Module 1: Development of the Human Reproductive System Flashcards
Basic components of the reproductive system
-gametes
-gonads
-reproductive ducts
-external sex organs
Haploid cells
-after gametogenesis resulting haploid will only contain one sex chromosome
The SRY gene
-presence of this gene will determine the process of gonadal differentiation
-found on the y chromosome
SRY in males
-present
-activates genes present required for development of testes at week 7
SRY in females
-not present
-different genes are expressed that lead to development of oogonia and ovaries
Intersex disorders
-cause physiological variations in sexual characteristics that do not fit the typical definition of female or male
Turner syndrome
-condition in which female is partially or completely missing one of her X chromosomes
-causes non-functioning ovaries, heart defects, hormonal imbalances and impaired skeletal development
Sex linked disorders
-caused by genetic abnormalities inherited through sec chromosomes only
-do not necessarily affect sexual characteristics of individual
Example of sex linked disorders
-color blindness
Early blastocyst
-inner layer is embryoblast
-outer layer is trophoblast
Late blastocyst
-embryoblast differentiates into epiblast and hypoblast
Gastrulation
-the embryo differentiates into 3 germ layers
3 germ layers of trilaminar disc
-ectoderm
-mesoderm
endoderm
What layer forms the reproductive system
-mesoderm
What weeks does embryonic folding take place
-weeks 3 and 4
Gonadal ridge appearance weeks
-4
Primordial germ cells
-earliest cells associated with emergence of gonads
Primary sex cords
-finger like tissue projections formed from gonadal rudges
When do primary sex cords begin to form primitive testes
-weeks 7-8
Testosterone
-directs the development of male reproductive ducts
DHT
-synthesized from testosterone and will direct the development of external male genitalia
When does descent of the testes begin
-month 3
When does gubernaculum develop
-week 7
Gubernaculum function
-between week 7-12 it shortens to pull testes towards future location in labioscrotal swelling
Female gonad development
-in absence of SRY the primary sex cords degenerate and cortical sex cords begin to develop
-cortical cords eventually form ovarian follicles
What does gubernaculum go on to form in women
-round ligament of uterus
Migration abnormalities
-inguinal hernias
-undescended testes
-cryptorchidism
Why are males more prone to inguinal hernias than females
-when testes descend they create a gap in abdominal muscle after birth
Cryptorchidism
-occurs when one or both testes fail to complete their migration toward the scrotum
How do the male and female ducts develop
-wolffian ducts
-mullerian ducts
Where do wolffian and mullerian ducts originate
-intermediate mesoderm
Mullerian duct regression in males
-testosterone and AMH cause them to regress by week 8
What do wolffian ducts form in males
-ejaculatory ducts
-seminal vesicles
-vas deferens
-epididymis
Wolffian duct regression in females
-regress by week 10 of development
What do mullerian ducts form in females
-fallopian tubes
-uterus
-upper portion of vagina
External genitalia development males
-cloacal folds form by week 5
-cloacal folds differentiate into urogenital and anal folds by week 7
-exposure to DHT results in growth of genital tubercle and genital swellings by week 10
-genital tubercle continues to grow to form phallus, and urogenital folds fuse to form scrotum
External genitalia development females
-cloacal folds form by week 5
-cloacal folds differentiate into urogenital and anal folds by week 7
-minimal growth of genital tubercle and swellings by week 10
-genital tubercle develops into clitoris, urogenital folds do not fuse and give rise to labia majora and minora
Disorders of sex development
-xx male syndrome
-5-alpha-reductase deficiency
-androgen insensitivity syndrome
XX male syndrome
-genetic females with 2 x chromosomes that develop male reproductive structures
5-alpha-reductase deficiency
-genetic males with abnormal development of external sex organs
Androgen insensitivity syndrome
-genetic males with x-linked recessive mutation leading to insensitivity to androgens
Penile tissues
-2 corpora cavernosa
-1 corpus spongiosum
Corpora cavernosa
-lie next to eachother on dorsal side
Corpus spongiosum
-lies between corpora cavernosa on ventral side
Tunica albuginea of the penis
-tough layer of connective tissue
Glans of penis
-bulbous end of penis formed by corpus spongiosum and supports foreskin
Penile fracture
-no bone but can still break
-involves rupture of the tunica albuginea
The scrotum
-dual-chambered suspended sac of skin and smooth muscle that contains the testes
Layers of the scrotal sac
-scrotal skin
-daros fascia and muscle
-external spermatic fascia
-cremaster muscle
-internal spermatic fascia
-tunica vaginalis
-tunica albuginea
Scrotal skin
-outer layer of penis
Dartos fascia and muscle
-layer of fascia and smooth muscle that carries blood supply from skin
-helps regulate temp
External spermatic fascia
-thin layer of fascia
Cremaster muscle
-layer of smooth muscle that carries blood and nerve supply to the testes and is responsible for cremasteric reflex of scrotum
Internal spermatic fascia
-thin layer of fascia
Tunica vaginalis
-serous layer that covers testis and continous with surface of testis and internal surface of scrotum
Tunica albuginea
-innermost layer covering the testes
Seminiferous tubules function
-site of spermatogenesis
Cells of the seminiferous tubules
-spermatogonial cells
-sertoli cells
-leydig cells
Spermatogonia cells
-cells that become mature sperm
Sertoli cells
-facilitate process of sperm maturation
Leydig cells
-in between seminiferous tubules produce and secrete testosterone
Male genital ducts
-seminiferous tubules
-rete testis
-efferent ducts
-epididymis
-vas deferens
Seminiferous tubules types
-convoluted (lateral side)
-straight (medial side)
Rete testis
-network of tubes where sperm are mixed and some fluid are reabsorbed
-exits into efferent ducts
Efferent ducts
-sperm are further concentrated via reabsorption of fluids
-connect with initial section of epididymis
Epididymis
-where sperm mature
Vas deferens
-move here after epididymis to be transported to ejaculatory ducts
-empty into urethra for expulsion
Vasectomy
-procedure where vas deferens are permanently cut
Genital (accessory) glands
-seminal vesicles
-prostate gland
-bulbourethral glands
Seminal vesicles
-produce molecules such as fructose and serve as energy sources for sperm
Prostate gland
-additional fluid for nourishment and sperm motility
Bulbourethral glands
-produces fluid that lubricates urethra and nuetralizes acidity associated with residual urine
Suspensory ligaments
-tether the ovaries to the body wall
Structures of the ovaries
-germinal epithelium
-tunica albuginea
-ovarian cortex
-ovarian medulla
Germinal epithelium of ovary
-outermost layer
Tunica albuginea of ovary
-fibrous layer of connective tissue that protects inner structures
Ovarian cortex
-contains supporting connective tissue and ovarian follicles
-site of oocyte production
Ovarian medulla
-vascular tissue that supports ovary
Ovarian hormones
-estrogen
-progesterone
Estrogen
-responsible for appearance of secondary sex characteristics in females
Progesterone
-functions with estrogen by promoting menstrual cycle changes in uterus and by helping sustain pregnancy
Layers of the uterus
-endometrium
-myometrium
-perimetrium
Endometrium
-inner layer
-responsible for implantation of embryo
-and for changes seen during menstrual cycle
Myometrium
-middle layer
-provides support during distension caused by pregnancy and facilitates contractions
Perimetrium
-outer layer
Uterine fibroids
-benign growths within myometrium
-growth is stimulated by estrogen so usually regress after menopause
Uterine fibroids symptoms
-abdominal pain
-excessive bleeding
-tissue necrosis
Parts of the fallopian tubes
-infundibulum
-ampulla
-isthmus
Infundibulum
-associated with fimbrae near ovary
Ampulla of fallopian tube
-major portion of lateral tube where fertilization takes place
Isthmus of fallopian tube
-narrower part of tube that links to uterus
Epithelium of fallopian tubes
-ciliated cells
-peg cells
Ciliated cells
-predominate throughout tube
-estrogen increases production of cilia on these cells
Peg cells
-interspersed between ciliated cells
-produce tubular fluid that contains nutrients for spermatozoa, oocytes and zygotes
2 primary functions of the vagina
-sex
-childbirth
Parts of the vulva
-mons pubis
-labia
-urinary orifice
-clitoris
-vaginal orifice
Mons pubis
-pubic region directly in front of pubic bone
Labia
-majora and minora
-folds of skin that cover and protect delicate structures
Urinary orifice
-external opening of urethra
Clitoris
-structurally homologous to penis
-highly innervated
Vaginal orifice
-external opening to vagina
Additional vaginal glands
-bartholins glands
-skenes glands
Bartholins glands
-pair of secretory glands located to the left and right of vaginal opening which secrete mucus for lubrication
-homologous to bulbourethral glands
Skenes glands
-pair of secretory glands which open to the left and right side of urethral orifice
-during arousal they secrete fluid
Mammary glands
-organ in female mammals that produce milk
Lobules of breast
-15-20 in each breast
-each of which contain alveolar glands and a lactiferous duct
