Embryology

sexual reproduction

sexual reproduction

union of female gamete with male gamete in fertilization process = zygote

sexual reproduction requires ___________

sexual differentiation

sexual differentiation is achieved through

gynogenesis, androgenesis

gametogenesis

cycle including division process (mitosis + meiosis) of formation of gametes (male + female sex cells) which thru their union will form egg/zygote

mitosis

division of cell into identical daughter cells

meiosis

maturation divisions, specific to gametes (in gametogenesis)

primary gametocyte

cell that begins meiosis

2 processes of meiosis

• 1 - reduction, chromosomes in half

• 2 - equational, cell halves without changing # chromosomes

reproductive sequence stages

ovulation, erection, copulation, ejaculation, insemination/fertilization

ovulation

process by which female gamete released from ovary, specifically release of secondary oocyte arrested in metaphase II

copulation

insertion of penis into vagina

stages of ejaculation

emission (contraction of genital tract smooth m, semen into prostatic urethra), proper ejaculation (spasmodic contraction of striated m of bulbospongiosus m)

insemination

placing the sperm in contact w/ egg, in vitro

male reproductive cycle takes place in

testicles

ontogenetic development of testis

infantile, prepubertal, pubertal, mature, involution

phase of active period of libido where testicles are capable of reproduction

mature phase

__________ is a long stage where the # of male gametes continuously decreases w/o specifying this activity stops

involution phase

the testicles through active period produce male gametes through ___________

spermatogenesis

sperm cell

haploid, flagellated, heterogamete

parts of the sperm cell

head (w/ nucleus + acrosome), neck, tail, flagellum (mobile part)

to be capable of fertilization, sperm must undergo what process

capacitation

capacitation

occurs naturally in female tract, lasts 7hrs → changes in glycoprotein membrane that covers acrosome → acrosomal rxn occurs to be able to fertilize

what does sperm contain

alkalaline ph, products of vesicular gland, prostate + bulbourethral glands

____________ <20m sperm cells is a cause of male infertility

oligospermia

fertilization before sperm penetration

last process of gametogenesis, sperm near ovum passes through shell along sperm track

sperm track consists of

coronal penetration track + sperm-zona contact

acrosomal rxn

release of acrosome of enzyme that helps it penetrate the transparent zone

_______________ crosses ovum’s last covering (subzonal or subcapsular space)

pellucidal penetration track

ovarian phases of ovary

infantile, prepubertal, pubertal, mature (active period), involution

the primary reproductive cycle is the ______________ cycle

ovarian

types of female reproductive cycle

ovarian, endometrial menstrual, vaginal, mammary gland

ovarian cycle

transformations that the ovarian cortex undergoes in the growth + dev of follicles, ovulation, involution of corpus luteum (luteogenesis)

diff bw ovarian cycle + oogenesis

both have tied transformations but oogenesis is with folliculogenesis

when does anovulatory ovarian cycle occur

within first yr of cycle

follicular phase

dev of ovarian follicles and selection of mature follicle, for 14d, ends w/ ovulation

luteal phase

postovulatory transformation of mature follicle → corpus luteum, for 14d

the corpus luteum phase ends with what phase

involution phase - fibrous degenerative transformations of corpus luteum w/ formation of scar at ovarian cortex

regular days of cycles

21-35d

folliculogenesis

linked to oogenesis, development of primordial follicles in ovarian cortex up to mature follicle stage (but not all follicles)

primordial ovarian follicle

small + round w/ primary oocyte surrounded by simple squamous epithelium formed by primordial follicular epithelial cell

secondary ovarian follicle

contains primary oocyte but with 2 more shells (follicular theca, then follicular BM), surrounded by transparent capsule + stratified cuboidal epithelium

primary ovarian follicle

round shape, includes primary oocyte surrounded by simple cuboidal epithelium, surrounded by zona pellucida

tertiary ovarian follicle

vesicular/antral, oval shape, contains primary oocyte surrounded by pellucid capsule, granulosa +follicle sheaths; oocyte located eccentrically opposite to follicular antrum (w/ fluid)

2 sheaths of tertiary follicle

theca interna (thecal endocrine cells) + theca externa (thecal fibroblasts)

mature ovarian follicle (de graaf, preovulatory)

resembles cyst, primary → secondary oocyte, surrounded by theca interna, granulosa, follicular antrum w/ fluid

follicular stigma

appearance of protrusion of mature follicle approaching surface of ovary

how does ovum detach in ovulation

after follicular stigma, albuginea thins + becomes avascular, ovum detaches from granular layer thru spaces in cumulus oophorus

endometrial menstrual cycle phases

ovulatory, secretory/luteal, ischemic

ovulatory phase of endometrial menstrual cycle

corresponds to ovulation, cervical plug mucus is clearer + alkaline

secretory/luteal phase of endometrial menstrual cycle

begins immediately after ovulation for 13d, corresponding to luteogenesis (of ovary), corpus luteum secretes progesterone → endometrium affected

effects of progesterone on endometrium in secretory/luteal phase of endometrial menstrual cycle

thickens, glands more branched, blood supply increased, arteries spiral, myometrium contractility decreases

ischemic phase of endometrial menstrual cycle

last phase of menstrual cycle, for 24h, blood vasodilation then constriction + endometrial ischemia, layers separate

period before appearance of first menstruation

primary amenorrhea

menarche

first menstruation

most common cause of secondary amenorrhea

pregnancy

postmenstrual phase

phase of endometrium after cessation of menstruation

climacteric peroid

period when woman doesn’t have menstrual cycle → menopause

pregnancy includes the period of intrauterine development of the concept, in which the human species is _______ days from first day of last menstruation

280

nulligravida

a woman who hasn’t been pregnant

primigravida

woman who’s in her first pregnancy

multigravida

woman who has been pregnant several times

birth order number (parity)

nullipara (no children), primipara, multipara

locations of uterine pregnancy

cornual, fundal, uterine body, cervical

gestational cycle includes 2 periods (from pov of localization of conceptus)

tubal period (zygote formed and migrates to uterus), uterine period (main stage)

gastrulation

moment of transformation of embryonic disc into embryo (critical moment teratologically)

phases of evolution of concept within gestational cycle

pregastrulation phase - preimplantation and implantation

pregastrulation phase

from conception until days 17-18

phases of pregastrulation

preimplantation phase (zygote free in fallopian tube + uterus before implantation), implantation phase

labour is classified into

premature, mature, postmature

birth is classified into

premature (<37), full term (40w), postmature (>40w),

puerperium

6 week post birth period

fertilization age is from the initial moment of fertilization and is calculated in

coital weeks

in clinical language, the term gestational weeks is used and a term’s concept age is

38 weeks

ovulation age

calculate from moment of ovulation (1 day before fertilization)

insemination age

initial moment of pregnancy, moment of contact of oocyte w/ sperm in vitro

most frequently used unit of measurement in medical practice

menstrual weeks (after first day of last normal menstruation)

term concept’s age according to different measurements

fertilization (embryological) - 38w, menstrual (medical) - 40w

crown-rump length CRL

sitting height, most used measurement in first trimester

crown-heel length CHL

standing height, corresponds to greatest length

diameter of umbilical vesicle or yolk sac is a measurement for which month of pregnancy

second month

ultrasound measured values of diameter of umbilical vesicle or yolk sac

yolk sac is 3mm but 6w, max value of 6mm at 8w, yolk sac disappears at 10w

ultrasound measurements of 2nd and 3rd trimesters of pregnancy that establish body weight

biparietal diameter (BPD), head circumference (HC), abd circumference (AC), length of ossified femur (FL)

when is foot length used in embryonic measurements

to highlight symmetry anomalies

infertility

absence of pregnancy after 12m of unprotected sexual activity in <30y.o couples

male sterility may or may not be associated w/

impotence

prenatal death

death of fetus in womb, at any gestational age

abortion vs stillbirth

abortion is expulsion of dead fetus <24w, stillborn is expulsion of dead fetus >24w

resorption

disappearance by resorption of concept without it being eliminated

retention

retention of concept stopped in evolution, must be resorbed or evacuated

zygote

single cell formed when egg and sperm cell fuse by fertilization

cleavage

rapid cell division in the first 12-24h after a zygote is formed

32 cell stage during cleavage of zygote is called

morula

what limits the growth of zygote in morula stage

zona pellucida

steps of embryogenesis

1. zygote formation by fertilization

2. cleavage

3. blastulation

4. cells differentiate + cavitate

5. gastrulation (primitive streak + notochord formed)

6. neurula formation (neural plate → tube + crest formed)

7. mesoderm division

what happens during blastulation

mass of cells form hollow ball

two layers developed around day 4 in embryogenesis

trophoblast and inner cell mass (pushed to one side by the trophoblast)

blastocoel

fluid-filled cavity made in 4th day of embryogenesis, w/ trophoblast + inner cell mass

blastocyst

formation around day 4 from blastocoel → this by disappearance of zona pellucida + differentiation of inner cell mass

cells differentiate into what during the second week of embryogenesis?

hypoblast (facing blastocoel) + epiblast(on other side) = 2 layers of the bilaminar disc