Copulation, Fertilization and Development

Biology 2122

Male Sexual Response (1) Erection – Parasympathetic reflex

• Affects arterioles

– Nitric oxide and smooth muscle

(2) Ejaculation – Sympathetic control – L1 and L2

Fertilization(1) Sperm – making it into the fallopian tube – Capacitation

(2) Penetration and Acrosomal Response – Corona Radiata – Hyaluronidase – Zona Pellucida and ZP3

Glycoprotein – Acrosomal reaction – Acrosomal process

Polyspermy (1) Monospermy – Cortical reaction – ZIP’s – Slow Block

(2) Completion of Meiosis II

– Formation of Male Pronucleus

– Female Pronucleus

(3) Fertilization – Formation of the Zygote

Embryonic Development – Cleavage and Blastocyst Formation

(1) Cleavage – Blastomeres (2-cell stage) – Morula – Days 3-4 (100 cells or

more)

(2) Blastocyst – Trophoblast cells – Inner cell mass – Emybryonic disc

Implantation (1) 6-7 days

– “Window of Implantation”

(2) Endometrial cell preparation

– Integrin binding

(3) Trophoblast cells– Digestive enzymes and

growth factors

– Endometrial thickening

(4) Trophoblast development – Cytotrophoblast

– Syncytiotrophoblast

– hCG

Placentation (1) Placenta – Inner cell mass – Chorion and Chorionic Villi – Intervillius spaces– Decidua basalis – Decidua capsularis

(2) Decidua– Birth

Placentation

Placentation

Gastrula Formation

(1) Gastrula – Germ layer formation

(2) Embyronic disc – Inner cell mass

– Epiblast and hypoblast

(3) Extraembryonic Membranes– Amnion

– Yolk sac

– Allantios

– Umbillical cord

Formation of Primary Germ Layers

Differentation of Germ Layers – Organogenesis (1) Primary Germ Layers

– Endoderm– Mesoderm – Ecoderm

(2) Differentation of Germ Layers

– Ectoderm • Brain and spinal cord

– Mesoderm • Somites• Sclerotome; dermatome and

myotome • Somatic mesoderm • Splanchnic mesoderm

– Endoderm • Primitive Gut

Ectoderm Tissue Area Tissue Formed

(1). Neural All nervous tissue!

(2). Skin Epidermis, hairs, follicles, sweat and oil glands

(3). Eye Cornea and lens

(4). Teeth Enamel

(5). Glands Epithelium of pineal, pituitary and adrenal

(6). Skin color Melanocytes

(7). Bones Some cranial bones

(8). Nasal Cavity Epithelium of nasal cavity, paranasal sinues

(9). Digestive Epithelium of anal canal

Endoderm Tissue FormationArea Tissue Formed

(1). GI Tract Epithelium of all except for oral and anal areas

(2). Digestive Tract Accessory glands (pancreas and liver)

(3). Respiratory Tract All Epithelium of respiratory tract and auditory tube; also of tonsils

(4). Glands Thyroid, parathyroid and thymus

(5). Reproductive All epithelium of reproductive ducts and glands

(6). Urinary All epithelium of urethra and bladder

Endoderm Differentiation

Figure 28.11

Somites - Mesoderm

Type Description

(1). Sclerotome Produce vertebra and rib

(2). Dermatome Outer wall of somites; form dermis of skin in dorsal area of the body

(3). Myotome Skeletal muscles of the neck, body trunk and limbs (via limb buds)

*Intermediate Mesoderm

Gonads and kidneys

**Lateral Mesoderm

(a). Somatic Mesoderm

Dermis of skin – ventral; parietal serosa – ventral body cavity; bones ligaments and dermis of limbs

(b). Splanchnic Mesoderm

Heart , blood vessels and most connective tissue

Mesoderm Tissues Area Tissue

(1). Muscle All types (skeletal, smooth and cardiac)

(2). Bone All cartilage, bone and connective tissues

(3). Blood All parts, bone marrow and lymph tissue

(4). Epithelium Endothelium of BVs, lymph vessels

(5). Eye Fibrous and vascular tunics

(6). Joints Synovial membranes of cavities

(7). Organs Ureters, kidneys, gonads, reproductive ducts of male and female

Fetal Development and Labor (1) Know events in table 28.1 ! (2) Labor

– Hormonal activation – Braxton Hicks contractions – Oxytocin and Prostaglandins

(3) Stages of Labor – Dilation

• 10 cm • 6-12 hours average

– Expulsion • Crowning

– Placental Stage

Effects of Pregnancy (1) Anatomical Changes – Lordosis

– Weight Gain

(2) Metabolic Changes – hPL and hCS

– hCT

(3) Physiological Changes– GI

– Urinary

– Respiratory

– Cardiovascular

Sexual Differentation (1) Gonadal Ridges- Sexually Indifferent Stage – Mullerian ducts – Wolffian ducts

(2) Primordial Germ Cells– Seeding stem cells

(3) Week 7 and 8 – Seminiferous tubule formation – Female process – week 8

(4) External Genitalia – Genital tubercle

Structures • General Tubercle --------- Penis and Clitorus

• Urethral folds ------- spongy urethra (penis) – fused

• Unfused Urethral folds ------------ labia minora; unfused labioscrotal folds -------- labia majora

• Labioscrotal swellings fuse ----------- scrotum

• Gonadal Ridges ---------- Testes and ovaries

• Formation of accessory structures and external genitalia depends on presence or absence of testosterone – Formation of testes ---------- testosterone