THE MALE AND FEMALE REPRODUCTIVE SYSTEMS Exercise 42

THE MALE AND FEMALE REPRODUCTIVE SYSTEMS Exercise 42 & 47 A&P 233

MALE REPRODUCTIVE SYSTEM Produces male games (sperm cells) in the seminiferous tubules in the testes Transports gametes to the female reproductive tract Secretes testosterone

SCROTUM The testes sit in the scrotum Sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis Contains paired testicles separated by a midline septum Its external positioning keeps the testes 3 C lower than core body temperature 3

WALL OF THE SCROTUM In the dermis, there is a thin layer of smooth muscle known as the dartos muscle. Contractions of this muscle causes wrinkling of the skin. The cremaster muscle is a thicker layer of skeletal muscle that lowers and raises the testes based on temperature.

INSIDE THE SCROTUM A fibrous (tough connective tissue) capsule covers each testis called the tunica albuginea.

TESTICLE The tunica albuginea gives rise to septa (partitions) that divide the testis into lobules (about 250) Each lobule contains 3 or 4 highly coiled seminiferous tubules These converge to become rete testis which transport sperm to the epididymis 6

CELLS OF THE TESTIS Interstitial cells: produce testosterone Spermatogonia: reproduce by mitosis to produce primary spermatocytes. Sustentacular (Sertoli) cells: form blood testis barrier (BTB), supplies nutrients to developing sperm, protect. (Also called nurse cells) Primary spermatocytes divide by meiosis to form secondary spermatocytes which are located closer to the lumen of the tubule. The process of sperm formation from spermatogonia to sperm cells is called spermatogenesis

SEMINIFEROUS TUBULES 8

SEMINIFEROUS TUBULES HISTOLOGY 9

SPERMATOGENESIS 10

SPERMIOGENESIS: SPERMATIDS TO SPERM 11

SPERM Sperm have three major regions 1. Head : contains DNA and has a helmet-like acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg 2. Midpiece: contains mitochondria spiraled around the tail filaments 3. Tail : a typical flagellum produced by a centriole 12

EPIDIDYMIS Epididymis: Storage and maturation area for sperm Its head joins the efferent ductules and caps the superior aspect of the testis The duct of the epididymis has stereocilia that: Absorb testicular fluid Pass nutrients to the sperm Nonmotile sperm enter, pass through its tubes and become motile (propelled by peristalsis) Upon ejaculation the epididymis contracts, expelling sperm into the ductus deferens 13

EPIDIDYMIS HISTOLOGY

SPERMATIC CORD Contains the structures running from the testicles to the pelvic cavity. Passes through the inguinal canal Contents: Vas Deferens Nerves Blood Vessels 15

ACCESSORY GLANDS: SEMINAL VESICLES Lie on the posterior wall of the bladder and secrete 60% of the volume of semen Seminal fluid: Fructose and other carbohydrates: provides energy for the sperm. As well as some protein, citrate and prostaglandins Join the ductus deferens enlarges to form ampulla. Each ductus deferens joins with the seminal vesicles which forms the ejaculatory ducts 16

POSTERIOR BLADDER 17

POSTERIOR BLADDER 18

ACCESSORY GLANDS: PROSTATE GLAND Doughnut-shaped gland that encircles part of the urethra inferior to the bladder Plays a role in the activation of sperm Enters the prostatic urethra during ejaculation Constitutes about 30% of semen. Prostatic secretions function to: Buffer the vaginal and seminal acidity, raising the p. H to about 7. 5 and activating the sperm (p. H of the vagina is about 3. 5 – 4. 0) 19

BULBOURETHRAL GLANDS (COWPER’S GLANDS) Pea-sized glands inferior to the prostate Add lubricant to the seminal fluid Seminal fluid consists of secretions from the seminal vesicles, prostate gland bulbourethral glands. Semen consists of seminal fluid plus the sperm cells from the testes. 20

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PENIS HISTOLOGY 22

SPERM SUMMARY Produced: Seminiferous tubules Stored: Epididymis Transported through epididymis by rhythmic peristaltic contractions as they mature Epididymis Vas Deferens Ejaculatory duct (ampulla of vas deferens fuses with duct of seminal vesicle “ejaculatory duct”) prostate prostatic urethra (then passes the bulbourethral gland) membranous urethra penile urethra 23

REVIEW QUESTIONS What is the difference between mitosis and meiosis? What are the results of meiosis?

SPERMATOGENESIS Spermatogenic stem cells of the seminiferous tubules give rise to sperm in a series of events Mitosis of spermatogonia, forming spermatocytes Meiosis forms spermatids from spermatocytes Spermiogenesis: spermatids form sperm 25

VASECTOMY Male sterilization Cutting and tying of the two ductus deferens. Prevents sperm from traveling from the testes to the spermatic cords Sperm is reabsorbed by the body

THE FEMALE REPRODUCTIVE SYSTEM Exercise 47 A&P 233

FEMALE REPRODUCTION Unlike males, who are able to produce sperm cells throughout their reproductive lives, females produce a finite number of egg cells. During early fetal development germ cells migrate into the ovaries and differentiate into oogonia

GROSS ANATOMY The ovaries are solid, ovoid structures, about 2 cm in length and 1 cm in width. Like the testes, they develop from embryonic tissue along the posterior abdominal wall, near the kidneys. Accessory organs include the uterine tubes, uterus, and vagina.

OVARIES Each follicle consists of an immature egg called an oocyte Cells around the oocyte are called: Follicle cells (one cell layer thick) Stimulated to mature by FSH from the pituitary gland Granulosa cells (when more than one layer is present) Thecal cells: Cells in the ovarian stroma Thecal & granulosa cells work together to produce estrogen A protective layer of glycoprotein forms around the egg called the zona pellucida 30

OVARY HISTOLOGY 31

Primary Follicle 1° Oocyte (arrested in prophase I) Nucleus Zona pellucida Thecal cells Granulosa cells 32

SECONDARY FOLLICLE Fluid-filled antrum 33

GRAAFIAN FOLLICLE 34 Fluid filled antrum Oocyte 2° Granulosa cells Stalk Corona radiata Zona pellucida

OVARIAN FOLLICLES

FOLLICLE DEVELOPMENT 1. 2. 3. 4. 5. Primordial follicle: one layer of squamouslike follicle cells surrounds the oocyte Primary follicle: one or more layers of cuboidal granulosa cells enclose the oocyte Secondary follicle: has a fluid-filled space between granulosa cells that coalesces to form a central antrum Graafian follicle: secondary follicle at its most mature stage that bulges from the surface of the ovary Corpus luteum : ruptured follicle after ovulation 36

CORPUS LUTEUM After ovulation, the remains of the follicle are transformed into a structure called the corpus luteum. If a pregnancy occurs, it produces progesterone to maintain the wall of the uterus during the early period of development.

CORPUS ALBICANS If fertilization does not occur, the corpus luteum will begin to break down about 2 weeks after ovulation. Degeneration occurs when fibroblasts enter the corpus luteum and a clump of scar tissue forms called the corpus albicans.

UTERINE TUBES (FALLOPIAN TUBES) Receive the ovulated oocyte and provide a site for fertilization The ampulla ends in the funnel-shaped, ciliated infundibulum containing fingerlike projections called fimbriae Expand distally around the ovary forming the ampulla Empty into the superolateral region of the uterus via the isthmus 39

UTERINE TUBES (FALLOPIAN TUBES) Fimbriae sweep oocyte into tube, cilia & peristalsis move it along, sperm reaches oocyte in ampulla, fertilization occurs within 24 hours after ovulation & zygote reaches uterus about 7 days after ovulation 40

FALLOPIAN TUBE HISTOLOGY 41 Cilia sweep egg/zygote toward the uterus

UTERUS Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder Body: Major portion of the uterus Fundus: Rounded region superior to the entrance of the uterine tubes Isthmus: Narrowed region between the body and cervix 42

UTERUS 43

UTERINE HISTOLOGY Endometrium Simple columnar epithelium Stroma of connective tissue and endometrial glands Stratum functionalis: Shed during menstruation Stratum basalis: Replaces stratum functionalis each month Myometrium 3 layers of smooth muscle Perimetrium Visceral peritoneum 44

UTERINE HISTOLOGY 45

ENDOMETRIUM 46 Simple columnar epithelium Endometrial glands

ENDOMETRIUM Proliferative phase: glands and blood vessels scattered throughout the functional zone with little or no branching. New glands form and endometrium thickens. Secretory phase: glands are enlarged and have branches. Preparing the endometrium for implantation If no implantation then endometrium breaks down and menstruation begins.

CERVIX Narrow lower neck of the uterus which projects into the vagina inferiorly Cervical canal – cavity of the cervix that communicates with: The vagina via the external os The uterine body via the internal os Cervical glands secrete mucus that covers the external os and blocks sperm entry except during midcycle 48

Endocervical canal Fornix 49

OVARIAN AND UTERINE CYCLES

FEMALE: LATERAL VIEW 51

VAGINA Thin-walled tube lying between the bladder and the rectum, extending from the cervix to the exterior of the body Wall consists of three coats: fibroelastic adventitia, smooth muscle muscularis, and a stratified squamous mucosa Mucosa near the vaginal orifice forms an incomplete partition called the hymen Vaginal fornix: upper end of the vagina surrounding the cervix 52

FEMALE EXTERNAL GENITALIA Vulva: all external female genital structures Mons pubis: fatty pad over the pubic symphysis Labia majora & minora: folds of skin encircling vestibule where find urethral and vaginal openings Clitoris: small mass of erectile tissue Bulb of vestibule: masses of erectile tissue just deep to the labia on either side of the vaginal orifice Perineum: Area between the vagina and anus 53

FEMALE EXTERNAL GENITALIA Perineum 54

BARTHOLIN’S GLANDS (AKA: VESTIBULAR GLANDS) The Bartholin's glands are located on each side of the vaginal opening. They secrete fluid that helps lubricate the vagina. Sometimes the ducts of these glands become obstructed. Fluid backs up into the gland causes swelling (Bartholin's cyst) 55

MAMMARY GLANDS Modified sweat glands that produce milk (lactation) Amount of adipose determines size of breast Milk-secreting glands open by lactiferous ducts at the nipple Areola is pigmented area around nipple Suspensory ligaments suspend breast from deep fascia of pectoral muscles (aging & Cooper’s droop) Mammary line is a thickened ridge of embryonic tissue that extends from the axilla to the groin. 56

BREAST Prolactin from the pituitary gland stimulates the synthesis of milk Oxytocin from the posterior pituitary gland stimulates milk ejection 57

LYMPHATIC DRAINAGE Lymph nodes draining the breast are located in the axilla. 58

TODAY’S LAB ID structures on the models View slides