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Where do the PGC’s arise from?

Epiblast

Where do the PGC’s migrate to first?

Gut tube

What does the movement to the dorsal body wall stimulate next?

Proliferation of epithelium and mesonephros

When are genital ridges formed?

6-12 weeks.

In males, when does spermatogenesis start?

Puberty

Gametogenesis

Process of meiosis and cytodifferation that converts germ cells into mature male and female gametes

What happens to the cells of the follicle just following puberty in females?

They change shape. Become cuboidal.

When does the formation of the zona pellucida occur?

When the primary follicle is formed

When does the surge of LH/FSH occur?

After the formation of the secondary follicle

What is triggered in the female immediately after fertilization?

Secondary oocyte resumes meiosis II producing definitive oocyte and 2 polar bodies

What produces HCG to support the corpus luteum in progesterone secretion?

The embryo! Then the placenta takes over after 4th month.

Where does the morula travel to? What does it called now?

Uterine cavity; blastocyst

morula

The ball of blastomere cells divide, flatten, and reorganize together during compaction where a convex inner cell mass(becomes the embryo) and concave outer cell mass(becomes the placenta) are established

Blastocele

Fluid filled Cavity formed by the morula while forming the blastocyst.

The blastocyst hatches from Zona Pellucida and implants, forming these two items….

Inner cell mass embryoblast

What days does the embryo differentiate into 2 layers?

Days 7-8 Epiblast and Hypoblast

What forms the syntiotrophoblast? What day?

Trophoblast cells at embryonic pole that loose cell membranes and syncycium day 6-9

What forms the cyntotrophoblast?

Trophoblast cells at abembryonic pole.

What do the cyntrophoblast secrete?

Hydrolytic enzymes

Bilaminar germ disk

After the epiblast and hypoblast differentiate from each other in the embryoblast, the embryo is called a bilaminar (two-layered) germ disc.

When is amniotic cavity formed? What are the surrounding cells called?

day 8, amnioblasts

What is the major event within the synctiotrophblast that occurs on Day 9?

Vacuoles (trophoblastic lacunae) open within the syncytiotrophoblast and anastome with maternal capillaries.

When is heusers membrane formed?What is it formed from?

Day 12, Hypoblast cells migrating over cytotrophoblast

Around day 12, the blastocyst is now called

Primary yolk sac

What is the acellular material formed between the heusers membrane and cyntrophoblast called?

Extraembyronic reticulum

The cyntrophoblast develops extensions that dvelop into the syntiotrophoblast. The extensions grow into the ____________ and are called ______

Lacunae; Primary stem villi

What becomes the placenta?

The primary stem villi

What converts primary into secondary villi?

Extraembryonic mesoderm

When does the chorionic cavity expand, separating the amnion from the cytotrophoblast?

Week 2

What is the fate of the primary yolk sac? (around day 12-13)

The old primary yolk sac is displaced toward the abembryonic pole. It ultimately degenerates into a group of exocoelomic vesicles which ultimately disappear.

What day is primitive streak complete?

Day 16

Gastrulation

process of epiblast ingress through the primitive streak forming the primary germ layers

The fundamental anatomical positions of the embryo are established by the ____

Primitive Streak

What four things happen once the two mesodermal structures are developed (prechordal plate and notochordal process)?

1. Lateral mesoderm become paraxial, intermediate, and lateral plate mesoderm. 2.Primitive streak regressing caudally 3.Prechordal plate and cranial portion of the notochordal process secrete 4. cells differentiate into neural plate

Which somitomeres develop into somites?

All but first 7.

What day is notochordal process completely formed?

Day 20

When do the blood vessels develop?

Week 3

Describe notochordal process’ transformation to solid rod

1.Ventral floor of tube fuses w/ endoderm 2.tube unzippers ventrally starting @ primitive pit 3.notochordal processes converted to notochordal plate 4.completely detaches from the endoderm and retreats back: notochord

The lateral plate splits into parietal and visceral layers….What does the parietal layer line?What does the visceral layer line?

1. lines the intraembryonic cavity 2. visceral lines the outer surfaces of the visceral organs

Neurulation

conversion of neural plate to neural tube

Prosencephalon

forebrain) portion cranial to flexure

Rhombencephalon

hindbrain) portion caudal to flexure

Describe neurulation

EDIT

When is Closure of the caudal neuropore

day 26

When is bidirectional Closure of the cranial neuropore at site of future forebrain

day 24

When does primitive streak disappear?

day 26

What are the two steps of Secondary neurulation?

1. Central mass of caudal eminence forms into a solid neural cord. 2. Forms lumen that joins with the neural canal. Caudal end of neural tube completed at apprx 8 weeks

Which way does cytodifferentiation proceed?

Caudally and cranially

what is the order for cytodifferentiation of neural tube?

Neuroepithethial cells surround; Neuroblasts migrate; Glioblasts migrate; Neuroepithelial cells differentiate

Differentiation of neural tube

Dorsal and ventral columns begin to form in the mantle layer of the spinal cord at end of 4th week. Fundamental morphology of spinalcord established

Implantation occurs during which week?

First

What does the trilaminar germ disk differentiate into?

Embryo

The urinary system and parts of the genital system develop from

intermediate mesoderm

The hormone responsible for ovulation is

luteinizing hormone or FSH

What is surrounded by the zona pellucida/

The morula

Primary oocytes begin the first meiotic division before birth, but only get so far as an uncompleted:

prophase

The sex of the embryo is determined at time of

fertilization

The amniotic cavity develops within the

epiblast

The primordial germ cells leave the yolk sac and migrate along the dorsal mesentery to reach the genital ridges by

ameboid movement

In oocytes, the second meiotic division is completed When??

following fertilization

The bilaminar germ disc (embryonic disc) consists of:

epiblast and hypoblast

During the process of meiosis, the DNA replicates itself when?

prior to the first meiotic division

Gonadotropin releasing hormone (GnRH) is produced by the

hypothalamus

The _______________ of the syncytiotrophoblast fuse to form spaces that will be filled with maternal blood

trophoblastic lacunae

The first cavity to appear in the embryo after fertilization is the:

blastocyst cavity

The process that leads to the formation of the three germ layers is called

gastrulation

The portion of the early embryo that gives rise to essentially all of the fetus is the:

epiblast

The amniotic cavity develops within the:

epiblast

After ovulation, the walls of the remaining Graafian follicular structure collapse and form a glandular structure, the:

corpus luteum

A polar body is the result of:

unequal division of the cytoplasm in oocytes during meiosis

Contact of the oocyte plasma membrane by a sperm and fusion of their cell membranes induces alteration of the zona pellucida so that no more sperms can penetrate it. This is mediated by release of the contents of:

cortical granules of the oocyte

Cells that give rise to the gametes in both males and females originate in the

epiblast

Spaces developing in the extraembryonic reticulum become confluent to form the

chorionic cavity

Human development is complete when the fetus is delivered at birth...true or false?

False

Primary chorionic villi are developed as projections of the _______________into the syncytiotrophoblast.

cytotrophoblast

describe the origin of primordial germ cells (PGCs) and the importance of the yolk sac for PGCs

PGCs originate in the epiblast, migrate to yolk sac and later migrate to the body cavity

HCG acts on the corpus luteum to maintain production of

progesterone

Which cells are the surface cell layer of the blastocyst?

the trophoblast cells

The chromosomal abnormality of Down syndrome (trysomy 21) can be detected by

A karyotype analysis of cells isolated by amniocentosis

Blastocyst hatching occurs before or after implantation?

before

What is the embryo-derived cell layer that forms the interface with the endometrium?

Syncytiotrophoblast

What is the embryo cell layer that is the source of the cells that form the yolk sac?

Hypoblast

What is the embryo cell layer that is the source of the cells that form the amniotic cavity?

epiblast

where gastrulating cells migrate out of the epiblast

primitive streak

The two main types of cells formed by the gastrulating cells are ________________

Definitive endoderm and primary endoderm

The notocord is formed by cells that gastrulate through

primitive node

What is the origin of the paraxial mesoderm, intermediate mesoderm and the lateral plate mesoderm?

Epiblast cells that gastrulate laterally through the primitive streak

What are condensations of cells that form in the paraxial mesoderm and usually develop further to form somites?

somitomers

The sclerotome, myotome, and dermatome arise directly from

somites

The cells of the neural plate have a distinct epithelial structure called

The neuroepithelium or neuroectoderm

structures formed by cells of the sclerotome?

vertebre

structures formed by cells of the myotome?

muscles

The folding of the neural plate to form the neural tube is called ____________

Neurulation

The dermal bones of the skull are formed by cells from

Cranial neural crest

The sensory neurons of the dorsal root ganglia are formed by cells from

Spinal neural crest

Neurons of the dorsal root ganglia project axons to which part of the spinal cord?

The dorsal columns

The costal processes of the vertebrae give rise to

ribs

Somatic motor neurons reside in ___________

ventral columns

Which dietary component is recommended in order to reduce the risk of neural tube defects?

folic acid

The ventral columns of the spinal cord are induced by sonic hedgehog (SSH) from the floor plate to for what type of neuron?

somatic motor nneuron

What is formed by cells of the dermatome?

connectie tissue

What hormone is produced by cells in the pituitary gland?

fsh

What is the early embryo cell layer that is the source of the cells that form the embryo proper, but not the extraembryonic tissues such as the yolk sac?

epiblast

Put the following into order: a.formation of sex cords b.PGC’s differentiate in endodermal layer c.Genital ridges appear d.PGC’s migrate via dorsal mesentery to the dorsal body wall

B D A C

Put these in order of occurance: a.Spermatogonia B b.Secondary spermatocyte c.Acrosome reaction d.Spermatid e.Spermatogonia A f.Primary spermatocyte g.Spermatozoa h.Spermatogonal stem cells i.Capatation

H, e, a, f, b, d, g, I, c, Spermatogonal stem cells; Spermatogonia A; Spermatogonia B; Primary spermatocyte; Secondary spermatocyte; Spermatid; Spermatozoa; Capitation; Acrosome reaction;

Put in order of occurance a.oogonia b.primary oocyte c.ovarian follicle d.development of primordial follicles e.secondary follicle f.secondary ooctye g.Meiosis I resume h.Pre ovulatory follicle i.Meiosis II j.Primary follicle

Ovarian follicle; Oogonia; Primary oocyte; Development of primordial follicles; Primary follicle; Secondary follicle; Pre ovulatory follicle; Meiosis I resumes; Secondary oocyte; Meiosis II;

Put in order: a)epiblast cells displace hypoblast creating definitive endoderm. b)Primitive streak migrates bt epiblast and hypoblast c)Third germ layer formed d)Prechordal plate developed e)Epiblast cells next to Prim Streak proliferate

Epiblast cells proliferate; Primitive Streak migrates; Epiblast displace hypoblast; Third germ layer forms Prechordal plate;