embryology exam 1

embryology

the study of early development in its broad sense, includes development through birth

prenatal

before birth

perinatal

around the time of birth; 3rd trimester - 1st month of life

trimester

a period of 3 months of development

gestation

divided into the first, second, and third trimester

fertilization and implantation period

0-2 weeks in utero

embryoic period

3-8 weeks in utero
when term embryo is first used
the period of greatest sensitivity to teratogenesis

fetal period

9-38 weeks in utero

infancy period

birth - 1 year

childhood period

1 year to puberty (10-13 years)
occurs earlier in females than males

adolescence period

puberty to adulthood (14-17 years)

adulthood period

between 18-21 years

what is an infant called for the first month after birth?

neonate

how long does a normal pregnancy last?

38 weeks after fertilization

neonatology

pediatric specialty involving disorder of neonates

teratogen

a drug or agent which can cause abnormal development
example: accutane retinoid for acne, metformin for diabetes

anatomical position

standing in erect position with head, eyes, and toes facing forward, heels and toes together, arms hanging at sides with palms facing forward

embryological term for superior

cranial or rostral

embryological term for inferior

caudal

embryological term for anterior

ventral

embryological term for posterior

dorsal

zygote

means yolked together / "paired"

mitosis is a __ cell division resulting in cells with a full _ __ in humans. these cells are known as __ __

single; 46 chromosomes; diploid cells

meiosis or _ _ division involves _ cell divisions and results in _ the typical amount of __ __ in humans. these cells are known as __ __

germ cell; 2; half; 23 chromosomes; haploid cells

prior to DNA synthesis chromosomes consist of a ___ or __

single strand; chromatid

all cells in the body except __ __ duplicate through __.

germ cells; mitosis

crossover

the interchange of chromatid segments between homologous chromosomes during the first meiotic division. occurs through chiasma

nondisjunction

failure of a pair of chromosomes to split during meiosis
- both chromosomes go to 1 daughter cell resulting in trisomies and monosomies

trisomy

a daughter cell with 3 chromosomes instead of 2
Turner's syndrome

monosomy

a daughter cell with only 1 chromosome instead of 2
Down's syndrome

spermatogenesis

a symmetrical process by which mature cells are produced

spermatogonia

diploid cells, dormant in seminiferous tubules, transformed into primary spermatocytes

primary spermatocytes

diploid cells that undergo 1st meiotic division
each forms 2 haploid secondary spermatocytes

secondary spermatocytes

undergo 2nd meiotic division to form 2 haploid spermatids

spermatids

transform gradually into mature sperm through spermiogenesis

mature sperm are made of

head, neck, tail, acrosome

acrosome

contain enzymes that allow sperm to penetrate the oocyte during fertilization

oogenesis

an asymmetrical process in which mature oocytes are formed
begins before birth, ends at fertilization

oogonia

diploid cells that enlarge to form primary oocytes before birth

primary oocytes

diploid cells, begin 1st meiotic division before birth but doesn't complete puberty, then completes each month just before ovulation
develops ovarian follicle
give rise to secondary oocyte and 1st polar body

ovulation

the release of a oocyte from its ovarian follicle
occurs once a month
primary oocyte completes first meiotic division just before

secondary oocytes

haploid cell, receives almost all cytoplasm
begins 2nd meiotic division at ovulation, stalls here waiting for sperm to penetrate to be completed
gives rise to fertilized (mature) oocyte and 2nd polar body

first polar body

small and non-functional, degenerates

fertilized (mature) oocyte

haploid cell, receives almost all cytoplasm

2nd polar body

small and non-functional, degenerates

zona pellucida

internal, amorphous, acellular layer

corona radiata

external, follicular cells

the female reproductive organs include the

ovary, uterine tube, uterus, vagina

ovary

paired organs that produce oocytes after puberty
have endocrine function
secrete: estrogen, progesterone, relaxin
located on lateral wall of true pelvis

uterine tubes

transport oocytes from ovary to uterus through ciliary action and muscular contractions
passing an oocyte takes 3-4 days
subdivided into 4 parts

4 parts of the uterine tube

infundibulum
ampulla
isthmus
uterine part

infundibulum

funnel-shaped portion nearest the ovary
letter C on diagram

ampulla

longest and widest part of the uterine tube
letter B on diagram

isthmus

narrowest external part nearest uterus
letter A on diagram

uterine part

portion of the tube which lies inside the uterus

abdominal ostium

the opening of the uterine tube near the ovary
shown in green on diagram

What connects the Abdominal Ostium and Ovary?

Nothing! There is a gap there because they're not connected

where does fertilization take place?

in the uterine tube, most commonly the ampulla
2nd most common in infundibulum (ectopic pregnancies)

fimbriae

finger-like projections around the margin of the infundibulum
catches oocytes discharged from ovary and passes it through the abdominal ostium
letter D on diagram

the cavities of the uterus and vagina together form what?

the birth canal

uterus

the organ in which the fertilized oocyte normally becomes embedded and where fetal development takes place
variable in shape, size, location and structure depending on age, and pregnancies

how will the uterus of a young female who's never been pregnant differ from one of an older female who's had several pregnancies?

the young nulliparous female's uterus will have thick and muscular walls and be in the shape of a pear.

parts of the uterus

fundus of uterus
body of uterus
isthmus of uterus
cervix of uterus
external os

fundus of uterus

rounded part of uterus located superior to the entrance of the uterine tubes
letter A on diagram

body of uterus

main part of the uterus located inferior to the fundus and superior to the isthmus
letter b on diagram

isthmus of uterus

narrow constricted portion between the body and cervix
also called internal os
letter c on diagram

cervix of uterus

the inferior part of uterus that extends from the isthmus to the opening in the vagina
letter C on diagram

external os

the opening of the cervical canal into the vagina

how many layers of the uterus are there?

3
perimetrium, myometrium, and endometrium

Perimetrium

letter a
the thin outer peritoneal layer

myometrium

letter b
thick, smooth muscle layer

endometrium

letter c
thin inner mucosal layer made of functional and basilar layers

functional layer

superficial, sloughs off during menstruation

basilar layer

deep, its retained and regenerates functional layer

uterine cavity

lies within body of uterus, funnel shaped being wide above and narrow below

cervical canal

lies within the cervix and extends from the internal os (isthmus) to the external os

vagina

the lower portion of the birth canal
vaginal cavity communicates with cervical canal above through the external os and the vestibule below through vaginal orifice

when does the female reproductive cycle start?

at puberty around 10-13 years old

Gonadotropin Releasing Hormone GnRH

produced in the hypothalamus
passes to the anterior pituitary gland via hypophyseal portal system
stimulates the production of 2 hormones by anterior pituitary

follicle-stimulating hormone (FSH)

stimulates development of ovarian follicles and estrogen secretion by follicular cells

luteinizing hormone (LH)

initiates ovulation and secretion of progesterone by follicular cells and corpus luteum

what do fertility drugs do?

they increase the output of FSH and LH
this also raises the chances of having multiple births due to stimulating multiple hormones

ovarian cycle

is controlled by FSH and LH and includes
follicle development
ovulation
formation of corpus luteum
ceases permanently at menopause, between 48-55 years old

ovulation

release of a secondary oocyte from a mature follicle
triggered by a mid-cycle surge in LH

ovarian follicles are __ __ __ __ structures within the __. each follicle contains a __ __.

hollow, spherical connective tissue; developing oocyte

about how many primary follicles begin to enlarge every month?

5-12

primary follicle

a follicle that has begun to enlarge and contains at least 2 layers of cells

how many primary follicles will complete the maturation process?

only 1, the rest degenerate into atretic follicles

secondary follicle

follicular fluid accumulates among follicular cells and enlarges to form the antrum

mature follicle

the dominant follicle of the cycle which eventually bulges from the surface of the ovary
does not contain a mature oocyte

corpus luteum

developed from an empty mature follicle triggered by LH
secretes progesterone and estrogen to prepare endometrium for implantation

if fertilization does NOT occur, the corpus luteum ___

involutes 10-12 days after ovulation and becomes a corpus albicans (white body)

if fertilization does occur, the corpus luteum ___

enlarges and increases its output of progesterone and estrogen to become the corpus luteum of pregnancy

corpus luteum of pregnancy

is active through first 20 weeks of gestation until function is taken over by placenta
maintained by secretion of human chorionic gonadotropin by trophoblast cells of developing blastocyst

hormonal methods of contraception

birth control pills
intrauterine devices (IUDs)

how do IUDs work?

1- inhibiting ovulation (suppress LH and FSH secretion)
2- thickening of cervical mucus (prevents sperm from entering uterus)
copper: copper ions are toxic to sperm

menstrual cycle

cyclic series of changes undergone by the endometrium before, during, and after ovulation
usually 28 days in length
ceases with pregnancy, resumes 6-10 weeks after end of pregnancy
breastfeeding delays return of menstration

menstrual flow begins on what day?

day 1

phases of menstrual cycle

menstrual phase
proliferative phase
secretory (luteal) phase
ischemic phase

menstrual phase

4-5 days
the functional layer of the endometrium sloughs off and is excreted