embryology quiz 1

subdivisions of embryology

descriptive

comparative

experimental

descriptive embryology

study of the mechanisms of development

comparative embryology

study that compares the development of one species to that of another species

experimental embryology

- study of external factors on development

- only area of embryology with active research

embryon

something that swells in the body

prenatal period

- before birth

- embryonic and fetal periods

embryonic period

0-8 weeks (most during weeks 3-8)

fetal period

8 weeks to birth

postnatal period

- after birth

- infancy, childhood, puberty, adolescence, adulthood

infancy

- 0-1 year

- first 4 weeks = neonatal period

childhood

1-13 years

puberty

girls: 12-15 years

boys: 13-16 years

adolescence

- 12-17 years

- ability to reproduce

adulthood

18-death

ventral

toward the belly

dorsal

toward the back

cranial

toward the head

caudal

toward the tail

rostral

toward the nose

median (midsagittal) plane

equal right and left halves

sagittal plane

right and left sections

transverse plane (cross section)

top and bottom sections

frontal (coronal) plane

- front and back sections

- frontal = body, coronal = head

oblique plane

any section that is not cut on the three main planes of the body

male reproductive system

- produce and deliver male gametes, sperm cells

- external system

- made up of testis, epididymis, ductus deferens, ejaculatory duct, urethra

testis

- primary sex organ

- where sperm cells are developed and where testosterone is produced

- located in scrotum

- contains inactive sperm cells

primary sex organ

where sex cells are produced

where hormones are produced

epididymis

- primary site of storage and activation of sperm cells

- sperm cells can spend up to 3 weeks here

- located in superior posterior aspect of scrotum

- made up of head, body, and tail

cremaster muscle

elevates or suspends testes to control temp

ductus (vas) deferens

- muscular tube that transports the sperm cells from the epididymis to the ejaculatory duct

- passes from epididymis through spermatic cord, through the inguinal canal and to the posterior aspect of the urinary bladder, then joins with duct of seminal vesicle to form the ejaculatory duct

ejaculatory duct

- short duct that forms the union of the ductus deferens and the duct of the seminal vesicle

- passes through the prostate gland to empty into the prostatic urethra

seminal vesicles

- secretory glands that add an alkaline fluid to the seminal fluid

- located on the posterior aspect of the urinary bladder

male urethra

prostatic urethra

membranous urethra

penile urethra

prostatic urethra

passes through the prostate gland and represents the union of the reproductive and urinary systems

membranous urethra

passes through the pelvic diaphragm

penile urethra

passes through the penis

prostate gland

- adds fructose sugar to the seminal fluid

- located at the base of the urinary bladder

- part of the urethra and ejaculatory duct run through it

bulbourethral gland

- small gland at base of penis

- secretes lubricating fluid, which passes through penile urethra

mitosis

- produces two daughter cells identical to the parent cells

- everyday cell division

- 2n cell divides into two 2n cells

meiosis

- produces cells with 1/2 of genetic material of the - parents

- 2n cell divides into two 1n cells

- how sperm and egg cells are made

- only occurs in testis and ovary

diploid cell

- 2n

- 46 chromosomes, 23 pairs

haploid cell

- 1n

- 23 chromosomes

- only sperm and egg cells in humans

spermatogenesis

formation of sperm cells

seminiferous tubules

small convoluted tubules in the testes where spermatogenesis takes place

spermiogenesis phases

golgi phase

acrosomal phase

maturation phase

golgi phase of spermiogenesis

golgi body forms acrosomal vesicle and centrioles migrate toward nucleus

acrosomal stage of spermiogenesis

acrosomal vesicle grows to cover anterior half of nucleus, nucleus condenses and mitochondria aggregate around the forming flagella

maturation phase of spermiogenesis

residual cytoplasm is lost and sperm cell is released into lumen of tubule

leydig cells

- makes and secretes testosterone

- found outside seminiferous tubules, next to capillaries

- directly affected by LH

- diploid

spermatagonia cells

- diploid cells, 23 pairs (46) chromosomes

- found in periphery of each tubule

- can either undergo mitosis and form more cells or enter into the development of mature sperm cells (primary spermatocytes)

primary spermatocyte

- diploid cell in the testis that undergoes meiosis I to form two secondary spermatocytes

- dark staining nucleus

- located more towards lumen in tubules

secondary spermatocytes

- haploid cells resulting from the first meiotic division of spermatogenesis from primary spermatocytes

- undergo meiosis II to form 4 spermatids

- under influence of FSH

- round shaped cell

spermatids

- 23 chromosomes

- products of meiotic division from secondary spermatocyte

- haploid

spermiogenesis

transformation of spermatids to mature sperm

sertoli cells (sustentacular cells)

- storage, scavenging, protection

- diploid

hypothalamus

secretes releasing factors (RF) to the anterior pituitary for FSH and LH

follicle stimulating hormone (FSH)

stimulates the seminferous tubules to produce sperm cells

luteinizing hormone (LH)

- stimulates interstitial cells of Leydig cells to produce testosterone

- causes follicle cells to transform into luteal cells

inhibin

- inhibitory effect on anterior pituitary and hypothalamus

- secreted in the testis

testosterone

- has an inhibitory effect on anterior pituitary and hypothalamus, creating a negative feedback loop

- secreted by leydig cells in the testes

female reproductive system

- implantation of the embryo and fetus

- internal system

- made up of the ovary, uterine tubes, uterus, and vagina

ovaries

- primary sex organ in females

- where egg cells are stored and developed, also where estrogen and progesterone are produced

- located on either side of the uterus, inferior and posterior to uterine tubes

uterine tubes

- provides a passageway from the ovary to the uterus for the egg cell and is the site of fertilization

- extend from the lateral surface of the uterus and cover the superior aspect of the ovary

- muscular tubes that can be divided into an isthmus, ampulla, and infundibulum

uterus

- site of implantation and where the embryo/fetus develops

- muscular organ in female pelvis

- divided into the cervix, isthmus, body, and fundus

vagina

muscular tube that serves as the site of introduction of sperm into the female reproductive system and as the birth canal

fornix

- site of union of the vagina and uterus

- found in vagina

isthmus

- narrowed (long) region between the body and cervix

- attaches directly to the uterus

ampulla

site of fertilization (most common)

infundibulum

funnel-shaped opening that is the distal end of each uterine tube

fimbria

- finger-like projection at the free end of the uterine tube

- attached to infundibulum

fundus

any part of the uterus that is above the uterine tubes

uterus wall

endometrium

myometrium

perimetrium

endometrium

- inner layer

- undergoes the monthly cycle

- where the baby develops

- made up of 3 layers

myometrium

middle layer

smooth muscle

perimetrium

outer layer of connective tissue

cervix

opening of the uterus into the vagina

endometrium layers

basal layer

spongy layer

compact layer

basal layer of endometrium

- nonfunctional outer layer

- helps regenerate functional layer

- straight arteries

spongy layer of endometrium

- functional layer

- bodies of glands

compact layer of endometrium

- functional layer

- epithelia

- opening

uterine cycle

approximately 28 days (23-35)

menstrual phase

proliferative phase

secretory phase

ischemic phase

menstrual phase of the uterine cycle

- days 1-5

- estrogen and progesterone at lowest

- spongy and compact layers lost

proliferative phase of the uterine cycle

- days 6-14

- estrogen increases

- functional layer rebuilt

secretory phase of the uterine cycle

- days 15-27

- progesterone increases

- glands begin to function

- implantation occurs on day 21

ischemic phase of the uterine cycle

- day 28

- estrogen and progesterone drop quickly

- smooth muscle walls spasm

- menstrual flow begins due to spasm

- spiral artery affected

egg nest

- where eggs are stored in the ovary

- made up of egg cells and one layer of follicle cells

thecal cells

make and secrete estrogen

antrum

- fluid-filled cavity that appears in a secondary follicle (6)

- formation of one marks the development of a mature follicle

zona pellucida

- a thick, transparent coating rich in glycoproteins that surrounds an oocyte

- protects the egg cell

ovarian cycle

- (under FSH) 12 egg nests per month develop into primary follicles

- antrum forms in 6 follicles (secondary follicles)

- one of 6 forms into a mature follicle

- (day 14 - ovulation) mature follicle ruptures and egg cells + corona radiata released

- (under LH) remaining cells in follicle swell, small blood clot formed (corpus hemorrhagicans)

- follicles swell and secrete progesterone (corpus luteum)

- if pregnancy occurs, corpus luteum remains for 3 months, if not it degenerates into corpus albicans

luteal cells

- makes and secretes progesterone

- swollen follicle cells

corpus luteum

- empty ovarian follicle that secretes progesterone after release of the egg cell

- forms under the influence of LH

- remains for 3 months if pregnancy, degenerates into corpus albicans

corpus albicans

- the scar tissue that replaces the corpus luteum

- caused by the drop of LH levels in the blood at the end of the 28 day-cycle

- as soon as progesterone production ends, the corpus luteum begins to degenerate and is replaced by this

primary follicle

- an immature ovum enclosed by a single layer of cells

- 12 egg nests per month develop

- under the control of FSH

secondary follicle

- under the control of FSH

- fluid filled antrum forms in 6 follicles

- one forms into a mature follicle

corona radiata

- outer layer of cells surrounding the oocyte

- secreted by follicle cells.

ovulation

day 14

anterior pituitary gland

- under the influence of RFs from hypothalamus, releases FSH, which causes the development of follicles in the ovary, which in turn causes the release of estrogen

- progesterone and estrogen feed back here and hypothalamus to form negative feedback loops

midpiece

where is the mitochondria located in mature sperm?

diploid (2n) cell examples

spermatogonium

sertoli cells

leydic cells

primary spermatocyte