Beginnings, Growth and Development - Practical 3We will study human development over a series of 3 practical classes spanning the overall human prenatal developmental timecourse. There will be an additional class covering the extramebryonic tissues formed from the conceptus (the embryonic membranes and placenta).
Practical 3 - Fertilization to Implantation |
Practical 6 - Implantation to 8 Weeks |
Practical 11 - Fetal Period |
Practical 8 - Placenta and Fetal Membranes |
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Aim: This laboratory is an introduction to the earliest event in development, from fertilization of the ovum (egg) by sperm through to implantation.
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Unfertilized Human Egg |
Spermatazoa |
Fertilized Human Egg |
Key Concepts: Gonad, gametogenesis, ovary, testes, menstral cycle, oocyte development (oogenesis), sperm development (spermatogenesis), sperm morphology/motility, meiosis/mitosis, follicle, ovulation, zona pellucida, polar bodies, hormonal changes, mechanism of fertilization, post-fertilization changes, corpus luteum, zygote, morula, blastocyst, zona pellucida, embryoblast, trophoblast, ectopic implantation, abnormalities.
Key Reading:
Human Embryology, WJ. Larsen Chapter 1, 2, 3
The Developing Human: Clinically Oriented Embryology. Moore & Persaud Chapter 1, 2
| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
blastocyst - (Greek, blastos = sprout + cystos = cavity) Term used to describe the hollow cellular mass taht forms in early development. In humans, this stage occurs in the first and second weeks after the zygote forms a solid cellular mass (morula stage) and before implantation. The blastocyst consists of cells forming an outer trophoblast layer, an inner cell mass (embryoblast) and a fluid-filled cavity. The blastocyst inner cell mass is the source of true embryonic stem cells capable of forming all cell types within the embryo. (More? Week 1 - Blastocyst | Week 2 Notes | Stem Cell Notes)
egg - (oocyte or ovum) An alternative term used to describe the haploid female reproductive cell (germ cell). The term is also used to describe the avian and reptilian shell enclosed structure. (More? Week 1 Notes)
fertilization - (fertilisation) The process of penetration of the oocyte (egg) by the spermatozoa and the combining of their genetic material that initiates development of the embryo. The union of two haploid gametes to form a diploid cell or zygote. (More? Fertilization)
follicle - (Latin, folliculus = little bag, dim. of Latin follis) The functional unit within the ovary that includes the developing oocyte (egg) and the surrounding layers of cells that support that oocyte. Some cells within the follicle are released along with the ooctye at ovulation, while other cells are involved with female sex hormone secretion into the maternal bloodstream. (More? Week 1 - Oogenesis | Human Menstrual Cycle | Genital System - Female)
folliculogenesis - The term used to describe the process of follicle development within the ovary. The follicle is the structure developing within the ovary that includes the oocyte (egg) and surrounding support cells. (More? Week 1 - Oogenesis | Human Menstrual Cycle)
gonad - (Greek, gonos = seed) A gamete-producing (germ cell) organ. A non-sexual term which is used to describe both the female ovary and male testis. (More? Week 1 Notes)
hCG - An acronym for the hormone human Chorionic Gonadotrophin.
human chorionic gonadotrophin - (hCG) Placental hormone initially secreted by cells (syncitiotrophoblasts) from the implanting conceptus during week two, supporting the ovarian corpus luteum, which in turn supports the endometrial lining and therefore maintains pregnancy. Hormone can be detected in maternal blood and urine and is teh basis of many pregnancy tests. Hormone also stimulates the onset of fetal gonadal steroidogenesis, high levels are teratogenic to fetal gonadal tissues. (More? Placenta Notes | Week 2 Notes)
implantation - The term used to describe process of attachment and invasion of the uterus endometrium by the blastocyst (conceptus). Abnormal implantation is where this process does not occur in the body of the uterus (ectopic) or where the placenta forms incorrectly. (More? Week 2 - Implantation | Week 2 Abnormalities)
last menstrual period - (LMP) Clinical term used to describe the menstrual period that occurs before a pregnancy and is used as the date to calculate clinical pregnancy development (gestational age). Note that in humans this is approximately two weeks different from embryonic development, which begins at fertilization around the mid-point of the menstrual cycle.
menstrual cycle - The human reproductive cycle, an endocrine regulated change in female anatomy and physiology that occur over 28 days (4 weeks, a lunar month) during reproductive life (between puberty and menopause). This cycle ceases during pregnancy and differs from other non-primate vertebrates (eg rats, mice, horses, pig) females that have a reproductive cycle called the estrous cycle (oestrous, British spelling). (More? Human Menstrual Cycle | Estrous Cycle)
oocyte - (Greek, oo = egg) term used to describe the egg or ovum formed within the ovary (female gonad). The mature oocyte is the cell released from the ovary during ovulation. (More? Week 1 - Oogenesis | Genital System - Female)
ovulation - The term used to describe the process of the mature follicle releasing the oocyte or ovum (and support cells) from the ovary surface into the peritoneal cavity. In humans, generally a single oocyte is released from a cohort of several maturing follicles. More than one follicle may be released (superovulation) following reproductive therapeutic treatment. (More? Week 1 - Oogenesis | Week 1 Notes)
pronuclear fusion - (Greek, pro = before) The process of the fusion of the two haploid nuclear structures (pronuclei) contributed from the spermatazoa and oocyte to form the first diploid nucleus cell. Can also be called fusion of pronuclei.
pronucleus (Greek, pro = before) The two haploid nuclear structures from spermatazoa and oocyte that will fuse together to form the first diploid nucleus cell. Therefore the nuclear structures that exist "before the nucleus", the plural term is pronuclei. (More? Week 1 Notes)
spermatogenesis - (Greek, genesis = origin, creation, generation) The term used to describe the process of diploid spermatagonia division and differentiation to form haploid spermatazoa within the testis (male gonad). The process includes the following cellular changes: meiosis, reoorganization of DNA, reduction in DNA content, reorganization of cellular organelles, morphological changes (cell shape). The final process of change in cell shape is also called spermiogenesis. (More? Week 1 - Spermatogenesis)
uterus - The female internal genital (reproductive) tract forming a hollow muscular walled organ, embryonically derived from the paramesonephric ducts. The human uterus has two uterine horns (fallopian tubes) where the first week of development occurs and a single hollow body where implantation of the blastocyst normally occurs. Following puberty, the non-pregnant uterus (epithelium and underlying stroma) undergoes cyclic changes under the influence of hormones, the menstrual cycle. This cycle of uterine changes ceases during pregnancy and it contributes the maternal component of the placenta. (More? Genital System - Female Uterus | Human Menstrual Cycle | Genital Notes)
More Genes note - a few genes are also located in each cell outside the nucleus, in mitochondria (mitochondrial DNA) which are involved in cellular respiration. These mitochondrial genes are always inherited from your mother (the egg) not your father (sperm).
Movie of Human Embryo Growth (this shows a human embryo growing, all images are to scale)
Movie of Mouse Embryo Growth (this shows a mouse embryo growing)
Welcome to your first Practical class in BGD Embryology with me in the new medical curriculum!
You already have had an Introduction to Human Development in Foundations, we will now explore development in more depth through a series of lectures and Practical classes.
We begin with the generation of gametes (egg and sperm) in gonads (ovary and testes), their coming together in the complex act of ferilization and the formation of the first cell, the zygote and it development in the first 2 weeks including the process of implantation.
Of all the steps we take in life, this combination of parental genomes specifies and sets much of what we will become and how our health outcomes will develop through our lives. Think about what these genetic setting mean and what other developmental consequences will eventually impact on patient health.
More recently the impact of birth control, in vitro fertilization techniques, "stem cell" research, ethical and legal issues, and social changes in reproductive decisions has focussed public attention on this critical biological event.
This class is going to take you through the earliest steps in human development using linked online resources you will use in the actual class.
The lefthand side menu has links to all pages (in sequence) required for this Lab, alternatively follow the white rabbit.... Also at the bottom of the same menu is a window to Search UNSW Embryology using any term/concept you do not understand. (note the search window uses Google, so will only work with an active internet connection.
If you are interested in a more detailed coverage, look at the Early Development 1 and Early Development 2 sections of Notes (from the lefthand menu).
These notes and linked materials have been prepared for Educational purposes only.
Please email Dr Mark Hill if you wish to make a comment about this current project.
Home Page
Embryo stages
Fetal Dev
Dev Notes 1
Dev Notes 2
System Notes
Acknowledgements
Introduction >
Ovary
Gametes
Fertilization
Week 1 Summary
Week 1 Summary
Early Division
Implantation
Week 2 Summary
Extraembryonic Spaces
Gastrulation
Notochord
Week 3 Summary
Medicine
Histology
References
Lecture 5
Lecture 6
Practical 3
Practical 4
Practical 11
Dev Notes 1
Menstrual Cycle
Week 1
Week 2
Week 3
Placenta
Embryo stages
Movies
Audio
News
Class Notes
Serial Images
K12 Students
Abnormal
Animal Embryos
Site Updates
Molecular
Histology
Statistics
History
Glossary
References
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School of Med Sci
UNSW Medicine
University of NSW
UNSW Cell Biology
NCBI Books
Dev Biol (Gilbert)
