Gamete Formation Male Haploid gametes produced by meiosis are called spermatozoa Spermatogenesis begins at puberty and continues throughout one’s life Under hormone and environmental control Female Haploid gamete produced by meiosis is called an oocyte Cell divisions at the end of meiosis one and two are uneven so one cell gets most of the cytoplasm (the EGG) and the other three are called polar bodies (don’t participate in reproduction) IMPORTANT! Female gametes are stuck in Prophase 1 until puberty Complete Meiosis 1 every month and the secondary is released from ovary Female gametes only reach and complete meiosis 2 if they are fertilized

Mitosis vs. Meiosis Mitosis Meiosis Results in the production of two genetically identical DIPLOID cells Daughter cells have sets of chromosomes identical to each other and to parent cell MITOSIS allows body to grow and replace other cells Asexual reproduction Meiosis Results in four genetically different HAPLOID cells MEIOSIS is how sexually reproducing organisms make gametes

Embryology and Reproduction

Embryology Zygote Blastula Gastrula Zygote formation Cleavage 4 cells Morula Blastocyst Embryology Zygote When male gamete fertilizes female gamete Gametes fuse, making one new cell with chromosomes from both parents 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) Differentiation begins…

Stages of Embryo Development Male gamete fertilizes female gamete Formation of Zygote Zygote cells divide into… Morula Dense ball of 64 cells Blastula/blastocyst Hollow ball made up of a single layer of cells Implants onto the female organ called the UTERUS Gastrula When 3 germ layers begin to differentiate Fetus Organogenesis has occurred

Stages of Early Development Implantation When blastocyst secretes enzymes that digest the soft tissue of the ENDOMETRIUM, the lining of the uterus and implants on the uterine wall of the mother After implantation, DIFFERENTIATION can occur 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 Neuralation Development of the nervous system Mesoderm tissue develops into the NOTOCHORD which becomes SPINAL CORD with an enlarged end that eventually becomes the BRAIN

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

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 Inner layer Forms digestive system and lungs

Stages of Fetal Development 1st trimester 0-3 months 2nd trimester 3-6 months 3rd Trimester 6-9 months Implantation on uterus wall Gastrula forms Organogenesis occurs Body structures become distinguishable Embryo is now called a FETUS Fetus is very active (feel movement) Fetus increases in size Heart beat can be heard Fully developed eyes Lungs begin to develop Lungs become fully developed Central Nervous System Develops Brain is actively growing the most Fetus can begin to regulate body temperature (maintain homeostasis) Layer of hair forms on head

Important Glands that Regulate The Release of Gametes Female Male Pituitary gland and the testes regulate the release of hormones that stimulate the production of TESTOSTERONE Pituitary gland and the ovary regulate the release of hormones that stimulates the production of ESTROGEN The hormones that regulate both male and female gamete formation are: LH- luteinizing hormone FSH- follicle stimulating hormone

Reproduction Part 2

Things to know about the Reproductive Systems Male Female Function and location of: Testes Seminal Vesicle Prostate gland Vas Deferenes Urethra Epididymis Function and location of: Ovaries Oviduct Uterus Cervix

Seminal Fluid + Sperm = Semen 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 Deferenes 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 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) Seminal Fluid + Sperm = Semen

Path of Male Gametes Testes contain seminiferous tubules (gametes produced) Epididymis (gametes Mature and are STORED) Vas deferens (gametes travel) Urethra (gametes travel) Out of the body

Female Reproductive System Ovaries (produce, store and release EGGS) Female gonads that produce ova (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 Site of attachment of the fertilized egg (implantation) Provided nourishment to embryo End of uterus is the opening called the CERVIX Cervix Opens up to canal (VAGINA) that carries unfertilized oocyte OR completely developed FETUS out of the body

The End