https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:the-cell-cycle-and-differentiation/x230b3ff252126bb6:fertilization-growth-and-cell-differentiation/v/human-fertilization-and-early-development 2024-05-06T19:22:43.24334365Z Human fertilization and early development Human fertilization and development begins with the race of hundreds of millions of sperm cells to fertilize an egg. The victorious sperm and egg unite, creating a zygote with genetic information from both parents. This single cell replicates, progressing through stages of a morula, blastocyst, embryo, and eventually a fetus. This complex process unfolds over approximately 36 to 42 weeks, resulting in a fully developed human being. Sal Khan video https://cdn.kastatic.org/googleusercontent/bAN5uHRndomqB3GR64jS5rdrrXDFDv629S8Z_r85RZHa5YC04wWWI8LdabLusWfzrhR2eSOX43S43Q-JyBqky-3-gw Human fertilization and early development Human fertilization and development begins with the race of hundreds of millions of sperm cells to fertilize an egg. The victorious sperm and egg unite, creating a zygote with genetic information from both parents. This single cell replicates, progressing through stages of a morula, blastocyst, embryo, and eventually a fetus. This complex process unfolds over approximately 36 to 42 weeks, resulting in a fully developed human being. https://cdn.kastatic.org/ka-youtube-converted/-7WKUNG9v-w.mp4/-7WKUNG9v-w.mp4 479 Sexual reproduction in humans https://www.khanacademy.org/science/health-and-medicine/human-anatomy-and-physiology/reproductive-system-introduction/v/reproductive-cycle-graph-follicular-phase 2023-08-17T23:33:36.770424498Z Reproductive cycle graph - Follicular phase Understand the complex interactions of hormones in the female reproductive cycle. This video explains the ovarian cycle, detailing how FSH, LH, Estrogen, Progesterone, and Inhibin work together to control follicle growth, ovulation, and endometrium changes. Vishal Punwani video https://cdn.kastatic.org/googleusercontent/1R2Rq6VGL9oEc5Cw-VsW6w895n4QFeE4NG-hfKGFl-VD14V9L5-6hqnCSperpIk8Dqf6JIDQ4KChfQDj-gEY93V1 Reproductive cycle graph - Follicular phase Understand the complex interactions of hormones in the female reproductive cycle. This video explains the ovarian cycle, detailing how FSH, LH, Estrogen, Progesterone, and Inhibin work together to control follicle growth, ovulation, and endometrium changes. https://cdn.kastatic.org/ka-youtube-converted/gmKAuceSf-s.mp4/gmKAuceSf-s.mp4 519 Sexual reproduction in humans https://www.khanacademy.org/science/health-and-medicine/human-anatomy-and-physiology/reproductive-system-introduction/v/reproductive-cycle-graph-luteal-phase 2023-08-17T23:33:36.770424498Z Reproductive cycle graph - Luteal phase Explore the luteal phase of the reproductive cycle, where the corpus luteum plays a vital role. Discover how hormones like progesterone prepare the uterus for potential pregnancy and learn what happens when fertilization does or doesn't occur. Vishal Punwani video https://cdn.kastatic.org/googleusercontent/dhyNaPDfSuApXSp0h-gQoEMgA1tM566dMgAuBZbRJJZo_-E98Nwid1OrQeafKtkpQZJoKw3CHfuWGFEbXMc-O2E Reproductive cycle graph - Luteal phase Explore the luteal phase of the reproductive cycle, where the corpus luteum plays a vital role. Discover how hormones like progesterone prepare the uterus for potential pregnancy and learn what happens when fertilization does or doesn't occur. https://cdn.kastatic.org/ka-youtube-converted/uA7Xny276sk.mp4/uA7Xny276sk.mp4 545 Sexual reproduction in humans https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:development-of-organisms-and-continuity-of-life/x2a084a90105205d2:sexual-reproduction-in-humans/v/manifestation-treatment-of-infectious-diseases-ur 2026-04-20T05:52:07.909428702Z Manifestation & treatment of infectious diseases Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Manifestation & treatment of infectious diseases Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/jSmMNDFhCeA.mp4/jSmMNDFhCeA.mp4 587 Sexual reproduction in humans https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:development-of-organisms-and-continuity-of-life/x2a084a90105205d2:sexual-reproduction-in-humans/a/egg-meets-sperm 2025-04-14T22:34:53.782134477Z Egg meets sperm article https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:development-of-organisms-and-continuity-of-life/x2a084a90105205d2:sexual-reproduction-in-humans/a/fertilization-and-implantation 2021-05-17T04:47:33Z Fertilization and implantation Formation of zygote, development of blastocyst, and implantation. article https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:development-of-organisms-and-continuity-of-life/x2a084a90105205d2:sexual-reproduction-in-humans/a/menstrual-cycle-review 2021-05-17T04:47:08Z Menstrual cycle review Phases, timeline, and hormones of menstrual cycle. article https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:the-cell-cycle-and-differentiation/x230b3ff252126bb6:fertilization-growth-and-cell-differentiation/a/fertilization-growth-and-cell-differentiation 2024-06-28T21:00:15.59562973Z Fertilization, growth, and cell differentiation Learn about reproduction, fertilization, human development, and cellular differentiation. article https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:development-of-organisms-and-continuity-of-life/x2a084a90105205d2:sexual-reproduction-in-humans/e/fertilization-and-implantation 2024-08-15T06:51:54.562347673Z Fertilization and implantation Zona pellucida, ootid, sperm, cleavage, zygote, blastomere, morula, blastocyst, trophoblast, inner cell mass, endometrium, implantation. exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:development-of-organisms-and-continuity-of-life/x2a084a90105205d2:sexual-reproduction-in-humans/e/structure-of-ovum-and-corpus-luteum 2025-11-30T11:20:42.704566488Z Structure of ovum and corpus luteum This exercise covers the ovarian cycle, showing how follicles mature into Graafian follicles, ovulate, and form the corpus luteum. Students learn how the ovum pauses at metaphase II, how the corpus luteum secretes progesterone, and how its regression triggers a new cycle. The sequence highlights structural changes and hormone dynamics that regulate reproduction. Khan Academy exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:development-of-organisms-and-continuity-of-life/x2a084a90105205d2:sexual-reproduction-in-humans/e/structure-and-properties-of-sperm 2026-04-21T09:50:34.424034119Z Structure and properties of sperm Structure, function of acrosome, midsection, tail of sperm cells, composition of semen and requirements for fertility. exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:development-of-organisms-and-continuity-of-life/x2a084a90105205d2:sexual-reproduction-in-humans/e/menstrual-cycle-events 2024-08-15T06:51:54.562347673Z Menstrual cycle events Menstrual phase, follicular and proliferative phase, secretory or luteal phase, ovulation, graafian follicle, endometrium exercise