anatomy: introduction to embryology
TRANSCRIPT
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Introduction to Embryology Introduction to Embryology &&
Reproductive System Reproductive System
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Human EmbryologyHuman Embryology
The science concerned with origin & development of human being from Zygote (?) to birth (prenatal development)
Stages of Human Development:
1. Prenatal development (before birth)
2. Postnatal development (after birth)
Birth: a dramatic event during development that results in a change in environment.
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TerminologyTerminology
Oocyte (ovum):
The female sex cell (gamete) that develops in ovaries
Sperm:
The male sex cell (gamete) that develops in testes
Gamete:
The germ cell of male or female that have the half number of chromosomes (Haploid, 23)
Fertilization (Conception):
The union of male gamete with female gamete to form a zygote (diploid, 46)
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Dizygotic twins: Non-identical twinsProduced from independent release of 2 oocytes & subsequent fertilization by different sperms.
Monozygotic twins:Identical twinsProduced from the separation of the Zygote within the first week of fertilization (~8 days)
*if the separation happened later than 8 days ??
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Cleavage:Mitotic cell division of the zygote to form blastomeres
Blastomeres:The emberyonic cells formed by cleavage (division) of the zygote
Morula:When 12 or more blastomeres have formed
berry-like shape (L, mulberry)3-4 days after fertilizationwithin uterine tube
Blastocyst:After the morula reaches the uterus uterine fluid passes into the morula forming a fluid-filled cavity
morula becomes = blastocyst
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BlastocystBlastocyst
Early blastocyst:
cavity in center (usually)
Late blastocyst:
blastomeres separated into:
1. Trophoblast:
outer cell layer = placenta
2. Inner cell mass:
a group of blastomeres gathered at periphery
give rise to the embryo = embryoblast
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Implantation:Attachment of the blastocyst to endometrial wall of the uterus
starts 6-7 days after fertilization (end of 1st wek)
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Embryo:The developing human during early stages of prenatal
development (first 2 months)
embryonic period: day 1 end of 8th week
Fetus:The developing human after 8 weeks & until birth
Infant: ? (L, infans)
Neonate: ? (L, newborn)
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Crown-Rump Length (CRL)Crown-Rump Length (CRL)
The measurement of the length of the embryo or fetus from vertex of skull (crown of head) to the rump (buttom of buttock)
“the sitting height”
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Male Reproductive SystemMale Reproductive System
Scrotum & Testes
System of Ducts:Epididymis & Vas deferensejaculatory duct, urethra
Accessory sex glandsSeminal vesiclesProstateBulbourethral glands
Penis
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ScrotumScrotumSupporting sac
Layers:
1. Skin (thin layer)
2. Superficial fascia
3. External spermatic fascia
4. Cremasteric fascia
5. Internal spermatic fascia
Contents:
1. Testes
2. Epididymis
3. Lower end of spermatic cord
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Testes (testicles):
Oval glands where sperms are formed (spermatogenesis)
lf. Testis lies at lower level than Rt. One
Epididymis:
The place where sperms are stored & mature
head, body & tail
Vas (ductus) Deferens:
The tube that carries the sperms from epididymis to ejaculatory duct ( 0.5 m)
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Accessory Sex GlandsAccessory Sex GlandsSeminal Vesicles
Post. to urinary bladder (on each side)
Secrete alkaline (?) viscous fluid containing fructose (?)
60% of S.F.
Prostate glandInf. to urinary bladderSecretes milky fluid containing
proteolytic enzymes (?) 25% of S.F.
Bulbourethral glands(Cowper’s glands)
Inf. To prostateSecrete alkaline fluid & mucus
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The PenisThe Penis
The male reproductive organ
Consists of:
Root body Glans penis
3 cylindrical masses of tissue:
corpus cavernosum (2)
corpus spongiosum (1)
Circumcision?
Surgical removal of extra skin covering the glans (foreskin)
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Female Reproductive SystemFemale Reproductive System
Ovaries
Uterus & Uterine tubes
Vagina
External Genitalia
(Vulva)
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OvariesOvaries
Almond-shaped reproductive glands
On the lat. Walls of the pelvis
Fxn.:
production of Oocytes
secretion of estrogen &
progesterone
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Uterine TubesUterine Tubes
Fallopian tubes, oviducts
uterus lat. ovaries
4 parts:
Infundibulum (funnel-shaped)
Ampulla (site of fertilization)
Isthmus
Uterine part (intramural)
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UterusUterus
The site for prenatal development & growth
8 cm in length & 5-7 cm in width
Consists of:
Fundus
Body
Cervix:
internal os
external os
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Walls of The UterusWalls of The Uterus
Perimetrium:
Thin layer of C.T.
(serosa or adventitia)
Myometrium:
Thick smooth m. layer
Endometrium:
Basal layer
Functional layer:
disintegrates during menstruation
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VaginaVagina
Communicating elastic tube (8cm) between the Vulva & Uterus
Ascends upward & backward (45o)
Fxn.:
1. Excretory passage for
Menstrual fluids
2. Receives the penis during
sexual intercourse
3. Inf. part of the birth canal
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Vulva (Ext. Genitalia)Vulva (Ext. Genitalia)
Composed of 4 parts:1. Labia majora:
folds of skin & fatty layerfxn.?
2. Labia minorafolds of skin surround the vaginal orifice
3. Clitoris:small erectile organat sup. jxn. of minoraglans clitoris equivalent to glans penis in male
4. Vestibule:urethral & vaginal orifices