Question | Answer |
Sexual reproduction involves | gonads that produce gametes ((haploid) and sex hormones ;
Male gonad is testes, gamete is sperm
Female gonad is ovary, gamete is secondary oocyte |
Fertilization is the process | results in the union of a male gamete with a female gamete |
Pregnancy begins with fertilization | a time when the fertilized egg undergoes implantation, embryonic and fetal development, and birth |
Testes | Paired male gonads in scrotum
Contain seminiferous tubules that produce sperm during spermatogenesis
Spermatogenic cells
Begin sperm production at puberty |
System of ducts | Epididymis, ductus deferens, ejaculatory ducts, and urethra |
Accessory glands | Seminal vesicles, prostate, and bulbourethral glands |
Supporting structures | Scrotum and penis |
Scrotum | Loose skin and underlying hypodermis support testes in two sacs
Normal sperm production in testes occurs at temperature a few degrees below body temperature
Testes descend through inguinal canals during fetal development
Cremaster and dartos muscles |
Sertoli (Sustentacular) cells – seminiferous tubules (Testes) | Nourish and control movement of developing sperm cells to release in lumen
Form blood-testis barrier to prevent immune response
Secrete inhibin hormone to decrease spermatogenesis
Other functions? |
Leydig (Interstitial) Cells – between tubules (Testes) | Produce male sex hormone testosterone |
Spermatogenesis | Spermatogonia begin mitosis at puberty
Some remain near basement membrane as stem cells
Others move between Sertoli cells to become primary spermatocytes (diploid; 2n) |
Spermatogenesis (Meiosis) | Meiosis I – a primary spermatocyte divides into two secondary spermatocytes (haploid; n) with two chromatids of one of each pair of chromosomes
Meiosis II – the two secondary spermatocytes divide forming four spermatids (n) (immature sperm) |
last stage of spermatogenesis | Influenced by testosterone
Developing sperm form an acrosome and flagellum, shed excess cytoplasm, and increase mitochondria
Elongated sperm cells are released into lumen of seminiferous tubule
Sertoli cells secrete fluid to push sperm toward the ducts |
acrosome: | enzyme (filled vesicle),cap the sperm cell
-needed to break protective barrier around the egg |
flagellum: | swim up female tract |
Mature Sperm | 300 million per day produced
Once ejaculated, survive 48 hours in female reproductive tract
Mature sperm structures
Head – contains nucleus and haploid DNA
Acrosome – enzymes for penetrating secondary oocyte
Middle piece – mitochondria produce ATP
T |
Hormone Control of Testes | At puberty, gonadotropin-releasing hormone(GnRH, hypothalamus) stimulates secretion of two anterior pituitary gonadotropin hormones
Negative feedback regulation mechanism |
male - Luteinizing hormone (LH) | Stimulates Leydig cells to secrete testosterone |
male - Follicle-stimulating hormone (FSH) | With testosterone, stimulates Sertoli cells to secrete androgen-binding protein which keeps testosterone level high in seminiferous tubules |
male - Inhibin (from Sertoli cells) | Inhibits FSH to help regulate the rate of spermatogenesis |
testosterone | masculinizes the fetus-development of male organs
-also stimulates the descent of testes into the scrotum-7 months gestation
-failure to descend=cryptorchidism
-leads to decrease sperm production and sterility because of |
Ducts of the testes | Seminiferous tubule lumen, straight tubules, rete testis |
Epididymis | Efferent ducts, ductus epididymis
Site of sperm maturation, storage, degeneration |
Ductus deferens (vas deferens) | Ascends in spermatic cord, through inguinal canal, loops over ureter, and ends at dilated ampulla
Stores sperm and conveys them to urethra |
Ejaculatory ducts | Union of ductus deferens and duct of seminal vesicles
Empties sperm and seminal fluid into prostatic urethra |
Urethra | Shared by reproductive and urinary systems
Prostatic urethra
Membranous urethra (intermediate urethra)
Spongy (penile) urethra (longest)
External urethral orifice |
Seminal vesicles | Alkaline, viscous fluid with fructose, used by sperm for ATP production
Secretion contributes to sperm viability
contribute to most semen volume (60%)
-secretion is alkaline (helps neutralize urethra and vagina)
-fructose is nutrient for sperm |
Prostate | Surrounds prostatic urethra
Secretion contributes to sperm motility and viability
contributes about 25% of semen and is alkaline because it has citric acid (nutreint) |
Bulbourethral glands (Cowper’s gland) | Either side of membranous urethra
Mucus for lubrication and alkaline fluid to neutralize acids from urine in urethra
on pelvic floor |
Semen | Mixture of fluids
Sperm and secretions from seminiferous tubules
Secretions from seminal vesicles, prostate, and bulbourethral glands |
Function of semen | Fluid in which sperm are transported
Supplies nutrients for sperm
Neutralizes the acidity of the male urethra and female vagina |
Ejaculation | expulsion of semen from the urethra to the exterior of the body |
Penis | Support structure
Contains urethra
Passageway for ejaculation of semen and excretion of urine
organ of copulation
-intercourse
-delivers sperm (in semen) into female tract |
Body of penis | Three erectile tissue masses
Two corpora cavernosa penis
One corpus spongiosum penis around urethra
Glans penis expanded distal tip with sensory receptors |
Erection | engorgement of penile blood sinuses under influence of sexual excitement |
Male Sexual Response | Upon sexual stimulation (visual, tactile, auditory, olfactory, or imagined), sacral parasympathetic fibers initiate and maintain an erection |
Under the influence of nitric oxide released from parasympathetic neurons (“neurogenic NO”,: | arteries that supply the penis dilate and blood enters penile sinuses in the erectile tissue; NO also causes the smooth muscle within the erectile tissue to relax, resulting in widening of the blood sinuses |
After an erection | sympathetic stimulation is necessary for the rest of the sexual response, including ejaculation (-ejaculate volume is around 5 mm (teaspoon)
The smooth muscle sphincter at the base of the urinary bladder must close, followed by semen being propelled into |
Ovaries | Paired female gonads in abdominal cavity
Suspended on either side of uterus in peritoneal cavity, held in position by ligaments
Broad ligament, ovarian ligament, and suspensory ligament
Produce secondary oocytes
Follicles in different stages of devel |
Uterine tubes or oviducts | Tubes transporting secondary oocyte to site of fertilization and zygote to uterus
-not continuous with ovaries but partially cover ovaries
-ends of oviducts will sweep the ovulated oocyte into the tube
-are extended laterally from the uterus
Cilia |
Uterus | Site of fetal development
- opens up into the fallopian tubes it is a continuous pathway
Major regions
Fundus, body, and cervix |
Vagina | Passageway from cervix to exterior
Receptacle for penis during sexual intercourse
Outlet for menstrual flow
Passageway for childbirth
Rugae |
Vulva | collective external structures
External genitals of female
Include mons pubis, labia majora, labia minora, clitoris, vestibule, vaginal and urethral orifice (separate in female), hymen, paraurethral glands, and greater vestibular glands
Many structures |
Mammary glands | Part of integumentary and reproductive systems
Each breast anterior to pectoralis major and serratus anterior muscles
-alveoli produce milk
-myoepithelial cells contract because of oxytocin to cause milk let down (positive feedback); posterior pituita |
male/female differences | -male does not have uterus, female does not have prostate
-female urethra shorter and wider and closer to other holes therefore they are more likely to develop infections (UTI); urethra only for urinary system
-male risk has an increase of urinary sta |
broad ligament: | wide band of connective tissue that anchors uterus and ovaries in the pelvic cavity |
suspensory ligament: | attaches/suspends ovaries to the pelvic wall |
ovarian ligament: | attaches ovaries to uterus but not a passageway |
secondary oocyte: | released at day 14 through ovulation
-ovulated in meiosis 2
-fertilization required to complete cell division (meiosis 2) which then becomes an ovum (egg) |
Ovarian cortex | Ovarian follicles surrounded by dense irregular connective tissue |
Ovarian medulla | Loosely arranged connective tissue with blood and lymph vessels and nerves |
Histology of Ovary | -female are born with gamete cells at first oocyte stage in primordial follicles
-several degenerate during childhood: atresia
-eventually menopause occurs
-inner part of ovary is called medulla |
Oogenesis | Oogonia complete mitosis during fetal development
Primary oocytes (diploid; 2n) formed before birth and many begin to degenerate (atresia)
-oogenesis
-oogonia (2n)
-primary oocyte (2n)
-arrested in meiosis 1 until puberty
-in fetal developme |
Oogenesis - Meiosis | Meiosis I – a few primary oocytes enter prophase
But arrested development until after puberty
After puberty, complete meiosis I as follicle develops to produce secondary oocyte and polar body (unequal cytoplasm distribution)
Usually one secondary oocyt |
Primordial follicle | Single layer of cells surrounding primary oocyte |
Primary follicle | Clear zona pellucida, multilayered granulosa cells |
Secondary follicle | Corona radiata, small antrum, more granulosa cells: secretes estrogen |
Graafian follicle | Mature follicle, large antrum: ruptures and ovulates |
Corpus luteum | Remnants after ovulation, produces hormones |
Corpus albicans | Degenerated corpus luteum; becomes fibrous scar |
Infundibulum | distal funnel shape end of tube, open to serous fluid of peritoneal cavity |
Fimbriae | fingerlike extensions sweep oocyte into infundibulum |
Ampulla | widest, longest portion, typically site of fertilization |
Isthmus | short, narrow connection to uterus |
ectopic pregnancy | -implantation outside of uterus
-often in tube potentially fatal, if tube rupture + hemorrhage |
Perimetrium | outer protective layer, supported by broad, uterosacral, cardinal and round ligaments
visceral peritoneum |
Myometrium | three smooth muscle layers important during labor
receptors for prostaglandins + oxytocin |
Endometrium | Stratum functionalis - sloughs off - faces uterine cavity; sloughs off each month (menstrual flow)=tissue + blood
-is replaced each month by proliferation of the stratum basalis
Stratum basalis - produces new stratum functionalis after menstruation |
Uterus functions: | Menstruation and regrowth of sloughed-off lining
Implantation of fertilized ovum
Contribute to structure of placenta
Support development of fetus during pregnancy
Labor |
Extensive blood supply | Uterine, arcuate, radial, straight and spiral arteries |
leiomyoma | -fibroids
-growth of myometrium |
Mammary gland functions for lactation | Modified sudoriferous gland that produces milk
Lobules composed of alveoli separated by adipose tissue
Myoepithelial cells contract to propel milk through ducts
Secondary tubules, mammary ducts, lactiferous sinuses, and lactiferous ducts |
Ovarian cycle | Occurs in ovary during and after maturation of oocyte |
Uterine cycle | Concurrent changes in endometrium of uterus to prepare to receive fertilized ovum and support its development |
Hormone Regulation of Female Cycle | At puberty, gonadotropin-releasing hormone (hypothalamus) stimulates secretion of two anterior pituitary gonadotropin hormones |
female - Follicle-stimulating hormone (FSH) | Initiates follicular growth and estrogen secretion |
female - Luteinizing hormone (LH) | Stimulates further follicular development and estrogen
Triggers ovulation and corpus luteum secretion of estrogen, progesterone, relaxin, and inhibin |
female - Inhibin | Inhibits FSH, and LH to lesser extent |
female - Relaxin | Relaxes uterine muscle and pubic symphysis |
secondary female sex characteristics | -enlarging breasts
-widening breasts
-development of pubic + axillary hair |
female - Estrogen | Stimulate development and maintenance of female reproductive structures and secondary sex characteristics
Stimulates protein anabolism
Decreases blood cholesterol levels |
female - Progesterone | Works with estrogen to prepare endometrium for implantation
Prepares mammary glands for milk secretion |
Menstrual phase menstruation
-days 1-5 | In ovaries, primordial follicle develop into primary, then secondary follicles
In the uterus, stratum functionalis of the endometrium is shed, discharging blood tissue fluid, mucus, and epithelial cells |
Preovulatory phase (days 6-13) | In ovaries, a group of follicles begins to undergo maturation
-One becomes dominant, and others degenerate
-Graafian follicle secretes estrogens and inhibin, which decreases FSH and
stops other follicles from growing
In uterus, estrog |
-female cycles | -assume 28 days
-variable in length of the preovulatory phase (days 1-13)
-always 14 days for ovulation to the first day of the next cycle, which begins with menses |
Ovulation -day 14
-release secondary oocyte | High levels of estrogen exert positive feedback effect on anterior pituitary and hypothalamus
Surge of LH causes rupture of Graafian follicle and release of secondary oocyte with zona pellucida and corona radiata cells into pelvic cavity |
Postovulatory phase (days 15-28) | In ovaries, the corpus luteum develops from the ruptured follicle
Stimulated by LH, secretes progesterone, estrogens, relaxin, and inhibin
In uterus, endometrium thickens in readiness for implantation
Also begins secretion of nutrients to suppo |
If fertilization and implantation do NOT occur | In the ovaries, corpus luteum degenerates and levels of progesterone and estrogens decrease
In the uterus, menstruation triggered by decreasing hormones
Initiation of another reproductive cycle |
If fertilization and implantation DO occur | In the ovaries, human chorionic gonadotropin secreted by the implanted embryo maintains corpus luteum , so it continues to secrete progesterone and estrogens
In the uterus, endometrium development continues in preparation for implantation by the zygote |
vasectomy | tube is cut therefore no sperm in semen |
-tubal ligation | fallopian tubes are cut therefore no egg to fertilize by the sperm |
Fertilization | Union of the genetic material from a haploid sperm and haploid secondary oocyte
Male and female pronuclei form a single nucleus
Typically occurs in uterine tube 12 to 24 hours after ovulation
Sperm use flagella to swim from vagina through cer |
Capacitation | changes that prepare for penetration of corona radiata to zona pellucida |
Acrosomal reaction | release of acrosomal enzymes to digest path through zona pellucida |
Polyspermy block | fast and slow reactions prevent another sperm penetration |
Fertilization | Sperm entering oocyte triggers completion of meiosis II by oocyte, producing second polar body and diploid zygote
secondary oocyte---penetrated by sperm and meiosis 2 occurs-----oocyte----pronucleus from sperm plus oocyte unite---zygote |
Dizygotic (fraternal) | if two secondary oocytes released and fertilized by two sperm |
Monozygotic (identical) | if single fertilized ovum separates into two embryos
can share placenta or have their own (both have different complications) |
Conjoined twins | if developing ovum forms two embryos, but cells do not separate within 8 days |
Embryo | from fertilization to 8th week of development
-teratogens can cross the placenta
-substance that can development of the embryo/fetus
-most damaging in embryonic stage-rapid cell division and establishment of organ systems
-alcohol, viruses, X-rays |
Cleavage (embryo) | rapid cell division of zygote, producing blastomeres |
Morula (embryo) | solid sphere of cells |
Blastocyst (embryo) | hollow ball of differentiated cells
Embryoblast – develops into embryo
Trophoblast – becomes placenta and other support structures |
Implantation | Blastocyst attaches to the endometrium
Endometrium becomes decidua basalis and later becomes the maternal part of placenta |
Embryonic Period - Placenta is site of exchange between mother and fetus | Fetal portion formed by chorionic villi
Maternal portion formed by endometrium
Functions for O2/CO2 exchange, protective barrier, stores nutrients, produces several hormones to maintain pregnancy
Detaches and becomes the “afterbirth” after delivery |
Embryonic Period - Umbilical cord connects placenta to embryo/fetus | Forms from extraembryonic mesoderm surrounded by amnion
Consists of two umbilical arteries (oxygen-poor blood) and one umbilical vein (oxygen-rich blood)
Scar after delivery becomes umbilicus (navel) |
Embryonic Period - Third to ninth week of embryonic development | Three primary germ layers differentiate from the embryonic disc
All major organs appear during fourth through eighth weeks of development
All major body systems have begun development by end of eighth week, although most functions are minimal
Fetal p |
Ectoderm | gives rise to nervous system and epidermis |
Mesoderm | gives rise to connective tissues and muscles |
Endoderm | gives rise to gastrointestinal tract, urinary bladder and urethra, and respiratory tract |
Hormones of Pregnancy - Human chorionic gonadotropin | Secreted by chorion to maintain corpus luteum until about 4th month, when placenta produces enough progesterone and estrogens |
Hormones of Pregnancy - Progesterone and estrogens | Secreted initially by corpus luteum, then chorion, and later placenta
High estrogen level prepares myometrium for labor; progesterone ensures myometrium is relaxed and cervix tightly closed |
Hormones of Pregnancy - Relaxin | Secreted initially by corpus luteum, and later by placenta
Increases the flexibility of pelvic ligaments and helps dilate cervix for delivery |
Hormones of Pregnancy - Human chorionic somatomammotropin | Secreted by chorion
Prepares the mammary glands for lactation, increases protein synthesis for maternal growth, and influences maternal and fetal metabolism |
Hormones of Pregnancy - Corticotropin-releasing hormone | Secreted by the placenta
Establishes timing of birth
Increases secretion of cortisol, which is needed for maturation of fetal lungs and production of surfactant (surfactant is sufficient for about 35 weeks -gestation- it prevents the lungs from collapsi |
Changes During Pregnancy | Maternal abdominal organs get pushed superiorly against the diaphragm, while the ureters and urinary bladder are compressed
Maternal weight gain, breast enlargement, and lower back pain resulting from lordosis (swayback)
Metabolic changes to meet fetal |
Labor | Process by which fetus is expelled from the uterus through the vagina
Controlled by complex interactions of several hormones
Rising levels of estrogens stimulate release of prostaglandins by placenta,
which cause softening of the cervix |
True labor | Uterine contractions at regular intervals and dilation of cervix, expulsion of fetus, and delivery of placenta |
False labor | Involves pain at irregular intervals that does not intensify |
Lactation | Secretion and ejection of milk from mammary glands |
Prolactin | Secreted by anterior pituitary gland
Promote milk synthesis and secretion
Inhibited by progesterone until maternal levels drop after delivery
Suckling of baby stimulates stretch receptors, initiating nerve impulses from hypothalamus |
Oxytocin | Secreted by posterior pituitary gland
Promotes milk ejection reflex and contraction of myoepithelial cells
Suckling of baby stimulates stretch receptors, initiating nerve impulses from hypothalamus |
benefits of vaginal birth | -promotes removal of fluid from baby
-contractions help uterus shrink after delivery
-helps with let down of milk |
Benefits of Breastfeeding | Colostrum
-Produced first few days after birth
-Not as nutritious as true milk, but contains important antibodies to
protect infant
Ideal nutrition for infant
Beneficial cells and molecules
Decreased incidence of disea |