulla consists largely of loose connective tissue and contains the major vascular and neural structures supplying the ovary.
An ovarian follicle consists of an oocyte and the surrounding supporting follicular cells. Follicular development is a continuous process regulated by gonadotropins and ovarian hormones.
| Follicle | Important Characteristics |
|---|---|
| Primordial follicle | Primary oocyte surrounded by a single layer of flattened follicular cells. |
| Primary follicle | Follicular cells become cuboidal and proliferate; zona pellucida develops. |
| Secondary/antral follicle | Fluid-filled antrum develops and granulosa/theca layers become prominent. |
| Mature/Graafian follicle | Large follicle containing the mature oocyte and prominent antrum. |
| Corpus luteum | Post-ovulatory structure that secretes mainly progesterone and also estrogen. |
| Corpus albicans | Fibrous remnant formed when the corpus luteum regresses. |
Granulosa cells surround the developing oocyte and are important in follicular support and estrogen production. Theca cells surrounding the follicle provide androgen precursors that granulosa cells can convert into estrogens under the influence of FSH.
The uterine tubes are paired muscular tubes extending from the region of the ovaries toward the uterus. They provide the route through which the oocyte travels toward the uterine cavity.
| Part | Description |
|---|---|
| Infundibulum | Funnel-shaped lateral end with finger-like fimbriae. |
| Ampulla | Widest part and usual site of fertilization. |
| Isthmus | Narrow muscular segment close to the uterus. |
| Uterine/intramural part | Passes through the wall of the uterus. |
The mucosa is highly folded and lined mainly by simple columnar epithelium. Two important epithelial cell types are ciliated cells and secretory cells. Ciliary movement helps transport the oocyte toward the uterus, while secretory cells contribute fluid that supports gamete and early embryo survival.
The muscular wall produces contractions that also assist movement of the oocyte and early embryo.
The uterus is a hollow, muscular, pear-shaped organ located in the pelvis between the urinary bladder and rectum. It is the organ in which implantation normally occurs and where the embryo and fetus develop during pregnancy.
| Part | Description |
|---|---|
| Fundus | Dome-shaped upper portion above the uterine tube openings. |
| Body | Main central portion of uterus. |
| Isthmus | Narrow region between body and cervix. |
| Cervix | Lower cylindrical portion projecting into the vagina. |
The uterine wall consists of three major layers: perimetrium, myometrium and endometrium.
The perimetrium is the outer serosal covering of much of the uterus. It is continuous with the surrounding peritoneal covering where applicable.
The myometrium is the thick middle layer composed predominantly of smooth muscle. It enlarges substantially during pregnancy and generates powerful contractions during labor.
The endometrium is the inner mucosal lining of the uterus. It undergoes cyclic changes in response to ovarian hormones and provides the site for implantation of the developing embryo.
The endometrium consists of a superficial functional layer and a deeper basal layer. The functional layer undergoes cyclic changes and is shed during menstruation when pregnancy does not occur. The basal layer remains and contributes to regeneration of the endometrium.
| Phase | Main Hormonal Influence | Main Endometrial Change |
|---|---|---|
| Menstrual phase | Withdrawal of ovarian hormones | Shedding of functional endometrium. |
| Proliferative phase | Estrogen | Regeneration and proliferation of endometrium. |
| Secretory phase | Progesterone | Endometrial glands become active and secretory. |
If fertilization and implantation occur, hormonal support maintains the endometrium. If pregnancy does not occur, the corpus luteum degenerates, progesterone and estrogen levels fall, and the functional endometrium is shed as menstruation.
The cervix is the lower part of the uterus and projects into the upper vagina. It contains a cervical canal that connects the uterine cavity with the vagina.
The endocervical canal is lined mainly by mucus-secreting simple columnar epithelium, whereas the ectocervix is lined by stratified squamous epithelium. The junction between these epithelial regions is clinically important and is known as the transformation zone.
The vagina is a fibromuscular canal extending from the cervix to the external genitalia. It functions as the female copulatory canal and forms part of the birth canal.
The vaginal mucosa is lined by non-keratinized stratified squamous epithelium. The underlying connective tissue contains blood vessels and elastic fibers. The muscular layer consists mainly of smooth muscle arranged in different orientations.
The vaginal epithelium contains glycogen-rich cells. Vaginal microbial communities metabolize available substrates and contribute to an acidic environment that helps limit growth of some pathogenic organisms.
The external female genital structures are collectively called the vulva. They protect the openings of the reproductive and urinary tracts and contribute to sexual function.
| Structure | Function |
|---|---|
| Mons pubis | Fat-containing tissue over the pubic region that provides protection. |
| Labia majora | Outer skin folds providing protection to deeper structures. |
| Labia minora | Inner folds surrounding the vestibule. |
| Clitoris | Erectile sensory organ involved in sexual arousal. |
| Vestibule | Area containing the external openings of the urethra and vagina. |
| Greater vestibular glands | Produce mucus that contributes to lubrication. |
The mammary glands are specialized glands of the anterior thoracic wall. Although they are not reproductive organs in the strict anatomical sense, they are functionally associated with reproduction because they produce milk after childbirth.
Each mammary gland contains glandular tissue organized into lobes and lobules. Milk produced by secretory alveoli passes through ducts toward the nipple.
The secretory units consist of alveoli lined by milk-secreting epithelial cells and surrounded by myoepithelial cells. Myoepithelial contraction helps expel milk into the duct system.
| Hormone | Main Role |
|---|---|
| Estrogen | Promotes ductal development. |
| Progesterone | Promotes development of lobuloalveolar structures. |
| Prolactin | Stimulates milk synthesis. |
| Oxytocin | Causes contraction of myoepithelial cells and milk ejection. |
| Function | Main Structure | Description |
|---|---|---|
| Oocyte production | Ovary | Produces and supports maturation of female gametes. |
| Hormone secretion | Ovary | Produces estrogen, progesterone, inhibin and AMH. |
| Fertilization | Uterine tube | Usually occurs in the ampulla. |
| Implantation | Uterus | Embryo implants into the endometrium. |
| Pregnancy | Uterus | Supports fetal growth and placental function. |
| Childbirth | Uterus and vagina | Uterine contractions and birth canal permit delivery. |
| Lactation | Mammary glands | Produces and delivers milk to the infant. |
Reproductive function is regulated by an integrated endocrine pathway called the hypothalamic-pituitary-gonadal axis. The hypothalamus releases gonadotropin-releasing hormone (GnRH) in a pulsatile manner. GnRH stimulates the anterior pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
In males, LH stimulates Leydig cells to produce testosterone, while FSH acts mainly on Sertoli cells and supports spermatogenesis. Testosterone and inhibin B provide feedback to the hypothalamus and pituitary.
In females, FSH promotes follicular development, while LH acts on theca cells, supports ovulation and contributes to corpus luteum formation. Estrogen, progesterone and inhibin participate in feedback regulation of the axis.
| Hormone | Target | Major Function |
|---|---|---|
| GnRH | Anterior pituitary | Stimulates FSH and LH secretion. |
| LH | Leydig cells | Stimulates testosterone production. |
| FSH | Sertoli cells | Supports spermatogenesis and Sertoli cell function. |
| Testosterone | Male reproductive tissues and other target tissues | Supports male differentiation, reproductive function and secondary sexual characteristics. |
| Inhibin B | Anterior pituitary | Provides negative feedback mainly on FSH secretion. |
| Hormone | Main Target | Major Function |
|---|---|---|
| FSH | Ovarian follicles | Promotes follicular growth and granulosa cell function. |
| LH | Theca cells/corpus luteum | Supports androgen production, ovulation and luteal function. |
| Estrogen | Female reproductive tissues | Supports reproductive tract development and endometrial proliferation. |
| Progesterone | Uterus and other reproductive tissues | Supports secretory endometrium and pregnancy. |
| Inhibin | Anterior pituitary | Suppresses FSH secretion. |
Spermatogenesis is the process by which diploid spermatogenic cells develop into haploid spermatozoa within the seminiferous tubules. It begins at puberty and normally continues throughout adult life, although the rate may decline with age.
Oogenesis is the development of female gametes in the ovary. Unlike spermatogenesis, the formation of primary oocytes begins before birth. During reproductive life, selected follicles resume development during each menstrual cycle. Usually one dominant follicle releases an oocyte during ovulation.
| Feature | Spermatogenesis | Oogenesis |
|---|---|---|
| Site | Seminiferous tubules | Ovarian follicles |
| Begins | At puberty | Before birth; cyclic maturation begins after puberty |
| Gamete produced | Spermatozoon | Oocyte |
| Number from one primary cell | Four haploid sperm cells | One functional ovum/oocyte plus polar bodies |
| Production pattern | Continuous after puberty | Cyclic and limited by ovarian reserve |
Fertilization is the process by which a spermatozoon fuses with the female gamete to form a diploid zygote. It usually occurs in the ampulla of the uterine tube.
The developing embryo undergoes cleavage while moving toward the uterus. After reaching the blastocyst stage, it attaches to and implants within the endometrium.
| Hormone | Major Source | Main Function |
|---|---|---|
| Testosterone | Leydig cells of testis | Male reproductive development, secondary sexual characteristics and support of spermatogenesis. |
| Estrogen | Ovarian follicles; placenta during pregnancy | Female reproductive development, endometrial proliferation and bone maintenance. |
| Progesterone | Corpus luteum; placenta during pregnancy | Supports secretory endometrium and pregnancy. |
| Inhibin | Sertoli cells and ovarian granulosa cells | Suppresses FSH secretion. |
| AMH | Granulosa cells; Sertoli cells in fetal male | Important in follicular physiology and fetal reproductive tract development. |
| hCG | Placental trophoblast | Maintains corpus luteum early in pregnancy. |
| Prolactin | Anterior pituitary | Stimulates milk synthesis. |
| Oxytocin | Posterior pituitary release | Promotes uterine contraction and milk ejection. |
Male infertility may result from abnormalities in sperm production, sperm motility, sperm morphology, ductal obstruction, endocrine dysfunction or other reproductive conditions. Evaluation commonly includes semen analysis and assessment of reproductive history.
Benign prostatic hyperplasia is non-malignant enlargement of the prostate that commonly occurs with aging. Because the prostate surrounds the proximal urethra, enlargement can cause lower urinary tract symptoms such as weak stream, hesitancy and incomplete emptying.
Cryptorchidism refers to failure of one or both testes to descend into the scrotum. Increased temperature in an undescended testis can impair normal spermatogenesis and is associated with increased risk of certain testicular tumors.
Polycystic ovary syndrome is a common endocrine and reproductive disorder associated with ovulatory dysfunction and variable androgen excess. It may present with irregular menstrual cycles, clinical or biochemical hyperandrogenism and difficulty with fertility. The term should not be interpreted as simply meaning multiple ovarian cysts.
Endometriosis is a condition in which tissue resembling endometrial tissue is present outside the uterine cavity. It may cause pelvic pain, painful menstruation and infertility.
An ectopic pregnancy occurs when implantation takes place outside the normal uterine cavity. The uterine tube is a common location. Rupture of a tubal ectopic pregnancy can cause severe internal bleeding and is a medical emergency.
Cervical cancer commonly develops from persistent infection with high-risk human papillomavirus (HPV) types followed by progressive cellular changes. The transformation zone is particularly important in cervical screening.
Erectile dysfunction is the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual activity. It may have vascular, neurological, endocrine, medication-related or psychological contributors.
| Feature | Male | Female |
|---|---|---|
| Primary gonad | Testis | Ovary |
| Gamete | Sperm | Oocyte |
| Main sex hormone | Testosterone | Estrogen and progesterone |
| Gamete production | Begins at puberty and is relatively continuous | Begins before birth; cyclic maturation after puberty |
| Accessory glands | Seminal vesicles, prostate, bulbourethral glands | No direct equivalent group of seminal glands |
| Fertilization | Produces and delivers sperm | Usually occurs in ampulla of uterine tube |
| Pregnancy | Does not provide fetal environment | Uterus supports pregnancy |
| Childbirth | Not directly involved | Uterus and vagina participate |
Write location, coverings, seminiferous tubules, Sertoli cells, Leydig cells and functions.
Describe their location and functions in spermatogenesis and endocrine regulation.
Location, hormonal regulation and functions of testosterone secretion.
Gross structure, histology and role in sperm maturation.
Structure and composition/functions of seminal secretion.
Gross anatomy, histology, secretion and clinical significance.
Gross structure, cortex, medulla, follicles and endocrine functions.
Explain follicular development from primordial follicle to corpus luteum.
Parts, microscopic structure and functions.
Parts and three layers of uterine wall with functions.
Functional and basal layers and cyclic changes.
Gross and microscopic anatomy and functions.
Histology and major functions.
Explain stages from spermatogonium to spermatozoon.
Explain formation and maturation of female gamete.
Explain GnRH, FSH, LH and gonadal hormones.
| Question | Key Answer |
|---|---|
| Define reproductive system. | Group of organs responsible for gamete production, reproductive hormone secretion and reproduction. |
| Name the male gonad. | Testis. |
| Name the female gonad. | Ovary. |
| What is the function of testis? | Sperm production and secretion of male reproductive hormones, mainly testosterone. |
| What are seminiferous tubules? | Highly coiled tubules in the testis where spermatogenesis occurs. |
| What are Sertoli cells? | Supporting cells of seminiferous tubules involved in germ-cell support and reproductive regulation. |
| What are Leydig cells? | Interstitial endocrine cells that secrete testosterone. |
| Function of epididymis? | Sperm maturation, storage and transport. |
| Name three male accessory glands. | Seminal vesicles, prostate and bulbourethral glands. |
| Function of seminal vesicle? | Produces fructose-rich seminal fluid that contributes to semen. |
| Function of prostate? | Produces prostatic fluid that contributes to semen and supports sperm function. |
| Name the female reproductive organs. | Ovaries, uterine tubes, uterus, cervix, vagina and external genitalia. |
| What is the function of ovary? | Produces oocytes and secretes ovarian hormones. |
| What is the usual site of fertilization? | Ampulla of the uterine tube. |
| What is the site of implantation? | Endometrium of the uterus. |
| Name the layers of uterine wall. | Perimetrium, myometrium and endometrium. |
| What is myometrium? | Thick smooth muscle layer of the uterus. |
| What is endometrium? | Inner mucosal lining of the uterus involved in cyclic changes and implantation. |
| What is corpus luteum? | Post-ovulatory ovarian structure that mainly secretes progesterone. |
| Name two major ovarian hormones. | Estrogen and progesterone. |
| What is testosterone? | Major male sex steroid hormone produced mainly by Leydig cells. |
| What is estrogen? | Major group of female sex steroid hormones involved in reproductive development and function. |
| What is progesterone? | Ovarian steroid hormone important for secretory endometrium and pregnancy support. |
| Define spermatogenesis. | Process by which spermatogenic cells develop into mature spermatozoa. |
| Define oogenesis. | Process of development and maturation of female gametes in the ovary. |
| What is GnRH? | Hypothalamic hormone that stimulates pituitary secretion of FSH and LH. |
| Function of FSH in male? | Acts mainly on Sertoli cells and supports spermatogenesis. |
| Function of LH in male? | Stimulates Leydig cells to produce testosterone. |
| Function of FSH in female? | Promotes ovarian follicular development. |
| Function of LH in female? | Participates in ovulation and corpus luteum formation. |
| Organ | Key Structure | Main Function |
|---|---|---|
| Testis | Seminiferous tubules | Sperm production and testosterone secretion. |
| Epididymis | Coiled duct with stereocilia | Sperm maturation and storage. |
| Vas deferens | Thick muscular wall | Sperm transport. |
| Seminal vesicle | Highly folded gland | Fructose-rich seminal secretion. |
| Prostate | Tubuloalveolar glands | Prostatic secretion. |
| Bulbourethral gland | Mucus-secreting gland | Lubrication and urethral preparation. |
| Penis | Erectile tissue | Copulation and semen delivery. |
| Organ | Key Structure | Main Function |
|---|---|---|
| Ovary | Follicles and corpus luteum | Oocyte development and hormone secretion. |
| Uterine tube | Ciliated mucosa | Oocyte/embryo transport and usual site of fertilization. |
| Uterus | Endometrium and myometrium | Implantation and fetal development. |
| Cervix | Cervical canal | Mucus production, barrier and birth canal contribution. |
| Vagina | Stratified squamous epithelium | Copulation, menstrual passage and birth canal. |
| Mammary gland | Alveoli and ducts | Milk production and delivery. |
| Point | Spermatogenesis | Oogenesis |
|---|---|---|
| Site | Testis | Ovary |
| Starting time | Puberty | Fetal life; maturation resumes after puberty |
| Pattern | Relatively continuous | Cyclic |
| Functional gametes | Four sperm from one primary spermatocyte | One functional gamete from one primary oocyte |
| Motility | Sperm are motile | Oocyte is non-motile and transported by tube mechanisms |
| Hormone | Source | Major Function |
|---|---|---|
| GnRH | Hypothalamus | Stimulates FSH and LH secretion. |
| FSH | Anterior pituitary | Spermatogenesis support and ovarian follicular development. |
| LH | Anterior pituitary | Testosterone production, ovulation and luteal function. |
| Testosterone | Leydig cells | Male reproductive development and function. |
| Estrogen | Ovarian follicles | Female reproductive development and endometrial proliferation. |
| Progesterone | Corpus luteum | Secretory endometrium and pregnancy support. |
| Inhibin | Gonads | Negative feedback mainly on FSH. |
| hCG | Placenta | Maintains corpus luteum during early pregnancy. |
| Prolactin | Anterior pituitary | Milk synthesis. |
| Oxytocin | Posterior pituitary release | Uterine contraction and milk ejection. |
For MSc/TU examinations, diagrams should be simple, clearly labeled and directly related to the answer. The following diagrams are especially useful for long questions.
Complete male reproductive system.
Gross and microscopic structure of testis.
Seminiferous tubule and spermatogenesis.
Structure of spermatozoon.
Complete female reproductive system.
Gross and microscopic structure of ovary.
Stages of ovarian follicular development.
Gross and microscopic structure of uterus.
Hypothalamic-pituitary-gonadal axis.
Menstrual cycle and hormonal changes.
The reproductive system is composed of male and female reproductive organs that collectively perform gamete production, reproductive hormone secretion, fertilization and, in females, pregnancy and childbirth. The male reproductive system consists mainly of the testes, ducts, accessory glands and penis. The testes contain seminiferous tubules for spermatogenesis and Leydig cells for testosterone secretion.
The female reproductive system consists mainly of ovaries, uterine tubes, uterus, cervix, vagina and external genitalia. The ovaries contain follicles and function as both gamete-producing and endocrine organs. The uterine tubes transport the oocyte and are the usual site of fertilization. The uterus provides the site for implantation and fetal development, while the vagina functions as the copulatory canal and part of the birth canal.
Both reproductive systems are regulated by the hypothalamic-pituitary-gonadal axis. GnRH from the hypothalamus regulates pituitary FSH and LH secretion, which in turn control gonadal activity. Testosterone, estrogen, progesterone and inhibin provide feedback regulation. Understanding the relationship between gross anatomy, microscopic anatomy, hormonal regulation and function is essential for answering MB 551 long questions effectively.