The document discusses sex cell differentiation and gamete formation in humans and other animals. It covers the processes of oogenesis and spermatogenesis, including the migration of primordial germ cells and proliferation of eggs and sperm. It also describes fertilization, including the structures and stages of egg and sperm cells, their fusion during conception, and the early cleavage and differentiation stages of embryonic development.

2.  SEX CELL DIFFERENTIATION
 OOGENESIS – EGG DIFFERENTIATION
 SPERMATOGENESIS – SPERM DIFF.
◦ SPERMIOGENESIS – TRANSFORMATION OF
THE MALE GAMETE

3.  IN MAN/MAMMALS, PRIMORDIAL GERM
CELL COMES FROM YOLK SAC ENTODERM
NEAR CAUDAL END OF BODY
 FROM THERE THEY MIGRATE FORWARD
THROUGH THE MESENCHYME OF THE
MESENTERY AND INTO THE GENITAL
RIDGE WHICH SOON BECOMES THE SEX
GLAND
 THEN PROLIFERATION

4.  PROLIFERATION IS PERIODIC (MONTHLY
IN FEMALES) URING THE POTENTIAL
CHILD-BEARING YEARS

5.  CELL PROLIFERATION – PRIMITIVE CELL
REPEATEDLY DIVIDES
 PERIOD OF GROWTH – RAPID
ENLARGEMENT OF THE CELLS PRODUCED
 PERIOD OF MATURATION – NUCLEAR
CHANGES LIMITED TO THE FINAL TWO
DIVISIONS

6.  ORIGIN OF THE FOLLICLES
◦ PRIMORDIAL CELLS (OOGONIA)
PROLIFERATE WITHIN THE CORTEX OF
THE OVARY
◦ SMALLER EPITH. CELLS, OF GERMINAL-
EPITH ORIGIN ENCASED THE OOGONIA
AND PRODUCED PRIMARY FOLLICLE
◦ AFTER BIRTH, FORMATION OF HUMAN
OOGONIA STOPS THEN CELLS ARE NOW
CALLED OOCYTES

7.  370,000 – AT BIRTH
 190,000 – AT PUBERTY
 26,000 – AT AGE 30
 AFTER 30 OR MORE YEARS (CHILD-
BEARING SPAN), FOLLICLES WILL NO
LONGER BE SEEN

8.  NO ADVANCE BEYOND THE STAGE OF
THE PRIMARY FOLLICLE UNTIL PUBERTY
(14TH YEAR)
 FEW HUNDREDS OF OOCYTES ARE
LIBERATED PERIODICALLY DURING
OVULATION

9.  GROWTH OF FOLLICLE STARTS SLOWLY
BUT GROWS RAPIDLY 1-3 DAYS PRIOR TO
RUPTURE
 MATURATION – ACHIEVED BY MEIOSIS
WITH 4 CELLS HAVING EQUAL NUCLEI
WHILE THE CYTOPLASM IS UNEQUALLY
DIVIDED

10.  1 LARGE RIPE OVUM
 3 RUDIMENTARY OVA (POLAR BODIES) OR
POLOCYTES
 CYTOPLASM – GRANULAR AND
CONTAINS FEW TO MANY INERT
GRANULES
 YOLK/DEUTOPLASM – MADE UP OF
FATTY AND ALBUMINOUS SUBSTANCE;
SERVES AS NOURISHMENT FOR THE
EMBRYO

11.  YOLK – USEFUL IN CLASSIFYING EGGS.
I. BASED ON RELATIVE ABUNDANCE OF
YOLK:
1. SMALL
2. MEDIUM
3. LARGE

12. II. DISTRIBUTION OF YOLK IN CELLS:
1. ISOLECITHAL – EQUAL YOLK
MEIOLECITHAL – LITTLE YOLK
- INVERTEBRATES
- ALL MAMALS EXCEPT LOWEST
FORMS
2. TELOLECITHAL EGGS – ABUNDANT
YOLK AND CONCENTRATED IN ONE
HEMISPHERE

13. -INVERTEBRATES
-ALL VERTEBRATES LOWER THAN
MARSUPIALS
- CHICK EGG
3. MEDIALECITHAL (MEDIUM YOLK) –
MODERATE YOLK – AMPHIBIANS
4. MEGALECITHAL- LARGE, YOLK RICH
EGGS OF BONY FISHES , REPTILES , BIRDS

14. 5. CENTROLECITHAL- DISTINCTIVE
ARRANGEMENT OF YOLK, MASSED
CENTRALLY BUT SORROUNDED BY A
PERIPHERAL SHELL OF CLEAR
CYTOPLASM.
EGG POLARITY:
ANIMAL POLE – SITE WHERE POLAR
BODIES PINCH OFF

15. - VIGOROUS PART IN DEVT. & WHERE
HIGHEST CAPACITY FOR ACTIVITY RESTS
- VEGETAL POLE- SLUGGISH END OF CELL
AND CONCERNED WITH THE DEVT. OF
NUTRITIVE ORGANS
- YOLK LADEN
PROTECTIVE MEMBRANES:
1° MEMBRANE-CELL/PLASMA MEMBRANE

16. 2° MEMBRANE- ZONA PELLUCIDA
3° MEMBRANE –ADDED BY THE OVIDUCT
AS THE EGG PASSES THROUGH IT
- JELLY OF FROG’S EGGS
- ALBUMEN OF RABBIT’S EGG
- ALBUMEN AND SHELL OF HEN’S EGG

17. CELLULAR CORDS ( GERMINAL
EPITHELIUM)
TESTES TUBULES
 SPERMATOGONIA (STEM CELLS)- LARGER
 INDIFFERENT CELLS- SMALLER
 PUBERTY – SOME SPERMATOGONIA
REMAIN AS STEM CELLS WHILE OTHERS
BECOME PRIMARY SPERMATOCYTE-2°
SPERMATOCYTE-SPERMATID-SPERM

18.  DETACHED FROM SERTOLI CELLS AND ARE SET
FREE INSIDE THE SEMINIFEROUS TUBULES
 SPERM CELL- SMALLEST CELL IN MASS MADE
UP OF HEAD, NECK & TAIL.
 AT THE END OF MATURATION (MEIOSIS)
THE DEVT. OF EGG IS COMPLETE AND THE EGG
BECOMES FUNCTIONAL WHILE THE MALE
GAMETE UNDERGOES A SERIES OF
TRANSFORMATIONS BEFORE A FUNCTIONAL
SPERM CELL IS DERIVED

19.  CHROMOSOME NUMBERS
(2N) MAN=46 (DIPLOID CHROMOSOME#)
(N) MAN=23 (HAPLOID CHROMOSOME#)
 FEMALE
-22 ORDINARY CHROMOSOME PAIR
-23RD PAIR(SEX CHROMOSOME)
(XX) PAIR
 MALE
22 ORDINARY CHROMOSOME PAIR
23RD PAIR (XY) PAIR

20.  24 DIFFERENT KINDS OF CHROMOSOMES
COMPARISON OF EGG & SPERM OF
ANIMALS IN GENERAL

21. FEATURES OVUM SPERMATO-
ZOON
SIZE LARGE SMALL
SHAPE SPHEROIDAL ELONGATED
QUANTITY FEW (ONE) OFTEN IN
MILLIONS
MOTILITY NON-MOTILE VIGOROUS
(FLAGELLATE)
PROTECTION EGG
ENVELOPES
NONE

22. CYTOPLASM BULKY MINIMAL
YOLK LITTLE TO
MUCH
NONE
CENTRO-
SOME
DISAPPEARS RETAINED –
CENTRIOLE &
AXIAL
FILAMENT
MITOCHON-
DRIA
DIFFUSED IN THE BODY
ONLY

23. GOLGI-
APPARATUS
DIFFUSED IN
ACROSOME
ONLY
NUCLEUS OPEN
STRUCTURED
CONDENSED
AS SPERM
HEAD
NUCLEOLUS TYPICAL INDISTINGUIS
HABLE
SEX
DETERMININ
G ROLE
RARELY TWO
KINDS(MOTH
S/BIRDS)
USUALLY
TWO
KINDS(MALE
&FEMALE)

29.  INTERNAL FERTILIZATION
-SMALL NUMBER OF EGGS
 EXTERNAL FERTILIZATION
-LARGE VOLUME OF EGGS
TYPES OF BREEDING:
• CONTINUOUS-ALL THOUGHOUT THE YEAR
• SEASONAL/ANNUAL SPAWNING PERIOD
• SPONTANEOUS- SEXUAL
EXCITEMENT/PERIOD OF HEAT / ESTRUS

30. • PROVOKED OVULATION- INDUCED BY
THE ACT OF COPULATION.
• PERIODIC (INTERVALS OF 4 WEEKS)
SPONTANEOUS
 HUMAN FEMALE
-OVULATION (14 YRS.) + 30 YEARS OF
SEXUAL ACTIVITY
 FOLLICLE RUPTURE- SIMILAR TO THE
RUPTURE OF A BOIL; TAKES PLACE AT
THE STIGMA

31. - HORMONAL FACTOR AND LOCAL
WEAKENING OF FOLLICULAR WALL
EGG TRANSPORT- MADE POSSIBLE BY
HORMONAL CONTROL AND OVARY
ACTIVITY.
TIME OF OVULATION- MIDDLE OF THE
CYCLE
28-DAY CYCLE
26-DAY CYCLE
30-DAY CYCLE

32.  EGG VIABILITY- FERTILIZABLE PERIOD IS
LESS THAN ONE DAY – GENERATION
TAKES PLACE
CORPUS LUTEUM- OVARIAN STRUCTURE
(COLLAPSED & FOLDED) VESICULAR
FOLLICLE- MADE UP OF LUTEIN CELLS
• CORPUS LUTEUM OF OVULATION
• CORPUS LUTUEM OF PREGNANCY
• CORPUS ALBICANS- WHITE SCAR LEFT
MADE UP OF FIBROUS TISSUE.

33. • PSEUDOCOPULATION- INCREASES
CERTAINTY OF UNION
• COPULATION- SEXUAL EMBRACE
SPERM STORAGE- ACCUMULATION AT
EPIDIDYMIS(TRAVERSED IN 12 DAYS)
SPERM DISCHARGE- EJACULATION(MALE
CLIMAX DURING COITUS)
SEMEN (SPERMATOZOA PLUS THE
SECRETIONS FROM 3 ACCESSORY
GLANDS:

34. • SEMINAL VESICLE
• BULBO-URETHRAL GLAND
• PROSTATE GLAND
 3 ML EJACULATE-250,000,000 SPERMS
SPERM TRANSPORT-LASHING,
FLAGELLATED MOVEMENT ; WILL
TRAVERSE UTERUS IN 70 MIN.(7 INCHES)
SPERM VIABILITY= 1-2 DAYS

35.  IN VITRO- TWO WEEKS
 HUMAN SEMEN(FROZEN IN GLYCEROL
 AT - 70℃ (CAN SURVIVE FOR MANY
MONTHS

36.  PROCESS WHEREBY 2 GAMETES FUSE
TOGETHER TO CREATE A NEW INDIVIDUAL
WITH A GENOME DERIVED FROM BOTH
PARENTS
 ACCOMPLISHES 2 SEPARATE ENDS; SEX (THE
COMBINING OF GENES DERIVED FROM 2
PARENTS) AND REPRODUCTION (THE
CREATION OF A NEW ORGANISM)
 CONCEPTION CONSISTS OF 4 MAJOR EVENTS:

37.  1. CONTACT AND RECOGNITION BETWEEN
SPERM AND EGG. THIS ENSURES THAT THE
SPERM AND EGG ARE OF THE SAME SPECIES
 2. REGULATION OF SPERM ENTRY INTO THE
EGG. ONLY ONE SPERM CAN ULTIMATELY
FERTILIZE THE EGG. THIS IS USUALLY
ACCOMPLISHED BY ALLOWING ONLY ONE
SPERM TO ENTER THE EGG AND INHIBITING
ANY OTHERS FROM ENTERING

38.  3. FUSION OF THE GENETIC MATERIAL OF
SPERM AND EGG
 4. ACTIVATION OF EGG METABOLISM TO
START DEVELOPMENT

39.  ANTON VAN LEEUWENHOEK – CO-
DISCOVERER OF SPERM
 NICOLAS HARTSOEKER – CO-DISCOVERER OF
SPERM
 DREW A PICTURE OF A PREFORMED HUMAN
(HOMUNCULUS)
 BELIEF THAT THE SPERM CONTAINED THE
ENTIRE EMBRYONIC ORGANISM

41.  POOLING TOGETHER OF SPERM AND EGG
NUCLEI
• INVERTEBRATES ( ROTIFERS,
CRUSTACEANS INSECTS) DEVELOP
WITHOUT THE BENEFIT OF
FERTILIZATION(PARTHENOGENESIS)

44.  RESULTS OF FERTILIZATON:
1. REASSOCIATION OF MALE AND FEMALE
SETS OF CHROMOSOMES , RESTORING
THEM TO THE FULL DIPLOID NUMBER.
2. SEX DETERMINATION
3. ACTIVATION OF OVUM INTO CELL
DIVISION OR CLEAVAGE.

45.  SEX DETERMINATION – IS ESTABLISHED
AT THE TIME OF FERTILIZATION
 DURING MEIOSIS, CHROMOSOME NUMBER
IS HALVED
 22+X – FEMALE
 22+X – MALE; 22+Y – MALE
 22+X + 22+X = 44+2X
 22+X + 22+Y = 44+X+Y

46.  PERIODS OF EARLY DEVELOPMENT:
1) GAMETOGENESIS
2) FERTILIZATION
3) CLEAVAGE
4) GASTRULATION
 FERTILIZED EGG-MANY CELLED
INDIVIDUAL(CLEAVAGE) - CELLS
TYPICALLY ARRANGE THEMSELVES INTO
A HOLLOW SPHERE, THE BLASTULA

47.  CELLS OF BLASTULA- REDISTRIBUTED AS
THE PRIMARY GERM
LAYERS(GASTULATION)
 IT CONTAIN THE MATERIAL OUT OF
WHICH THE EMBRYO AND ALL ITS PARTS
WILL DIFFERENTIATE.
• ECTO
• MESO
• ENTO/ENDODERM

48.  THE VERTEBRATE GROUPS
I. ANAMNIOTA- WITHOUT AMNION
 FISHES-LAMPREY ,
STURGEON,SHARK,BONY FISHES
 AMPHIBIANS-
FROGS,TOAD,SALAMANDERS
II. AMNIOTA- WITH AMNION
 REPTILES
-LIZARD,CROCODILES,SNAKES,TURTLES

49. MAMMALS – HAIR AND MAMMARY
GLANDS
• MONOTREMES- DUCK-BILL /ECHIDNA
• MARSUPIALS-OPOSSUM/ KANGAROO
• PLACENTALS-YOUNG NOURISHED IN THE
UTERUS VIA PLACENTA
• PRIMATES- WITH NAILS
(LEMUR,MONKEY,APE AND MAN) –
SUBORDER ANTHROPOIDA

50. -DOUBLING/FRACTIONATING PROCESS
PRODUCING COHERING,STICKY,
BLASTOMERES ARRANGED AROUND A
CENTRAL,FREE SPACE(BLASTOCOELE)
 EGG CLASSIFICATION ON THE BASIS OF
ABUNDANCE AND YOLK DISTRIBUTION:
A. TOTAL- HOLOBLASTIC OVA; ENTIRE
OVUM DIVIDES

51. 1. EQUAL-ISOLECITHAL OVA
-EQUAL SIZED BLASTOMERES
• AMPHIOXUS/MARSUPIAL/PLACENTAL
MAMMALS
2. UNEQUAL- MODERATELY
TELOLECITHAL OVA
• LOWER FISHES / AMPHIBIANS

52. B. PARTIAL- MEROBLASTIC OVA; ONLY
PROTOPLASMIC REGION DIVIDES.
1. DISCOIDAL-HIGHLY TELOLECITHAL
OVA
-MITOSIS RESTRICTED TO THE ANIMAL
POLE.
• HIGHER FISHES/REPTILES/BIRDS/
MONOTREME MAMMALS

53. 2. SUPERFICIAL – CENTROLECITHAL OVA;
DIVISION RESTRICTED TO THE
PERIPHERAL CYTOPLASMIC INVESTMENT
• ARTHROPODS
 AMPHIOXUS-FISH-SHAPED; LOW
CHORDATE
 AMPHIBIANS
 REPTILES/ BIRDS
 MAMMALS

54. - FISH SHAPED; LOW CHORDATE
- EARLY STAGES OF DEVT. IS SIMILAR TO
SOME INVERTEBRATES
- ISOLECITHAL EGGS
- CLEAVAGE IS TOTAL AND NEARLY EQUAL
- SUBSEQUENT CELL DIVISIONS IN
ALTERNATE PLANES PRODUCES 32,64
ANO 128 CELL STAGES
- SIZE OF CELLS ARE PROGRESSIVELY
DIMINISHED WHILE THE CENTRAL CAVITY
ENLARGES TO FORM THE BLASTOCOELE

55. MODERATELY TELOLECITHAL (FAIR
AMOUNT OF YOLK)
- CLEAVAGE IS TOTAL BUT UNEQUAL
- UPPER 4 MICROMERES ARE SMALLER
THAN THE LOWER 4
- FORMS A CENTRAL BLASTOCOELE WHERE
BLASTOMERES AT THE ANIMAL POLE ARE
SMALLER; LARGER & FEWER AT VEGETAL
POLE

56. WALL IS MORE THAN 1 CELL THICK
BLASTOCOELE IS RELATIVELY SMALL;
LOCATED ABOVE CENTER DUE TO THE
THICK WALL OF THE VEGETAL POLE

57. WITH LARGE EGGS
- CLEAVAGE IS PARTIAL & DISCOIDAL
- PRODUCES A DISCOIDAL PLATE OF CELLS
PERCHED ON THE SURFACE OF THE YOLK
AND SEPERATED FROM IT BY A CLEFT
- CLEAVAGE PRODUCES A MODIFIED
BLASTULA( DISCOBLASTULA) WITH THE
CELLULAR CAP CALLED A BLASTOCOELE

58. MARSUPIAL & PLACENTAL MAMMALS HAVE
EMBRYOS THAT ARE DEVELOPED WITH
DEPENDENCE ON THE MOTHER.
- EGGS ARE ISOLECITHAL
- CLEAVAGE TAKES PLACE IN THE ZONA
PELLUCIDA & THE BLASTOMERES
ACCOMMODATE THEMSELVES TO THE
SPHEROIDAL CAVITY.
- CLEAVAGE IS TOTAL AND NEARLY
EQUAL/

59. - DIVISION BEGINS IN THE UTERINE TUBE
& COMPLETED IN THE UTERUS
- COMPLETED WITHIN A RANGE OF 70
HRS.(RABBIT) TO 190 HRS. FOR THE
COW.

60. INVOLUTION , ELONGATION &
CONVERGENCE
- CHARACTERIZE GASTRULATION IN ALL
CHORDATES

63. ANIMAL
TYPE
TYPE OF
EGG
CLEA-
VAGE
BLAS-
TULA
BLASTU
-LA
CAVITY
METHO
DS OF
GASTRU
LATION
COMMEN
T ON
GASTRUL
ATION
AMPHIOX
US
ISOLECIT
HAL
(LITTLE
YOLK)
TOTAL;
EQUAL
SPHERE;
WALL A
SINGLE
LAYER
SPHERI-
CAL
RELATIVE
LY
LARGE
INVAGI-
NATION;
INVOLU-
TION VIA
BLASTO-
PORE
EARLY
INNER
LAYER IS
A
COMPO-
SITE
AMPHI-
BIANS
TELOLE-
CITHAL
(MODE-
RATE
YOLK)
TOTAL;
UNEQUA
L
SPHERE;
WALL
LAYERED
;THICK-
NESS
VARIES
SPHERI-
CAL;
RELATIVE
LY
SMALL;
ECCEN-
TRIC
CHIEFLY
IN VOLU-
TION VIA
BLASTO-
PORE
INVOLU-
TED
LAYERS
ARE
SEPARA-
TE FROM
START

64. BIRDS TELOLE-
CITHAL
(MASSIV
E YOLK)
PARTIAL;
DISCOI-
DAL
CELL-
DISC;
BLASTO-
DERM)
LIES ON
MASSIVE
YOLK
SHA-
LLOW;
DELAYE
D UNTIL
ENTO-
DERM
FORMS
DELAMI-
NATION;
INVOLU-
TION
VIA
PRIMI-
TIVE
STREAK
OCCURS
IN TWO
STAGES;
MODI-
FIED
AMPHIBI
AN
STYLE
MAMALS
(EXCEPT
LOWEST)
ISOLECI-
THAL
(LITTLE
YOLK)
TOTAL;
EQUAL
BLASTO-
CYST,
WITH
INNER
CELL
MASS
MERGED
WITH
YOLK-
FREE
BLASTO
CYST
CAVITY
DELAMI
NATION;
INVOLU-
TION
VIA
PRIMI-
TIVE
STREAK
OCCURS
IN TWO
STAGES;
BASICA-
LLY
SIMILAR
TO
BIRDS

66. ECTODERM MESODERM
(INCLUDING
MESENCHYME)
ENTODERM
1. EPIDERMIS,INCLU
DING:
CUTANEOUS
GLANDS HAIR,
NAILS &LENS
2. EPITHELIUM OF:
SENSE ORGANS.
NASAL
CAVITY;SINUSES.
MOUTH ,
INCLUDING:
ORAL GLANDS;
ENAMEL,
1. MUSCLE(ALL
TYPES)
2. CONNECTIVE
TISSUE ;
CARTILAGE;BONE
;NOTOCHORD
3. BLOOD;BONE
ARROW
4. LYMPHOID
TISSUE.
EPITHELIUM OF:
5.BLOOD VESSELS;
LYMPHATICS.
EPITHELIUM OF:
1. PHARYNX,INCLU
DING: ROOT OF
TONGUE ,
AUDITORY TUBE,
ETC. TONSILS;
THYROID
PARATHYROIDS ;
THYMUS
2. LARYNX;
TRACHEA;
LUNGS

67. 3. NERVOUS
TISSUE ,
INCLUDING;
HYPOPHYSIS,
CHROMAFFIN
TISSUE
6. BODY
CAVITIES
7.KIDNEY;
URETER
8.GONADS;
GENITAL
DUCTS
9.SUPRARENAL
10.JOINT
CAVITIES ,
ETC
3.DIGESTIVE
TUBE ,
INCLUDING :
ASSOCIATED
GLANDS
4.BLADDER
5.VAGINA(ALL?),
VESTIBULE.
6.URETHRA ,
INCLUDING:
ASSOCIATED
GLANDS.