Development

Question 1

Gestation Period

Answer 1

The time span from fertilization to birth ( 38 weeks )

Question 2

Prenatal period ( before birth )

Answer 2

Embryological development: developing human for the first 2 months after fertilization ( the embryo )
Fetal development: from 9 weeks until birth ( is not the fetus and not the embryo )
By the end of the 3rd month, the placenta is now functioning

Question 3

Events before fertilization

Answer 3

This all occurs in the uterine tubes within 24 hours after ovulation
Fertilization likely 2 days before to 1 day after ovulation
Oocyte travels towards the uterus through the uterine tubes and the movement of cilia
The sperm swim towards the oocyte by flagella
-uterine contractions help the sperm move towards the oocyte
Final maturation of the sperm occurs inside the female
-acrosomal membrane becomes fragile
Sperm spends 7 hours in the female reproductive tract before capable of fertilization
*sperm only survives 48 hours in female
*Oocyte viable 24 hours after ovulation

Question 4

Embryonic period

Answer 4

Extends from fertilization through the eighth week of development

Question 5

Fertilization

Answer 5

The merging of genetic information between a

Haploid sperm cell and a haploid secondary oocyte merging into a single diploid nucleus

Question 6

Fertilization of an egg

Answer 6

Sperm penetrates the corona radiata and the zona pellucida around the oocyte

Question 7

Acrosome enzymes

Answer 7

allows the sperm to penetrate the corona radiata

Question 8

Fertilization cycle

Day1-12

Answer 8

1. Zygote
   Day 1: Begins mitotic division, known as cleavage. First division takes about 6 hours
   Day 2: two days after fertilization, a second cleavage is completed, now 4 cells (blastomeres)
   Day 3: there are 16 cells. all small cells are blastomeres
   Day 4: the clusters are now a morula, still surrounded by the zona pellucida
   On day 4 or 5: Morula enters uterine cavity, nourished by the uterine milk.
   At the 32 cell stage , the fluid inside morula rearrange the blastomeres into blastocyst.
   Day 6 or 7: blastocyst implants to endometrium wall of uterus
   Day 8: trophoblast develops into syncytiotrophoblast and cytotrohoblast, becoming part of the chorion.
   The embryo blast develops two layers, cells of those structures form bilaminar embryonic disc.
   The amniotic cavity forms from the epiblast & fills with amniotic fluid
   Yolk sac is formed
   Day 9: lacunae form
   Day 12: yolk sac and lacunae form lacunar networks

Question 9

Blastocyst

Answer 9

Two cells populations:

Embryoblast and trophoblast

Question 10

Placenta

Answer 10

provides nutrients to embryo

Question 11

The chorion

Answer 11

Blocks antibody production by the mother
Promotes the production of T lymphocyte
Produces human chorionic gonadotropin
Secretes estrogens after the first 3-4 weeks of pregnancy and progesterone by the 6th week

Question 12

Gastrulation

Answer 12

first major event of the 3rd week

• Bilaminar disc transforms into a two dimensional trilaminar disc, made up of ectoderm, mesoderm and endoderm
• Involves rearrangement and migration of epiblast cells

Question 13

Placentation

Answer 13

Process of forming the placenta
Produced hormones used to sustain the pregnancy
Site of exchange for nutrients and wastes between the mother and fetus

Question 14

Placenta

Answer 14

Two parts
Fetal portion
maternal portion

Question 15

True labor

Answer 15

Stage of dilation
Stage of expulsion
Placental stage

Question 16

Development anatomy

Answer 16

The study of the sequence of events from the fertilization of a secondary oocyte to the formation of an adult organism

Question 17

Syngamy

Answer 17

The fusion of a sperm with a secondary oocyte

Question 18

Dizygotic twins

Answer 18

Fraternal twins

Produced from the independent release of two ova and the subsequent fertilization of each by different sperms

Question 19

Monozygotic twins

Answer 19

Derived from a single fertilized ovum that splits at an early stage in development
Contain exact same genetic material and always the same sex

Question 20

Yolk Sac

Answer 20

Transfers nutrients to the embryo, is an early source of blood cells and produced primitive germ cells

Question 21

Capacitation (ZP3)

Answer 21

The series of functional changes that prepare its plasma membrane to fuse with oocyte’s

Question 22

Polyspermy

Answer 22

The fusion of sperm cells and oocytesets in motion events to block another sperm from fertalizing the egg

Question 23

Embryoblast

Answer 23

Inner cell mass- develops into embro

Question 24

Trophoblast

Answer 24

Outer layer that forms wall and will ultimately develop into outer chronic sac surrounding fetus and fetal portion of placenta

Question 25

Implantation

Answer 25

7 days after fertilization, it attaches more firmly and burrows in Endometrium becomes more vascularized and glands enlarge now called a dicidua (endometrium that is modified after implantation )

Question 26

Development of trophoblast

Answer 26

Day 8. Digests its way into endometrium(dicidula), to become part of the chorion (where vasculature develops) Now secretes hCG, signals corpus luteumn to stay in place and not shed ( aka period) Which leads to estrogen and progesterone continue to secrete THIS STOPS MENSTRATION FROM OCCURING NOW GOES A DIFFERENT PATH

Question 27

Development of bilaminar disc

Answer 27

8 days after fertilixzation | Cells of embryoblast, into 2 layers : hypoblast & epiblast

Question 28

Development of amnionic fluid

Answer 28

Amnion forms roof of amniotic cavity and epiblast forms floor Amnion eventually surrounds the entire embryo, cavity is now filled with amniotic fluid

Question 29

Development of yolk sac

Answer 29

from exocoelomic membrane Relativley small and empty since nutrition derived from endometrium Will give a rise to easy nutrients, source of blood cells, germ cells that will migrate to form gametes, form part of the gut, shock absorber and prevent desiccation

Question 30

Development of sinusoids

Answer 30

creating endometrium capillaries dilate to form maternal sinusoids, more material will diffuse into and will allow chorion to develop

Question 31

Cloacal membrane

Answer 31

Once it appears in gastrulation, wall of yolk sac forms allantois

Question 32

Development of somites

Answer 32

3 regions myotome: skeletal muscles of neck, trunk and limbs dermatome: connective tissue sclerotome: vertebrae and ribs

Question 33

Angiogenisis

Answer 33

Formation of blood vessels | By end of 3rd week, heart forms and begins to beat

Question 34

Process of forming placenta

Answer 34

2 umbilical arteries carry deoxygenated fetal blood to placenta 1 umbilical vein carries oxygenated blood away from placenta Afterbirth it detaches from uterus

Question 35

Hormones of pregnancy

Answer 35

3-4 months: corpus lute secretes estrogen and progesterone 3rd month on the Placenta produces high levels of estrogen and progesterone and produces CRH Chorion secretes hCG and produces hCS Relaxin is produced by corpus lute and placenta

Question 36

LAbor

Answer 36

expelled from uterus through vagina estrogen rises to overcome effect if progesterone on contractions estrogen increases number of receptors for oxycontin, which stimulates contractions Relaxin increases flexibility of pubic synthesis and dilates the cervix

Question 37

Control of labor through positive feedback

Answer 37

Contractions force fetal head to the cervix which stretches stretching causes release of more oxycontin more oxycotin=more stretching

Question 38

Adjustnentf of infants after birth

Answer 38

Foramen vale closes -diverts blood to lungs for the first time now called fossa ovalis Ductus arterioles constricts and becomes the ligaments arteriosum Umbilical arteries become medial umbilical ligaments and umbilical been becomes round ligaments of the liver

Question 39

Lactation after birth

Answer 39

Prolactin promotes milk secretion secreted by anterior pit. After delivery, inhabitation removed as estrogen and progesterone levels fall and prolactin can begin -Sucking maintains prolactin secretion