OVULATION Secondary oocyte covered by follicular cells, Cumulus
oophorecus. Follicular cells secrete actively Estrogen. Day 14
ovulation takes place. Graffian follicle enlarges,bulges on the
surface of the ovary and burst open. By the time ovum is surrounded
by Corona radiata cells. Ovum is released into the peritoneal
cavity and is taken up by fimbriated end of Uterine tube. Sudden
dip &raise of body temperature,mild pain in abdomen at the of
ovulation.
Slide 12
CORPUS LUTEUM The empty graffian follice is converted into
corpus luteum. C.L lasts for 10 -12 days,if Ovum is not fertilized.
C.L lasts for 2-3 months,if ovum is fertilized and pregnancy
continues. Cells of Graffian follicle secretes Estrogen. Cells of
Corpus luteum secrete Progesterone.
Slide 13
Layers of Uterine Wall Outer wall : Perimertium Middle wall:
Myometrium Inner wall: Endometrium Endometrium consists of lining
epithelium which is columnar. Endometrial Dip Invagination. Glands
are formed & projects into Myometrium,Perimetrium.
Slide 14
PARTS
Slide 15
Endometrial Layer Basal layer is thick and supporting the
superficial layers. Endometrium shows 3-parts. Stratum Basale:
Thin,Outer layer Stratum Spongiosum: Thick,Middle layer Stratum
Compactum: Thin, Inner layer. S.basale permanently present
throughout cycle. S.c & S.s are shed during Menstruation. B.S :
Uterine artery-Spiral arteries.
Slide 16
Endometrial Layer
Slide 17
Early Development of Embryo Secondary oocyte is covered by
Acellular,Amorphous Glycoprotein layer called ZONA PELLUCIDA. Zona
pellucida is covered by Corona radiata cells.
Slide 18
PHASES OF FERTILIZATION Passage of Sperm through Corona
Radiata. Penetration of Zona pellucida. Fusion of plasma membranes
of the Oocyte and sperm. Completion of 2 nd meiotic division of
oocyte &formation of female pronucleus. Formation of Male
pronucleus Fusion of both Male & Female Pronuclei. Zygote has
formed (2n)
Slide 19
Phases of Fertilization
Slide 20
Slide 21
Penetration
Slide 22
Penetration
Slide 23
Penetration
Slide 24
Cleavage of Zygote
Slide 25
Slide 26
Slide 27
2 celled stage
Slide 28
4-celled stage
Slide 29
2,4,8,16 celled stage
Slide 30
FORMATION OF BLASTOCYST 16 celled stage is called MORULA.
Morula is converted to Blastocyst. As the Morula moves towards the
uterine cavity,fluid enters the Morula through zona pellucida and
partially seperates the cells into Outer cell mass and inner cell
mass. As fluid as entered a cavity is formed. Cavity enlarges,Outer
cell mass becomes flattened called as Trophoblast. Inner cell mass
is called Embryoblast. This results in the formation of
BLASTOCYST.
Slide 31
BLASTOCYST
Slide 32
BLASTOCYST Blastocyst enlarges &Zona pellucida disappears.
Blastocyst is now Implanted in the wall of the uterus. Trophoblast
forms future Placenta. Inner cell mass forms Embryo proper.
Slide 33
Slide 34
Slide 35
IMPLANTATION Implantation is completed by the end of 2 nd
week-time between 6-10 days after Ovulation. Trophoblast
differentiates into outer synctiotrophoblast and inner
Cytotrphoblast cells. Synctiotrophoblast invades the Endometrial
wall layer and the Blastocyst is Superficially Implanted by the end
of SECOND WEEK. Synctiotrophoblast secretes Human chorionic
gonadotrophin hormone. 9 th Day.
Prochordal plate 14 th day Embryo has a flat Bilaminar Germ
disc. At one end of embryonic disc near its margin a round area
becomes thicker than the rest of the disc.The rounded area is
called Prochordal plate. In this region flattened endodermal cells
becomes Columnar and are firmly adherent to ectoderm. With the
formation of prochordal plate the cranial & caudal ends of
embryonic disc is identified.
Slide 39
Prochordal Plate
Slide 40
Slide 41
Slide 42
DURING 3 RD WEEK Appearance of Primitive Streak.
Differentiation of Three germ layers. Notochord Neural plate Neural
tube Formation of Intra-embryonic mesoderm.
Slide 43
PRIMITIVE STREAK Beginning of 3 rd week & dissapears by end
of 4 th week. Longitudinal ridge or elevation that appears at
caudal end of embryo. Primitive streak visible on the upper surface
towards the amniotic cavity of Embryonic disc. Ectodermal cells
proliferates and move towards the midline and the cells elevates to
form an elevation called as PRIMITIVE STREAK. Intially it is at
Caudal end.. Now it elongates Cranially. At the cranial end
Primitive streak proliferate to form PRIMITIVE NODE or KNOT or
Hensens node.
Slide 44
PRIMITIVE STREAK Primitive streak invaginate deep between
ectoderm and endoderm.These cells extends now and forms
Intraembryonic Mesoderm. Anterior to Prochordal plate the Mesoderm
of two sides is continous with each other to form SEPTUM
TRANSVERSUM. Now embryonic disc enlarges and becomes pear shaped.
Cranial end is Broad & Caudal end is narrow. At caudal end IEM
passes beyond embryonic disc and becomes Connective stalk. (EXTRA
EMBRYONIC MESODERM) Primitive streak after giving rise to MESODERM
gradually disappears.
Slide 45
PRIMITIVE STREAK
Slide 46
Sacrococcygeal Teratoma Remants of Primitive streak persists
and gives rise to Sacrococcygeal teratoma. Common in New borns.
Prevalence : 1:35,000 Affected : 80 % female babies. Surgically
excised.
Slide 47
Slide 48
Third week
Slide 49
Slide 50
Embryo is straight. Has 12 somites. Neural tube formed. Day :24
First & Second arch develops. (Mandibular,Hyoid). Maxillary
prominence starts upper jaw formation. Now embryo is slightly
folded due to Head & Tail folds. Day :26 3 pairs of pharyngeal
arches are visible. Day : 26 Rostral Neuropore closes. Forebrain
starts developing.
Slide 51
Day :26.27 - Upper limb buds, Otic pits.Lens placodes appears.
Day :28 - 4 th pair of Pharyngeal arch develops. Day:28 - Lower
limb bud appears. End of 4 th week : Caudal neuropore closes,CVS
develops.
Slide 52
Rapid Head development due to development of Brain.Rapid
development of 2 nd,3 rd,4 th pharyngeal arches. Mesonephric kidney
starts developing
Slide 53
Embryo show reflex response to touch. Upper limb shows regional
differentation-Elbow and Hand plates,Primordia of digits develop
called as Digital rays. Spontaneous movements of Trunk &limbs.
Development of Lower limb occurs 4 or 5 days later than Upper limb.
External Acoustic meatus develops.(External Ear). Retinal pigment
in eye formed.(eye formation). Head is now much Larger,Bending in
cervical region. Trunk & Neck begin to straighten.formation of
Intestines.
Slide 54
Slide 55
Slide 56
DEVELOPMENT OF LIMBS
Slide 57
Limb undergoes considerable changes during 7 th week. Notches
appears between Digital rays,Handplates clearly indicating future
digits. By the end of 7 th week Ossification of the bones of the
Upper limb appears.
Slide 58
7 th Week
Slide 59
Slide 60
Digits of the Hand are Webbed. Notches are clearly visible
between the Digital rays of Feet. Digits are lengthened &
seperated completely. Profuse Limb movement occurs. Ossification
begins in Femur. Head size is large comparably. Scalp vascular
plexus appears around the Head. Neck region is established. Eye
lids are formed. Eye lids are closing.
Slide 61
8 th week
Slide 62
Slide 63
Auricles assume their final shape. Sex differences appear.
External genitalia are clearly distinct so,accurate sexual
identification is not permitted.
Slide 64
8 th week
Slide 65
Slide 66
Head size more increased and increases rapidly upto 12 th week.
Early in 9 th week Legs are long,Thighs are relatively short. 9 th
week face is Broad,Eyes are widely placed,Eyelids are fused,Low set
Ears. 9 th week Liver is the site for Erythropoiesis. End of 9 th
week External genitalia develops both male & females appears
similar.
Slide 67
End of 10 th week intestinal coils appears. End of 11 th week
intestinal coils placed in abdomen proper. End of 12 th week Upper
limb has almost reached final development. End of 12 th week
Primary Ossification centers appear in the skeleton (skull &
Long bones). End of 12 th week Activity of Rbc is decreased and in
spleen it starts. Between 9 th -12 th week Urine formation begins
and discharged into Amniotic fluid.
Slide 68
9 th week
Slide 69
Slide 70
Slide 71
Slide 72
Slide 73
10 th week
Slide 74
11 th week
Slide 75
Slide 76
Slide 77
12 th week
Slide 78
Slide 79
By 14 th week : Slow eye movements occurs. By 14 th week :
Scalp hair patterning is determined. By 16 th week : Head is
relatively small when compared to 12 th week. By 16 th week : Lower
limbs have extended & Limb movements appears. By 16 th week :
Ossification of Fetal skeleton & Bones are clearly visible. By
16 th week : Ovaries are differentiated. By 16 th week : Eye faces
anteriorly (before its antero- laterally). By 16 th week : External
ears are placed in its position. Between 12 th -16 th weeks : sexes
can be determined.
Slide 80
13-16 th weeks
Slide 81
Genital organs
Slide 82
Fetal movements quickened commonly felt by the mother. Skin is
now covered greasy,cheeselike vernix caseosa.(consists of mixture
of dead epidermal cells and fatty subustance.) Vernix caesosa
protects delicate fetal skin from abrasions,hardening,chapping
results from exposure to amniotic fluid. Brown fat is formed
&prevents from heat production.(Neck,sternum,perirenal areas).
18 th week : Uterus has formed. 20 th week : Testes has formed. 20
th week : Eye brow hair & Head hair clearly visible.
Slide 83
17-20 weeks
Slide 84
Slide 85
Fetus is proportionately better & weighted. Skin is
wrinkled & colour is pink to red. 21 st week : Rapid eye
movements visible. 24 th week : Type II pneumocytes appear in the
lung. (secretory epithelial cells) 24 th week : Finger nails are
developed. Babies born between 22-25 weeks survived in intensive
care.Some cases babies die due to because Respiratory system has
not developed or immature.
Slide 86
21-25 th weeks
Slide 87
Slide 88
Slide 89
Lungs & Pulmonary vasculature has developed. Central
nervous system starts matured. Rythemic breathing movements
&Control over body temperature occurs. 26 th week : Eye lids
opens 26 th week : Head hair fully develops. 26 th week : Toe nails
are visible. 26 th week : Quantity of white fat increases. 26 th
week : Fetal spleen has been important site for
Erythropoiesis.
Slide 90
Slide 91
Slide 92
Slide 93
Slide 94
Slide 95
Slide 96
Slide 97
30 th week : Papillary light reflex of the eye can be elicited.
Skin is smooth, Upper limb & Lower limbs are chubby in
appearance.
Slide 98
Fetuses born at 35 th week have firm grasp & exhibit
spontaneous orientation to light. 36 th week circumference of head
and abdomen are equal in size. Full term fetus has 360mm CRL.3400
gms in weight. Male foetuses are larger in weight than female.
Thorax is promonent. Testes are usually in the scrotum.