Embryology and reproduction
- 2. Embryology Zygote formation Cleavage 4 cells • Zygote – When male gamete fertilizes female gamete Morula – Gametes fuse, making one new cell with chromosomes from both parents Blastocyst – Zygote will divide into 2 new cells…each of those into 4 and so on… – Cleavage division of embryonic cells to form two new cells • Genetic material is copied before each cleavage • Blastula – Hollow ball of cells • Gastrula – When blastula implants itself on the uterine wall (to get nourishment from mother) – Ball of cells composed of three layers “GERM LAYERS” (undifferentiated)
- 3. Stages of Embryo 1. Development Male gamete fertilizes female gamete 2. Formation of Zygote – Zygote cells divide into… 3. Morula – Dense ball of 64 cells 4. Blastula/blastocyst – Hollow ball made up of a single layer of cells – Implants in the uterus 5. Gastrula – When 3 germ layers begin to differentiate
- 4. Stages of Early 1. Development Implantation – When blastocyst secretes enzymes that digest the soft tissue of the uterus and implants on the uterine wall of the mother – After implantation, DIFFERENTIAT ION can occur 2. Gastrulation – When the 3 germ layers form in the embryo – Cells in blastocyst begin to differentiate into 3 germ layers – Blastocyst now becomes a GASTRULA 3. Neuralation
- 6. Gastrula • Germ layers – Differentiation the process by which a cell develops in different ways to perform different functions…begins with the forming of three germ layers – Ectoderm • Outer layer • Forms skin, nerves and sense organs – Mesoderm • Middle layer • Forms bones, muscles and connective tissue – Endoderm
- 7. Embryo becomes a Fetus when… • When the structures of the developing embryo have become distinguished • Cells have differentiated into their permanent role in that organism • This occurs during first trimester
- 11. Stages of Fetal 1st trimester 0-3 months Development Trimester 6-9 months nd 2 trimester 3-6 months 3 rd •Implantation on uterus wall •Fetus is very active (feel •Lungs become fully •Gastrula forms movement) developed •Organogenesis occurs •Fetus increases in size •Central Nervous System •Body structures become •Heart beat can be heard Develops distinguishable •Fully developed eyes •Brain is actively growing the •Embryo is now called a FETUS •Lungs begin to develop most •Fetus can begin to regulate body temperature (maintain homeostasis) •Layer of hair forms on head
- 12. Important Glands that Regulate The Release of Gametes Male Female • Pituitary gland • Pituitary gland and the testes and the ovary regulate the regulate the release of release of hormones that hormones that stimulate the stimulates the The hormones that regulate both male and production of production of female gamete formation are: TESTOSTERONE hormone ESTROGEN 1. LH- luteinizing 2. FSH- follicle stimulating hormone
- 15. Things to know about the Reproductive Systems Male Female • Function and • Function and location of: location of: – Testes – Ovaries – Seminal Vesicle – Oviduct – Prostate – Uterus gland – Cervix – Vas Defernes – Urethra – Epididymis
- 16. •Testes •Organs that produce and store millions of male gametes(spermatocytes) after puberty, when testosterone is produced •Contain hundreds of tiny coiled tubes called SEMINIFEROUS TUBULES ( production of gametes) •Epididymis •Structure that sits on top of testes •Spermatocytes produced in SEMINIFEROUS TUBULES leave and travel here to MATURE •Vas Defernes •Mature spermatocytes leave EPIDIDYMIS and move into these tubes that extend upward from the scrotum to the abdomen •These tubes eventually merge with the URETHRA •Seminal Vesicle and Prostate Glands •GLANDS that line the reproductive tract •Glands that produce liquid (seminal fluid) that carries male gametes out of the body •seminal fluid-nutrient rich fluid that nourishes and protects male gametes from the acidity of the female reproductive tract Seminal Fluid + Sperm = Semen •Seminal Vesicles are attached to the Vas Deferns, the tube that the spermatocytes travel through •Urethra •Tube that carries MATURE gametes out of the body through the penis (always responsible for carrying urine out of the body)
- 19. Path of Male Gametes • Testes contain seminiferous tubules (gametes produced) • Epididymis (gametes Mature) • Vas deferens (gametes travel) • Urethra (gametes travel) • Out of the body
- 20. • Reproductive Ovaries (produce, store and release EGGS) System ova • Female gonads that produce (oocytes)and estrogen • Contains about 400,000 primary oocytes, contained in protective cluster of cells called FOLLICLES • Only 400 eggs will be released • Every 28 days one follicle moves to edge of ovary, follicle breaks open and egg is released into oviduct (FT) • Oviduct/Fallopian Tube (FT) • Where fertilization occurs if male gamete is here • Cilia move egg along • Development of embryo (morula and blastula occur) • Dumps egg into cavity called UTERUS • Uterus • Lining of uterus received fertilized egg (implantation) • Provided nourishment to embryo