1st Week of embryonic development (incl intro to male/female genital tract)

Male genital tract: Primary sex organ (Number, site, function & structure)

Testis

Number: 2 (paired)

Site: Inside scrotum

Function: Make sperm (germ cell) , Make testosterone (sex hormone)

Structure:

• Seminefrous tubules - Site of sperm production

• Leydig cells (interstitial cells) - Secrete testosterone

• Sertoli cells - support spermatogenesis, forms blood-testis barrier

• Tunica albuginea - fibrous capsule covering testis

Male genital organs: 2ry sex organs (where sperm pass to exit male) & External genital organs

2ry sex organs

Epipididymis (Storage , Maturation)

Vas deferens (transport)

Ejaculatory duct (release sperm)

Urethra

Accessory glands = seminal vesicles, prostate & ,bulbourethral glands (release for mucus before ejaculation)

External genital organs

Penis and Scrotum (No fat, smooth muscle, controls testes)

 

Female genital tract: Primary sex organs (Number, site , function & structure)

Ovaries

Number: 2 (paired)

Site: Within pelvic cavity attached to uterus by ovarian, broad and suspensory ligaments

Function: Produces Oocytes (germ cell) , Secretes Estrogen,Progesterone

Structure:

• Outer cortex contains ovarian follicles at various stages

• Inner medulla - loose connective tissue with blood vessels, nerves and lymphatic

• Germinal epithelium - Simple cuboidal layer covering ovary

• Corpus lutem - temporary endocrine struct formed after ovulation that secretes progesterone

• Corpus albicans - Fibrous scar from a degenerated corpus luteum

Female genital organs: 2ry organs ( site, length/shape , parts , struct & function) & external genital organs

(Vagina just function and definition)

2ry organs

1.     Uterine tubes

·       Site: Free board of broad ligament

·       Length: 10-12 cm

·       Parts: Intramural, Isthmus(narrowest) ampulla (widest) infundibulum

·       Function: Transport of oocyte/zygote to uterus and Site of fertilization (ampulla).

2. Uterus

·       Site: In pelvic cavity anterior to rectum and posterior to urinary bladder

·       Shape: Pear shaped (Anteflexed & anteverted / retroverted & retroflexed)

·    Parts: Fundus, Body, Cervix

·    Structure: Endometrium,Myometrium,Perimetrium

·   Function: Fetus Implantation an development . Menstrual cycle and labour.

3. Vagina

• Fibromuscular canal from cervix to vestibule.

• Function: Copulatory organ, Birth canal.Menstrual flow passage.

External genital organs = Labia majora, Labia minora, and hymen

Sperm parts

Head

Nucleus (Haploid 23) (incl sex chromosome)

Acrosome ( in Golgi complex is a source of enzyme)

Neck (has proximal centriole)

Tail

Middle piece: Has mitochondria (sheet motility energy)

Principal piece: Flagella + axial filament Contains the axoneme (9+2 microtubule arrangement) + fibrous sheath – provides whip‑like movement.

End piece: flagella end (Motility)

Ovum (Parts + layers outside to in)

Ovum (2ry Oocyte) : Released during ovulation and 2ry Oocyte arrest in 2nd meiosis until fertilisation

(Sperm pierce / Outside → Inside)

1. Corno radiata

2. Zona pellucida (glycoprotein layer)

3. Oolemma (plasma membrane)

4. Cytoplasm

5. Nucleus (fertilization)

What happens in the first week of embryonic development

1. Fertilization

2. Cleavage

Fertilisation (Definition , Site , Process)

Def: Union of sperm (23) + Ovum (23) to form zygote

Site: Ampulla (Biggest uterine tube)

Process:

1. Deposit sperms ( 200-600 mill)

2. Transport sperm (200-300 reach rest die) ( strong uterine contraction/peristalsis suck up sperms and sperm moves up by tail)

3. Capacitation of sperm

4. Penetration phases (incl Acrosome reaction)

Capacitation (Def,Site, Duration . Mech, If sperm direct on cell?)

Capacitation

Definition: Sperm can penetrate/fertilize ovum

Site: Female genital tract

Duration: 7hrs

Mechanism: Loss of glycoprotein in cell wall so acrosome can pierce corona radiata

If sperm direct on ovum wont fertilise and why?: Not capacitated in male (cant penetrate ovum

Penetration phases (incl definition of acrosome reaction)

Acrosome reaction: Acrosome release Hyalurindase (digestive enzyme) and acrosin (digests zona pellucida) to penetrate Ovum

1. Penetration of corona radiata by hyalurindas (Acrosomal reaction)

2. Penetration of zona pellucida by zona lysine (Acrosomal reaction)

3. Fusion of sperm and oocyte plasma membrane

4. Zona cortical reaction to prevent other sperms (prevents Acrosin/ Neuramide enzyme)

5. oocyte completes 2nd meiotic division

6. Formation of male pronucleus

7. union of male and female pronuclei

Result of fertillization and abnormalities

Results:

1. Restoration of diploid number of chromosome

2. Sex determination of embryo

3. Determined state of health/disease of embryo (& genetic division)

4. Oocyte completes 2nd meiotic division

5. Zygote starts division cleavage

Abnormalities

Parthogenesis = Division without sperm fertilisation

Dispermy (Triploidy) = 2 sperm + 1 ovum → 69 chromosome (Hydatidiform mole)

Cleavage (Definition, Site, Time)

Definition: Repeated mitosis of zygote →