ANATOMY: Introduction to Embryology
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Transcript of ANATOMY: Introduction to Embryology
Introduction to Embryology Introduction to Embryology &&
Reproductive System Reproductive System
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.
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)
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 ??
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
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
Implantation:Attachment of the blastocyst to endometrial wall of the uterus
starts 6-7 days after fertilization (end of 1st wek)
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)
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”
Male Reproductive SystemMale Reproductive System
Scrotum & Testes
System of Ducts:Epididymis & Vas deferensejaculatory duct, urethra
Accessory sex glandsSeminal vesiclesProstateBulbourethral glands
Penis
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
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)
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
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)
Female Reproductive SystemFemale Reproductive System
Ovaries
Uterus & Uterine tubes
Vagina
External Genitalia
(Vulva)
OvariesOvaries
Almond-shaped reproductive glands
On the lat. Walls of the pelvis
Fxn.:
production of Oocytes
secretion of estrogen &
progesterone
Uterine TubesUterine Tubes
Fallopian tubes, oviducts
uterus lat. ovaries
4 parts:
Infundibulum (funnel-shaped)
Ampulla (site of fertilization)
Isthmus
Uterine part (intramural)
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
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
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
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