Germ cell migration

1. Migration of Germ Cell in Vertebrates
Presentation topic:
Submitted to:
DR. SAGHIR AHMED
Submitted by:
Name: Yusra Sardraz
Roll No: 864
Class: BS. Zoology
Semester: 6TH
Session : (2017-2021)

3. Important terms to know:
 Epiblast (also known as the primitive ectoderm) is one of two distinct layers arising
from the inner cell mass in the mammalian blastocyst or from the blastodisc in reptiles
and birds
 Blastocyst is a structure formed in the early development of mammals. It possesses an
inner cell mass (ICM) which subsequently forms the embryo. The outer layer of
the blastocyst consists of cells collectively called the trophoblast.
 DORSAL MESENTERY extends from the lower esophagus to rectum and throughout its
length serves as a pathway to the gut for blood vessels, nerves, and lymphatics
 Genital ridge is the somatic precursor of gonads in both sexes. This is a unique
primordium in organ formation because of its bipotential nature. A single primordium
gives rise to one of two organs, a testis or an ovary.

4.  Primitive streak is a transient structure whose formation, on day 15 of human
development, marks the start of gastrulation, the process in which the inner
mass in converted into the trilaminar embryonic disc, which is comprised of
three germ layers (ectoderm, mesoderm and endoderm).
 Gastrulation is the process during embryonic development that changes the
embryo from a blastula with a single layer of cells to a gastrula containing
multiple layers of cells.
 Yolk sac: The yolk sac is a small, membranous structure situated outside of the
embryo that has a variety of functions during embryonic development. It
attaches ventrally to the developing embryo via the yolk stalk.
 Filopodia : Epithelial cells often produce extensions, known variously
as filopodia

5. In developmental biology, an embryo is divided into two
hemispheres: the animal pole and the vegetal pole within a
blastula. The animal pole consists of small cells that divide
rapidly, in contrast with the vegetal pole below it.
At one pole, known as the animal pole, the cytoplasm appears
to be more active and contains the nucleus (meiotic divisions
occur in this region); at the other, called the vegetal pole, the
cytoplasm is less active and contains most of the yolk

6. GERM CELLS MIGRATION IN VERTEBRATES:
IT INCLUDES:
AMPHIBIANS
REPTILES
BIRDS
MAMMALS

9. In Amphibians

10. There is no obvious germ plasm in mammals, and mammalian germ cells are not
morphologically distinct during early development. However, by using monoclonal antibodies
that recognize cell surface differences between the PGCs and their surrounding cells
Pathway for the migration of mammalian primordial germ cells.
A. PGCs seen in the yolk sac near the junction of the hindgut and allantois.
B. The PGCs migrate through the gut and, dorsally, up the dorsal mesentery and into the genital ridges.
C. Four large PGCs in the hindgut of a mouse embryo (near the allantois and yolk sac) stain positively
for high levels of alkaline phosphatase.
D. Such alkaline phosphatase-staining cells can be seen migrating up the dorsal mesentery and entering
the genital ridges
Germ Cell migration in mammals